[Federal Register Volume 79, Number 192 (Friday, October 3, 2014)]
[Rules and Regulations]
[Pages 59992-60038]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2014-23640]



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Vol. 79

Friday,

No. 192

October 3, 2014

Part V





Department of the Interior





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Fish and Wildlife Service





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50 CFR Part 17





Endangered and Threatened Wildlife and Plants; Determination of 
Threatened Status for the Western Distinct Population Segment of the 
Yellow-billed Cuckoo (Coccyzus americanus); Final Rule

  Federal Register / Vol. 79 , No. 192 / Friday, October 3, 2014 / 
Rules and Regulations  

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R8- ES-2013-0104; 4500030113]
RIN 1018-AY53


Endangered and Threatened Wildlife and Plants; Determination of 
Threatened Status for the Western Distinct Population Segment of the 
Yellow-billed Cuckoo (Coccyzus americanus)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine 
threatened status under the Endangered Species Act of 1973 (Act), as 
amended, for the western distinct population segment (DPS) of the 
yellow-billed cuckoo (Coccyzus americanus), a species located from the 
western portions of the United States, Canada, and Mexico. This final 
rule implements the Federal protections provided by the Act for this 
DPS.

DATES: This rule is effective November 3, 2014.

ADDRESSES: This final rule is available on the Internet at http://www.regulations.gov and at the Sacramento Fish and Wildlife Office at 
http://www.fws.gov/sacramento/. Comments and materials received, as 
well as supporting documentation used in the preparation of this rule, 
will be available for public inspection, by appointment, during normal 
business hours at: U.S. Fish and Wildlife Service, Sacramento Fish and 
Wildlife Office, 2800 Cottage Way, Room W-2605, Sacramento, CA 95825; 
by telephone 916-414- 6600; or by facsimile 916- 414-6712.

FOR FURTHER INFORMATION CONTACT: Jennifer Norris, Field Supervisor, 
Sacramento Fish and Wildlife Office (see ADDRESSES). If you use a 
telecommunications device for the deaf (TDD), call the Federal 
Information Relay Service (FIRS) at 800- 877-8339.

SUPPLEMENTARY INFORMATION: 

Executive Summary

    Why we need to publish a rule. Under the Endangered Species Act, a 
species may warrant protection through listing if it is endangered or 
threatened throughout all or a significant portion of its range. 
Listing a species as an endangered or threatened species can only be 
completed by issuing a rule. On October 3, 2013, we published in the 
Federal Register a proposed rule (78 FR 61621) to list the western DPS 
of the yellow-billed cuckoo (hereafter referred to as western yellow-
billed cuckoo). This rule finalizes our determination for listing the 
western yellow-billed cuckoo.
    The basis for our action. Under the Endangered Species Act, we can 
determine that a species is an endangered or threatened species based 
on any of five factors: (A) The present or threatened destruction, 
modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) the inadequacy of 
existing regulatory mechanisms; or (E) other natural or manmade factors 
affecting its continued existence.
    We have determined that the western yellow-billed cuckoo meets the 
definition of a threatened species and is likely to become endangered 
throughout its range within the foreseeable future, based on the 
immediacy, severity, and scope of the threats to its continued 
existence. These include habitat loss associated with manmade features 
that alter watercourse hydrology so that the natural processes that 
sustained riparian habitat in western North America are greatly 
diminished. Loss and degradation of habitat has also occurred as a 
result of livestock overgrazing and encroachment from agriculture. 
These losses are exacerbated by the conversion of native habitat to 
predominantly nonnative vegetation. Habitat loss results in the 
additional effects associated with small and widely separated habitat 
patches such as increased predation and reduced dispersal potential. 
This threat is particularly persistent where small habitat patches are 
in proximity to human-altered landscapes, especially agricultural 
fields, resulting in the potential for pesticides to poison individual 
western yellow-billed cuckoos and reduce their prey base.
    What the rule does. We are making a final listing determination 
regarding the western distinct population segment of the U.S. 
population of the yellow-billed cuckoo pursuant to the Endangered 
Species Act. This species occurs in the western United States, Canada, 
and Mexico. The western U.S. States include Washington, Idaho, Montana, 
Oregon, California, Nevada, Wyoming, Utah, Colorado, Arizona, New 
Mexico, and Texas. This document adds the western DPS of the yellow-
billed cuckoo (Coccyzus americanus) as a threatened species to the List 
of Endangered and Threatened Wildlife (50 CFR 17.11(h)).
    Peer review and public comment. We sought comments from independent 
specialists to ensure that our determination is based on scientifically 
sound data, assumptions, and analyses. We invited these peer reviewers 
to comment on our listing proposal. We also considered all other 
comments and information we received during the three open comment 
periods. We have considered and incorporated any pertinent information 
from all comments and information we received into this final rule. See 
the Summary of Comments and Recommendations section, below, for a 
summary of comments we received on the proposed listing.

Previous Federal Actions

    On October 3, 2013, the proposed rule to list the western yellow-
billed cuckoo as a threatened species under section 4 of the Act (16 
U.S.C. 1531 et seq.) was published in the Federal Register (78 FR 
61621). This rule finalizes the Federal action for this species. For 
additional information on previous Federal actions for the western 
yellow-billed cuckoo, please see the 12-month petition finding (66 FR 
38611; July 25, 2001) and proposed listing rule (78 FR 61621; October 
3, 2013).
    We proposed critical habitat for the western DPS of the yellow-
billed cuckoo on August 15, 2014 (79 FR 48547).

Background

    In this section of the final rule, it is our intent to discuss only 
those topics directly relevant to the listing of the western yellow-
billed cuckoo as a threatened species. Please refer to the proposed 
listing rule for the western yellow-billed cuckoo for detailed 
background and species information (78 FR 61621; October 3, 2013).

Species Information

    The yellow-billed cuckoo (Coccyzus americanus) is a member of the 
avian family Cuculidae and is a Neotropical migrant bird that winters 
in South America and breeds in North America. Yellow-billed cuckoos 
spend the winter in South America, east of the Andes, primarily south 
of the Amazon Basin in southern Brazil, Paraguay, Uruguay, eastern 
Bolivia, and northern Argentina (Ehrlich et al. 1992, pp. 129-130; 
American Ornithologists' Union (AOU) 1998, p. 247; Johnson et al. 
2008b, pp. 18-29). The breeding range of the entire species formerly 
included most of North America from southeastern and western Canada 
(southern Ontario, Quebec, and southwestern British Columbia) south 
throughout the continental United States to the Greater Antilles and

[[Page 59993]]

northern Mexico (AOU 1957, pp. 269-270; AOU 1983, p. 284; AOU 1998, p. 
247). Currently, the species no longer breeds in western Canada and the 
northwestern continental United States (Washington, Oregon, and 
Montana).
    Adult yellow-billed cuckoos have a fairly stout and slightly down-
curved bill; a slender, elongated body with a long-tailed look; and a 
narrow yellow ring of colored, bare skin around the eye. The plumage is 
loose and grayish-brown above and white below, with reddish primary 
flight feathers. The tail feathers are boldly patterned with black and 
white below. They are a medium-sized bird about 12 inches (in) (30 
centimeters (cm)) in length, and about 2 ounces (oz) (60 grams (g)) in 
weight. The bill is blue-black with yellow on the basal half of the 
lower mandible. The legs are short and bluish-gray. All cuckoos have a 
zygodactyl foot with two toes pointing forwards and two toes pointing 
backwards. Juvenile yellow-billed cuckoos resemble adults, except the 
tail patterning is less distinct and the lower bill has little or no 
yellow. Males and females differ slightly and are indistinguishable in 
the field (Hughes 1999, pp. 2-3).
    Typically a secretive and hard-to-detect bird, adult yellow-billed 
cuckoos have a distinctive ``kowlp'' call, which is a loud, nonmusical 
series of notes that slows down and slurs toward the end. Yellow-billed 
cuckoos advertise for a mate using a series of soft ``cooing'' notes, 
which they give at night as well as during daytime. Both members of a 
pair use a soft knocking call as a contact or warning call near the 
nest (Hughes 1999, pp. 8-9). Please refer to the October 3, 2013, 
proposed listing rule (78 FR 61623-61642) for additional species 
information.

Taxonomy

    Recent research on yellow-billed cuckoo genetics using 
mitochondrial DNA did not find any fixed genetic differences between 
eastern and western yellow-billed cuckoos (Farrell 2013, pp. 165-170). 
The author concluded that the separation into distinct subspecies may 
be too recent to be expressed in a single mitochondrial gene and 
recommended future studies using next-generation sequencing techniques. 
Avian geneticist Janice Hughes, Ph.D., a peer reviewer of the proposed 
listing rule, concluded that close examination of the DNA studies 
conducted to date on cuckoos infers a deeper genetic divergence between 
western and eastern cuckoos that with further analysis would likely 
support division of the yellow-billed cuckoo into two subspecies. She 
indicated that genetic markers used in all three previously conducted 
genetics studies evolve too slowly to reveal genetic structure within 
the species. She recommended that future studies use microsatellite 
techniques because they would be more informative to a study of DNA at 
the subspecies level. The existing DNA studies, however, show that 
western yellow-billed cuckoos have developed unique genetic haplotypes 
not present in eastern cuckoos and that these are reflected in 
phenotypic (outwardly visible) divergence that has been observed 
between eastern and western yellow-billed cuckoos. Please refer to the 
October 3, 2013, proposed listing rule (78 FR 61624-61645) for a more 
detailed discussion of information on taxonomy for the species.

Distinct Vertebrate Population Segment Analysis

    Under the Act, we must consider listing any species, subspecies, 
or, for vertebrates, any DPS of these taxa if there is sufficient 
information to indicate that such action may be warranted. To implement 
the measures prescribed by the Act and its Congressional guidance, we 
(along with the National Marine Fisheries Service) developed policy 
that addresses the recognition of DPSs for potential listing actions 
(61 FR 4722; February 7, 1996). The policy allows for more refined 
application of the Act that better reflects the biological needs of the 
taxon being considered, and avoids the inclusion of entities that do 
not require its protective measures.
    Before we can evaluate whether a given population segment is a DPS 
under the Act, we must first determine if any population segments exist 
for the vertebrate species. As discussed in the Taxonomy section of the 
proposed rule (78 FR 61621; October 3, 2013), much of the available 
scientific information supports the yellow-billed cuckoos that nest in 
western North America as a biologically separate population segment.
    To establish the range of the population segment under 
consideration, we used the area occupied by the western yellow-billed 
cuckoo (the subspecies) originally defined by Ridgway (1887, p. 273) 
and later refined by other researchers (AOU 1957, pp. 269-270; 
Oberholser and Kincaid 1974, pp. 434-435; Hughes 1999, Figure 1). After 
careful consideration of other possible population segment 
configurations, we determined that the Continental Divide (generally 
the crest of the Rocky Mountains based on watershed boundaries), the 
watershed divide between the Rio Grande and Pecos River, and the 
Chihuahuan Desert in Mexico was the best division between eastern and 
western populations. The area that we are considering occupied by the 
potential western DPS for the yellow-billed cuckoo is closely aligned 
with the traditionally defined range of the western yellow-billed 
cuckoo subspecies as partially described in the July 25, 2001, 12-month 
finding (66 FR 38611). Our goal is to determine if this western 
population meets the criteria of a DPS and, if so, whether the range 
boundaries identified in the literature are appropriate for the 
boundary of the DPS. This DPS analysis is based solely on the range 
during the breeding season because the migration route and winter range 
of western yellow-billed cuckoos are poorly known.
    The geographical breeding range of the yellow-billed cuckoo in 
western North America includes suitable habitat within the low- to 
moderate-elevation areas west of the crest of the Rocky Mountains in 
Canada, Mexico, and the United States, including the upper and middle 
Rio Grande, the Colorado River Basin, the Sacramento and San Joaquin 
River systems, the Columbia River system, and the Fraser River. In 
Mexico, the range includes the Cape Region of Baja California Sur, and 
river systems in the Mexican States of Sonora, Sinaloa, western 
Chihuahua, and northwestern Durango. Eastern yellow-billed cuckoos 
(Coccyzus americanus americanus) breed east of the Rocky Mountains; 
north to North Dakota and southern Ontario, Canada; south to eastern 
Mexico; and on the islands of the Caribbean (AOU 1957, pp. 269-270) 
(Figure 1).

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[GRAPHIC] [TIFF OMITTED] TR03OC14.004

    Under our DPS policy, three elements are considered in a decision 
regarding the status of a possible DPS as endangered or threatened 
under the Act. The elements are: (1) Discreteness of the population 
segment in relation to the remainder of the species to which it 
belongs; (2) the significance of the population segment to the species 
to which it belongs; and (3) the population segment's conservation 
status in relation to the Act's standards for listing. In other words, 
if we determine that a population segment of a vertebrate species being 
considered for listing is both discrete and significant, we would 
conclude that it represents a DPS, and thus a ``species'' under section 
3(16) of the Act, whereupon we would evaluate the level of threat to 
the DPS based on the five listing factors established under section 
4(a)(1) of the Act to determine whether listing the DPS as an 
``endangered species'' or a ``threatened species'' is warranted.
    Below, we evaluate under our DPS policy whether the population 
segment of yellow-billed cuckoos that occurs in the western United 
States, northwestern Mexico, and southwestern Canada qualifies as a DPS 
under the Act.

Discreteness

    Under our DPS Policy, a population segment of a vertebrate species 
may be considered discrete if it satisfies either of the following two 
conditions: (1) It is markedly separated from other populations of the 
same taxon as a consequence of physical, physiological, ecological, or 
behavioral factors (quantitative measures of genetic or morphological 
discontinuity may provide evidence of this separation); or (2) it is 
delimited by international governmental boundaries within which 
significant differences in control of exploitation, management of 
habitat, conservation status, or regulatory mechanisms exist that are 
significant in light of section 4(a)(1)(D) of the Act.
    The analysis of the population segment of the yellow-billed cuckoo 
in western North America is based on the first of those two conditions, 
the marked separation from other populations. From southwest British 
Columbia along the Canadian border to the southern end of the Sangre de 
Cristo Mountains in northern New Mexico, nesting yellow-billed cuckoos 
in western North America are separated from nesting yellow-billed 
cuckoos in eastern North America by the high-elevation zone of the 
Rocky Mountains. Yellow-billed cuckoos breed both east and west of the 
crest of the Rocky Mountains, where suitable habitat occurs (Johnsgard 
1986, p. 201). We generally define the crest of the Rocky Mountains and 
Continental Divide as the high-elevation zone between the drainages 
flowing west and east in the United States, Canada, and Mexico, 
although some areas such as near the Sangre de Cristo Range in southern 
Colorado and northern New Mexico is east of the east-flowing Rio Grande 
River. The division between the western and eastern population segments 
spans a distance of about 2,200 miles (mi) (3,540 kilometers (km)) from 
southwest British Columbia near the Canadian border along the crest of 
the Rocky Mountains based on watershed boundaries, south along the Rio 
Grande-Pecos Rivers watershed divide to the United States-Mexico border 
in the Big Bend area of Texas, then into Mexico along the eastern and 
southern boundaries of the State of Chihuahua south to the southern 
border of the State of Durango and to the Pacific Ocean along the 
southern border of the State of Sinaloa. The distance of separation 
between breeding yellow-

[[Page 59995]]

billed cuckoos in the east and west varies along this division from 160 
mi (257 km) to more than 400 mi (644 km), and consists entirely of 
areas of unoccupied, unsuitable habitat for breeding yellow-billed 
cuckoos. The one exception to this distance of separation is along the 
Rio Grande in Brewster County, in southwestern Texas, where eastern 
yellow-billed cuckoos breed as far west as Rio Grande Village and 
western yellow-billed cuckoos are found upstream along the river 
approximately 50 mi (80 km) to the west.
    Yellow-billed cuckoos historically bred at the southern tip of 
Vancouver Island and in the Fraser River valley north to Kamloops in 
southwestern British Columbia, Canada (Bent 1940, p. 64; Campbell et 
al. 1990, p. 481). The species was apparently never common, with 23 
records (18 specimen and 5 sight records) between 1881 and 1927. Two of 
these observations were of pairs believed to be nesting but not 
confirmed. Since the 1920s, the species has been recorded five times in 
British Columbia, with four of those records occurring since 1990 from 
the eastern half of the Province in areas not considered breeding 
habitat (Campbell et al. 1990, p. 481; Siddle 1992, p. 1169; Cornell 
Lab of Ornithology 2012). Today, the species is considered extirpated 
as a breeder from the Province, but adult, nonbreeding individuals 
still occur irregularly (British Columbia Conservation Data Centre 
2013).
    In the northern Rocky Mountains and northern Great Plains--from the 
Canada border south through Colorado--the yellow-billed cuckoo is 
``extremely rare and local'' as a breeding bird both east and west of 
the Rocky Mountains (Hughes 1999, p. 3). While the species breeds 
locally in river valleys in southern Idaho, southwestern Wyoming, 
western Colorado, and in Utah (Hughes 1999, pp. 1-3), it is quite rare 
or absent within the higher Rocky Mountains (Johnsgard 1986, p. 201). 
An examination of the distributional records for the Rocky Mountain 
region indicates that the area has had few records of yellow-billed 
cuckoos and the species is even scarcer at elevations above 
approximately 6,000 feet (ft) (1,850 meters (m)), and almost never 
breeds above 7,000 ft (2,154 m) (Bailey 1928, pp. 307-309; Phillips et 
al. 1964, p. 45; Bailey and Niedrach 1965, pp. 404-406; Johnsgard 1986, 
p. 201; Corman and Magill 2000, pp. 10, 15; Howe and Hanberg 2000, p. 
1-20). Exceptions to the elevational limit do occur and recent records 
of yellow-billed cuckoos have been confirmed above 6,000 ft (1,850 m) 
in the areas of Lower Green River Basin from the Seedskadee National 
Wildlife Refuge (NWR) to the Flaming Gorge Reservoir and west to the 
Bear River Drainage in Wyoming; along the Yampa River near Craig in 
northwest Colorado, and the Rio Grande River near Del Norte, and San 
Luis Valley of south-central Colorado; and the Henry's Fork River in 
Utah and Wyoming. Nevertheless, most of the crest of the Rocky 
Mountains includes a wide region of higher elevation where habitat for 
the species does not occur. In Colorado and Wyoming, the region above 
6,000 ft (1,850 m) is typically more than 150 mi (240 km) wide on an 
east-west axis (Oxford 1995, p. 82).
    The separation of the western yellow-billed cuckoo population 
segment from yellow-billed cuckoos in the eastern population segment 
continues south along the crest of the Rockies into southern Colorado 
and northern New Mexico, then the Rocky Mountains end and the 
separation is along the watershed boundary between the Rio Grande and 
the Pecos Rivers in central New Mexico (Sangre de Cristo Mountains), 
and southwest Texas, terminating at the Rio Grande in the Big Bend 
National Park. In this region, the eastern and western yellow-billed 
cuckoo populations are separated by arid basins and isolated mountain 
ranges that emerge from a high desert plateau. These mountain ranges 
from north to south include the Sangre de Cristo Mountains and 
Sacramento Mountains in central and southern New Mexico, the Guadalupe 
Mountains and Delaware Mountains on the Texas-New Mexico border, and 
the Davis Mountains, Del Norte Mountains, and Santiago Mountains in 
western Texas south to the Chisos Mountains in the Big Bend National 
Park on the border with Mexico.
    In southern New Mexico and western Texas where western yellow-
billed cuckoos nest along the Rio Grande and eastern yellow-billed 
cuckoos nest along the Pecos River, the geographical separation is as 
little as 160 mi (257 km) and even closer along the Rio Grande (50 mi; 
80 km). The closer proximity of western and eastern yellow-billed 
cuckoos in this region may be caused in part by the lower height of the 
mountain range being a less effective barrier (Hubbard 1978, p. 32; 
Howe 1986, p. 2). Historically, this gap was wider, because the banks 
of the Pecos River did not have riparian woodland and the area was not 
used by the species. Today, the riverine habitat along the Pecos River 
consists primarily of introduced tamarisk (Tamarix spp.), and it is 
thought that yellow-billed cuckoos from eastern North America have 
colonized the Pecos River system. Much of the area between the Pecos 
River and the Rio Grande in New Mexico and Texas consists of internal 
ephemeral drainages that are not connected to any major river systems 
and have no riparian habitat. Considering these factors along with the 
information on physical factors, we have included Texas west of the Rio 
Grande-Pecos River watershed boundary within the range of the western 
population. This physical division coincides with behavioral 
differences between eastern and western yellow-billed cuckoos, as 
discussed below.
    South of the United States-Mexico border, yellow-billed cuckoos are 
separated by extensive areas of desert that lack suitable nesting and 
foraging habitat. In Mexico, the Chihuahuan Desert widens to 350 mi 
(563 km), and includes nearly all of the States of Chihuahua and 
Coahuila. There are very few records of yellow-billed cuckoos for this 
region, and we are not aware of any nesting records for either State. 
Suitable breeding habitat or connective riparian corridors are also 
lacking. Published range maps for the species do not include the 
eastern three-quarters of Chihuahua or the western three-quarters of 
Coahuila as part of the species' breeding range (Howell and Webb 1995, 
p. 347; Hughes 1999, p. 1). There are only 12 records of yellow-billed 
cuckoos from Chihuahua: 11 specimens from the 1940s to 1960, and a 
sight observation in 2003. There are only nine records of the species 
from Coahuila: six specimen and three sight records (1958, 1988, and 
2011). Three of the specimens from Coahuila were identified as eastern 
yellow-billed cuckoos on their museum records, and the others were not 
identified to subspecies. Seven specimens from Chihuahua were 
identified to subspecies and six of these were considered the western 
subspecies. It is likely that many, if not most, of the records from 
this region are of migrating yellow-billed cuckoos, as 16 are from May 
to mid-June or from late September, and only 5 are from late June or 
July, the primary breeding season.
    From this information we concluded that the Chihuahua-Coahuila 
border was the most biologically supportable boundary for the 
population segment. The boundary then follows the southern border of 
Chihuahua west to the Continental Divide, then south along the divide 
through the State of Durango and west along the southern border of 
Durango and Sinaloa. There are no breeding season records for yellow-
billed cuckoos from the State of Nayarit or Jalisco or farther south 
along the

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Pacific coast of Mexico. The species has occurred sporadically in the 
State of Zacatecas, but the records are from east of the Continental 
Divide.
    Eastern and western yellow-billed cuckoos are highly migratory, and 
the two populations may spend winters in overlapping regions in South 
America. However, we do not have information to indicate that there is 
anything more than an extremely low level of interchange (if any at 
all) between the two populations during the breeding season. This 
conclusion is supported by differences in habitat use and morphology, 
which are genetically controlled traits, as discussed in the following 
sections.
    Although the Rocky Mountains and the Chihuahuan Desert may not 
wholly prevent movement of yellow-billed cuckoos between the east and 
west, especially in a migratory species that winters far to the south, 
and moves thousands of miles between its wintering and breeding 
grounds, the available information indicates that this mountain range 
and desert substantially separates yellow-billed cuckoo populations 
during the breeding season, thereby effectively separating them into 
discrete populations. The separation between yellow-billed cuckoo 
population segments in the east and west is a physical one that is 
maintained by their behavioral differences, which we discuss below.

Behavioral Discreteness

    Data collected from publications and other sources demonstrate the 
existence of behavioral differences between yellow-billed cuckoos in 
the east and west.
    Yellow-billed cuckoo populations in the east and west differ in the 
timing of arrival on the breeding grounds in the spring. Yellow-billed 
cuckoos in western North America arrive on the breeding grounds 4 to 8 
weeks later than eastern yellow-billed cuckoos at similar latitude 
(Franzreb and Laymon 1993, pp. 24-25; Hughes 1999, pp. 5-6, 12-13; 
Laymon 2000, in. litt., pp. 15-16). Timing of spring migration and 
arrival on the breeding grounds has been determined to be the result of 
an evolved response under genetic control, and is likely caused by 
east-west climatic, habitat, and food availability differences 
(Cresswell et al. 2011, pp. 13-15; Pulido et al. 2001). The watershed 
boundary between the Rio Grande and the Pecos Rivers also appears to 
separate yellow-billed cuckoos that arrive in spring migration earlier 
on the Pecos River and those that arrive later on the Rio Grande in 
addition to separating morphological differences.
    Information, including timing of migration, indicates that yellow-
billed cuckoos from Texas west of the Pecos River (from the Rio Grande 
upstream of Big Bend) and from northwestern Mexico (Chihuahua, Sonora, 
Sinaloa, Durango, Baja California Sur) exhibit greater similarity to 
yellow-billed cuckoos in western North America, and those on the Pecos 
River in Texas and eastern Mexico (Coahuila, Nuevo Leon, Tamaulipas, 
San Luis Potosi) are more similar to yellow-billed cuckoos in the east 
(Wauer 1971, p. 96; Oberholser and Kincaid 1974, pp. 434-435; Franzreb 
and Laymon 1993, pp. 17-28; Hughes 2000, in litt. pp. 1-2, 26; Sproul 
2000, in litt., pp. 1-5). Based on the best available science, the 
watershed boundary between the Rio Grande and Pecos Rivers is the 
optimum dividing line between eastern and western yellow-billed cuckoo 
in this area.
    Based on migration timing, yellow-billed cuckoos split into two 
populations. This split occurs along the line that corresponds with the 
traditional subspecies boundary (see Figure 1, above).

Discreteness Conclusion

    The available information indicates that the yellow-billed cuckoo 
population segment that occurs west of the Continental Divide (as 
defined above) in the United States, in southwestern Canada, and in 
northwestern Mexico is markedly separated from the eastern population 
segment of yellow-billed cuckoo, including those that nest in eastern 
North America, eastern Mexico, certain Caribbean Islands, and the 
Yucatan Peninsula. The distribution of the western populations is 
markedly separated physically (geographically) during the breeding 
season from the distribution of other yellow-billed cuckoo populations 
by high mountains, extensive desert, or nonhabitat areas with the 
shortest geographical separation occurring across 160 mi (257 km) of 
desert between the Pecos River and Rio Grande in southern New Mexico 
and western Texas with the exception of nesting of western yellow-
billed cuckoos near Big Bend National Park in Texas. Evidence that this 
geographical separation between populations has been consistent through 
time may be found in the differences in the two populations' biology 
and morphology. Even in this area of closest proximity, information on 
genetically controlled behavior available in the scientific literature 
provides evidence of a biological separation between the western 
populations and eastern populations.
    Under our DPS policy, the standard for discreteness does not 
require absolute separation because this can rarely be demonstrated for 
any population of organism. For the yellow-billed cuckoo populations in 
western North America, we have met this standard, and, therefore, we 
consider the western population segment of the yellow-billed cuckoo 
from southern British Columbia, Canada south along the Continental 
Divide (including the Rio Grande basin) in the United States into 
Mexico, and ending at the coast in the State of Sinaloa, Mexico, to be 
discrete per our DPS policy. We conclude that the western population 
segment of the yellow-billed cuckoo is discrete from the remainder of 
the species because the yellow-billed cuckoo population segment that 
nests west of the Continental Divide (as defined above) and in 
northwestern Mexico is markedly separated geographically and 
behaviorally from all other populations of yellow-billed cuckoo, 
including those that nest in eastern North America.

Significance

    Under our DPS policy, once we have determined that a population 
segment is discrete, we consider its biological and ecological 
significance to the larger taxon to which it belongs. Our DPS policy 
provides several potential considerations that may demonstrate the 
significance of a population segment to the remainder of its taxon, 
including: (1) Evidence of the persistence of the discrete population 
segment in an ecological setting unusual or unique for the taxon, (2) 
evidence that loss of the discrete population segment would result in a 
significant gap in the range of the taxon, (3) evidence that the 
population segment represents the only surviving natural occurrence of 
a taxon that may be more abundant elsewhere as an introduced population 
outside its historic range, or (4) evidence that the discrete 
population segment differs markedly from the remainder of the species 
in its genetic characteristics.
    We have found substantial evidence that two of these four 
significance criteria (numbers 2 and 4) are met by the discrete 
population segment of yellow-billed cuckoos that occurs west of the 
Continental Divide (as defined above). We address these significance 
factors below as they relate to the population segment of western 
yellow-billed cuckoo. We focus on whether the loss of this population 
segment would result in a significant gap in the range of the taxon and 
evidence that the discrete

[[Page 59997]]

population segment differs from other population segments in its 
genetic characteristics in demonstrating significance of the DPS.

Evidence That Loss of the Discrete Population Segment Would Result in a 
Significant Gap in the Range of the Taxon

    Loss of the discrete population segment would result in a 
significant gap in the range of the taxon because an extensive area 
would be without yellow-billed cuckoos if the western population 
segment were lost. Seven entire States and substantial portions of five 
additional States in the United States, and six States in Mexico, that 
are currently occupied would have no breeding populations of the 
species. Bird migration experts divide the North American continent 
into four migratory flyways: The Atlantic, Mississippi, Central, and 
Pacific. The range of the yellow-billed cuckoo west of the Rocky 
Mountains covers the entire Pacific flyway and half of the Central 
flyway. Additionally, the range of the yellow-billed cuckoo west of the 
Rocky Mountains covers 1,350,000 square (sq) mi (3,496,500 sq km), or 
approximately 40 percent of the lower 48 States. Even though the actual 
area occupied by the species in western North America is less than the 
total area identified above, the potential loss of the western 
population of the yellow-billed cuckoo would constitute a significant 
gap in the range of the species in North America.

Evidence That the Discrete Population Segment Differs Markedly From 
Other Populations of the Species in Its Genetic Characteristics

    Data collected from publications and other sources demonstrate the 
existence of morphological and physiological differences between 
yellow-billed cuckoos in the east and west. Morphologically, the 
yellow-billed cuckoos in western North America are generally larger, 
with significantly longer wings, longer tails, and longer and deeper 
bills (Franzreb and Laymon 1993, p. 25). Banks, in a review of the 
species taxonomic status (1988, pp. 473-477), grouped yellow-billed 
cuckoo specimens into 19 regional groups, 7 in the western United 
States and western Mexico, 10 in the eastern United States and eastern 
Mexico, 1 in New Mexico, and 1 in the Caribbean. He found yellow-billed 
cuckoos in the east to be uniform in measurement throughout their range 
and yellow-billed cuckoos in the west to be uniform in measurements 
throughout their range (Banks 1988, p. 475). Banks stated that the 
change from smaller to larger yellow-billed cuckoos appeared to take 
place in extreme western New Mexico or extreme eastern Arizona (Banks 
1988, p. 476). A subsequent analysis, based on available specimens from 
New Mexico and western Texas, showed the watershed boundary between the 
Pecos River and the Rio Grande as the apparent boundary between the 
smaller eastern and larger western birds, with a majority of yellow-
billed cuckoos on the Rio Grande above Big Bend being larger western 
birds (63 percent, n=19) and the majority of yellow-billed cuckoos on 
the Pecos River being smaller eastern birds (82 percent, n=11) 
(Franzreb and Laymon 1993, p. 25). This is the only area where the 
ranges of the western and eastern population segments are in close 
proximity; elsewhere the two populations are separated by wide expanses 
of unsuitable, unoccupied habitat (see Figure 1, above).
    One peer reviewer measured 35 cuckoos from the Rio Grande and 25 
cuckoos from the Pecos River in the field. With the exception of wing 
and tail measurements, accurate measurements are hard, if not 
impossible, to obtain from live birds under field conditions. Male and 
female cuckoos averaged longer wings and tails on Rio Grande than on 
the Pecos River, with the difference being more pronounced on male than 
on female cuckoos. Sample sizes were insufficient to do t-tests to 
compare the means for the wing and tail data. The bill measurements 
that the reviewer took in the field were not reliable and therefore 
could not be compared, and as a result the comparison using the 
Discriminant Function equations developed by Franzreb and Laymon (1993, 
pp. 17-28) could not be used reliably on the data.
    Other physical and morphological differences exist between yellow-
billed cuckoos in the east and west, and provide additional evidence of 
ecological significance. These include:
     Yellow-billed cuckoos in western North America produce 
larger eggs (1.2 percent longer, 0.6 percent wider, and 3.2 percent 
heavier) with thicker eggshells (7.1 percent thicker) (Hughes 1999, p. 
14), which is an evolved trait that would help yellow-billed cuckoos in 
the west to cope with potential higher egg water loss in the hotter, 
drier conditions of western North America (Hamilton and Hamilton 1965, 
pp. 426-430; Ar et al. 1974, pp. 153-158; Rahn and Ar 1974, pp. 147-
152).
     Juvenile yellow-billed cuckoos in the east have yellow 
bills (Oberholser and Kincaid 1974, pp. 434-435), while juvenile 
yellow-billed cuckoos in the west have all-black bills (Franzreb and 
Laymon 1993, p. 26).
     Adult yellow-billed cuckoos in the west have a lower 
mandible that is orange-yellow, while yellow-billed cuckoos in the east 
have lower mandibles that are bright yellow (Franzreb and Laymon 1993, 
p. 26; Laymon 2000, in litt., p. 14).
     As noted previously, adult yellow-billed cuckoos in the 
west are larger and heavier, on average, than adult yellow-billed 
cuckoos in the east. More than 80 percent of individuals can be 
assigned to east or west based on morphological measurements (see also 
Oberholser and Kincaid 1974, pp. 434-435; Banks 1988, pp. 473-477; 
1990, p. 538; Franzreb and Laymon 1993, pp. 17-28). The size 
differences between eastern and western cuckoos are discussed in detail 
in the Taxonomy section of the proposed rule (78 FR 61624-61625; 
October 3, 2013).
    Information, including morphology, indicates that yellow-billed 
cuckoos from Texas west of the Pecos River (from the Rio Grande 
upstream of Big Bend) and from northwestern Mexico (Chihuahua, Sonora, 
Sinaloa, Durango, Baja California Sur) exhibit greater similarity to 
yellow-billed cuckoos in western North America, and those on the Pecos 
River in Texas and eastern Mexico (Coahuila, Nuevo Leon, Tamaulipas, 
San Luis Potosi) are more similar to yellow-billed cuckoos in the east 
(Wauer 1971, p. 96; Oberholser and Kincaid 1974, pp. 434-435; Franzreb 
and Laymon 1993, pp. 17-28; Hughes 2000, in litt. pp. 1-2, 26; Sproul 
2000, in litt., pp. 1-5). Based on the best available science, the 
watershed boundary between the Rio Grande and Pecos Rivers is the 
optimum dividing line between eastern and western yellow-billed cuckoo 
in this area.
    Based on morphological measurements, bill color of young and 
adults, egg size and weight, and migration timing, yellow-billed 
cuckoos split into two populations. This split occurs along the line 
that corresponds with the traditional subspecies boundary (see Figure 
1, above). Phenotypically or outwardly expressed traits present 
substantial evidence that the western population segment of yellow-
billed cuckoo differs markedly from other populations of the species.
    However, the strongest evidence of differences between yellow-
billed cuckoos in the western population segment and those of the east 
in genetic characteristics is the difference in timing of migrations. 
This difference can only have developed as an evolved trait in response 
to environmental factors over a long period of time, and thus is 
genetically linked (Cresswell et al. 2011, pp. 13-15; Pulido et al. 
2001). As previously discussed, the difference

[[Page 59998]]

in size of yellow-billed cuckoos between east and west, as well as 
differences in size, weight, and shell thickness of eggs, are also 
evolved genetically linked traits. As discussed in the October 3, 2013, 
proposed rule, researchers have developed methods using these 
phenotypic (outwardly expressed) traits that correctly predicted 
separation for nearly 90 percent of yellow-billed cuckoos that were 
eastern, and up to approximately 86 percent that were western (Franzreb 
and Laymon 1993, pp. 17-28). Thus, based on the phenotypic traits, 
there is indirect evidence that the discrete population segment differs 
markedly from other populations of the species in its genetic 
characteristics.

Significance Conclusion

    The best available information indicates that the discrete yellow-
billed cuckoo population segment that nests west of the Continental 
Divide (as defined above) and in northwestern Mexico is important to 
the taxon to which it belongs because: (1) Loss of the population 
segment would leave a significant gap in the species' range (more than 
one third of the species' range would be vacant); and (2) it differs 
markedly from other yellow-billed cuckoo populations in morphology 
(e.g., western yellow-billed cuckoos are larger) Therefore, we conclude 
that the western population segment of the yellow-billed cuckoo is 
significant per our DPS Policy.

DPS Conclusion

    Based on the best scientific and commercial data available on 
distribution as well as behavioral and morphological characteristics of 
the species, we have determined that the western population segment of 
the yellow-billed cuckoo is both discrete and significant per our DPS 
policy. Therefore, we conclude that the western distinct population 
segment of the yellow-billed cuckoo is a DPS, and thus a ``species'' 
under section 3(16) of the Act. Our determination of biological and 
ecological significance is appropriate because the population segment 
has a geographical distribution that is biologically meaningful.
    The term ``distinct population segment'' is not commonly used in 
scientific discourse. As such, and in contrast to taxonomically defined 
species and subspecies, there is no established name for the western 
distinct population segment of the yellow-billed cuckoo in the 
available literature; we will refer to this ``species'' (DPS) as the 
western yellow-billed cuckoo. The range of the western yellow-billed 
cuckoo in Canada includes the area of Vancouver Island and along the 
Fraser River system upstream to Kamloops to the Rocky Mountains west of 
the Continental Divide. In the United States the DPS includes the area 
west of the Continental Divide, south through Montana, Wyoming, 
Colorado, and along the watershed divide between the upper and middle 
Rio Grande and Pecos Rivers in New Mexico and Texas, south to Big Bend 
in southwestern Texas, and extending to the States of the west coast. 
In Mexico, the DPS is the area west of the eastern and southern border 
of the State of Chihuahua, west of the Continental Divide in the State 
of Durango, and the southern border of the State of Sinaloa (Figure 2).

[[Page 59999]]

[GRAPHIC] [TIFF OMITTED] TR03OC14.005

Summary of Comments and Recommendations

    In the proposed rule published on October 3, 2013 (78 FR 61621), we 
requested that all interested parties submit written comments on the 
proposal by December 2, 2013. The comment period was reopened on 
December 26, 2013, and remained open until February 24, 2014 (78 FR 
78321). The comment period was reopened again on April 10, 2014, and 
remained open until April 25, 2014 (79 FR 19860). We also contacted 
appropriate Federal and State agencies, scientific experts and 
organizations, and other interested parties and invited them to comment 
on the proposal. Newspaper notices inviting general public comment were 
published in the Idaho State Journal (Pocatello, ID), Post Register 
(Idaho Falls, ID), Idaho Mountain Express (Sun Valley, ID), Idaho 
Statesman (Boise, ID), Coeur d'Alene Press (Coeur d'Alene, ID), Las 
Vegas Sun (Las Vegas, NV), Las Vegas Review-Journal (Las Vegas, NV), 
Reno Gazette-Journal (Reno, NV), The Oregonian (Portland, OR), Yakama 
Herald, (Yakima, WA), Wenatchee World (Wenatchee, WA), The Olympian 
(Olympia, WA), The Spokesman Review (Spokane, CA), Bellingham Herald 
(Bellingham, WA), Salt Lake Tribune (Salt Lake City, UT), Helena 
Independent Record (Helena, MT), The Missoulian (Missoula, MT), Valley 
Courier (Alamosa, CO), Craig Daily Press (Craig, CO), (The Daily 
Sentinel (Grand Junction, CO), El Paso Times (El Paso, TX), Albuquerque 
Journal (Albuquerque, NM), The Arizona Republic (Phoenix, AZ), The 
Californian (Bakersfield, CA), and Press-Enterprise (Riverside, CA). We 
did not receive any requests for a public hearing.
    During the comment periods for the proposed rule, we received 
34,459 comment letters directly addressing the proposed listing of the 
western DPS of the yellow-billed cuckoo as a threatened species. The 
vast majority of these comment letters voiced their support or 
opposition to the action, but did not provide significant supporting 
information on the proposed listing. A total of 34,380 letters were in 
support of the listing, while 54 letters were in opposition to listing, 
with 25 commenters providing additional information, but took no 
position on the listing of the species. Approximately 141 of these 
comment letters provide additional information or comments. All 
substantive information provided during comment periods has either been 
incorporated directly into this final determination or is addressed 
below.

Peer Review

    In accordance with our peer review policy published on July 1, 1994 
(59 FR 34270), we solicited expert opinion from five knowledgeable 
individuals with scientific expertise that included familiarity with 
the yellow-billed cuckoo and its habitat, biological needs, and 
threats. We received responses from all five of the peer reviewers.
    We reviewed all comments we received from the peer reviewers for 
substantive issues and new information regarding the listing of the 
western DPS of the yellow-billed cuckoo. The peer reviewers generally 
concurred with our methods and conclusions, and provided additional 
information, clarifications, and suggestions to improve the final

[[Page 60000]]

rule. Peer reviewer comments are addressed in the following summary and 
incorporated into the final rule as appropriate.

Peer Reviewer Comments

    (1) Comment: One reviewer discussed the heritability of migration 
timing, indicating that the difference in migration timing between 
eastern and western cuckoos is reflective of genetic differences and 
added a supportive reference (Pulido et al. 2001).
    Our Response: In the proposed and this final rule, we outlined our 
reasoning for determining that the western populations of the yellow-
billed cuckoo constitute a valid DPS (see Distinct Vertebrate 
Population Segment Analysis, above). In our determination, we relied on 
behavioral and morphological and other characteristics of the species 
to support separation and distinctness from yellow-billed cuckoos in 
the east. Although genetics most likely play a role in behavioral and 
morphological aspects of a species, in our determination we did not 
rely on specific genetic information or separation to come to our 
conclusion. The views of the peer reviewer and the information they 
provided (Pulido et al. 2001, pp. 149-158) further support our 
conclusions reached in determining a valid DPS for the western yellow-
billed cuckoo. We revised this final rule to include the information 
provided.
    (2) Comment: One reviewer stated that a close examination of the 
DNA studies conducted on cuckoos to date would infer a deeper genetic 
divergence between western and eastern cuckoos than presented in the 
proposed rule and that further analysis would likely support division 
of species into two subspecies. The reviewer also provided a critique 
of the techniques used in the studies to date, noting that markers used 
in all three genetics studies evolve too slowly to reveal genetic 
structure within the species, and that the choice of outgroup for study 
comparison was flawed in one study.
    Our Response: See response to Comment 1 above for a discussion of 
how we used genetic information in our DPS determination. Although we 
agree that further studies and information on the genetics for the 
yellow-billed would assist in further validating our determination of 
separation between eastern and western yellow-billed cuckoo 
populations, we must rely on the best scientific or commercial data 
available to make our listing determinations. We appreciate the 
information provided and have made some revisions to the DPS analysis 
to incorporate citations provided by the peer reviewer, as needed.
    (3) Comment: Two reviewers indicated that recent research has shown 
that vocalizations cannot be reliably used to determine the sex of 
cuckoos in the field. Two public commenters also raised this concern.
    Our Response: We concur and have revised the text to clarify 
information on vocalizations for the western yellow-billed cuckoo.
    (4) Comment: One reviewer indicated that the habitat section could 
be strengthened by presenting habitat models that have been developed. 
This reviewer suggested that the presentation of tamarisk as a habitat 
component could be improved by using information from several 
references from research on the Colorado River (see Johnson et al. 
2008a, Johnson et al. 2012, McNeil et al. 2012). Within-patch 
vegetation measurements show that sites occupied by western yellow-
billed cuckoos do not include dense tamarisk patches.
    Our Response: Based on observations of western yellow-billed 
cuckoos, we have identified riparian trees including willow (Salix 
sp.), Fremont cottonwoods (Populus fremontii), alder (Alnus sp.), 
walnut (Juglans sp.), sycamore (Platanus sp.), boxelder (Acer sp.), ash 
(Fraxinus sp.), mesquite (Prosopis sp.), and tamarisk (Tamarix sp.) as 
habitat that provides cover, shelter, foraging, and dispersing habitat 
for the western yellow-billed cuckoo. Tamarisk is considered a 
nonnative, invasive species across the West. Although the western 
yellow-billed cuckoo uses tamarisk as a component of its habitat, it is 
usually in areas where the habitat has been degraded. We appreciate the 
peer reviewer's information on habitat modeling and will review this 
information in development of any final critical habitat determination 
for the species. We have reviewed the information provided by the 
reviewer and have revised our discussion of habitat selection and 
tamarisk use and compatibility for the western yellow-billed cuckoo in 
this final rule (see ``Use of Tamarisk by Western Yellow-billed Cuckoos 
and the Spread of the Introduced Tamarisk Leaf Beetle into the 
Southwest,'' below).
    (5) Comment: One reviewer suggested that estimates of breeding 
populations of western yellow-billed cuckoos may be overestimates and 
the numbers may be even lower than indicated in the proposed rule.
    Our Response: We are aware of the difficulties in obtaining 
accurate counts of western yellow-billed cuckoos. Survey methods for 
western yellow-billed cuckoos have evolved over time since the first 
play-back surveys were conducted in California in the 1970s. Some 
changes in survey method include changes in the distance between 
calling stations (100 vs. 200 meters), changes in the number of calls 
played at calling stations (5 vs. 10 calls), number of surveys carried 
out during the breeding season (2 to 5 surveys), and the timing of the 
surveys (1 June to 15 August vs. 15 June to 1 August). Despite these 
changes, general response rates have remained constant. On average, an 
individual western yellow-billed cuckoo will respond to playback call 
50 percent of the time, and one member of a pair will respond 75 
percent of the time. With a second visit, the probability of an 
individual responding has risen to 75 percent, and the probability of 
one member of a pair responding has risen to 94 percent. With three 
visits, the probability of an individual responding is 94 percent, and 
the probability of one member of a pair responding is 99.6 percent.
    Obtaining accurate survey results are made more difficult because: 
(1) Western yellow-billed cuckoos often have helper males at the nest; 
(2) they are only loosely territorial; (3) nests of adjacent pairs can 
be very close to each other; (4) female western yellow-billed cuckoos 
often lay a second and third clutch sometimes with different mates; and 
(5) it is likely that they move from one river system to another 
between clutches. These unusual behaviors can lead to either an over 
count or an under count of individuals, pairs, or territories.
    Many of the earlier population estimates were made of pairs of 
western yellow-billed cuckoos. For the reasons listed above, some 
recent researchers have decided that it is more accurate to use the 
term territories rather than pairs. An assessment of the methodology 
used to determine pairs in the older studies and territories in the 
more recent studies concludes that very similar methodology is used and 
that the numbers are comparable.
    In some cases, we were able to use the original survey data and 
simply compare the number of survey hours and number of western yellow-
billed cuckoos surveyed and compare them from one year to the next and 
one time period to another. This is a very reliable and accurate method 
of comparison. In other cases, such as that at the South Fork Kern 
River Valley in California from 1985 to 2001, when all nesting pairs 
were either documented by finding a nest or seeing positive nesting 
behavior (e.g., western yellow-billed cuckoos carrying food to young) 
the

[[Page 60001]]

number of pairs were compared over time.
    We have taken all of these difficulties and changes of survey 
methods and changes of data and behavior interpretation into account in 
our assessment of survey results and western yellow-billed cuckoo 
population trends. We have used the best available data and science in 
determining population estimates and trends. Because we have been aware 
of the changes in survey methods and have factored that information 
into our analysis, we are confident that our estimates of breeding 
populations are accurate.
    (6) Comment: One reviewer indicated that habitat use separates 
eastern and western cuckoos; observations suggest that in eastern New 
Mexico and Texas yellow-billed cuckoos from eastern populations nest in 
monotypic stands of tamarisk, while western yellow-billed cuckoos do 
not.
    Our Response: We have considered this information in our 
determination of the DPS for the yellow-billed cuckoo. Although 
credible observations of species behavior are valuable, peer-reviewed 
published materials would further support these observations, and 
additional research on this topic would be valuable. The information 
provided will be considered further in the development of the final 
critical habitat designation for the species and in recovery planning.
    (7) Comment: Two reviewers suggested that the section on climate 
change could be condensed and that uncertainties in forecasting 
precipitation could bog down conservation actions that would clearly 
benefit western yellow-billed cuckoos in the near future.
    Our Response: The Service used the climate change information that 
was available in the literature. Because the western DPS of the yellow-
billed cuckoo covers such a large area, the effects of climate change 
will be different in the various regions. The Pacific Northwest may 
become cooler and wetter, the desert Southwest may become warmer and 
dryer. The exact effect of these changes on western yellow-billed 
cuckoos is difficult to predict. However, based on our review of the 
literature, we have concluded that a warmer and dryer Southwest, an 
area that is already water-stressed, with a growing human population, 
is likely to have an adverse effect on riparian habitat. This will 
exacerbate the changes that have already occurred in the region and 
should not be ignored. We appreciate the expressed concerns; however, 
we have retained the information presented in the section.
    (8) Comment: One reviewer provided survey results indicating that 
western yellow-billed cuckoos have been detected along the San Juan and 
Green rivers in Utah, although it is not yet known whether breeding 
occurs in these areas. The reviewer notes that further surveys are 
needed.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. This information will 
also be considered in our final critical habitat designation.
    (9) Comment: One reviewer commented that a potential planned 
activity is the reallocation of water from the San Juan River on Navajo 
Tribal lands, which could negatively affect water delivery on the 
Colorado River and western yellow-billed cuckoo habitat on the Lower 
Colorado River.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. This information will 
also be useful in recovery planning and implementation.
    (10) Comment: One reviewer provided information that describes the 
ecological cascade process that leads to loss of western yellow-billed 
cuckoo habitat in riparian areas. The peer reviewer stated that the key 
to sustaining western yellow-billed cuckoo habitat is maintaining an 
ongoing process of new land creation and flow patterns conducive to 
colonization of willow and cottonwood. The peer reviewer also noted 
that it is problematic that a National Wildlife Refuge (NWR) on 
Sacramento River only occurs on one side of the river, and the opposite 
bank is not allowed to erode.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. The information will be 
helpful when developing a recovery plan for the western yellow-billed 
cuckoo.
    (11) Comment: One reviewer adds an additional pervasive threat is 
the design of open channel flood control channels with inappropriately 
smooth roughness coefficients. This over-scours the floodplains and 
requires removal of woody riparian vegetation that regenerates on 
floodplains. This leads to floodplains with no western yellow-billed 
cuckoo habitat.
    Our Response: We have added this information to section 
``Encroachment of Levees and Flood Control and Bank Stabilization 
Structures into the River Channel and Floodplain'' in the Factor A 
discussion in this final rule.
    (12) Comment: One reviewer provides information on several 
additional projects that he indicates are impacting western yellow-
billed cuckoo habitat. The reviewer notes that the U.S. Army Corps of 
Engineers (USACE) Sacramento River Bank Protection Project has been 
channelizing and rip-rapping river banks for many decades and that the 
project impedes the dynamic riverine processes that create western 
yellow-billed cuckoo habitat. The reviewer adds that the California 
Department of Water Resources has proposed a new reservoir project (the 
Sites Reservoir) for off-stream water storage, suggesting that the 
project would be a major water diversion project that would further 
degrade stream power on the Sacramento River, and contribute to an 
ecological cascade on the river (see Comment 10 above and the 
discussion under Factor A below). The reviewer also noted two proposed 
projects that he thinks would provide a potential conservation benefit 
to western yellow-billed cuckoo habitat. Both projects involve the 
creation of several miles-long oxbow lakes on the Sacramento River, at 
Woodson Bridge, and at a pumping facility across from Llano Seco unit 
of Sacramento River NWR.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. This information will be 
helpful in developing and implementing the recovery plan for the 
species.
    (13) Comment: One reviewer indicated that in Conservation Efforts 
section under the Factor E discussion, a distinction should be made 
between ``active'' restoration and ``process-based'' restoration.
    Our Response: We have revised the text in the section to clarify 
the difference in types of restoration activities.
    (14) Comment: One reviewer measured 35 cuckoos from the Rio Grande 
and 25 cuckoos from the Pecos River. He found that Rio Grande males and 
females were larger for all measurements than Pecos cuckoos, but Pecos 
cuckoos are larger than eastern or Trans Pecos cuckoos reported in 
Franzreb and Laymon's (1993, pp. 17-28) subspecies paper. He applied 
the Discriminant Function Analysis (DFA) equation (developed by 
Franzreb and Laymon, 1993, pp. 17-28) to 35 cuckoos from Rio Grande, of 
which 86 percent tested as western and 25 cuckoos from Pecos River of 
which 68 percent tested as western.
    Our Response: We thank the reviewer for this information. However, 
we are concerned that the measurements may have been taken incorrectly 
for the

[[Page 60002]]

following reasons. We first note that, with the exception of wing 
measurements, accurate measurements are hard, if not impossible, to 
obtain from live birds under field conditions. We are concerned that in 
the given sample, bill-depth measurements may have been measured 
incorrectly because all individuals measured, regardless of area of 
origin, had deeper bills than any of the cuckoos measured by Banks 
(1988, pp. 473-477) or Franzreb and Laymon (1993, pp. 17-28). It is 
likely that these measurements were taken on an incorrect location on 
the bill. We note that several of the bill-length measurements reported 
were also record lengths for cuckoos, regardless of origin and suspect 
that they too were likely measured incorrectly. The use of these 
incorrect measurements in the DFA equations would be expected to yield 
incorrect ``likely area of origin.'' Therefore, we have not used this 
information in our final listing determination.

Federal Agency Comments

    During the development of the proposed and this final listing rule, 
we coordinated with Federal agencies and asked for their input on the 
information presented and any concerns they may have. We have not 
included specific comments and responses to Department of the Interior 
(DOI) agencies in this rule (Bureau of Land Management, Bureau of 
Reclamation, and National Park Service). We have worked with the DOI 
agencies during the development of this rule, and their comments and 
concerns are included in the record materials for this final 
determination. We have reviewed any DOI comments and information, and 
have made changes that we determined were appropriate to the final 
listing of the western yellow-billed cuckoo. A total of seven comment 
letters were received from five Federal agencies from outside the DOI, 
and they are outlined below.
    (15) Comment: The U.S. Air Force stated that training flights from 
Luke Air Force Base (AFB) may pass over western yellow-billed cuckoo 
habitat, but they are unlikely to disturb the western yellow-billed 
cuckoos because the airplanes fly over 500 ft. above ground level, 
while western yellow-billed cuckoo fly, forage, and nest within the 
canopy of the trees. Also, the duration of the sound from the jet 
airplanes is only for a few seconds and the flights are infrequent.
    Our Response: We appreciate receiving the information on Air Force 
training flights at Luke AFB. We will consider this information during 
any consultation regarding the species in the future.
    (16) Comment: The USACE provided references that deal with 
southwestern willow flycatcher (Empidonax traillii extimus) 
consultations and management at Lake Isabella, California. They stated 
that their conservation plan and associated conservation easements for 
southwestern willow flycatchers provide habitat protections for the 
western yellow-billed cuckoo as well as least Bell's vireos (Vireo 
bellii pusillus). They are concerned that if the western yellow-billed 
cuckoo is listed and formal consultation for long-term operations of 
Isabella Reservoir are triggered, the USACE may be required to 
``reoperate'' the reservoir, which would increase risk of loss of human 
life and cause significant impacts to economics downstream. This 
concern was also voiced by one public commenter.
    Our Response: Although specific project activities may require 
additional review and potentially result in formal consultation for 
various Federal actions, it is reasonable to assume that the 
conservation plan and associated conservation easements for the 
southwestern willow flycatcher may provide habitat protections for the 
western yellow-billed cuckoo. However, consultation with the Service 
will not likely result in operation decisions that would cause a risk 
of loss of human life or cause significant impacts to downstream 
economies. We have been coordinating with the USACE on their activities 
and dam operation at Lake Isabella as it relates to all listed species 
and will continue to do so into the future.
    (17) Comment: The U.S. Forest Service (USFS) provided several 
reports on western yellow-billed cuckoo surveys conducted at Isabella 
Reservoir. The Southwest Region of the USFS does not think they have 
western yellow-billed cuckoos on the Carson or Cibola National Forests. 
They also had several questions about wording in the proposed rule 
regarding grazing and listed several references regarding the effects 
of well-managed grazing, which they say has less adverse impact on 
western yellow-billed cuckoos and their habitat than traditional, 
poorly managed grazing. Lastly, they stated that mesquite bosque 
habitat was very important to western yellow-billed cuckoos and that 
the habitat was more important than the proposed rule indicated.
    Our Response: We appreciate the additional information provided by 
the USFS and have considered it or incorporated changes to language 
into our final listing determination. Well-controlled grazing activity 
can be compatible within riparian zones and in western yellow-billed 
cuckoo habitat depending on the conservation measures implemented for 
the grazing activity. The amount of management depends on the 
sensitivity of the habitat at any given location and would most likely 
need to be managed on a site-by-site basis. For example, a grazing 
regime used on Audubon California's Kern River Preserve in the South 
Fork Kern River Valley limits grazing to outside the growing season 
(October to March). This time restriction allows for regeneration of 
willows and cottonwoods and precludes the tree browsing and high-lining 
that often accompanies heavy summer (growing season) grazing. We concur 
that mesquite bosque habitat is very important to western yellow-billed 
cuckoos, and this has been stated clearly in the proposed and this 
final rule.
    (18) Comment: The U.S. Department of Agriculture (USDA), Natural 
Resources Conservation Service (NRCS) in Texas stated that they are 
interested in helping landowners conserve and manage critical habitat 
for the western yellow-billed cuckoo.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. NRCS' cooperation and 
assistance will be very helpful during the recovery phase for the 
species.
    (19) Comment: The International Boundary and Water Commission 
provided information on riparian habitat restoration along the Rio 
Grande as well as results of recent western yellow-billed cuckoo 
surveys.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. Restoration of riparian 
habitat will be an important phase in the recovery of the western 
yellow-billed cuckoo. This information will also be helpful in the 
development and implementation of a recovery plan for the western 
yellow-billed cuckoo.
    (20) Comment: The USDA NRCS in Texas expressed concern regarding 
economic impacts to local landowners and municipalities. This concern 
was echoed by several public commenters.
    Our Response: According to section 4(b)(1)A) of the Act, we are to 
base our listing determinations solely on the basis of the best 
scientific and commercial data available as they relate to the five 
factors listed in section 4(a)(1) of the Act. The consideration of 
economics is only related to the designation of critical habitat under 
section 4(b)(2) of the Act.

[[Page 60003]]

Comments From States

    Section 4(i) of the Act states, ``the Secretary shall submit to the 
State agency a written justification for his failure to adopt 
regulations consistent with the agency's comments or petition.'' 
Comments received from the States regarding the proposal to list as a 
``threatened species'' for the western DPS of the yellow-billed cuckoo 
are addressed below. We received 17 comment letters from 17 State 
agencies in 11 States. Of the 17 letters submitted, 9 were from State 
wildlife agencies. We did not receive comments from the State of 
Oregon.

Washington State

    (21) Comment: The Washington State Department of Fish and Wildlife 
supports the DPS determination and listing of the western yellow-billed 
cuckoo as threatened. This is based on their observations that reports 
of individual occurrences for the State have been very rare for the 
past several decades and that the species is not confirmed to be 
breeding in the State. This is despite having some sizable areas of 
riparian habitat still remaining along the Lower Columbia River and 
additional habitat improvements, acquisition, and restoration efforts 
elsewhere in the State. The Washington State Department of Fish and 
Wildlife provided suggestions for clarification of habitat use by the 
western yellow-billed cuckoo in moist riparian habitat areas of western 
Oregon, western Washington, and southwestern British Columbia. They 
also provided information on several records of wider habitat use in 
the Northwest and suggested that there is historical evidence that the 
species may have used conifer woodlands and open brushy hillsides in 
Washington as secondary nesting habitat (Bent 1940, pp. 54-70; Jewett 
et al. 1953, pp. 342-343).
    Our Response: We appreciate this additional information and have 
considered this in our final listing determination. This habitat 
information has been discussed in detail in our proposed critical 
habitat designation. See the proposed critical habitat rule for the 
western yellow-billed cuckoo published in the Federal Register on 
August 15, 2014 (79 FR 48547). Also see the Summary of Changes from 
Proposed Rule section of this final rule and the Habitat Use and Needs 
section from the proposed listing rule for additional discussion on 
habitat use in Washington and Oregon (78 FR 61633-61634; October 3, 
2013).
    (22) Comment: The Washington State Department of Natural Resources 
(DNR) stated that they have developed a conservation strategy on its 
trust lands for conservation of salmonid freshwater stream habitat and 
other riparian obligate species habitat (DNR Trust Lands Habitat 
Conservation Plan). DNR stated that they would expect that 
implementation of the plan would assist in benefiting the western 
yellow-billed cuckoo's habitat and any future recovery efforts for the 
species. DNR also stated that they would continue to participate in the 
development of any future critical habitat designation.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. This information will 
also be considered in our final critical habitat designation.

Idaho

    (23) Comment: The Idaho Office of Species Conservation and the 
Idaho Department of Fish and Game stated that the Service fails to 
define foreseeable future in the proposed rule. This comment was echoed 
by several other commenters.
    Our Response: The Act does not specifically define the term 
``foreseeable future,'' and does not require the Service to quantify 
the time period of foreseeable future in making listing determinations. 
The Solicitor for the Department of the Interior conducted a review of 
the Congressional intent behind the term ``foreseeable future'' in the 
Act, and concluded that Congress intended the term ``foreseeable 
future'' to describe the extent to which the Secretary can reasonably 
rely on predictions about the future in making determinations about the 
future conservation status of the species. The Secretary's ability to 
make reliable predictions may vary according to the threat at issue; 
consequently, the Solicitor concludes that this timeframe of ``the 
foreseeable future is not necessarily reducible to a particular number 
of years. Rather, it relates to the predictability of the impact or 
outcome for the specific species in question.'' In addition, the 
opinion notes that ``definitive quantification is rarely possible . . . 
and not required for a `foreseeable future' analysis'' (Department of 
the Interior Memorandum M-37021, January 16, 2009; available at: http://www.doi.gov/solicitor/opinions/M-37021.pdf).
    In considering the foreseeable future as it relates to the status 
of the western yellow-billed cuckoo, we considered the factors acting 
on the species and looked to see if reliable predictions about the 
status of the species in response to those factors could be drawn. We 
considered the historical data to identify any relevant existing trends 
that might allow for reliable prediction of the future conservation 
status of the species (in the form of extrapolating the trends). We 
also considered whether we could reliably predict any future events 
that might affect the status of the species, recognizing that our 
ability to make reliable predictions into the future is limited by the 
variable quantity and quality of available data. Available population 
information for western yellow-billed cuckoo is limited for determining 
trends because no long-term rangewide status survey has been completed 
and the threats facing the species are variable in intensity and scope 
across the species' range and do not reliably provide a sound basis for 
specific timeframe predictions. The available data do not allow us to 
determine a specific timeframe for the foreseeable future for the 
western yellow-billed cuckoo; therefore, we rely on a qualitative 
assessment of the foreseeable future, in terms of that period of time 
over which we can reasonably predict the future population trends and 
threats to the species, and the likely consequences of those threats 
and trends for the status of the species. We have discussed the 
timeframe for when we have determined the threats are acting on the 
species under each factor in the Summary of Factors Affecting the 
Species and in our Determination sections below.

Montana

    (24) Comment: Montana Fish, Wildlife, and Parks indicated that the 
portion of the State that is shown as being within the DPS has 
historically not been considered within the range of the species. The 
agency indicated that there are only 8 records for western Montana, and 
only 3 of those were found in the past 30 years. They stated that the 
western quarter of the State, west of the Continental Divide, should be 
excluded from the DPS and the species not listed in Montana. This 
comment was also echoed by commenters in Utah, Colorado, and Wyoming 
who wanted their States removed from the DPS.
    Our Response: We are aware of the limited number of sightings for 
the species in western Montana and other areas within the DPS. However, 
we consider yellow-billed cuckoos that are found in the portion of 
Montana west of the Continental Divide are western yellow-billed 
cuckoos based on dispersal and migratory patterns, the large gap 
between this region and southeastern Montana where eastern yellow-
billed cuckoos sporadically

[[Page 60004]]

occur, and criteria used to map the DPS boundary. We based our boundary 
for the DPS on watershed boundaries along the upper elevation areas 
along the Rocky Mountains and on species occurrence records. It would 
be inconsistent and arbitrary to move the boundary or not include the 
western yellow-billed cuckoos in western Montana from the DPS 
regardless of how seldom they are found in the area.

Wyoming

    (25) Comment: The Wyoming Game and Fish Department (WGFD) provided 
information on additional surveys for the Green River and on the 
State's classification of the species as a Tier III Species of Greatest 
Conservation Need with unknown population status and trends due to an 
extremely limited number of detections during targeted survey work 
(WGFD 2010, pp. IV-i-8). The WGFD stated it does not differentiate 
between eastern and western yellow-billed cuckoos but that habitat for 
the species continues to decline primarily as a result of nonnative 
plant (tamarisk) invasion. The WGFD believes that the estimate in the 
proposed rule of five or fewer pairs is an overestimate for the State, 
that it is highly unlikely that western yellow-billed cuckoos breed in 
the State on a consistent basis, and they doubt that the small numbers 
in Wyoming add to population viability of the subspecies. The WGFD 
recommended not designating any critical habitat or land use 
restrictions for the species in the State as most of the potential 
habitat for the species is above 7,000 ft (2,134 meters (m)). The State 
also recommended that ongoing and planned tamarisk removal should not 
be impeded as a result of the Service's final determination.
    Our Response: As stated in the proposed rule and this final rule, 
we agree that the number of western yellow-billed cuckoos nesting in 
Wyoming is small. It is also possible that western yellow-billed 
cuckoos do not nest in the State every year. However, the species most 
likely uses the available habitat as movement corridors or stop-over 
areas during its migration to areas farther north or as foraging areas 
during prey outbreaks. We will consider any information on critical 
habitat during the development of the final critical habitat 
designation. As a result of listing the species, we would expect 
agencies and organizations conducting tamarisk removal projects to do 
so in a manner compatible with conservation of the western yellow-
billed cuckoo (see response to Comment 28 below for additional 
information on tamarisk removal and the conservation of the western 
yellow-billed cuckoo).

California

    (26) Comment: The California Department of Fish and Wildlife 
supports the DPS determination and listing of the western yellow-billed 
cuckoo as the species is already listed as endangered under the 
California Endangered Species Act (CESA) and the populations of the 
species in the State continue to decline. The California Department of 
Fish and Wildlife will continue to provide support in habitat 
management that will encourage recovery for the species in California.
    Our Response: We appreciate the review and support of the 
California Department of Fish and Wildlife. This information will help 
with the development and implementation of the recovery plan for the 
western yellow-billed cuckoo.

Nevada

    (27) Comment: Nevada State Department of Wildlife concurred with 
the Service's concerns regarding declines of the western yellow-billed 
cuckoo and summarized the status of the species in the State. The 
Nevada State Department of Wildlife also provided clarifications and 
updated information on occurrence records and habitat for the State. 
The western yellow-billed cuckoo is a species of conservation priority 
in Nevada, and the Nevada State Department of Wildlife is dedicated to 
conserving the species and improving its habitat whether it is listed 
or not.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. This information will 
also be used in the development of our final critical habitat 
designation and implementation of a recovery plan for the western 
yellow-billed cuckoo.
    (28) Comment: Nevada State Department of Wildlife, Wyoming Game and 
Fish Department, Utah Office of Governor, and Colorado Department of 
Agriculture listed tamarisk invasion as a major threat for western 
yellow-billed cuckoos and their habitat. There is some concern that 
listing the western yellow-billed cuckoo will curtail tamarisk removal 
projects and riparian restoration. Several commenters would like us to 
develop a rule under section 4(d) of the Act for riparian habitat 
restoration.
    Our Response: The Service agrees that tamarisk is a major threat to 
the western yellow-billed cuckoo's habitat. We expect that in areas 
where restoration of native riparian vegetation is possible, removal of 
tamarisk would be considered a net benefit, as native riparian 
vegetation has a greater habitat value for the western yellow-billed 
cuckoo. If western yellow-billed cuckoos are documented to use an area 
slated for tamarisk removal, consultation with the Service may be 
necessary in order to jointly develop appropriate measures to avoid or 
minimize the potential for adverse effects to the western yellow-billed 
cuckoo. However, the process of listing a species as threatened under 
the Act is not designed to curtail projects that have the potential to 
benefit that species, and it is unlikely that beneficial tamarisk 
removal and riparian restoration projects would be negatively impacted 
from listing the western yellow-billed cuckoo. At this time, we are not 
developing a rule under section 4(d) of the Act for this species.

Utah

    (29) Comment: The Director for the Utah Public Lands Policy 
Coordination Office stated that: (a) Utah has made great strides in 
conserving the yellow-billed cuckoo and its habitat and that the 
Service did not characterize the conservation benefits for the yellow-
billed cuckoo as a State-sensitive species adequately in the proposed 
rule; (b) the DPS boundary is arbitrary and includes unoccupied areas 
or migratory habitat; and (c) the Service did not use or consider the 
best available scientific information provided by the Utah Division of 
Wildlife Resources (e.g., Beason 2009, additional Statewide surveys, 
GIS habitat models). The State requested that the Service not list the 
species as endangered or threatened under the Act, as it believes that 
the State is in the best position to manage and conserve the species 
and its habitat.
    Our Response: We commend the State of Utah on the efforts they have 
made in conserving the western yellow-billed cuckoo and its habitat. 
However, we were not supplied with any information by the State on 
specific conservation efforts for the western yellow-billed cuckoo, so 
characterization of the conservation benefits for the species is not 
possible.
    We disagree that the DPS line is arbitrary. The DPS line used to 
separate the western yellow-billed cuckoo from yellow-billed cuckoos in 
the east in the vicinity of Utah was the watershed boundaries along the 
Continental Divide. This boundary does not imply that all areas within 
the DPS contain suitable habitat. In fact, most areas within the DPS do 
not contain suitable habitat for the species because the

[[Page 60005]]

species is restricted to riparian habitat and most of western United 
States is upland habitat covered by forest, desert, shrubland, or 
agriculture. Riparian habitat, by definition, is limited to the banks 
of rivers and streams, and comprises a very small percentage of the 
arid West. The DPS simply shows the outer limits that one can expect to 
find western yellow-billed cuckoos during the breeding season and 
during migration to breeding areas.
    We received GIS data from the State of Utah and excel spreadsheets 
with location data apparently derived from surveys and incidental 
observation within the State. We did not receive the information 
mentioned in the comment letter (e.g., Beason 2009, additional 
statewide surveys, and GIS habitat models) from the State. During the 
development of this proposed rule and in response to the State's 
comment, we independently obtained a copy of the information cited 
(Beason 2009, pp. 1-19). The results of that study, which surveyed 
areas in and around Dinosaur National Park in Utah and Colorado, did 
not confirm any western yellow-billed cuckoo observations. We contacted 
the researcher and they confirmed the information.

Colorado

    (30) Comment: The Colorado Department of Agriculture asked to 
participate in the recovery of the species and is actively removing 
tamarisk and Russian olive and restoring native riparian vegetation.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. This cooperation in 
recovering the species will be important in the development and 
implementation of a recovery plan for the species.
    (31) Comment: The Water Resources Division of the Colorado 
Department of Natural Resources stated that riparian habitat is not 
threatened in Colorado and the western yellow-billed cuckoo should not 
be listed because adequate conservation efforts are underway.
    Our Response: Riparian systems in Colorado have been highly 
impacted by the nonnative, invasive tamarisk and Russian olive. Many of 
the other threats detailed in the proposed and this final rule also 
apply to riparian habitats in that State. In addition, the State of 
Colorado contains only a small portion of both the range and population 
of the western DPS of the yellow-billed cuckoo. Our obligation is to 
review and assess the population status as a whole and not on a 
regional or Statewide basis.

Arizona

    (32) Comment: The Arizona Game and Fish Department supported the 
Service's overall determination of the western yellow-billed cuckoo as 
a DPS, but stated that using morphological information in the DPS 
significance section weakened the argument.
    Our Response: We appreciate this additional information and have 
considered this in our DPS analysis and listing determination. 
Morphological information is just one of the reasons we have determined 
that the western yellow-billed cuckoo is a valid DPS under our policy. 
In order to be more transparent in describing our rationale for our DPS 
determination, we included the morphological information as further 
evidence of the DPS. We conclude that including morphological 
information in the DPS Significance section helps to provide a complete 
picture of the differences between eastern and western yellow-billed 
cuckoos.
    (33) Comment: The Arizona Game and Fish Department stated that they 
did not support listing the western yellow-billed cuckoo as it would be 
counterproductive to current conservation efforts.
    Our Response: Some restoration projects, especially where existing 
poor-quality, tamarisk-dominated habitat that is occupied by western 
yellow-billed cuckoo is being removed and higher quality, willow-
cottonwood or mesquite habitat is being planted, may require 
consultation with the Service in order to jointly develop appropriate 
measures to avoid or minimize the potential for adverse effects to the 
western yellow-billed cuckoo. However, the process of listing a species 
as threatened under the Act is not designed to curtail projects that 
have the potential to benefit that species, and it is unlikely that 
beneficial tamarisk removal and riparian restoration projects would be 
negatively impacted from listing the western yellow-billed cuckoo. It 
is more likely that listing the western yellow-billed cuckoo will 
complement the recovery efforts and potentially provide additional 
sources of funding through section 6 of the Act.
    (34) Comment: The Arizona Game and Fish Department stated that they 
agreed that western yellow-billed cuckoos have declined in Arizona over 
the last 100 years due to habitat loss. The Arizona Game and Fish 
Department went on to state that the western yellow-billed cuckoo 
population and habitat loss have stabilized over the past 30 years and 
populations will increase as a result of riparian restoration on the 
Lower Colorado River. The Arizona Game and Fish Department stated that 
4,000 acres (ac) (1,619 hectares (ha)) of habitat is scheduled for 
restoration, and in locations where restoration has occurred, western 
yellow-billed cuckoos are using the created habitat within 2 years of 
planting. They asked us to add references that show that western 
yellow-billed cuckoos have declined as a result of riparian habitat 
loss and degradation (they cite Noss et al. 1995). They also stated 
that there was a need to quantify the benefits of riparian habitat 
restoration to western yellow-billed cuckoos.
    Our Response: Most locations in Arizona that have western yellow-
billed cuckoo populations have not been surveyed regularly enough to 
provide population trend information. The only two locations with semi-
regular monitoring (the Bill Williams River and the San Pedro River) 
both show downward trends in western yellow-billed cuckoo populations. 
The western yellow-billed cuckoo population on the Colorado River on 
the Arizona-California border appears to be increasing with the 
riparian restoration activities at that location. More years of survey 
data are needed to determine whether or not that is a long-term trend.
    While the results of the riparian restoration work on the Lower 
Colorado River are promising, based on the scientific information 
available we conclude that it is too soon to tell what effect this 
planned restoration will have on western yellow-billed cuckoo 
populations. As population goals for recovery of the western yellow-
billed cuckoo have not yet been established, it is not known what the 
overall effect of an addition of the 40 or so pairs of western yellow-
billed cuckoos on the Lower Colorado River will have on the overall 
status of the yellow-billed cuckoo in the West. In addition, so far it 
appears that western yellow-billed cuckoos nesting on restoration sites 
tend to have lower nesting success than western yellow-billed cuckoos 
nesting in areas still containing healthy native riparian forests 
(McNeil et al. 2012, p. 53).
    We have added citations in this final rule that show that western 
yellow-billed cuckoos have declined as a result of riparian habitat 
loss and degradation (see section in Factor A discussion). We have 
concluded that this is a well-documented pattern in California and 
Arizona.
    To date it is difficult to quantify the benefit of riparian habitat 
restoration to western yellow-billed cuckoo populations. Most 
restoration efforts are carried out on a small scale in

[[Page 60006]]

comparison to the home-range size of the western yellow-billed cuckoo. 
In the Kern River Valley where riparian restoration has been ongoing 
for the past 30 years, the western yellow-billed cuckoo population has 
stabilized but has not increased. Along the Sacramento River, where 
several thousands of acres of riparian restoration has occurred over 
the past 30 years, the western yellow-billed cuckoo population has 
continued to decline. The one location where restoration work is 
appearing to have a positive effect on western yellow-billed cuckoo 
populations is along the Lower Colorado River, but this work is very 
recent and the long-term effect on western yellow-billed cuckoo 
populations there is still unknown. The largest positive effects for 
western yellow-billed cuckoos have occurred in the reservoir draw-down 
zones (e.g., Isabella Reservoir and Elephant Butte Reservoir), when 
riparian habitat has regenerated during droughts. These benefits are 
ephemeral, as the habitat will be inundated and lost when wet periods 
return.

New Mexico

    (35) Comment: New Mexico Game and Fish requested a delay in listing 
so that more research can be conducted in New Mexico to better define 
the DPS line. They state that data from e-bird [Cornell Lab of 
Ornithology] and New Mexico Ornithological Society (2007) do not 
support difference in migration timing between eastern and western New 
Mexico, and cite Sechrist and Best (2012) to say that cuckoos from 
Pecos and Rio Grande had the same migration timing and direction. 
Twenty additional commenters questioned the DPS' status, indicating 
that the DPS was neither discrete nor significant, without providing 
additional information to support their comments.
    Our Response: In making listing determinations under the Act, we 
are to rely solely on the best scientific and commercial data currently 
available. Our DPS policy outlines the criteria for determination of 
whether a segment of a vertebrate species population qualifies as a 
DPS. In reviewing the most current information available, we have 
determined that the western DPS of the yellow-billed cuckoo is valid 
and meets the criteria outlined in our policy. As we stated above in 
the Distinct Vertebrate Population Segment Analysis section, we 
understand that the area in southern New Mexico and western Texas is an 
area where there may be overlap between both eastern and western 
populations of the yellow-billed cuckoo. Our DPS policy allows for some 
``mixing'' of populations, and absolute separation is not required for 
a population segment of a species to be considered a DPS (61 FR 4723-
4725; February 7, 1996). The location and boundaries of a western DPS 
for the yellow-billed cuckoo has been under consideration since the 
Service first received a petition to list the species in 1986. As 
detailed in the proposed rule and this final rule, yellow-billed 
cuckoos on the Rio Grande above Big Bend are more similar to yellow-
billed cuckoos in the West than they are to yellow-billed cuckoos in 
the East. Yellow-billed cuckoos on the Pecos River and in eastern New 
Mexico are more similar to yellow-billed cuckoos in the East than they 
are to yellow-billed cuckoos in the West. Peer reviewer Dr. Janice 
Hughes, the only avian taxonomist who has conducted research on yellow-
billed cuckoos in this region, believes that the highlands between the 
Rio Grande and the Pecos River are the dividing line between eastern 
and western yellow-billed cuckoos.
    As discussed above in Comment 14, one peer reviewer measured 
yellow-billed cuckoos on the Rio Grande and Pecos River and found the 
Rio Grande yellow-billed cuckoos to be larger than those on the Pecos 
River. The differences were not statistically significant, but the 
sample sizes were small, so a significant difference would not be 
expected. Also the measurements were not taken in a similar way as 
measurements taken by Banks (1988, pp. 473-477) and Franzreb and Laymon 
(1993, pp. 17-28) so they cannot be compared to measurements from those 
studies. At this time, a definitive study has not been completed on 
morphology, genetics, or behavior (including migration timing) 
comparing yellow-billed cuckoos on the Rio Grande and Pecos River. 
Until that is done, the best available science on the subject is in 
Franzreb and Laymon (1993, pp. 17-28) and in the opinion of Dr. Janice 
Hughes, which divides eastern and western yellow-billed cuckoos along 
the highlands separating the Rio Grande and the Pecos Rivers.
    (36) Comment: New Mexico Game and Fish and several other commenters 
suggest that western yellow-billed cuckoos have been found at 
elevations higher than reported in the proposed rule.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. Most of these higher 
elevation sightings in the Rocky Mountains are likely of migrant 
western yellow-billed cuckoos, though a few may refer to nesting pairs.
    (37) Comment: New Mexico Game and Fish would like us to develop a 
rule under section 4(d) of the Act to allow for economic and 
agricultural growth in conjunction with conservation efforts, 
especially while developing the State's comprehensive conservation 
program.
    Our Response: Section 4(d) of the Act allows the Secretary the 
discretion to issue such regulations as [s]he deems necessary and 
advisable to provide for the conservation of a species. The Service's 
standard policy (under 50 CFR 17.31(a)) for issuing prohibitions for 
threatened species is to apply all the prohibitions of an endangered 
species to a threatened species unless otherwise revoked by issuance of 
more specific prohibitions. In the case of the western yellow-billed 
cuckoo, we are in the process of reviewing whether the ``standard'' 
prohibitions apply or whether more specific prohibitions are 
appropriate. If we determine that more specific prohibitions apply and 
that they are necessary and advisable to provide for the conservation 
of the western yellow-billed cuckoo, we will issue a proposed rule 
under section 4(d) of the Act for public comment. However at this time, 
we do not have and the commenter did not provide enough information on 
whether a section 4(d) rule for agricultural activities is appropriate. 
We would be available for future discussion on potentially developing 
measures to maximize the conservation value of agricultural practices 
and develop some type of conservation mechanism with the commenter in 
the future; however, due to time constraints for developing a final 
rule we cannot currently develop and implement such measures.
    (38) Comment: New Mexico Game and Fish stated that there was a 
large discrepancy between population estimates of 100-155 pairs for 
western New Mexico listed in the proposed rule and 7,000 individuals in 
the State as reported by the Partners in Flight program (PIF 2014).
    Our Response: The Partners in Flight Web site for New Mexico (New 
Mexico Partners in Flight 2014, entire) reports that the western 
yellow-billed cuckoo population in New Mexico is much less than 1 
percent of the total species population of 9.2 million, or less than 
92,000 yellow-billed cuckoos. This was then converted to 0.1 percent of 
the global population, which should have been 9,200 yellow-billed 
cuckoos, but was transcribed or rounded to 7,000 yellow-billed cuckoos 
or 3,500 pairs of yellow-billed cuckoos. This is a questionable method 
to determine the yellow-billed cuckoo population for a State and should 
not be accepted as

[[Page 60007]]

valid. This is much higher than Howe's (1986, pp. 1-16) estimate of 
1,000 pairs of yellow-billed cuckoos Statewide in New Mexico and 315 
pairs for the western half of the State. Howe's estimates were made 
based on an estimate of available habitat and an understanding that 
western yellow-billed cuckoo territories were much smaller than they 
actually are, leading to an overestimate for New Mexico. It is likely 
that fewer than 1,000 pairs of western yellow-billed cuckoos existed in 
New Mexico in 1986. The population for western yellow-billed cuckoos 
estimated for the State by Hughes (1999, p. 19) was 100 to 200 pairs. 
The Service's estimate of 100 to 155 pairs is based on the best 
available science of surveys conducted over the past 10-15 years.
    (39) Comment: The New Mexico Department of Agriculture asked that 
the Service address management of the western yellow-billed cuckoo as a 
watershed health issue and not list the species.
    Our Response: Listing of the western yellow-billed cuckoo under the 
Act is based on the species' population status and trends, and the 
threats to the species. Recovery of a species will be based on criteria 
developed by the Recovery Team once it becomes established. Solving the 
threats to the western yellow-billed cuckoo is an important part of the 
recovery process, and watershed health will be very important when 
developing recovery criteria and implementing recovery actions.
    (40) Comment: New Mexico Interstate Stream Commission commented 
that because western yellow-billed cuckoos are listed by New Mexico 
Fish and Game as a ``Species of Greatest Conservation Need'' the 
Service should not state that it has no protective status in New 
Mexico.
    Our Response: Although the identification of the western yellow-
billed cuckoo by the State of New Mexico as a ``Species of Greatest 
Conservation Need'' is encouraging, this designation is for planning 
purposes and provides no regulatory protective status for the species 
in New Mexico. Any actions or conservation measures implemented for the 
cuckoo as a result of its State status would be recommendations and 
voluntary, and would not ensure that actions or measures would be 
implemented.
    (41) Comment: New Mexico Interstate Stream Commission states that 
if the western yellow-billed cuckoo is listed, we should develop a rule 
under section 4(d) of the Act for ongoing and future water management 
in the State. Other commenters expressed concern about the impact of 
listing the western yellow-billed cuckoo on water delivery.
    Our Response: The disruption and changes to ``natural'' river and 
stream processes, which help the development and regeneration of 
riparian vegetation, have been identified as a threat to the species. 
The majority of streams and water delivery facilities within the range 
of the western yellow-billed cuckoo are at least partly managed by 
Federal entities or proposed activities that would have a Federal 
nexus. As a result, these Federal agencies have an obligation under 
section 7 the Act to conserve endangered or threatened species and 
their habitat. Section 4(d) of the Act states that the Secretary shall 
issue such regulations as [s]he deems necessary and advisable to 
provide for the conservation of any threatened species. New projects on 
Federal land or funding by the Federal government will be subject to 
section 7 consultations, as will reauthorization of Federal projects. 
Because of the interrelatedness between water management, the health of 
riparian habitat, and the dependence of riparian habitat by the western 
yellow-billed cuckoo, we are not currently considering a rule under 
section 4(d) of the Act for this species to limit the prohibitions of 
the Act for ongoing and future water management activities.
    (42) Comment: The New Mexico Interstate Stream Commission stated 
that because humans do not have control over caterpillar population, 
lack of caterpillars should not be listed as a threat.
    Our Response: Caterpillar and other insect populations can be 
affected by health of the riparian habitat, tree and shrub species in 
the riparian zone, and pesticide use (e.g., pesticide drift into the 
riparian zone or applying pesticides directly on the riparian zone). 
All of these factors are influenced by human activities at some level. 
Lack of an adequate food supply is a major threat for the western 
yellow-billed cuckoo.
    (43) Comment: The New Mexico Interstate Stream Commission stated 
that climate change effects have so far not been as great as they are 
predicted to be in the future.
    Our Response: We appreciate the New Mexico Interstate Stream 
Commission's comments on climate change and have considered them in our 
listing determination. The New Mexico Department of Game and Fish in 
their Comprehensive Wildlife Conservation Strategy for New Mexico 
(2006) stated that ``[t]he effects of climate change on ecosystems and 
species are likely to be exacerbated in areas that have already been 
substantially affected by human activities such as habitat loss and 
fragmentation, air and water pollution, and the establishment of 
invasive species.'' They also state that riparian habitat is one of the 
key habitats that may have the highest risk of being altered by 
synergistic effects of factors that influence habitats (New Mexico 
Department of Game and Fish. 2006, pp. 74-79).
    We agree that climate change projections and prediction can be 
difficult due to the availability of information and variability of 
climate and habitat conditions over time. However, in a study looking 
at the recent effects of climate change on temperature and 
precipitation over the past 36+ years (1970-2006), Enquist et al. 
(2008, pp. 1-32) found that in New Mexico, observed climate-linked 
effects include declines in snowpack, earlier peak stream flows, forest 
mortality, and population declines in some sensitive species. To avoid 
issues of uncertainty associated with future climate change 
predictions, the study used a retrospective approach that analyzed 
changes over time. Their study found that: (1) 93 Percent of New 
Mexico's watersheds have become relatively drier over the 36+ year 
period; and (2) snowpack has declined in 98 percent of New Mexico's 
major mountain ranges and the timing of peak streamflow from snowmelt 
in the State is an average of one week earlier than in the 1950s. In 
addition, the study found that the watersheds with the highest numbers 
of sensitive species tend be those showing the greatest increase in 
moisture stress or drying and that these watersheds have already 
experienced climate change-linked ecological effects. We have 
determined that the long-term effects of climate change are and will 
continue to be a factor in sensitive species or habitat conservation 
regardless of any short-term trends.
    (44) Comment: The New Mexico Interstate Stream Commission commented 
that western yellow-billed cuckoos may rely on tamarisk, like 
southwestern willow flycatchers do, but even if true, tamarisk beetles 
should not be listed as a threat to western yellow-billed cuckoos.
    Our Response: Western yellow-billed cuckoos do not rely on tamarisk 
in the same way that southwestern willow flycatchers do. Western 
yellow-billed cuckoos may on rare occasions nest in tamarisk, but they 
forage almost entirely in native riparian habitat. Western yellow-
billed cuckoos are primarily dependent on large caterpillars, which 
depend on cottonwoods and willows and are not found on tamarisk. On the 
other hand, southwestern willow

[[Page 60008]]

flycatchers feed on small flying insects and both nest and forage in 
tamarisk as long as water or super-saturated soil is in the vicinity of 
the nest and flying insects are available. In areas where the hydrology 
is still intact and will support native riparian habitat, the tamarisk 
beetle could assist in the restoration of the riparian zone. In areas 
that can no longer support willows, cottonwoods, and mesquite, the 
beetle could suppress the tamarisk to the point that western yellow-
billed cuckoos will no longer use the habitat. In this latter case, the 
tamarisk beetle could be considered a threat, as spontaneous 
regeneration of native vegetation is difficult due to the degraded 
nature of the habitat and disrupted hydrologic conditions.

Texas

    (45) Comment: The Deputy Commissioner for the Texas General Land 
Office stated that listing the western yellow-billed cuckoo would lead 
to increased economic costs and delay in the development of oil, gas, 
wind, and solar projects for the State. Royalties collected by the 
State from such activities would be reduced, and this would indirectly 
affect funds available for Texas public schools. The Deputy 
Commissioner also stated that the Service's analysis of the information 
is not sufficient to support listing and that the Service is only 
moving forward at this time with listing due to its settlement with 
outside litigants and not because listing is warranted under the Act.
    Our Response: Under section 4(a)(1) of the Act, we are to determine 
if a species is endangered or threatened based on one of five listing 
factors. Economics or loss of revenue is not one of the factors used in 
determining if a species should be listed. Although we understand that 
listing a species as either endangered or threatened causes some 
regulatory oversight and the potential need for consultation, we are 
obligated to make such determinations solely on the threats facing the 
species or its habitat. Listing a species does not mean projects cannot 
proceed, it only means they must be implemented in a manner that still 
conserves the species and its habitat. In addition, because the species 
occurs in riparian habitat along streams, it is most likely that 
projects involving the development of oil, gas, wind, and solar 
projects would not result in significant direct impacts on the species, 
as these projects typically do not occur in riparian corridors.
    We believe we have used the best scientific and commercial 
information available in coming to our decision to list the western 
yellow-billed cuckoo as a threatened species. The western yellow-billed 
cuckoo has been a candidate for listing since 2001. Although we were 
litigated to develop a timeframe for moving forward on the review of 
candidate species, the Act requires us to promptly make our evaluations 
for species considered candidates. Any settlements reached as a result 
of litigation took into consideration what was best for conservation 
and protection of candidate or sensitive species and were not dictated 
by litigants.
    (46) Comment: The Texas Comptroller of Public Accounts stated that 
they were concerned that listing of the western yellow-billed cuckoo 
would have potential economic impacts on landowners, businesses, and 
communities within the boundary of the DPS in Texas. The Comptroller 
also stated that additional information is needed on the status of the 
species and that the benefits of ongoing conservation efforts for the 
southwestern willow flycatcher are adequate to conserve the western 
yellow-billed cuckoo.
    Our Response: See our response to Comment 45 above for economic 
considerations in the listing process and our view on the information 
used to determine the status of the species. In regard to conservation 
measures for the southwestern willow flycatcher being adequate to 
conserve the western yellow-billed cuckoo, we disagree. Although the 
range of the southwestern willow flycatcher and the western yellow-
billed cuckoo overlap to some degree and they are found in similar 
habitats, that is not always the case and the two species have very 
different habitat and ecological requirements.

Public Comments

Comments on ``Endangered'' vs. ``Threatened'' Status

    (47) Comment: More than 12,000 commenters stated that the western 
yellow-billed cuckoo should be listed as ``endangered'' rather than the 
proposed ``threatened'' status.
    Our Response: The Act defines an endangered species as any species 
that is currently ``in danger of extinction throughout all or a 
significant portion of its range'' and a threatened species as any 
species ``that is likely to become endangered throughout all or a 
significant portion of its range within the foreseeable future.'' Based 
on the available information on the range and distribution of the 
species, the immediacy and severity of threats facing the species, the 
persistence of the species throughout most of its historical range, and 
the rate of decline of the species, we have determined that the western 
yellow-billed cuckoo meets the definition of a threatened species 
rather than an endangered species under the Act. See the Determination 
section below for additional discussion of our rationale for a 
``threatened'' determination.
    (48) Comment: One commenter stated that the entire species (both in 
the eastern and western United States) should be listed as a threatened 
species under the Act.
    Our Response: Our analysis in the rule is limited to the petitioned 
entity (western United States), and we have not evaluated the status of 
the eastern population of the yellow-billed cuckoo. Should new 
information become available about the status, trends, or threats 
facing the eastern population of the yellow-billed cuckoo, we would 
evaluate that information at that time, as budget and staffing allow.

Comments on the Distinct Population Segment

    (49) Comment: One commenter stated that the western DPS of the 
yellow-billed cuckoo also meets significance because of persistence of 
population on unusual or unique ecological setting (i.e., streamside 
riparian areas in arid West).
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. Yellow-billed cuckoos in 
both the East and West nest in riparian habitat. The species in the 
eastern United States has a wider range of habitat use, including 
nesting in upland broadleaf woodlands that are not available to the 
species in the West. We do not consider riparian habitat as unusual or 
unique habitat under our DPS policy.
    (50) Comment: Several commenters stated that there had been too 
many studies on the yellow-billed cuckoo and other commenters stated 
that there had been too few studies. Genetics and taxonomic uniqueness 
was a suggested area of study by one commenter.
    Our Response: Although there has been much focus on research on the 
yellow-billed cuckoo, most of these efforts have been on survey and 
monitoring. Additional research activity is a common response once a 
species is identified for listing under the Act. However, other 
information, such as migratory routes, timing, and wintering ground 
use, has been scarce, and we agree that there are many areas of the 
life history, ecology, genetics, and taxonomy of the western yellow-
billed cuckoo that need further research. However, in making our 
listing

[[Page 60009]]

determination, we must use the best scientific and commercial data 
available in coming to any conclusions on whether the species should be 
listed.
    (51) Comment: One commenter stated that the eastern and western 
yellow-billed cuckoos may be interbreeding on the wintering grounds.
    Our Response: Because yellow-billed cuckoos do not breed on their 
wintering grounds in South America, it is not plausible that they are 
interbreeding during this time.
    (52) Comment: Several commenters do not believe that differences in 
migration timing between eastern and western yellow-billed cuckoos are 
evidence that there is a marked separation between the two groups.
    Our Response: The proposed rule and this final rule identify a wide 
variety of factors that separates western yellow-billed cuckoos from 
the rest of the taxon. Migration timing is one of these factors. In 
general, migration timing is governed by forces of natural selection 
that operate over long periods of time. Given that populations of 
eastern and western yellow-billed cuckoos arrive on their breeding 
grounds, at the same latitude, a month or more apart is significant and 
is most likely governed by evolutionary forces. This pattern of 
consistently arriving on their respective breeding grounds a month or 
more apart is different from year to year, and variations in weather 
may lead to individual birds arriving on the breeding grounds a few 
days earlier or later than normal. Please see the Distinct Vertebrate 
Population Segment Analysis section, above, for further explanation of 
our rationale for determining that the western yellow-billed cuckoo is 
a valid DPS.
    (53) Comment: Three commenters stated that they believed that the 
species was not distinct.
    Our Response: The Service is listing a DPS rather than a species or 
subspecies. As detailed in the Taxonomy section under Background and 
Discreteness section of the Distinct Vertebrate Population Segment 
Analysis above, the western DPS of the yellow-billed cuckoo coincides 
with the range of the proposed subspecies boundary of the ``western'' 
yellow-billed cuckoo (Coccyzus americanus occidentalis). However, 
because there is some scientific uncertainty to the validity of the 
subspecies, the Service is not listing the subspecies, but rather is 
listing the western DPS.

Population Numbers

    (54) Comment: Twelve commenters stated that there have been recent 
declines of breeding populations of western yellow-billed cuckoos in 
various locations of California, Arizona, New Mexico, and Colorado. 
Several additional commenters provided their personal observations in 
Arizona, New Mexico, and Colorado, which indicated that local 
populations of western yellow-billed cuckoos have declined over the 
last 30 years.
    Our Response: These additional observations support the information 
that we presented in the proposed and this final listing rule regarding 
population trends for the species in these States.
    (55) Comment: Nine commenters stated that the western yellow-billed 
cuckoo was not threatened, that they were either not declining or not 
declining at a rate that would lead to extinction, and that yellow-
billed cuckoos were doing well in the East.
    Our Response: Yellow-billed cuckoos in the East are declining at 
1.4 to 1.6 percent per year over the past 43 years (Sauer et al. 2012, 
entire). Based on the best available science and data, western yellow-
billed cuckoos have declined dramatically throughout their range over 
the past 150 years. This decline has continued in recent years, and 
with very few exceptions (e.g., the South Fork Kern River Valley, where 
the small populations appears to be stable, and the Lower Colorado 
River, where the population is showing an increase), it is continuing 
to decline. The data and information we have used in this final rule 
lead us to conclude that the western DPS of the yellow-billed cuckoo is 
threatened with extinction. No data were presented by commenters that 
show increasing population trends or population numbers that contradict 
our conclusion that the western yellow-billed cuckoo is a threatened 
species.
    (56) Comment: Eight comments were received on data analysis and 
proposed rule preparation. Issues raised included the lack of a 
population viability analysis, the lack of a global population 
analysis, inadequate citations support for statements made in the 
document, not providing the names of Service biologists who reviewed 
data, taking a California-centric approach in the proposed rule, and 
only providing range maps showing the breeding season's range.
    Our Response: Current available scientific data on the western 
yellow-billed cuckoo are not sufficient to conduct a meaningful 
population viability analysis. Too many of the important parameters are 
not known well enough for the results to be reliable. The State-by-
State and region-by-region analysis of the entire range of the western 
DPS of the yellow-billed cuckoo is essentially a global population 
analysis. Every attempt has been made to be certain that citations 
support the statements made in the proposed and this final rule. Where 
we do not have specific reference support we explained our rationale 
based on the best available information on coming to any conclusions. 
It is not Service policy to list names of document authors or those who 
reviewed data. Much of the research that has been conducted on the 
western yellow-billed cuckoos has occurred in California, which may 
lead readers to the opinion that the proposed rule is California-
centric. The winter range of the western yellow-billed cuckoo is not 
well-known and therefore could not be mapped.
    (57) Comment: Several commenters stated that western yellow-billed 
cuckoo survey data were missing from the proposed rule or the data have 
been updated after the proposed rule was published (e.g., Utah, New 
Mexico, Arizona).
    Our Response: We have considered this updated information in our 
final listing determination, and the information will be considered in 
the final critical habitat designation and future recovery plan.
    (58) Comment: One commenter asked why western yellow-billed cuckoos 
are continuing to decline with all the habitat protection that has been 
happening over the past 25 years.
    Our Response: It is true that significant habitat protection and 
restoration has been underway for the past 25 to 30 years. Much of this 
work has been done on a project-by-project basis or on a smaller scale 
than will likely be necessary for the stabilization and recovery of the 
species. Recovery goals for western yellow-billed cuckoos and their 
habitat will be set in the recovery plan for the species as it is 
developed. In some areas, such as the Sacramento River, western yellow-
billed cuckoo populations have continued to decline even though 
significant habitat restoration activities have been carried out. Aging 
of the existing habitat and increased occupancy by invasive species, 
especially edible fig (Ficus carica) and black walnut (Juglans sp.), 
may be contributing factors. In addition, effects of pesticides on 
caterpillars may be a factor in many areas. It is indeed a concern that 
western yellow-billed cuckoos have declined even in areas where habitat 
has been protected and has either been stabilized or has increased. 
Further research is needed to determine the exact causes of this 
continued decline.
    (59) Comment: One commenter questioned our science and asked that

[[Page 60010]]

all information on western yellow-billed cuckoo populations and 
declines should be removed from the discussion in the rule.
    Our Response: The information on western yellow-billed cuckoo 
population and declines presented in the proposed and this final rule 
is based on the best available science. In making listing 
determinations under the Act, we must conduct a five-factor analysis on 
the threats facing a species based on the best available scientific and 
commercial information. In some cases the information on a species' 
status and trends is unclear or the information available is sparse. In 
these cases, we nonetheless must base our determinations on the best 
available information. In the case of the western yellow-billed cuckoo, 
the available information on population status and declines is 
appropriate to include in our discussion of the status of the species 
and in making our final determination on the species' listing status of 
threatened.
    (60) Comment: Numerous commenters have concerns regarding survey 
methods, comparison of survey data, accuracy of survey counts, and 
changes in survey protocols over the years for the yellow-billed 
cuckoo.
    Our Response: Please see response to Comment 5 above for our 
response to concerns over the survey protocols and other survey 
concerns.

Comments on Habitat Use and Species Information

    (61) Comment: Several commenters indicated that habitat use 
separates eastern and western yellow-billed cuckoo populations. One 
commenter further stated that in eastern New Mexico and western Texas, 
yellow-billed cuckoos from eastern populations nest in monotypic stands 
of tamarisk, while western yellow-billed cuckoos do not. The commenter 
did not provide any specific study but based their statement on 
observations.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. Additional research on 
this topic would be valuable. The information provided will also be 
considered further in recovery planning. See response to Comment 6, 
above, for additional information.
    (62) Comment: One commenter stated that yellow-billed cuckoos 
select much different habitat in the East than they do in the West.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. We recognize that habitat 
use is different between eastern and western populations of yellow-
billed cuckoos. See our response to Comment 6, above, for additional 
discussion on habitat use in the eastern and western United States.
    (63) Comment: One commenter stated that understory vegetation was 
as important to western yellow-billed cuckoos as overstory vegetation.
    Our Response: As stated in the proposed listing rule and cited by 
reference in this final rule, the amount, size, composition, and 
density of habitat are important habitat selection criteria for the 
western yellow-billed cuckoo. Although habitat characteristics vary 
across the range of the species, understory vegetation is an important 
characteristic for the species. For example, along the Sacramento 
River, the size of the site, the amount of riparian habitat in each 5-
mi (8-km) river segment, and the presence of young woody vegetation 
(understory) were the most important factors in a model explaining the 
distribution of yellow-billed cuckoo pairs (Halterman 1991, p. 30). 
Along the lower Colorado River, in a comparison of occupied versus 
unoccupied habitat, yellow-billed cuckoos were found at sites with 
denser riparian vegetation and more variation in vegetation density, 
and less tamarisk and shrubby vegetation, compared to unoccupied sites 
(Johnson et al. 2012, pp. 15-17).
    (64) Comment: Two commenters stated that western yellow-billed 
cuckoos do not need large blocks of riparian habitat, and one commenter 
stated that they do not need riparian habitat at all. Another commenter 
stated that habitat use and patch size needed were not well-defined.
    Our Response: The use of large blocks of riparian habitat for 
yellow-billed cuckoos in western United States is well-documented. 
Recent studies of habitat use using radio telemetry have shown that a 
western yellow-billed cuckoo will use 100 ac (40 ha) of habitat or more 
during the breeding season. See our response to Comment 63, above, for 
additional discussion on habitat use by the western yellow-billed 
cuckoo.
    (65) Comment: Eight commenters stated that yellow-billed cuckoos 
were providing ecosystem services by eating caterpillars.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. Yellow-billed cuckoos in 
eastern United States, where they are more abundant, may be numerous 
enough to control caterpillar populations. It is unlikely that the 
small populations in the West are able to have an impact on the 
caterpillar population.

Comments on Specific Habitat Areas

    (66) Comment: Two commenters stated that water transfers from 
agriculture to urban areas and from the Kern River Valley to southern 
California were threats to the western yellow-billed cuckoo.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. We have identified the 
disruption of ``natural'' stream hydrology and flows as a threat to the 
species. The occupied habitat for the western yellow-billed cuckoo in 
the South Fork of the Kern River is upstream of the control facilities 
at Lake Isabella. Large-scale water diversions from the Kern River do 
not take place until downstream of the dam. For the Kern River, the 
majority of water available for potential transfer to southern 
California is part of a ground water storage program (underground water 
bank). Any actions associated with this transfer of water would not 
affect occupied western yellow-billed cuckoo habitat upstream.
    (67) Comment: One commenter stated that western yellow-billed 
cuckoo habitat was declining along the Verde River in Arizona.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. This is consistent with 
the pattern of habitat loss and degradation described in the Factor A 
section of this document.
    (68) Comment: Several commenters pointed out the importance of the 
San Pedro River (AZ) and the Gila River (AZ and NM) for western yellow-
billed cuckoos.
    Our Response: We appreciate this additional information and have 
considered this in our listing determination. The San Pedro River has 
the largest population of western yellow-billed cuckoos in Arizona and 
one of the largest in the western DPS, and the Gila River also contains 
an important population of western yellow-billed cuckoos in both New 
Mexico and Arizona.
    (69) Comment: Commenters in Arizona, Wyoming, Montana, and Colorado 
all stated that their State was fringe habitat for the western yellow-
billed cuckoo and did not contribute to the conservation of the 
species.
    Our Response: Southwestern Wyoming and western Montana are at the 
northeastern edge of the range of the western DPS of the yellow-billed 
cuckoo. These areas at the margin of the

[[Page 60011]]

range can be very important in monitoring the health of a population, 
as they may become unoccupied when the population is declining and 
reoccupied when the population is increasing. Habitat in Colorado is 
important for the conservation of western yellow-billed cuckoos not 
only for the small breeding population, but more importantly for 
habitat for migrating western yellow-billed cuckoos that nest to the 
north in Idaho. Arizona is at the center of the range of the western 
DPS of the yellow-billed cuckoo, and habitat there is vital to the DPS' 
survival.
    (70) Comment: One commenter mentioned that land in New Mexico is 
being retired from agriculture, not converted to agriculture.
    Our Response: We appreciate the commenter's statement, but they did 
not provide specific information on the subject. Our research on 
agricultural land use changes for New Mexico also did not provide any 
specific information on the extent, location, or nature of agricultural 
lands being converted or retired; however, it has been estimated that 
over 90 percent of riparian habitat within New Mexico has been lost 
during the last century (Krzysik 1990, entire).
    (71) Comment: One commenter stated that recent information shows 
that yellow-billed cuckoos that breed in the eastern United States then 
move to northwestern Mexico and breed as was speculated in another 
paper is wrong.
    Our Response: Researchers (Rowher and Wood 2013 pp. 243-250) have 
recently retracted an earlier assertion that yellow-billed cuckoos bred 
in eastern North America and then flew to northwestern Mexico and bred 
a second time. We have revised our discussion on the subject in this 
final rule.

Comments on Factors Affecting the Species

    (72) Comment: Three commenters addressed the threat of proposed 
mining operations in the Patagonia Mountains in south-central Arizona, 
the declining water table, and the decline in western yellow-billed 
cuckoo populations in that area.
    Our Response: We concur that gravel mining and other mining 
activity can impact the western yellow-billed cuckoo and its habitat. 
This is a localized threat that is discussed under Factor A section of 
the final rule. See Factor A. The Present or Threatened Destruction, 
Modification, or Curtailment of its Habitat or Range, for additional 
discussion on the threat of mining.

Grazing Impacts

    (73) Comment: One commenter indicated that impacts to livestock 
ranchers are unequal east and west of the DPS line, making for unfair 
economic competition.
    Our Response: According to the Act, we are to make listing 
determinations solely on the basis of the best scientific and 
commercial data available. The economic impact of listing is only 
considered when designating critical habitat for a listed species. We 
will consider the incremental impacts on livestock grazing operations 
during our designation of critical habitat for the species.
    (74) Comment: One commenter stated that livestock grazing improves 
the ecological condition of riparian systems, while another stated that 
in the past cattle grazing was destructive, but that it was no longer a 
problem in riparian habitats.
    Our Response: We identified past and current grazing activity in 
riparian areas occupied by the species to be a threat to the western 
yellow-billed cuckoo. We are not aware of any science or data that 
support the statement that livestock grazing improves the ecological 
condition of riparian systems. The western yellow-billed cuckoo nesting 
habitat is structurally complex with tall trees, a multistoried 
vegetative understory, low woody vegetation (Halterman 1991, p. 35), 
and higher shrub area than sites without western yellow-billed cuckoos 
(Hammond 2011, p. 48). Livestock grazing alters understory vegetation, 
trampling existing vegetation, reducing density, or eliminating new 
growth in riparian areas and thereby hampering recruitment of woody 
species that, when mature, provide nest sites. Furthermore, the 
relatively cool, damp, and shady areas favored by western yellow-billed 
cuckoos are those favored by livestock over the surrounding drier 
uplands. This can concentrate the effects of habitat degradation from 
livestock in western yellow-billed cuckoo habitat (Ames 1977, p. 49; 
Valentine et al. 1988, p. 111; Johnson 1989, pp. 38-39; Clary and Kruse 
2004, pp. 242-243).
    Controlled and seasonal livestock grazing can occur in a manner 
that is compatible with the management of western yellow-billed cuckoo 
habitat, although effective monitoring and management would most likely 
be needed especially in the more arid regions of the Southwest. Current 
grazing management practices are less harmful to riparian systems than 
some past practices. However, especially during droughts, riparian 
zones can still be grazed in a manner that may degrade riparian habitat 
attributes and prevent long-term health and persistence of these 
systems.

Habitat Loss

    (75) Comment: One commenter stated that just because California 
destroyed its riparian habitat that other States should not bear the 
burden of listing.
    Our Response: Listing determinations are based on habitat and 
population trends and threats. A severe threat in one portion of the 
range can lead to listing throughout the range. However, for the 
western yellow-billed cuckoo, there is abundant evidence that riparian 
habitat has been lost throughout the range of the species. This loss is 
greater in some areas than in others, but the threats to the western 
yellow-billed cuckoo through habitat loss, as detailed in this final 
rule, are widespread and not limited to California (see Summary of 
Factors Affecting the Species for additional discussion of threats 
affecting the species).
    (76) Comment: Three commenters stated that the proposed rule does 
not show a causal link between habitat loss and population declines.
    Our Response: We disagree. The data and information utilized for 
the proposed and final rules show a strong link between the declines in 
the western DPS of the yellow-billed cuckoo and riparian habitat. The 
Historical and Current Status section of the proposed rule, which is 
incorporated (by reference) into this final rule, lists numerous 
examples where riparian forests were removed and the western yellow-
billed cuckoo population declined. In addition, literature is 
referenced in the rule that provides abundant additional supporting 
examples connecting loss of habitat to western yellow-billed cuckoo 
population declines. Factor A under the Summary of Factors Affecting 
the Species section in this final rule details the threats to riparian 
habitat both in the past and present.
    (77) Comment: Three commenters said that riparian habitat may have 
declined by 90 percent in the past, but that it now is increasing. One 
commenter said that there is no evidence that habitat is being 
adversely affected by natural or manmade factors.
    Our Response: Riparian habitat is increasing in some areas, but at 
the same time is decreasing or becoming less suitable in other areas. 
The overall trend throughout the range of the western yellow-billed 
cuckoo is not known. Simply measuring the extent of riparian habitat 
from one time period to

[[Page 60012]]

the next will not tell what the effect on western yellow-billed cuckoos 
will be. Tens of thousands of acres of riparian habitat still exist on 
the Lower Colorado River, but almost all of it, with the exception of 
the recently planted restoration sites, is comprised only of tamarisk 
that does not support western yellow-billed cuckoos. Tamarisk 
domination has occurred on many river systems through the range of the 
western yellow-billed cuckoo. Along other streams like the Sacramento 
River, other invasive species, such as edible fig and black walnut, 
have become dominant, and these areas now provide lower quality habitat 
for western yellow-billed cuckoos even though the overall acreage of 
riparian habitat has risen over the past 20 years. In many river 
systems in the Great Basin, Russian olive (Elaeagnus angustifolia) is 
now the dominant species, and it has reduced the habitat value for 
western yellow-billed cuckoos. In response to the second part of the 
comment, the discussion under the section The Present or Threatened 
Destruction, Modification, or Curtailment of its Habitat or Range 
details the effect that human activities have had and are continuing to 
have on riparian systems throughout the range of the western yellow-
billed cuckoo.
    (78) Comment: One commenter asked that all statements regarding 
threats from water projects and water management should be removed from 
the document.
    Our Response: Threats from water projects and water management are 
significant threats as detailed in the proposed and this final rule. As 
such, discussion of these threats is appropriate. See discussion under 
the Habitat Loss from Dams and Alteration of Hydrology section for 
additional information.

Drought

    (79) Comment: One commenter stated that western yellow-billed 
cuckoos had declined because of the drought and will recover now that 
the rains have returned.
    Our Response: While drought may have a negative effect on western 
yellow-billed cuckoo populations, the declines in the western yellow-
billed cuckoo's range and populations have occurred through both wet 
and dry periods over the past 150 years.

Pesticides and Disease

    (80) Comment: One commenter stated that 
dichlorodiphenyltrichloroethane (DDT) does not thin eggshells and that 
western yellow-billed cuckoo eggshells in the West are thicker because 
there is more calcium in the West.
    Our Response: There is a large body of literature linking 
environmental DDT and its derivatives (e.g., 
dichlorodiphenyldichloroethylene (DDE)) to eggshell thinning in birds. 
Calcium deficiency can cause eggshell thinning in bird eggs, but this 
effect has not been demonstrated through region-by-region comparisons 
or a population-to-population comparisons. Trees and shrubs rarely show 
the effects of calcium deficiency within either the eastern or western 
range of the yellow-billed cuckoo in North America. Yellow-billed 
cuckoos would obtain calcium from their prey, which would obtain 
calcium from the leaves they eat. It is not clear that environmental 
calcium is more available in riparian zones in the West than it is in 
the East. It is also unclear as to what effect an abundance of 
environmental calcium has on yellow-billed cuckoo bird eggshells. There 
are no scientific studies that the Service is aware of on this topic.
    (81) Comment: One commenter stated that rotenone used by Game and 
Fish agencies to kill fish may have injured western yellow-billed 
cuckoos.
    Our Response: Although rotenone is classified as a broad-spectrum 
pesticide and has been used to control insects, we are not aware of any 
information that the use of the chemical as a piscicide (control of 
fish) has harmed the western yellow-billed cuckoo. The exposure risk of 
rotenone to terrestrial birds is low, and studies have shown that it 
would take levels of consumption of fish, vegetation, and/or water that 
are not physically possible or probable to reach a lethal dose 
(Finlayson et al. 2000, p. 193). The commenter did not provide 
information on the possible mechanism behind this perceived threat.
    (82) Comment: One commenter stated that West Nile virus was a 
reason that yellow-billed cuckoos have declined.
    Our Response: As discussed below in the Disease or Predation 
section, the U.S. Geological Survey's National Wildlife Health Center 
has identified the yellow-billed cuckoo as a species that is subject to 
the effects of West Nile virus and the Center for Disease Control's 
(CDC) Vector-Borne Disease Web site reports that West Nile virus has 
been documented in a dead yellow-billed cuckoo (Center for Disease 
Control 2012). The information on the impact of West Nile virus to the 
western yellow-billed cuckoo does not suggest that it has undergone a 
precipitous decline coincident with the relatively recent arrival of 
West Nile virus in western North America, and no scientific data 
indicate this disease as a major factor in the western yellow-billed 
cuckoo's decline.
    (83) Comment: One commenter stated that most pesticides are used in 
highly populated areas by people who do not follow label instructions.
    Our Response: While this statement may be true, western yellow-
billed cuckoos rarely occur in or near highly populated areas and are 
much more likely to be affected by application of pesticides on 
adjacent agricultural fields. See ``Pesticides'' section, below, for 
further information on the impacts of pesticides on the western yellow-
billed cuckoo.
    (84) Comment: Two commenters mentioned, and included references on, 
the new threat of neonicotinoid pesticides, which are extremely toxic 
to caterpillars.
    Our Response: Neonicotinoid pesticides are systemic chemicals that 
are taken up through various plant parts and can be distributed through 
a plant's tissues. These chemicals can be applied to a plant as a seed 
coating, through soil contact, through irrigation water, or as a foliar 
spray. Many of these chemicals are long-acting, with half-lives up to 2 
years. Plant tissues that have been treated are toxic to both sap-
sucking (e.g., aphids and true bugs) and foliage-eating insects (e.g., 
caterpillars, katydids, grasshoppers, and beetles). Many of these 
foliage-eating insects are potential prey of the western yellow-billed 
cuckoo. This information has been incorporated into this final rule.

Additional Threats

    (85) Comment: Several commenters stated that there were threats to 
western yellow-billed cuckoos that were not discussed in the proposed 
rule. These included threats from recreational shooting, threats from 
solar generation sites, and threats from wind power.
    Our Response: All the activities may impact the western yellow-
billed cuckoo. In our evaluation of threats, we identified those 
threats that rise to the level of being a threat to the continued 
existence of the species. Although these activities affect the species, 
we do not find that these activities would have a significant effect on 
the species.

Comment on Regulatory Mechanisms

    (86) Comment: Five commenters stated that Factor D, inadequacy of 
existing regulatory mechanisms, is also a significant threat. Other 
commenters stated that the proposed rule ignored the Federal regulatory 
mechanisms that protect western yellow-billed cuckoos and their 
habitat.

[[Page 60013]]

    Our Response: The proposed and this final rule present a detailed 
discussion of Federal, State, and international laws and regulations 
that provide some protection and conservation benefit to the western 
DPS of the yellow-billed cuckoo. The western yellow-billed cuckoo has 
continued to decline, and its habitat has continued to be lost and 
degraded. In determining if a species is to be added to the List of 
Endangered or Threatened Wildlife, the species needs only to be 
threatened by one of the five factors listed in section 4(a)(1) of the 
Act. According to our analysis of the best scientific and commercial 
information available, the western yellow-billed cuckoo is threatened 
by both Factors A and E. Our evaluation of Factor D discusses the 
extent to which the inadequacy of each existing regulatory mechanism 
exacerbates the threats evaluated in Factors A and E. An individual 
regulatory mechanism may reduce a threat to a greater or lesser extent, 
but none separately or in combination reduces any of the threats to the 
point that they are no longer threats to the western yellow-billed 
cuckoo.

Comment on Cumulative Effects

    (87) Comment: Several commenters stated that the proposed rule 
needs more emphasis on cumulative effects.
    Our Response: We recognize that cumulative effects are important. 
Cumulative effects are discussed in several sections of the proposed 
and this final rule, including the section of water management, 
grazing, climate change, and pesticide use. Please see those sections 
for additional information on the impacts of cumulative effects on the 
western yellow-billed cuckoo.

Comment on Conservation Measures

    (88) Comment: Eighteen commenters discussed conservation measures 
and indicated that benefits from conservation measures were not 
discussed and that conservation measures for other species should 
``take care'' of the western yellow-billed cuckoo. Others stated that 
there was a need to quantify the benefits of riparian habitat 
restoration to western yellow-billed cuckoos.
    Our Response: Conservation measures and their effect on western 
yellow-billed cuckoos are discussed in the proposed and this final 
rule. The majority of currently implemented conservation measures focus 
on species other than the western yellow-billed cuckoo. Conservation 
measures that are carried out for other species may have a positive 
effect on the western yellow-billed cuckoo, but western yellow-billed 
cuckoos, while being a riparian obligate species, have different 
ecological requirements than other species that are already listed 
(e.g., southwestern willow flycatcher and least Bell's vireo). As a 
result, it has not been proven that the conservation measures outlined 
by commenters would ``take care'' of the western yellow-billed cuckoo 
and its habitat. In regards to quantification of the benefits habitat 
restoration, we readily acknowledge that any well-developed and 
maintained restoration efforts will most likely benefit the western 
yellow-billed cuckoo and its habitat. However, we have found that, in 
some cases, even when habitat restoration has been completed, the 
benefit to the species has not been clear, as some areas still remain 
unoccupied or their numbers continue to decline.
    (89) Comment: Two commenters were concerned that the listing of the 
western yellow-billed cuckoo would disrupt recovery efforts for the 
southwestern willow flycatcher and the Rio Grande silvery minnow 
(Hybognathus amarus).
    Our Response: We disagree. Although additional coordination would 
be required to ensure that the habitat and species needs for all three 
species was occurring for a potential recovery action, we do not 
believe that that process would favor or harm any one single species in 
particular. In fact, by implementing recovery efforts for two or more 
species it would present opportunities that may be larger in scale or 
allow greater flexibility than smaller disjointed efforts for single 
species conservation.

Comments on Potential Exemptions (Section 4(d) Rule)

    (90) Comment: Several commenters requested that rules under section 
4(d) of the Act be included in the listing to exempt the following 
activities: (a) Oil and gas development and other economic activities; 
(b) riparian restoration activities; (c) all existing conservation 
activities; and (d) land and water use activities.
    Our Response: Section 4(d) of the Act allows the Secretary the 
discretion to issue such regulations as [s]he deems necessary and 
advisable to provide for the conservation of a species. The Service's 
standard policy (under 50 CFR 17.31(a)) for issuing prohibitions for 
threatened species is to apply all the prohibitions applicable to 
endangered species to a threatened species unless otherwise revoked by 
issuance of more specific prohibitions. In the case of the western 
yellow-billed cuckoo, we reviewed whether the ``standard'' prohibitions 
apply or whether more specific prohibitions might be appropriate for 
the western yellow-billed cuckoo. Based on our review, we have 
determined that modifying our ``standard'' regulations for a threatened 
species would not be necessary and advisable in providing for the 
conservation of the western yellow-billed cuckoo. If new or additional 
information is received that may suggest that a rule issued under 
section 4(d) of the Act may be appropriate, we would review such 
information and, if appropriate, issue a proposed section 4(d) rule for 
public comment prior to developing any final section 4(d) prohibitions 
for the species.

Listing Process Public Input

    (91) Comment: Eight comments were received on the listing process. 
This included statements regarding: Inadequate public feedback, that 
listing decisions should reflect customs and cultures of the local 
community, that court settlements should not be a factor in listing 
decisions, and that a finding of warranted but precluded should have 
been maintained as a possibility.
    Our Response: In accordance with the Act and the Administrative 
Procedure Act (5 U.S.C. Subchapter II), and our regulations in Title 50 
of the Code of Federal Regulations (CFR), we have solicited public 
comment on our proposed listing action. The comment period was reopened 
twice to insure that the public had ample opportunity to comment on the 
proposed rule. Listing endangered or threatened species is a process 
that examines threats to the species. Although customs and cultures of 
local communities are important considerations, they are not part of 
the listing process under the Act. Court settlements were not a factor 
in preparation of the proposed rule to list the western DPS of the 
yellow-billed cuckoo as a threatened species. The court settlement 
simply guaranteed that the Service would do an analysis of the western 
DPS of the yellow-billed cuckoo and determine if it should be listed as 
an endangered species or a threatened species or not listed. Regarding 
maintaining the warranted-but-precluded category as a listing 
possibility, the western yellow-billed cuckoo was previously found to 
be ``warranted but precluded,'' in 2001; the next step in the listing 
process is to either propose it for listing (and finalize the proposal 
if appropriate) or make a finding that the species is no longer 
warranted for listing.

Use of the Best Available Scientific and Commercial Information

    (92) Comment: Ten commenters said that the science used in the 
proposed

[[Page 60014]]

rule is flawed, inaccurate, and biased and is not the best available 
science. Several commenters indicated that the Service should only 
select the ``best'' data from the data that was available.
    Our Response: All available sources of data on distribution and 
abundance of yellow-billed cuckoos in the western United States were 
consulted, reviewed, and used in the proposed rule. We also provided 
the proposed rule for peer review to five knowledgeable individuals 
with scientific expertise that included familiarity with the yellow-
billed cuckoo and its habitat, biological needs, and threats. We 
reviewed all comments we received from the peer reviewers for 
substantive issues and new information regarding the listing of the 
western DPS of the yellow-billed cuckoo. The peer reviewers generally 
concurred with our methods and conclusions, and provided additional 
information, clarifications, and suggestions to improve this final 
rule. Additional data were provided by commenters, including Federal 
and State wildlife and resource agencies, but none of that additional 
data changed the pattern of western yellow-billed cuckoo distribution 
and abundance presented in the proposed rule. In response to the 
selection of data, we conclude that it is much better to present and 
discuss all available pertinent data in our determinations, rather than 
be subjective and select which data to present and review. We have made 
our determination in this final rule solely based on the best available 
scientific and commercial data available as required by section 
4(b)(1)(A) of the Act.
    (93) Comment: One commenter stated that the Service did not cite 
papers in the proposed rule that were cited in the 12-month finding.
    Our Response: The proposed rule is an updated and more thorough 
review of the best available information on the western yellow-billed 
cuckoo and is an independent document from the 12-month finding (66 FR 
38611; July 25, 2001). Additional research has been completed on the 
species, and additional peer-reviewed papers have been published and 
reports written over the past 13 years that supersede previously 
published paper and reports. The new information in some cases has 
confirmed, updated, or revised older research. These are all reasons 
that some papers that were cited in the 12-month finding are not 
directly cited in the proposed rule. However, information and research 
cited in the 12-month finding is still part of the decisional record 
for the western yellow-billed cuckoo and included (by reference) in 
this final rule.
    (94) Comment: One commenter said that two recent peer reviewed 
papers (Villarreal et al. 2014 and Wallace et al. 2013) that were not 
cited in the proposed rule are not valid.
    Our Response: The Service appreciates the commenter drawing our 
attention to these papers that had published after the proposed rule 
was published in the Federal Register (October 3, 2013). We will 
evaluate these peer-reviewed papers, which deal with modeling western 
yellow-billed cuckoo habitat using remote sensing, and with the 
commenter's concerns in mind, we will consider them in our final 
critical habitat designation as appropriate.
    (95) Comment: One commenter stated that they did not like the use 
of data from the Arizona Breeding Bird Atlas (Corman and Wise-Gervais 
2005, pp. 202-203) in the proposed rule.
    Our Response: Arizona Breeding Bird Atlas data (Corman and Wise-
Gervais 2005, pp. 202-203) were used in the proposed rule to 
demonstrate that western yellow-billed cuckoos are found on a small 
percentage of the landscape in Arizona. Breeding bird atlases are an 
important source of information on bird distribution and abundance in 
areas where they are available. To not present these data would be 
contrary to our requirement to use the best available science in 
listing decisions.

Property Rights

    (96) Comment: Two commenters stated that listing the western 
yellow-billed cuckoo will restrict property rights and access to public 
lands.
    Our Response: This comment was presented generally with no specific 
instances or information. It is very unlikely that listing the western 
yellow-billed cuckoo will have the effect of limiting access to public 
lands. Direct human disturbance is not seen as a major threat to the 
western yellow-billed cuckoo as discussed in the final rule. It is 
unclear what the commenter meant by restriction of property rights, but 
it is not likely that listing the western yellow-billed cuckoo will 
have an adverse effect on private property ownership or use.

Summary of Changes From Proposed Rule

    Based upon our review of the public comments, comments from other 
Federal and State agencies, peer review comments, and any new relevant 
information that may have become available since the publication of the 
proposal, we reevaluated our proposed rule and made changes as 
appropriate. Other than minor clarifications and incorporation of 
additional information on the species' biology, this final rule has not 
changed significantly from the proposed rule. Changes to the final rule 
include: (1) Updates to the life-history information of the species' 
vocalizations and how these changes may have affected survey results 
for the species; (2) updates to survey data (though no new populations 
have been located and no major increases have been noted in the past 2 
years); (3) updates to the threats in Factor A; and (4) the addition of 
threats of neonicotinoid pesticides in Factor E.
    We did receive information from the State of Washington regarding 
habitat use in the Pacific Northwest including western Oregon, western 
Washington, and southwestern British Columbia. This information updates 
our Habitat Use and Needs section of the proposed listing rule. In 
describing habitat use by the species, we stated that the species 
requires large blocks of habitat in riparian landscapes for breeding. 
In the description of breeding habitat, the document generally focuses 
on riparian areas in arid environments as this is where the majority of 
confirmed breeding now occurs. The result gives the impression that the 
species does not currently use or has not historically used more moist 
riparian areas such as northern California, western Oregon, western 
Washington, and southwestern British Columbia, Canada, as breeding 
habitat. Although breeding for the western yellow-billed cuckoo has not 
been recently confirmed in Oregon, Washington, and British Columbia, 
these more moist areas are within the historic breeding range of the 
species. Recent observations indicate that western yellow-billed 
cuckoos occasionally occur in these areas and the possibility of 
breeding in Oregon, Washington, and British Columbia cannot be ruled 
out at this time. We are not including the Habitat Use and Needs 
section in this final rule, but are updating the information here and 
incorporating the remainder of the discussion contained in the proposed 
rule by reference.

Summary of Factors Affecting the Species

    Section 4 of the Act and its implementing regulations (50 CFR 424) 
set forth the procedures for adding species to the Federal Lists of 
Endangered and Threatened Wildlife and Plants. A species may be 
determined to be an endangered or threatened species due to one or more 
of the five factors described in section 4(a)(1) of the Act: (A) The 
present or threatened destruction, modification, or

[[Page 60015]]

curtailment of its habitat or range; (B) overutilization for 
commercial, recreational, scientific, or educational purposes; (C) 
disease or predation; (D) the inadequacy of existing regulatory 
mechanisms; or (E) other natural or manmade factors affecting its 
continued existence. Listing actions may be warranted based on any of 
the above threat factors, singly or in combination. Each of these 
factors is discussed below.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

    The decline of the western yellow-billed cuckoo is primarily the 
result of riparian habitat loss and degradation. Within the three 
States with the highest historical number of western yellow-billed 
cuckoo pairs, past riparian habitat losses are estimated to be about 90 
to 95 percent in Arizona, 90 percent in New Mexico, and 90 to 99 
percent in California (Ohmart 1994, pp. 276-281; DOI 1994, p. 215; Noss 
et al. 1995, pp. 37, 46; Greco 2008, p. 5). Many of these habitat 
losses occurred historically, and although habitat destruction 
continues, many past impacts have subsequent ramifications that are 
ongoing and are affecting the size, extent, and quality of riparian 
vegetation within the range of the western yellow-billed cuckoo. The 
connection between habitat loss and the decline of western yellow-
billed cuckoos is thoroughly documented in California (Gaines and 
Laymon 1984, pp. 49-80). These adverse impacts to the western yellow-
billed cuckoo's habitat including habitat loss and degradation are 
occurring now and are anticipated to continue for decades to come.
    Moreover, these impacts are often subtle. As described in the 
Habitat Use and Needs section in the proposed rule, during the breeding 
season the habitat of the western yellow-billed cuckoo consists of 
expansive blocks of riparian vegetation containing trees of various 
ages, including in particular larger, more mature trees used for 
nesting and foraging. In order for these areas to remain as viable 
western yellow-billed cuckoo habitat, the dynamic transitional process 
of vegetation recruitment and maturity must be maintained. Without such 
a process of ongoing recruitment, habitat becomes degraded and is 
eventually lost. In our discussion below, we identify human impacts to 
riparian vegetation as resulting in current and ongoing destruction and 
modification of existing and future potential habitat for the western 
yellow-billed cuckoo.
    Past actions by humans have resulted in changes to the landscape, 
the hydrology, or both such that they prevent the riparian plants that 
are the basis of the species' habitat from growing at all. The 
consequences of these past actions may have initially resulted in 
destruction or modification of then-existing riparian habitat; however, 
once that habitat is lost, the changed conditions (such as changed 
hydrologic regime) also prevents riparian habitat from regenerating, 
even in the absence of other impacts. For example, channelization--
through manmade levees or other constructs, or through channel incising 
as a consequence of other actions--may leave the geographical area 
where riparian plants once grew (such as the watercourse's floodplain) 
physically untouched, but the altered hydrology prevents riparian plant 
species from germinating and growing.
    Principal causes of riparian habitat destruction, modification, and 
degradation in the range of the western yellow-billed cuckoo have 
occurred from alteration of hydrology due to dams, water diversions, 
management of riverflow that differs from natural hydrological 
patterns, channelization, and levees and other forms of bank 
stabilization that encroach into the floodplain. These losses are 
further exacerbated by conversion of floodplains for agricultural uses, 
such as crops and livestock grazing. In combination with altered 
hydrology, these threats promote the conversion of existing primarily 
native habitats to monotypic stands of nonnative vegetation, which 
reduce the suitability of riparian habitat for the western yellow-
billed cuckoo. Other threats to riparian habitat include long-term 
drought and climate change. These threats are summarized in a recent 
detailed review of the literature on the subject (Poff et al. 2011, pp. 
1241-1254). Water management and delivery throughout the western United 
States is contentious, and resolving issues related to water allocation 
is difficult and often a lengthy, heavily contested process. The exact 
timeframe for resolving water management and delivery issues and their 
impact on the western yellow-billed cuckoo and its habitat would vary 
on the location, resource demands, sensitive habitat or species 
concerns, stakeholders, and amount of water available. As a result, we 
would expect that resolving water issues for the various uses 
(agriculture, urbanization, wildlife, and tribal interests) in the west 
will be a lengthy ongoing process and not be resolved in the near 
future (10-20 years) and may take substantially longer considering the 
increased demands and the effects of climate change. The Factor A 
threats are described in more detail below. Moreover, past and ongoing 
impacts to the species' habitat are working in combination with other 
threats, which are discussed in greater detail in Factors C and E, 
below.
Habitat Loss From Dams and Alteration of Hydrology Dams
    Several researchers and scientific organizations including the 
Service reviewed the following effects of human modification of natural 
hydrological processes on riparian habitat, including those from dams 
(Poff et al. 1997, pp. 769-784; Greco 1999, pp. 36-38; National Academy 
of Sciences (NAS) 2002, pp. 145-150; Service 2002, Appendix I, pp. 1-
12). Dams result in an immediate effect of destroying riparian 
structure and functioning due to habitat displacement from dam 
construction and by permanent inundation, sometimes flooding miles of 
upstream riparian areas. This results in the physical loss of riparian 
vegetation. In the absence of vegetation, the western yellow-billed 
cuckoo cannot breed, feed, or find shelter. Current and future releases 
of water downstream from dams at unnatural rates of flow or timing that 
differ from preconstruction hydrologic circumstances, or at too 
frequent or too infrequent intervals, may lead to flooding or 
desiccation beyond the tolerance limits of the native riparian 
vegetation, thus resulting in loss of habitat of the western yellow-
billed cuckoo.
    Dam construction has been occurring since the settlement of western 
North America with its peak in the mid-20th century. These include most 
major western rivers, many of which have a series of dams, and include, 
but are not limited to, the Sacramento, Kern, San Joaquin, Mojave, 
Snake, Gila, Salt, Verde, and Rio Grande, including 25 major reservoirs 
built on the Colorado and Green Rivers alone between the 1930s and 
1970s (Richter et al. 1998, p. 332). In northern Mexico, these rivers 
include the R[iacute]o Conchos, Yaqui, and Mayo, R[iacute]o Bambuto, 
R[iacute]o Bravo, Tubutama, La Reforma, Cuchujaqui River in Alamos, 
Aconchi and Baviacora in R[iacute]o Sonora, and Upper San Pedro River 
in Sonora (Instituto del Media Ambiente y el Desarrollo Sustentable del 
Estado de Sonora (IMADES) 2003, p. 4; Kelly and Arias Rojo 2007, pp. 2-
3; Cornell et al. 2008, p. 96).
    There are now dozens of large dams and scores of smaller dams on 
rivers throughout the range of the western yellow-billed cuckoo. Today, 
the rate of building new dams has slowed because most of the highest 
quality dam sites

[[Page 60016]]

already have dams constructed on them. There were proposals to build 
two dams on Cottonwood Creek, one of the major tributaries of the 
Sacramento River (USACE 1982), but it is not clear when or if these 
dams will be built. A larger current threat is the enlargement (raising 
of dams or control structures) of existing dams. The enlargement of 
Terminus Dam on the Tule River in California by 21 ft (6.5 m) in height 
was completed in 2004 (Barcouda et al. 2006, p. 12), and proposals to 
enlarge Shasta Dam on the Sacramento River by up to 18.5 ft (5.7 m) in 
height and increasing its storage capacity (Reclamation 1999, pp. 3-8; 
Reclamation 2013, pp. ES 15-22) and Friant Dam on the San Joaquin River 
by up to 140 ft (43 m) in height are being explored (Reclamation 2003, 
pp. 3.1-3.8), and the raising of Lake Isabella on the Kern River by the 
USACE is in the final stages of implementation (USACE 2012, pp. 1-4). 
Larger dams with additional storage would likely flood potential 
western yellow-billed cuckoo habitat upstream and cause additional 
hydrologic disruption downstream.
    While the amount of habitat lost within the construction zone of a 
dam is relatively small, far greater amounts of habitat are destroyed 
in the areas of inundation and through the ongoing effects of the 
amount and timing of water releases through the dam operation, which 
affects both upstream and downstream habitats. Ongoing downstream 
effects to riparian habitat from dams include changes in sediment 
transport due to sediment retention behind the dams so that channels 
below a dam become increasingly ``sediment starved.'' This situation 
causes vertical erosion (downcutting), which can lead to loss of river 
terraces that sustain riparian vegetation (NAS 2002, pp. 145-150; Poff 
et al. 2009, pp. 773-774; Poff and Zimmerman 2010, pp. 196-197).
    Ongoing operations of large dams can also dampen the magnitude of 
normal high flows, thus preventing cottonwood germination (Howe and 
Knopf 1991, p. 218), and dewater downstream reaches, causing 
substantial declines of riparian forests (NAS 2002, pp. 145-150). For 
example, Groschupf (1987, p. 19) found that almost all cottonwoods and 
over half of all willow trees were eliminated from one waterway in 
Arizona that was exposed to repeated large releases of water from a 
dam. This situation reduced the density of western yellow-billed 
cuckoos from 13 per 100 ac (40 ha) before the flooding to 3 per 100 ac 
(40 ha) after the flooding (Groschupf 1987, p. 19). In another example, 
a study of the San Joaquin River from downstream of the Friant Dam to 
the Merced River confluence found that, between 1937 and 1993, the area 
of riparian forest and scrub decreased 28 percent, from 6,787 to 4,914 
ac (2,727 to 1,989 ha), and the herbaceous riparian vegetation 
decreased from 4,076 to 780 ac (1,650 to 316 ha) (Jones and Stokes 
Associates, Inc. 1998, Chap. 5, pp. 1-2). These losses are most likely 
attributed to reduced stream flow down the river as a result of water 
diversions.
    In the case of the San Joaquin River, efforts are under way for 
restoring a more natural functioning hydrologic system and to restore 
riparian habitat (Reclamation 2012, pp. 7-8). Generally, in the absence 
of ongoing dam operations, where areas are allowed to flood and deposit 
sediment, the habitat is likely to regenerate naturally. However, 
because of the way the majority of dams are operated, the ability for 
the stream courses to promote natural regeneration and maintenance of 
riparian habitat has been greatly diminished. These impacts are 
happening now and are likely to continue without changes to water 
release strategies and management.
    After the completion of the larger dams on the Colorado River 
system starting in the 1930s, limited pulse flows reached the lower 
Colorado River in Mexico for nearly 50 years, resulting in the loss of 
cottonwood-willow forests and the establishment of tamarisk (Glenn et 
al. 2001, pp. 1175-1186; Nagler et al. 2005, pp. 1843-1844). Local 
decline of the western yellow-billed cuckoo and other riparian birds 
has been attributed to that habitat loss and degradation (Hinojosa-
Huerta et al. 2008, p. 81). Additionally, along the R[iacute]o Altar in 
northern Mexico, completion of the Cuauht[eacute]moc Dam and Reservoir 
(Presa Cuauht[eacute]moc) in 1950 diverted surface water and 
contributed to increased vegetation clearing for agriculture, 
degradation of mature cottonwood forests, and subsequent declines in 
distribution and abundance of riparian bird species associated with 
these forests (Flesch 2008, p. 43), including the western yellow-billed 
cuckoo, which is known to occur there. In addition to past habitat 
losses, the altered hydrology caused by dams continues to have an 
ongoing impact on riparian habitat.
    While alteration of hydrology due to dam construction and other 
water supply projects has been widely implicated in the loss and 
degradation of downstream riparian habitat for the western yellow-
billed cuckoo (Gaines and Laymon 1984, p. 73; Greco 1999, pp. 36-38; 
Greco 2012, pp. 8-9), some dams have resulted in temporary habitat 
expansion for the western yellow-billed cuckoo within the immediate 
upstream influence of the associated reservoirs. For example, one of 
the largest concentrations of western yellow-billed cuckoo in New 
Mexico occurs at the inflow to Elephant Butte Reservoir on the middle 
R[iacute]o Grande (Sechrist et al. 2009, p. 1; Ahlers and Moore 2011, 
pp. 19-20). Western yellow-billed cuckoo numbers increased following 
several years when water levels receded and riparian vegetation 
expanded into the exposed area of the reservoir pool. The western 
yellow-billed cuckoo population there continues to increase, likely as 
a result of continued drawdown from long-term drought that allows 
maturation of the riparian forest into suitable breeding habitat 
(Ahlers and Moore 2011, pp. 19-20). Drought patterns are cyclical, and, 
when wetter conditions return to the region, Elephant Butte Reservoir 
likely will be refilled. When this happens, approximately 92 percent of 
44 to 87 pairs of western yellow-billed cuckoos there (detected during 
the 2007 and 2008 surveys) would be displaced through inundation 
(Reclamation 2009, pp. 64-65).
    The threat to the western yellow-billed cuckoo's habitat from 
fluctuating water levels behind dams is likely to occur elsewhere in 
the range of the western yellow-billed cuckoo. In California, the 
State's second largest population of western yellow-billed cuckoos 
occurs within the inflow delta footprint of Lake Isabella, a dammed 
reservoir on the Kern River. Breeding western yellow-billed cuckoos are 
also found at other reservoir inflow deltas, such as Horseshoe 
Reservoir on the Verde River (Dockens and Ashbeck 2011a, p. 1) and the 
Tonto Creek and Salt River inflows to Roosevelt Lake in Arizona (Salt 
River Project 2002, pp. 61-67).
    The temporary gain in riparian habitat at the inflow of reservoirs 
can be beneficial to the western yellow-billed cuckoo by providing 
large expanses of additional nesting and foraging habitat during a 
sequence of low-water years. However, the value of such habitat is 
affected by fluctuating water levels between years. Drastically 
fluctuating water levels with alternating inundation and desiccation 
cycles have been associated with fluctuations in populations of western 
yellow-billed cuckoos that breed in reservoir inflow sites (Laymon and 
Williams 2002, pp. 12-13; Henneman 2008, pp. 12-13). For example, along 
the Kern River, western yellow-billed cuckoo numbers increased during 
low reservoir levels for multiple years when vegetation recolonized the 
drawdown area (Laymon et al. 1997, p.

[[Page 60017]]

10), but western yellow-billed cuckoos moved to other sites during a 
wet year when lake levels rose and flooded out habitat (Launer et al. 
1990, p. 10; Halterman et al. 2001, p. 20). When the water receded, it 
took up to 2 years for western yellow-billed cuckoos to return to breed 
in the area; however, this return was at reduced numbers even though 
the habitat returned to previous levels (Laymon and Williams 2002, pp. 
12-13; Henneman 2008, pp. 12-13). The reason for this delay in 
recolonization needs further study (Henneman 2010, pp. 12-14).
    The water level continues to remain below capacity at Lake Isabella 
due to dam safety concerns (Stewart 2012, pers. comm.). Once Lake 
Isabella fills again to capacity, the riparian habitat that has since 
formed at the inflow and that supports western yellow-billed cuckoos 
will become inundated, at least periodically (Whitfield 2012, pers. 
comm.), thereby impacting the habitat of the western yellow-billed 
cuckoo. In addition, the USACE and the USFS are developing a proposal 
and have completed a final environmental impact statement on options to 
repair dam deficiencies and raise the height of the dam an additional 
16 ft (4.9 m) (Isabella Lake Dam Safety Modification Project 
Environmental Impact Statement Final October 2012). Pursuant to section 
7 of the Act, consultation was completed for the proposed action, but 
the western yellow-billed cuckoo was not a species addressed in the 
biological opinion.
    Lake Isabella is currently managed to minimize incidental take of 
the southwestern willow flycatcher (flycatcher) (Empidonax traillii 
extimus) from reservoir operations and recreation using reasonable and 
prudent measures developed during consultation with the Service 
(Service 1996, 1999, and 2005, entire). Some of these measures to 
conserve the flycatcher may be beneficial to the western yellow-billed 
cuckoo; however, the eventual inundation of the drawdown area of the 
reservoir will result in some degree of temporary habitat loss and 
degradation under current operational guidelines and may result in 
permanent loss of habitat for the western yellow-billed cuckoo if the 
proposed dam raise is implemented. Similar periods of inundation and 
drawdown, resulting in corresponding development and destruction of 
suitable western yellow-billed cuckoo habitat, occur at Roosevelt Lake 
(Salt River Project (SRP) 2002, entire).
    In Arizona, following the high water levels of 1983-1984 and 1986 
on the Bill Williams River Delta, which is influenced by fluctuating 
water levels from dams in the Colorado River system (Rosenberg et al. 
1991, pp. 18-23), the western yellow-billed cuckoo numbers declined by 
70-75 percent. Habitat has since improved on the Bill Williams River 
Delta, but western yellow-billed cuckoo numbers remained low for 
several years (Laymon and Halterman 1987a, pp. 10-18). The actual 
mechanism that influences the yellow-billed cuckoo's response to 
fluctuations in water levels is unknown, but loss of prey has been 
implicated; areas that were inundated normally support ground-nesting 
invertebrates, such as katydids and sphinx moths, that western yellow-
billed cuckoos feed upon, and it may take several years for these prey 
populations to rebound (Laymon and Williams 2002, pp. 12-13; Henneman 
2008, pp. 12-13).
    In Sonora, Mexico, large dams exist on the Mayo, Yaqui, and Sonora 
Rivers (Villase[ntilde]or-Gomez 2006, p. 107). We do not have 
information on the magnitude or frequency of effects, positive or 
negative, from water management activities, to the western yellow-
billed cuckoo in those locations. However, we have no reason to believe 
that the dams are managed in a substantially different manner in Mexico 
than dams in the southwestern United States, and the effects to 
riparian habitat are expected to be similar.
    Despite some positive effects of dams on increasing western yellow-
billed cuckoo habitat in a few areas, these gains in habitat are only 
temporary, and overall, the net effect of dams on the species has been 
negative. As such, dams and their ongoing operations are a threat to 
the western yellow-billed cuckoo over most of its range. This threat 
has resulted in substantial historical losses of western yellow-billed 
cuckoo habitat resulting in a curtailment of the species' range. The 
ongoing operation of these dams is likely to have minor impacts to the 
species at any given location, but because so many of the waterways 
within the range of the species have been dammed, we believe this 
threat has a substantial cumulative impact on the habitat of the 
western yellow-billed cuckoo, especially when considered with other 
threats. Moreover, we expect the operation of these dams will continue 
in a similar manner for decades to come, and thus we expect this threat 
to be an ongoing impact to the western yellow-billed cuckoo's habitat.
    The areas where the floodplain is still hydrologically connected to 
the river and has relatively unconstrained riverflow, such as in some 
areas of California and Sonora, Mexico, support the highest number of 
western yellow-billed cuckoos (Villase[ntilde]or-Gomez 2006, pp. 107-
108; Greco 2008, p. 6; Greco 2012, pp. 8-9). For example, the 
Sacramento River from Red Buff to Colusa has a highly dynamic mosaic of 
habitat patches of varying ages that form, disappear, and reform in 
response to active river channel processes that operate over decades 
(Greco 2008, p. 6; Greco 2012, pp. 8-9). Although this section of the 
Sacramento River is also affected by altered hydrology, it is far 
enough below Shasta Dam and below several major undammed tributaries, 
such as Cottonwood Creek and Battle Creek, that it still has flood 
events every few years that help support riparian habitat processes 
(Werner 2012, pers. comm.).
    The river provides habitat characteristics that Laymon (1998, p. 4) 
indicated were important for the western yellow-billed cuckoo in 
California, such as a meandering system with young riparian habitat 
that, compared to mature woodlands, provides preferred nesting sites; 
high productivity of invertebrate prey; and reduced predator abundance 
(Laymon 1998, p. 4). Another example of relatively intact riparian 
habitat in the range of the western yellow-billed cuckoo is found in 
the highlands of central Sonora, Mexico, which supports occupied 
habitat of the western yellow-billed cuckoo. Villase[ntilde]or-Gomez 
(2006, p. 108) found that the maintenance of the natural flooding 
regimes due to the limited number of water development structures has 
allowed riparian vegetation along sections of the Sonora, Moctezuma, 
and Sahiaripa Rivers to persist in very good condition in some areas. 
Most of the known occurrences of western yellow-billed cuckoo in 
central Sonora are associated with these regions.
    We conclude that dams continue to affect both the downstream and 
upstream habitat through alteration of flows. These effects can include 
widely fluctuating water levels at inflow sites that inundate nesting 
habitat, limit food resources, and flood or desiccate habitat (Poff et 
al. 1997, pp. 769-784; Greco 1999, pp. 36-38; NAS 2002, pp. 145-150; 
Service 2002, Appendix I, pp. 1-12). Downstream effects caused by 
sediment retention behind dams, or sediment scouring and removal caused 
by excessive water releases, do not mimic the natural flow regimes and 
often result in the inability for cottonwoods to become established or 
regenerate and provide habitat for the western yellow-billed cuckoo. 
Woody and herbaceous debris accumulates in the absence of these 
scouring flows,

[[Page 60018]]

increasing fire risk and intensity (Stromberg and Chew 2002, pp. 195-
219) (see section on Wildfire below).
    Dams and their flow modifications have ongoing effects to habitat 
and will likely do so for decades to come, further modifying the 
habitat of the western yellow-billed cuckoo. Therefore, direct and 
indirect destruction of riparian habitat resulting from altered 
hydrology from past dam-building activities continues to contribute to 
the curtailment of the range of the western yellow-billed cuckoo. 
Additionally, as a result of future predicted climate change (see 
Climate Change section below), the climate within the range of the 
western yellow-billed cuckoo will likely become drier, which will 
increase the demand for water storage and conveyance systems, which in 
turn will likely increase the frequency and severity of impacts on 
western yellow-billed cuckoo habitat (Stromberg et al. 2013, pp. 411-
415).
Surface and Ground Water Diversion
    Water extractions, both from surface water diversions and ground 
water pumping, can negatively affect riparian vegetation (Poff et al. 
1997, pp. 769-784; Service 2002, Appendix I, pp. 1-8). Water diversions 
and withdrawals can lower ground water levels in the vicinity of 
riparian vegetation. Because ground water and surface water are 
generally connected in floodplains, lowering ground water levels by 
only about 3 ft (1 m) beneath riparian areas is sometimes sufficient to 
induce water stress in riparian trees, especially in the western United 
States (NAS 2002, p. 158). Physiological stress in native vegetation 
from prolonged lower flows or ground water results in reduced plant 
growth rate, morphological change, or mortality, and altered species 
composition dominated by more drought-tolerant vegetation, and 
conversion to habitat dominated by nonnative species (Poff et al. 1997, 
p. 776). These effects reduce and degrade habitat for the western 
yellow-billed cuckoo for foraging, nesting, and cover.
    Adverse effects of excessive ground water extraction on riparian 
vegetation have been well-documented in the southwestern United States. 
Case histories on many river systems in Arizona including the Santa 
Cruz River and on the Owens River in California have documented the 
connection between overutilization of the ground water, lowering of the 
water table, and the decline and eventual elimination of riparian 
vegetation (Zektser et al. 2005, pp. 400-401; Webb and Leake 2006, pp. 
317-320). Ground water extraction is also affecting river flows and 
riparian vegetation along rivers that support the western yellow-billed 
cuckoo in Mexico, including the R[iacute]o Conchos in Chihuahua (Kelly 
and Aria-Rojo 2007, p. 174; Cornell et al. 2008, p. 98) and the 
R[iacute]o Altar in Sonora, where the quantity of surface water 
declined greatly between 2000 and 2007 (Flesch 2008, pp. 44-45). 
Therefore, ground water extraction and water diversions create an 
ongoing threat to western yellow-billed cuckoo habitat.
    The hydrologic regime (stream flow pattern) and supply of (and 
interaction between) surface and subsurface water is a driving factor 
in the long-term maintenance, growth, recycling, and regeneration of 
western yellow-billed cuckoo habitat (Service 2002, p. 16). As streams 
reach the lowlands, their gradients typically flatten and surrounding 
terrain opens into broader floodplains (Service 2002, p. 32). In these 
geographic settings, the stream-flow patterns (frequency, magnitude, 
duration, and timing) will provide the necessary stream-channel 
conditions (wide configuration, high sediment deposition, periodic 
inundation, recharged aquifers, lateral channel movement, and elevated 
ground-water tables throughout the floodplain) that result in the 
development of riparian habitat suitable for use by western yellow-
billed cuckoos (Poff et al. 1997, pp. 770-772; Service 2002, p. 16).
    Allowing the river to flow over the width of the floodplain, when 
overbank flooding occurs, is integral to allow deposition of fine moist 
soils, water, nutrients, and seeds that provide the essential material 
for plant germination and growth. An abundance and distribution of fine 
sediments extending farther laterally across the floodplain and deeper 
underneath the surface retains much more subsurface water, which in 
turn supplies water for the development of the vegetation that provides 
western yellow-billed cuckoo habitat and microhabitat conditions 
(Service 2002, p. 16). The interconnected interaction between ground 
water and surface water contributes to the quality of the riparian 
vegetation community (structure and plant species) and will influence 
the ability of vegetation to germinate, regenerate, and maintain its 
foliage density, vigor, and species composition (Arizona Department of 
Water Resources 1994, pp. 31-32).
    In many instances, western yellow-billed cuckoo breeding site occur 
along streams where human impacts are minimized enough to allow more 
natural processes to create and maintain the habitat. However, there 
are also breeding sites that are supported by various types of 
supplemental water including agricultural and urban runoff, treated 
water outflow, irrigation or diversion ditches, reservoirs, and dam 
outflows (Service 2002, p. D-15). Although the waters provided to these 
habitats might be considered ``artificial,'' they are often important 
for maintaining the habitat in appropriate condition for breeding 
western yellow-billed cuckoos within the existing environment.
Encroachment of Levees and Flood Control and Bank Stabilization 
Structures Into the River Channel and Floodplain
    Other alterations in river hydrology with ongoing effects on 
western yellow-billed cuckoo habitat include river channelization, 
construction of levees, bank stabilization, and placement of any flood 
control structures that encroach into the river and its floodplain. 
These actions result in direct loss of habitat from construction and 
from maintenance activities that remove woody vegetation that has 
become established on the structures. Furthermore, these structures are 
effective, by design, at severing the hydrologic connection of the 
river's main channel and the river's immediate floodplain, thereby 
preventing overbank flooding. By preventing overbank flooding, levees 
and other similar structures reduce the amount of water available to 
riparian vegetation in the floodplain, which results in desiccation and 
eventual loss and degradation of riparian habitat (Vogl 1980, pp. 84-
86; NAS 2002, p. 155; Greco 2012, pp. 8-9). Such effects are less 
destructive, however, for those levees located farther from the stream 
system, such as those outside the meander belt of a river (Greco 2012, 
p. 4).
    As an illustrative example, we provide a brief summary of how river 
channelization, construction of levees close to the river, and rock 
riprap armoring along the levees have caused destruction and 
modification of western yellow-billed cuckoo habitat on the Sacramento 
River, one of the most substantial historical nesting and foraging 
habitat areas for the western yellow-billed cuckoo. The Sacramento 
River is now disconnected from ecological processes that both renew and 
restore riparian and aquatic habitats (Laymon and Halterman 1987a, pp. 
11-14; Halterman 1991, pp. 1-2; Greco 2008, p. 6; Greco 2012, pp. 8-9). 
More than one-half of the Sacramento River's banks within the lowermost 
194 mi (312 km) of river have now been rip-rapped by 40 years of bank 
protection (Service

[[Page 60019]]

2000, pp. 26-29). Rock riprap armoring a river reach often changes the 
river dynamics and leads to channel downcutting and erosion immediately 
downstream from the riprap. Therefore, riprapping banks leads to the 
need for more riprapping.
    Channelizing the river and severing the connection to the 
floodplain has severely altered the natural disturbance regime that 
would have allowed riparian habitat to regenerate now and in the future 
(Poff et al. 1997, pp. 769-784; Greco 2008, p. 6; Greco 2012, pp. 8-9). 
The result is that much of the river's remaining riparian habitat is 
modified, and now occurs in narrow, disconnected, linear strips 
(Service 2000, pp. 26-29; Halterman et al. 2001, p. 4) that are not 
utilized by the western yellow-billed cuckoo for breeding (Gaines 1974, 
p. 204; Greco 2012, p. 9). With the example of the Sacramento River, 
nesting western yellow-billed cuckoos no longer occur south of Colusa 
as the river has been channelized and riprapped from that point into 
the Sacramento-San Joaquin River Delta. These flood control and bank 
stabilization structures also keep the riparian habitat from 
regenerating and maturing. The factors that reduce western yellow-
billed cuckoo breeding in these areas are not well-understood, but 
reductions of breeding population have been attributed to lack of 
patches of adequate size for nesting (Greco 2012, pp. 8-9), increased 
predators, and the species' inability to use highly isolated patches 
(Halterman 1991, pp. 33-38), as discussed under Factor E. The 
Sacramento River is but one of many rivers within the range of the 
western yellow-billed cuckoo where these activities have destroyed and 
modified riparian habitat and where the ramifications of these past 
actions are continuing to impact the western yellow-billed cuckoo's 
habitat today. These ongoing impacts will likely continue for decades 
to come.
    An additional pervasive threat is the design of open-channel flood 
control channels with inappropriately smooth roughness coefficients. 
This creation over-scours the floodplains and requires removal of woody 
riparian vegetation that regenerates on floodplains, which in turn 
leads to floodplains with no western yellow-billed cuckoo habitat 
(Greco 2013, pp. 707-717).
Transportation Systems
    Similarly, transportation systems have directly and indirectly 
altered a large number of riparian areas in western North America (NAS 
2002, p. 182). Road and rail systems are frequently sited along rivers, 
and often entail removing riparian vegetation for construction of the 
roadbed, and modifying local hydrology to reroute surface water and 
ground water. Bridges or culverts require abutments along the bank to 
provide roadway support. Because abutments and roadbeds physically 
constrain the stream, future lateral adjustments by the stream, which 
can affect floodplain dynamics, are effectively eliminated, which 
reduces and degrades riparian habitat (NAS 2002, p. 182). Such impacts 
result in additional destruction and modification of habitat for the 
western yellow-billed cuckoo. In comparison with construction of dams 
and altered hydrology, this threat, by itself, is less likely to result 
in severe impacts to riparian habitat. However, this threat is but one 
of many that, in combination, results in substantial changes to 
physical and hydrological properties of a watercourse, which in turn 
contributes to a substantial curtailment in the habitat of the western 
yellow-billed cuckoo.
Gravel Mining
    Other past and ongoing effects to riparian habitat result from 
gravel mining (Kondolf et al. 2001, pp. 54, 59). Extraction of gravel, 
primarily for construction products, typically occurs along rivers and 
adjacent floodplains where gravel deposits are naturally found. Large 
amounts of gravel removal from the stream and active floodplain result 
in channel downcutting or incision, which affects groundwater levels, 
frequency of overbank flows, bank stability, and the extent and 
character of riparian vegetation of specific stream reaches (Collins 
and Dunne, 1989, pp. 213-224; Kondolf 1995 pp. 133-136; NAS 2002, p. 
179). Some examples of downcutting on streams in California that 
historically had, but no longer have, populations of western yellow-
billed cuckoos, include: Cache Creek, Yolo County (15.0 ft (4.6 m) 
average and 26.0 ft (8.2 m) maximum downcutting); Merced River, Merced 
County (5.9 ft (1.8 m) average and 7.8 ft (2.4 m) maximum downcutting); 
Putah Creek, Yolo County (7.8 ft (2.4 m) average and 15.0 ft (4.6 m) 
maximum downcutting); Russian River, Sonoma County (11.4 ft (3.5 m) 
average and 17.9 ft (5.5 m) maximum downcutting); and Santa Clara 
River, Ventura County (15.6 ft (4.8 m) average and 20.2 ft (6.2 m) 
maximum downcutting) (Kondolf et al. 2001, p. 50).
    Furthermore, gravel extraction creates a knickpoint (a sharp change 
in channel slope) that typically erodes upstream in a process known as 
headcutting, which has the potential to propagate upstream for miles on 
the main river and its tributaries. As headcuts migrate upstream, the 
incision propagates upstream (Kondolf et al. 2001, p. 49). This process 
creates ongoing and future impacts to habitat from past as well as 
current gravel mining operations. Similar to the effects of manmade 
levees when they disconnect floodplain habitat from the active river 
channel, artificial channel incision as a result of gravel mining and 
similar activities reduces overbank flooding. This situation reduces 
the hydrological connection to the floodplain (Kondolf et al. 2001, p. 
56), thereby resulting in subsequent loss and degradation of riparian 
habitat for the western yellow-billed cuckoo, throughout its range, 
including Mexico (Cornell et al. 2008, p. 98). The effects of incision 
and channel erosion are further exacerbated where gravel mining occurs 
in sediment-starved reaches below dams (Kondolf et al. 2001, p. 10). We 
expect past and ongoing gravel mining activities, either alone or in 
combination with other hydrological changes in riparian areas, to 
continue to modify habitat and further curtail the range of the western 
yellow-billed cuckoo for decades.
    In conclusion, dams, channelization, and other manmade features 
that alter the watercourse hydrology and encroach into the active 
channel and floodplain are threats to the habitat of the western 
yellow-billed cuckoo because they, separately or in combination, 
significantly reduce and degrade nesting and foraging habitats. The 
natural processes that sustain riparian habitat in these and similar 
dammed and channelized river systems in the American West and in 
northwestern Mexico have been altered, resulting in only fragments or 
remnants of formerly large tracts of native riparian forests that no 
longer support breeding western yellow-billed cuckoos or support them 
in fewer numbers. The multiple effects from altered hydrology comprise 
the most widespread and greatest magnitude of current threats to 
habitat that supports the western yellow-billed cuckoo. Such processes 
continue to modify habitat and further curtail the range of the western 
yellow-billed cuckoo. Moreover, we expect these alterations in the 
hydrology to continue to affect habitat of the western yellow-billed 
cuckoo into the future.
Habitat Loss and Degradation From Agricultural Activities
    Following the effects from alterations in hydrology in severity, 
conversion of riparian areas for agricultural crops and livestock 
grazing has been, and continues to be, a major contributor to

[[Page 60020]]

riparian habitat loss and degradation (NAS 2002, p. 161; Johnson et al. 
2007, p. 61).
    Large areas of cottonwood-willow floodplain vegetation have been 
converted to agricultural uses, further reducing the extent of habitat 
available to western yellow-billed cuckoos for breeding (Swift 1984, 
pp. 225-226; Rosenberg et al. 1991, pp. 18-23). For example, within 
areas that support the western yellow-billed cuckoo, clearing for 
agricultural uses occurred extensively in the past. On the floodplains 
of the Sacramento River (Greco 1999, pp. 2, 107), riparian habitat was 
reduced from 775,000 ac (314,000 ha) in the 1850s to less than 18,000 
ac (7,287 ha) by 1977 (Swift 1984, p. 226). Clearing for agriculture is 
also extensive along the lower Colorado River (Rosenberg et al. 1991, 
pp. 18-23), San Pedro River, Gila River (Swift 1984, p. 226), 
R[iacute]o Grande, and several river courses in northern Mexico 
including, but not limited to, the R[iacute]o Yaqui, R[iacute]o Mayo, 
R[iacute]o Bambuto, R[iacute]o Tubutama, and R[iacute]o Sonora (Russell 
and Monson 1998, p. 11; IMADES 2003, p. 4; Villase[ntilde]or-Gomez 
2006, p. 108). Clearing also occurred along the coasts of Sinaloa and 
southern Sonora, Mexico, resulting in massive losses of thorn forest to 
industrial agriculture (Rohwer et al. 2009, p. 19054).
    Although most riparian and thorn scrub habitat losses largely stem 
from past agricultural clearing, effects from cultivated agricultural 
lands are ongoing. Agricultural lands continue to dominate much of the 
remaining riparian landscape, particularly along the Sacramento (Greco 
1999, pp. 94, 104, 107), parts of the Gila, and lower Colorado Rivers 
(Johnson et al. 2007, p. 207); along the latter, 65 percent of western 
yellow-billed cuckoo survey sites are bordered on at least one side by 
agriculture fields (Johnson et al. 2007, p. 61). Riparian areas are 
sometimes viewed as a potential source of plant and animal pests, a 
source of shade that may reduce crop yields, and competition for scarce 
water resources (NAS 2002, pp. 170-171). For example, in the Salinas 
Valley in California, a vigorous program is under way to comply with 
food safety practices that involve the clearing of riparian habitat 
adjacent to certain types of crops in an effort to eliminate wildlife 
presence, which has been linked to contamination of crops with a 
virulent strain of the bacteria Escherichia coli (Beretti and Stuart 
2008, pp. 68-69; Gennet et al. 2013, pp. 236-242). While western 
yellow-billed cuckoos do not currently breed along the Salinas River 
(Gaines and Laymon 1984, p. 52), if these same rules are applied to 
farmland along the Gila, Rio Grande, Sacramento, and Colorado Rivers, 
western yellow-billed cuckoo habitat could be eliminated to meet these 
food safety concerns.
    Accidental fire from farm workers operating machinery or burning 
weeds sporadically escapes into adjacent riparian habitat. Recent fires 
on western yellow-billed cuckoo and southwestern willow flycatcher 
conservation properties occurred in 2011, burning 58 ac (24 ha) and 6 
ac (2 ha), respectively, within the Fort Thomas Preserve, on parcels 
owned by the Salt River Project and U.S. Bureau of Reclamation. Both 
fires were determined to be human-caused, likely from farm workers 
burning weeds along irrigation drains (SRP 2011, p. 39).
    Other ongoing effects from cultivated agriculture on the western 
yellow-billed cuckoo are addressed under Factor E. These include 
fragmentation of habitat into smaller, more widely disjunct patches; 
ongoing influence of agriculture on riparian bird community 
composition; and effects from pesticides, which can negatively impact 
insect prey populations of the western yellow-billed cuckoo.
Habitat Loss and Degradation From Livestock Grazing Activities
    Domestic livestock grazing is a traditional agricultural land use 
practice in the southwestern United States since the first Spanish 
settlement along the Rio Grande in New Mexico in 1598 (Little 1992, p. 
88; Clary and Kruse 2004, p. 239). Livestock grazing continues to be a 
widespread agricultural use of riparian areas in the western United 
States and is one of the most common sources of past and ongoing 
riparian habitat degradation (Carothers 1977, p. 3; Rickard and Cushing 
1982, pp. 2-4; Cannon and Knopf 1984, p. 236; Klebenow and Oakleaf 
1984, p. 202; Swift 1984, pp. 225-226; Clary and Webster 1989, pp. 1-2; 
Schultz and Leininger 1990, pp. 298-299; Bock et al. 1993, p. 300). 
Livestock grazing occurs in western yellow-billed cuckoo habitat along 
sections of the middle Rio Grande in New Mexico (Lehman and Walker 
2001, p. 12), R[iacute]o Conchos (Cornell et al. 2008, p. 96), 
R[iacute]o Bambuto, Tubutama, La Reforma, and Cuchujaqui River in 
Alamos, Aconchi and Baviacora in R[iacute]o Sonora, and upper San Pedro 
River (IMADES 2003, p. 4), and several other rivers in central Sonora, 
Mexico (Villase[ntilde]or-Gomez 2006, p. 108). Grazing also occurs 
extensively along watercourses in a protected reserve on the R[iacute]o 
Aros and R[iacute]o Yaqui in Sonora, Mexico, where the western yellow-
billed cuckoo has been documented (O'Brien et al. 2008, p. 8). Grazing 
intensity in northern Sonora, Mexico, is generally much higher than in 
adjacent Arizona (Balling 1988, pp. 106-107; Flesch 2008, pp. 44-45), 
which leads to greater degradation of riparian habitat than in Arizona.
    The Service (2002, Appendix G, pp. 5-7) and Krueper et al. (2003, 
p. 608) reviewed the effects of livestock grazing, primarily in 
southwestern riparian systems. The frequency and intensity of effects 
vary across the range of the species, due to variations in grazing 
practices, climate, hydrology, ecological setting, habitat quality, and 
other factors (Service 2002, Appendix G, p. 1). However, these effects 
generally include the removal and trampling of vegetation and 
compaction of underlying soils, which can inhibit germination and 
change hydrology (Rea 1983, p. 40; Belsky et al. 1999, pp. 419-431) and 
promote the dispersal of nonnative plant species. Such effects are most 
significant when riparian areas have been subject to overuse by 
livestock (NAS 2002, pp. 24, 168-173). Overuse occurs when grazed 
vegetation does not recover sufficiently to maintain itself and soils 
are left bare and vulnerable to erosion. Over time, livestock grazing 
in riparian habitats, combined with other alterations in streamflow, 
typically results in reduction of plant species diversity and density 
and may increase the distribution and density of nonnative tamarisk by 
eliminating competition from native cottonwood and willow saplings, 
which are preferred forage for livestock (Krueper et al. 2003, p. 608).
    Long-term cumulative effects of livestock grazing involve changes 
in the structure and composition of riparian vegetation (Service 2002, 
Appendix G, pp. 5-7), which may affect suitability of habitat for 
western yellow-billed cuckoo breeding and prey population abundance. 
The western yellow-billed cuckoo nesting habitat is structurally 
complex with tall trees, a multistoried vegetative understory, low 
woody vegetation (Halterman 1991, p. 35) and higher shrub area than 
sites without western yellow-billed cuckoos (Hammond 2011, p. 48). 
Livestock grazing alters understory vegetation, reducing height and 
density or eliminating new growth in riparian areas, and thereby 
hampering recruitment of woody species that, when mature, provide nest 
sites. Furthermore, the relatively cool, damp, and shady areas favored 
by western yellow-billed cuckoos are those favored by livestock over 
the surrounding drier uplands. This preference can

[[Page 60021]]

concentrate the effects of habitat degradation from livestock in 
western yellow-billed cuckoo habitat (Ames 1977, p. 49; Valentine et 
al. 1988, p. 111; Johnson 1989, pp. 38-39; Clary and Kruse 2004, pp. 
242-243).
    Removal, reduction, or modification of cattle grazing has resulted 
in increases in abundance of some riparian bird species. For example, 
Krueper (1993, pp. 322-323) documented responses of 61 bird species, 
most of which increased significantly 4 years after removal of 
livestock grazing in Arizona's San Pedro River Riparian National 
Conservation Area. The bird species guilds that increased most 
dramatically were riparian species, open-cup nesters, Neotropical 
migrants, and insectivores, all species that share characteristics with 
the western yellow-billed cuckoo. The western yellow-billed cuckoo 
numbers in the study increased, although not significantly (p=0.13) 
(Krueper et al. 2003, p. 612), but their survey methodology was not 
designed to detect western yellow-billed cuckoos. Recovery of 
vegetation in response to grazing removal in that study was quickest 
and most pronounced in the lower vegetation layers, the most accessible 
to grazing cattle. Thus, this situation would allow a greater number of 
seedlings and saplings of cottonwoods and other nest trees to attain 
maturity as suitable nesting sites.
    In another example, livestock grazing was terminated along portions 
of the South Fork Kern River at the Kern River Preserve in the 1980s, 
and western yellow-billed cuckoos increased in number in the years 
following livestock removal. Smith (1996, p. 4) contended that 
termination of grazing at the Kern River Preserve was responsible for 
the dramatic increase in riparian vegetation, which was concurrent with 
the increase in western yellow-billed cuckoo numbers. These examples 
suggest that even severely degraded riparian systems can recover 
quickly, in at least some cases, after livestock removal (Krueper et 
al. 2003, p. 615), and that damage to riparian vegetation from grazing 
is at least partly reversible. They also illustrate the extent to which 
livestock grazing destroys and modifies nesting and foraging habitat of 
the western yellow-billed cuckoo.
    In conclusion, most of the direct loss of habitat from agricultural 
conversion has occurred in the past, but ongoing agricultural 
activities, in whole or in combination with other impacts, especially 
those that result in changes in a watercourse's hydrology, have 
resulted in the curtailment of nesting and foraging habitat for the 
western yellow-billed cuckoo by restricting or preventing the growth of 
riparian plants, and such activities present an ongoing threat. Most of 
the current impacts from agricultural land uses arise from livestock 
overgrazing in riparian areas. Riparian vegetation can recover 
relatively quickly from these effects after livestock removal (Smith 
1996, p. 4; Krueper et al. 2003, p. 615). However, without proper 
management to reduce overgrazing, ongoing overgrazing will continue to 
contribute to habitat modification in the range of the western yellow-
billed cuckoo into the future.
Habitat Loss and Degradation Due to Conversion to Nonnative Vegetation
    Throughout most of its range, habitat for the western yellow-billed 
cuckoo is threatened by the conversion of native riparian woodlands to 
riparian vegetation dominated by tamarisk and other nonnative 
vegetation. The major threat from this habitat conversion is the change 
from vegetation that supplies the western yellow-billed cuckoos with 
essential food and adequate thermal cover to vegetation that does not 
provide these necessary components of habitat for the western yellow-
billed cuckoo. The establishment and persistence of tamarisk is often, 
but not always, aided by altered hydrology, as described above. Altered 
hydrology is not the cause for establishment and persistence of other 
types of nonnative vegetation; therefore, we present information on 
nonnative vegetation in this separate section.
    Tamarisk is the most widespread nonnative woody plant species found 
in habitat for the western yellow-billed cuckoo. Glenn and Nagler 
(2005, pp. 420-423) provide most of the following overview of tamarisk. 
Tamarisk is present in nearly every southwestern riparian plant 
community, but varies in dominance from stream to stream. On streams 
where altered hydrology can no longer support native species, it has 
replaced native plant communities entirely, but occurs at a low 
frequency on other streams. Tamarisk was introduced into western North 
America in the 1800s to serve as ornamental windbreaks, and for erosion 
control and other purposes. Several species escaped cultivation and 
have since spread rapidly. The center of tamarisk distribution is 
currently Arizona, New Mexico, and Utah, and it has spread throughout 
most of the range of the western yellow-billed cuckoo at least as far 
north as the Yellowstone River in Montana in the Rockies, and at least 
as far south as the Yaqui River Valley in Sonora, Mexico. Recent 
studies in the northwest have located major populations of tamarisk in 
southwestern Idaho, and eastern Washington and Oregon. Models based on 
projected climate change predict that this invasive species will become 
more dominant in this region over the next 100 years (Kerns et al. 
2009, pp. 200-215). Tamarisk also occurs west to the Owens, San 
Joaquin, and Sacramento Rivers in California, although it is still 
nearly absent from the mainstem Sacramento River in California and 
suitable habitat west of the Cascades in Oregon and Washington.
    Tamarisk also occurs as isolated individuals along sections of the 
Sonora, Moctezuma, and Sahiaripa Rivers in Sonora, Mexico, where the 
hydrology has been little altered by human modifications 
(Villase[ntilde]or-Gomez 2006, pp. 107-108). Its presence is highly 
variable within sections of the R[iacute]o Conchos in Chihuahua, 
Mexico, and becomes dominant in some reaches of that river (Kelly and 
Arias Rojo 2007, pp. 177-178; Cornell et al. 2008, p. 4).
    The threshold (in terms of percent tamarisk) for abandonment of a 
riparian system by western yellow-billed cuckoos is not known. They are 
not found in areas that are totally dominated by tamarisk with the 
complete lack of willows or cottonwoods. In California, two native-
dominated areas occupied in 1977 by several pairs of western yellow-
billed cuckoos had, by 1986, converted to monotypic stands of tamarisk 
and were found to be uninhabited by western yellow-billed cuckoos. 
Above Laguna Dam on the Colorado River in 1977, at least three pairs of 
western yellow-billed cuckoos occupied a 30-ac (12-ha) site that was 
approximately 20-40 percent willow (Laymon and Halterman 1987a, p. 12). 
By 1986 no western yellow-billed cuckoos were detected on the site 
where the dominant vegetation had become tamarisk, with less than 1 
percent willow cover. In the vicinity of Picacho State Recreation Area, 
on the California side of the Colorado River, in 1977, 21 western 
yellow-billed cuckoos were found in 297 ac (120 ha) of a 230-ft-wide 
(70-m-wide) willow forest (Gaines and Laymon 1984, p. 72). By 1986, 
tamarisk and aquatic vegetation dominated this area, and no western 
yellow-billed cuckoos were found in the 12 ac (5 ha) of scattered 
willow-cottonwood habitat that remained (Laymon and Halterman 1987a, 
pp. 12-13).
    Human disturbance, such as water diversion, flood control, 
vegetation clearing, and improper grazing management, often facilitates 
replacement of native vegetation with tamarisk (Kerpez and Smith 1987, 
pp.

[[Page 60022]]

1-5; Hunter et al. 1988, p. 113; Rosenberg et al. 1991, pp. 18-23). 
Altered hydrologic regimes (flooding or reduction in water flows from 
dams) has disrupted natural flooding events that are essential for 
maintaining native riparian ecosystems (Vogl 1980, pp. 84-86; Rosenberg 
et al. 1991, pp. 18-23), and the disruption (usually elimination) of 
flooding tends to favor tamarisk. In contrast to native cottonwoods, 
tamarisk does not need flooding to regenerate (Kerpez and Smith 1987, 
pp. 1-5).
    Tamarisk is also tolerant of high salt levels, which can be present 
in river systems as a combined result of water diversions that lower 
the near-surface ground water and irrigation water runoff that contains 
high levels of dissolved salts (Kerpez and Smith 1987, pp. 1-5; Busch 
and Smith 1993, pp. 186-194). This higher tolerance to water stress and 
salt accumulation is a principle mechanism by which tamarisk has become 
dominant on some regulated western rivers (Glenn and Nagler 2005, p. 
439). In addition, tamarisk takes salts from the ground water and 
exudes them from its leaves, rendering the soil even more unsuitable 
for germination of native riparian vegetation. This is a significant 
problem in streams with artificially reduced streamflows where salts 
accumulate and are not flushed from the system. These factors favor 
regeneration of tamarisk over native trees and shrubs and are an 
ongoing threat. Additional areas of native habitat are continuing to be 
lost to this process. In summary, the persistence and expansion of 
tamarisk-dominated habitat is the result of multiple forms of ongoing 
human-related disturbances, which result in degradation of native-
dominated riparian habitat, thus reducing its suitability as breeding 
habitat for the western yellow-billed cuckoo.
    Other nonnative tree and shrub species have become established 
within the range of the western yellow-billed cuckoo. In western 
Colorado and Utah, Russian olive (Elaeagnus angustifolia) has become 
established and is a dominant tree species in many riparian systems. 
Giant reed (Arundo donax), common edible fig (Ficus carica), and the 
Himalayan blackberry (Rubus discolor) are some of the more conspicuous 
nonnative plants widely established along the Sacramento River, with 
Himalayan blackberry dominating the understory at some restoration 
sites (Borders et al. 2006, p. 310). Along the Sacramento River, 
western yellow-billed cuckoos were far less likely to be detected at 
sites with an understory dominated by Himalayan blackberry than sites 
with a predominant native understory. Himalayan blackberry may prevent 
establishment of native understory species due to its dense growth 
habit (Hammond 2011, pp. 48-49). Nesting of the western yellow-billed 
cuckoo has not been documented in riparian stands dominated by giant 
reed, common fig, or Himalayan blackberry that lack at least some 
native canopy trees.
    In conclusion, because of the absence or near absence of nesting by 
western yellow-billed cuckoos in nearly monotypic stands of tamarisk 
and other nonnative vegetation, the available literature suggests that 
conversion of native or mixed (native and nonnative) riparian woodlands 
to nearly monotypic stands of tamarisk and other nonnative vegetation, 
coupled with the inability of native vegetation to regenerate under 
altered hydrological conditions, is a significant threat to the western 
yellow-billed cuckoo now and in the future. Nonnative vegetation, such 
as tamarisk, occurs across most of the range of the western yellow-
billed cuckoo; its establishment can be caused by altered hydrology or 
other disturbances, which are widespread throughout the range. We 
expect nonnative vegetation to increasingly modify and curtail habitat 
for the western yellow-billed cuckoo within a majority of its range in 
the United States and northern Mexico into the future.
Use of Tamarisk by Western Yellow-Billed Cuckoos and the Spread of the 
Introduced Tamarisk Leaf Beetle Into the Southwest
    Western yellow-billed cuckoos use habitat with some tamarisk 
component for nesting in southern California, Arizona, and western New 
Mexico, but are not found in monotypic stands of tamarisk. Western 
yellow-billed cuckoo presence in tamarisk-dominated habitats does not 
necessarily equate to habitat suitability (Sogge et al. 2008, p. 149; 
Hammond 2011, p. 50), and additional research is needed to determine 
productivity, survivorship, physiological condition, and food 
availability in these habitats.
    Tamarisk can add to foliar cover that contributes toward reducing 
temperatures in riparian areas (Paxton et al. 2011, p. 259). Even 
relatively small decreases in foliar cover may render a site unsuitable 
for nesting western yellow-billed cuckoos (Paxton et al. 2011, p. 260). 
Removal of tamarisk in drainages occupied by western yellow-billed 
cuckoos can have unintended negative consequences if the removal leaves 
little or no woody vegetation and native riparian vegetation is unable 
to reestablish. The available literature that pertains to riparian 
restoration in New Mexico and Arizona (Poff et al. 1997, pp. 769-784; 
Glenn and Nagler 2005, pp. 439-441; Sogge et al. 2008, pp. 151-152; 
Stromberg et al. 2009, pp. 181-182) suggests that restoration of 
natural hydrological processes, rather than direct removal programs, 
would be a more effective method for promoting regeneration of native 
riparian vegetation and diminishing the presence of tamarisk. However, 
tamarisk removal programs coupled with native riparian plantings can 
speed up the restoration process assuming that the hydrologic system 
will support the native vegetation.
    Tamarisk leaf beetle insects (leaf beetles) (Diorhabda spp.) were 
released into many locations throughout the southwest to control 
tamarisk. Leaf beetles are now spreading within the more arid range of 
the western yellow-billed cuckoo in Nevada, Utah, Arizona, New Mexico, 
and Texas. Defoliation of tamarisk by the beetles occurs in the summer 
months when western yellow-billed cuckoos are in the process of 
nesting. Tamarisk leaf beetles could eventually occur throughout the 
western United States and northern Mexico (Tracy et al. 2008, pp. 1-3). 
The future effects of the beetle introductions to the western yellow-
billed cuckoo are unknown. If beetles succeed in killing tamarisk, 
western yellow-billed cuckoo numbers may decline in areas where the 
hydrology is no longer capable of supporting a native riparian habitat 
and the numbers may increase in areas where native riparian vegetation 
is able to become reestablished.
Wildfire
    Historically, wildfire was uncommon in native riparian woodlands 
(Busch and Smith 1993, pp. 186-194). However, the lack of scouring 
floods on regulated and unregulated rivers has resulted in the 
accumulation of fuel on the floodplain, which increases fire risk and 
intensity (Stromberg and Chew 2002, pp. 195-219). Water withdrawal, 
dams, climate change, drought, and human use also contribute toward an 
increased fuel load and probability of wildfire occurrence. Most fires 
today are human-caused (Service 2002, p. L-8). In degraded habitat with 
tamarisk the threat of fire may be greater. Tamarisk ignites quickly, 
further increasing the incidence of periodic fires. Exacerbating the 
immediate loss of native trees from fire, tamarisk recovers more 
quickly than native trees (Glenn and Nagler 2005, pp. 435-436). Along 
the Rio Grande River in New Mexico and Texas, wildfire has been 
documented as destroying, degrading, or setting back

[[Page 60023]]

successional stages of vegetation development of western yellow-billed 
cuckoo habitat (Sproul 2000, in litt., p. 3). In summary, the 
alteration of riparian systems through changes in hydrologic 
functioning and the introduction of nonnative tamarisk have increased 
the incidence of wildfire into western yellow-billed cuckoo habitat. 
These fires further degrade, isolate, or fragment western yellow-billed 
cuckoo habitat.
Environmental Impacts of Cross-Border Foot Traffic in the Southwest
    The environmental impact caused by cross border foot traffic has 
been increasingly occurring in more fragile and remote areas. The 
number of U.S. Border Patrol apprehensions of border crossers varies 
annually. Between October 1, 1999, and September 30, 2012, a yearly 
average of 333,517 border crossers were apprehended by the United 
States Border Patrol in the Tucson Sector, which does not account for 
the many others who were not caught (U.S. Border Patrol 2013, p. 1). 
Impacts associated with border crossings include creation of erosion 
and watershed degradation, loss of vegetation and wildlife, and human-
caused wildfire (Defenders of Wildlife 2006, pp. 1-42). Drainages used 
by border crossers include the San Pedro River, Santa Cruz River, 
Cienega Creek, and many remote drainages in the mountain ranges of 
southeastern Arizona.
    Human-caused wildland fires have been particularly damaging to 
areas of riparian habitat in Arizona, especially within 100 mi (161 km) 
of the United States-Mexico border where border crossers are known to 
set fires to divert law enforcement agents. Border crossers are also 
responsible for campfires that can escape and spread as wildfires. At 
least 2,467 wildfires began along the Arizona border with Mexico from 
2006 to 2010 (Government Accounting Office 2011, p. 1). Federal 
officials have officially investigated only 77 of those fires. Of the 
fires investigated, 30 were started by border crossers. The resulting 
environmental impacts include the expansion of nonnative plant species, 
degraded endangered species habitat, and soil erosion.
Climate Change
    Climate change may be impacting the western yellow-billed cuckoo. 
Climate change is discussed here under Factor A because, although it 
may affect the western yellow-billed cuckoo directly by creating 
physiological stress, the primary impacts of climate change on the 
species are expected to be through changes in the availability and 
distribution of western yellow-billed cuckoo habitat.
    Our analyses under the Act include consideration of ongoing and 
projected changes in climate. The terms ``climate'' and ``climate 
change'' are defined by the Intergovernmental Panel on Climate Change 
(IPCC). The term ``climate'' refers to the mean and variability of 
different types of weather conditions over time, with 30 years being a 
typical period for such measurements (IPCC 2013a, p. 1450). The term 
``climate change'' thus refers to a change in the mean or variability 
of one or more measures of climate (for example, temperature or 
precipitation) that persists for an extended period, whether the change 
is due to natural variability or human activity (IPCC 2013a, p. 1450).
    Scientific measurements spanning several decades demonstrate that 
changes in climate are occurring, and that the rate of change has 
increased since the 1950s. Examples include warming of the global 
climate system, and substantial increases in precipitation in some 
regions of the world and decreases in other regions (for these and 
other examples, see Solomon et al. 2007, pp. 35-54, 82-85; IPCC 2013b, 
pp. 3-29; IPCC 2014, pp. 1-32). Results of scientific analyses 
presented by the IPCC show that most of the observed increase in global 
average temperature since the mid-20th century cannot be explained by 
natural variability in climate and is ``very likely'' (defined by the 
IPCC as 90 percent or higher probability) due to the observed increase 
in greenhouse gas (GHG) concentrations in the atmosphere as a result of 
human activities, particularly carbon dioxide emissions from use of 
fossil fuels (Solomon et al. 2007, pp. 21-35; IPCC 2013b, pp. 11-12 and 
figures SPM.4 and SPM.5). Further confirmation of the role of GHGs 
comes from analyses by Huber and Knutti (2011, p. 4), who concluded it 
is extremely likely that approximately 75 percent of global warming 
since 1950 has been caused by human activities.
    Scientists use a variety of climate models, which include 
consideration of natural processes and variability, as well as various 
scenarios of potential levels and timing of GHG emissions, to evaluate 
the causes of changes already observed and to project future changes in 
temperature and other climate conditions (Meehl et al. 2007, entire; 
Ganguly et al. 2009, pp. 11555, 15558; Prinn et al. 2011, pp. 527, 
529). All combinations of models and emissions scenarios yield very 
similar projections of increases in the most common measure of climate 
change, average global surface temperature (commonly known as global 
warming), until about 2030. Although projections of the magnitude and 
rate of warming differ after about 2030, the overall trajectory of all 
the projections is one of increasing global warming through the end of 
this century, even for the projections based on scenarios that assume 
that GHG emissions will stabilize or decline. Thus, there is strong 
scientific support for projections that warming will continue through 
the 21st century, and that the magnitude and rate of change will be 
influenced substantially by the extent of GHG emissions (Meehl et al. 
2007, pp. 760-764, 797-811; Ganguly et al. 2009, pp. 15555-15558; Prinn 
et al. 2011, pp. 527, 529; IPCC 2013b, pp. 19-23). See IPCC 2013b 
(entire), for a summary of other global projections of climate-related 
changes, such as frequency of heat waves and changes in precipitation.
    Various changes in climate may have direct or indirect effects on 
species. These effects may be positive, neutral, or negative, and they 
may change over time, depending on the species and other relevant 
considerations, such as threats in combination and interactions of 
climate with other variables (for example, habitat fragmentation) (IPCC 
2014, pp. 4-11). Identifying likely effects often involves aspects of 
climate change vulnerability analysis. Vulnerability refers to the 
degree to which a species (or system) is susceptible to, and unable to 
cope with, adverse effects of climate change, including climate 
variability and extremes. Vulnerability is a function of the type, 
magnitude, and rate of climate change and variation to which a species 
is exposed, its sensitivity, and its adaptive capacity (Glick et al. 
2011, pp. 19-22; IPCC 2014, p. 5). There is no single method for 
conducting such analyses that applies to all situations (Glick et al. 
2011, p. 3). We use our expert judgment and appropriate analytical 
approaches to weigh relevant information, including uncertainty, in our 
consideration of the best scientific information available regarding 
various aspects of climate change.
    Global climate projections are informative, and, in some cases, the 
only or the best scientific information available for us to use. 
However, projected changes in climate and related impacts can vary 
across and within different regions of the world (IPCC 2013b, pp. 15-
16). Therefore, we use ``downscaled'' projections when they are 
available and have been developed through appropriate scientific 
procedures, because such projections provide higher resolution 
information

[[Page 60024]]

that is more relevant to spatial scales used for analyses of a given 
species (see Glick et al. 2011, pp. 58-61, for a discussion of 
downscaling). With regard to our analysis for the western yellow-billed 
cuckoo, downscaled projections are available.
    The Southwest is already experiencing the impacts of climate 
change. The region has heated up markedly in recent decades, and the 
period since 1950 has been hotter than any comparably long period in at 
least 600 years (Graumlich 1993, pp. 249-255; Salzer and Kipfmueller 
2005, pp. 465-487; Millar et al. 2006, pp. 273-287; Ababneh 2008, pp. 
59-78; Bonfils et al. 2008, pp. 6404-6424; Stevens et al. 2008, pp. 1-
15; Salzer et al. 2009, pp. 20348-20353; Woodhouse et al. 2010, pp. 
21283-21288; Hoerling et al. 2012, pp. 74-92). The decade 2001-2010 was 
the warmest in the 110-year instrumental record, with temperatures 
almost 2 [deg]F higher than historic averages, with fewer cold snaps 
and more heat waves (Hoerling et al. 2012, pp. 74-92). Compared to 
temperature, precipitation trends vary considerably across the region, 
with portions experiencing both decreases and increases (Hoerling et 
al. 2012, pp. 74-92). There is mounting evidence that the combination 
of human-caused temperature increases and recent drought has influenced 
widespread tree mortality (Van Mantgem et al. 2009, pp. 521-524; Allen 
et al. 2010, pp. 660-684), increased fire occurrence and area burned 
(Westerling et al. 2006, pp. 940-943), and forest insect outbreaks 
(Bentz et al. 2010, pp. 602-613). Human-caused temperature increases 
and drought have also caused earlier spring snowmelt and shifted runoff 
to earlier in the year (Barnett et al. 2008, pp. 1080-1083).
    There are three predictions for anticipated effects from climate 
change in the southwestern United States and parts of northwestern 
Mexico. First, climate change is expected to shorten periods of 
snowpack accumulation, as well as reduce snowpack levels. With 
gradually increasing temperatures and reduced snowpack (due to higher 
spring temperatures and reduced winter-spring precipitation), annual 
runoff will be reduced (Smith et al. 2003, p. 226; Ellis et al. 2010, 
p. 236), consequently reducing ground water recharge. Second, snowmelt 
is expected to occur earlier in the season because increased minimum 
winter and spring temperatures could melt snowpacks sooner, causing 
peak water flows to occur much sooner than the historical spring and 
summer peak flows (Smith et al. 2003, p. 226; Stewart et al. 2005, pp. 
217-218, 224, 230) and reducing flows later in the season. Third, the 
hydrological cycle is expected to become more dynamic on average with 
climate models predicting increases in the variability and intensity of 
rainfall events. This change will modify disturbance regimes by 
changing the magnitude and frequency of floods.
    Precipitation events under most climate change scenarios will 
decrease in frequency but increase in severity so that, paradoxically, 
a warmer atmosphere and an intensified water cycle are likely to mean 
not only a greater likelihood of drought for the Southwest, but also an 
increased risk of flooding (Karl et al. 2009, pp. 132-133; Dominguez et 
al. 2012, pp. 1-7). Precipitation patterns are already observed to be 
shifting in the Southwest, with more rain falling in heavy downpours 
that can lead to flooding (Karl et al. 2009, p. 133). Adding to flood 
risk is that the earlier streamflow from earlier snowmelt may impinge 
on the flood protection stages of reservoir operations so that less 
streamflow can be captured safely in key reservoirs, increasing spring 
flooding downstream (Smith et al. 2005, p. 1154; Karl et al. 2009, p. 
133). In some sites, where natural floodplain dynamics allow for 
overbank flooding, this could result in a positive regenerating effect 
on habitat for the western yellow-billed cuckoo. However, where 
floodplains have been constrained, as in many areas of the range, such 
changes in hydrology could excessively scour remaining habitat, thus 
preventing their reestablishment and resulting in smaller patch size or 
loss of habitat for the western yellow-billed cuckoo. Long drought 
cycles could also hamper recruitment of riparian vegetation following 
scouring floods and lead to reduced cover and nest sites for the 
western yellow-billed cuckoo.
    Exactly how climate change will affect precipitation from site to 
site within the range of the western yellow-billed cuckoo in the 
southwestern United States and northwestern Mexico is uncertain. 
However, consistent with recent observations of regional effects of 
climate change, the projections presented for the Southwest predict 
overall warmer, drier, and more drought-like conditions (Hoerling and 
Eischeid 2007, p. 19; Seager et al. 2007, p. 1181; Ellis et al. 2010, 
p. 243). For example, climate simulations of the Palmer Drought 
Severity Index (a calculation of the cumulative effects of 
precipitation and temperature on surface moisture balance) for the 
Southwest for the periods of 2006 to 2030 and 2035 to 2060 show an 
increase in drought severity with surface warming. Additionally, 
drought-like conditions will increase even during wetter simulations 
because of the effect of heat-related moisture loss through evaporation 
and evapotranspiration (Hoerling and Eischeid 2007, p. 19). Annual mean 
precipitation is likely to decrease in the Southwest, as is the length 
of snow season and snow depth (Sun et al. 2013, pp. 21-22; Garfin et 
al. 2014, pp. 462-486). Most models project a widespread decrease in 
snow depth and earlier snowmelt in the Rocky Mountains (Clow et al. 
2012, 2583-2591; Pederson et al. 2013, 1811-1816).
    Assessments for the Sonoran Desert are few, but the region is also 
expected to warm (Weiss and Overpeck 2005, pp. 2065-2077; National Park 
Service 2010, pp. 1-4; Munson et al. 2012, pp. 1083-1095). Since about 
the 1970s, the Sonoran Desert region appears to have experienced 
``widespread warming trends in winter and spring, decreased frequency 
of freezing temperatures, lengthening of the freeze-free season, and 
increased minimum temperatures per winter year'' (Weiss and Overpeck 
2005, p. 2065). The Sonoran Desert area is expected to warm faster and 
experience reduced annual precipitation, resulting in a reduction in 
soil moisture in an already dry environment. The area will also 
experience increases in the intensity of heat waves, decreases in the 
frequency of freezing temperatures, and lengthening of the freeze-free 
season. Munson et al. (2012) stated that ``Climate models and long-term 
trends predict increased variability in precipitation seasonality, with 
fewer, larger, and more intense precipitation events'' (Munson et al. 
2012, pp. 1083-1095). Other researchers have also concluded similar 
climactic changes for the area (Easterling et al. 2000, pp. 2068-2074; 
Weiss and Overpeck 2005, pp. 2065-2077; Seager et al. 2007, pp. 1181-
1184).
    In California, regional downscaled climate change assessments 
(Point Reyes Bird Observatory (PRBO) Conservation Science 2011, pp. 1-
68) indicate changes in precipitation and temperature of varying 
magnitude across ecoregions. Assessments for areas occupied by the 
western yellow-billed cuckoo, such as the Sacramento River, Sierra 
Nevada (southern), and Sonora Desert (lower Colorado River) (PRBO 
Conservation Science 2011, pp. 25, 28, 48), mostly indicate an overall 
reduction in precipitation and increase in average temperature, which 
can alter hydrology and negatively affect habitat for the western 
yellow-billed cuckoo, as

[[Page 60025]]

described previously. Furthermore, Gardali et al. (2012, pp. 8-10) 
ranked 358 avian taxa in California, and classified 128 as vulnerable 
to climate change. They ranked the western yellow-billed cuckoo as 
subject to a moderate level of climate vulnerability, owing in part to 
its specialization in habitat (riparian) that has already experienced 
significant loss or alteration. Of the 128 species that were rated 
vulnerable, only 48 were rated as having high or moderate climate 
vulnerability.
    Regionally downscaled climate models for the Pacific Northwest 
project higher air temperatures in the next century (Littell et al. 
2009, pp. 6-7) that will lead to lower soil moisture and increased 
evaporation from streams and lakes (Climate Leadership Initiative (CLI) 
and the National Center for Conservation Science and Policy 2009, p. 
8). While high uncertainty exists in the total precipitation 
projections for the region (Littell et al. 2009, p. 1), effective 
precipitation (precipitation that contributes to runoff) may be reduced 
significantly even if there is no decline in total precipitation (CLI 
and the National Center for Conservation Science and Policy 2009, p. 
8). Increases in extreme high precipitation falling as rain in the 
western Cascades and reductions in snowpack are key projections from 
high-resolution regional climate models (Littell et al. 2009, p. 1). 
These may result in more winter flooding and reduced summer streamflows 
in rivers that depend on snowmelt, which include many of the rivers in 
the Pacific Northwest.
    In drier climates overall, there will be increases in riverine 
system temperatures that are predicted to result in periods of 
prolonged low flows and stream drying (Stromberg et al. 2013, pp. 411-
415) and increased demand for water storage and conveyance systems 
(Stromberg et al. 2013, pp. 411-415). Warmer water temperatures across 
temperate regions are likely to increase the density and expand 
distribution of tamarisk because it has a higher tolerance for drought 
and salt than native cottonwoods and willows (Glenn and Nagler 2005, p. 
439). This situation is expected to lead to the conversion of native 
and mixed (native and nonnative) riparian habitat to monotypic stands 
of tamarisk, which provides very little or no suitable breeding habitat 
for the western yellow-billed cuckoo (as described previously above).
    Increased drought is expected to adversely affect food availability 
for western yellow-billed cuckoos (Newton 1980, pp. 11-12; Durst 2004, 
pp. 40-41; Scott et al. 2004, p. 70) through the disruption of the 
timing between a species and its food resources (Visser and Both 2005, 
pp. 2561-2569). For example, changes in precipitation or temperature 
may influence the peak timing of insect emergence or timing of the 
western yellow-billed cuckoo's arrival from its wintering grounds so 
that the nesting season does not coincide as closely with peak insect 
abundance (Anders and Post 2006, p. 225). This change in timing could 
result in reduced food availability for the western yellow-billed 
cuckoo and breeding success, possibly causing further population 
decline and curtailment of its occupied range.
    Virtually all future climate scenarios for the Pacific Northwest 
predict increases in wildfire in western North America, especially east 
of the Cascades, due to higher summer temperatures, earlier spring 
snowmelt, and lower summer flows, which can lead to drought stress in 
trees (Littell et al. 2009, p. 14). These effects could result in both 
short-term and long-term loss of riparian habitat from excessive winter 
scouring, summer drying, and wildfire. Regional downscaled climate 
change models for the Intermountain West also provide similar 
projections for warmer, drier climate with a reduced snowpack and 
episodic precipitation events. Prolonged drought in the southwestern 
United States and northern Mexico is expected to increase fire 
frequency, which results in a short-term loss of patches of riparian or 
thorn forest habitat for breeding. When fire frequency increases, 
riparian and thorn forests do not have sufficient time to recover, 
resulting in habitat conversion to fire-adapted nonforested vegetation 
types unsuitable for nesting. Furthermore, the effects of climate 
change and ongoing reduction in habitat and patch fragmentation, 
discussed previously, would increase.
    Little is known about the wintering habitat of the western yellow-
billed cuckoo in South America, and uncertainty exists about how 
climate change will affect it there. Regional downscaled models project 
an increase in wet-season precipitation and a decrease in dry-season 
precipitation over most of South America (Kitoh et al. 2011, p. 1). In 
the future, precipitation intensity will increase over most of South 
America. In particular, precipitation intensity will be greatest over 
southeast South America, implying an increasing risk of flooding in 
this region (Kitoh et al. 2011, p. 1). At the same time, a large 
increase of consecutive dry days is projected over the western part of 
the Amazon, where extremes in seasonal precipitation and resulting 
runoff is projected to increase in the Amazon River, implying more 
floods in the wet season and droughts in the dry season (Kitoh et al. 
2011, p. 1). Uncertainty exists regarding the specific effects of such 
changes on the wintering habitat of the western yellow-billed cuckoo.
    In summary, the available climate change models are predicting 
altered future environmental conditions across the breeding range of 
the western yellow-billed cuckoo. In the southwestern United States, 
northern Mexico, California, Intermountain West, and Pacific Northwest, 
climate change is generally predicted to result in an overall warmer, 
drier climate, with periodic episodic precipitation events that, 
depending on site conditions, are expected to have adverse effects on 
habitat of the western yellow-billed cuckoo. In rivers that depend on 
snowmelt, these changes are expected to result in more winter flooding 
and reduced summer stream flows. The amount of surface ground water 
available to regenerate and sustain riparian forests is expected to 
decline overall with persistent drought, favor the spread of tamarisk 
and other nonnative vegetation, and increase fire frequency. 
Precipitation events under most climate change scenarios will decrease 
in frequency and increase in severity. This change may reduce available 
nesting sites, patch size, and affect prey abundance as a result of 
lower humidity in riparian areas from reduced moisture retention, and 
through periods of prolonged desiccation followed by scouring flood 
events. In addition, evidence shows that climate change may disrupt the 
synchrony of nesting western yellow-billed cuckoos and their food 
supply, causing further population decline and curtailment of its 
occupied range.
    Impacts to habitat from climate change exacerbate impacts from 
impoundments, channelization, and alteration of river flows across the 
western United States and Mexico, and from conversion of habitat from 
native to mostly nonnative vegetation. Changing climate is expected to 
place an added stress on the species and its habitats. While we do not 
have evidence to suggest that the habitat of the western yellow-billed 
cuckoo is being substantially affected by climate change at this time, 
we expect long-term climate trends to have an overall negative effect 
on the available habitat throughout the breeding range of the western 
yellow-billed cuckoo. Moreover, a drying trend associated with global 
climate change may result in more dams, levees, or other activities to

[[Page 60026]]

ensure fresh water for human consumption, which may result in 
additional habitat loss from the activities described in the Habitat 
Loss from Dams and Alteration of Hydrology section, above.
Summary of Factor A
    We have identified a number of threats to the habitat of the 
western yellow-billed cuckoo that have operated in the past, are 
impacting the species now, and will continue to impact the species in 
the future. The curtailment and decline in the habitat of the western 
yellow-billed cuckoo is primarily the result of the long-lasting 
effects of habitat loss from manmade features that alter watercourse 
hydrology so that the natural processes that sustained riparian habitat 
in western North America are greatly diminished. Loss and degradation 
of habitat has also occurred as a result of livestock overgrazing and 
encroachment from agriculture. All of these have the potential to 
promote, and are exacerbated by, the conversion of native habitat to 
predominantly nonnative vegetation. The curtailment, degradation, 
fragmentation, and loss of habitat for the western yellow-billed cuckoo 
is ongoing and, absent changes in the landscape, hydrology, or other 
factors, it will likely continue to be negatively impacted or lost into 
the future.
    We recognize that climate change is a critical issue with 
potentially severe wide-ranging effects on the species and its habitat. 
The available scientific literature suggests that the effects of 
climate change will likely exacerbate multiple existing threats to the 
western yellow-billed cuckoo and its habitat. These threats include 
habitat loss and degradation from altered hydrology, with secondary 
effects from increases in nonnative vegetation and wildfire. These 
threats may result in smaller patch sizes of habitat such that many 
will be no longer occupied by the western yellow-billed cuckoo.
    Conservation actions, such as habitat protection and restoration 
described above, have strong potential to be beneficial to the species 
by increasing the amount of available habitat and patch size. However, 
these efforts offset only a small portion of past losses and 
degradation of riparian habitat in the range of the western yellow-
billed cuckoo. Habitat elsewhere in the range continues to be 
vulnerable to loss and degradation from ongoing alterations in 
hydrology, nonnative vegetation, and agricultural activities combined 
with additional or synergistic effects associated with climate change. 
Moreover, we expect these multiple stressors to continue to affect 
habitat of the western yellow-billed cuckoo into the future. The amount 
of time required for willow and cottonwood vegetation to mature and 
provide habitat for the western yellow-billed cuckoo under optimal 
hydrologic, environmental, and ecological conditions varies by location 
but may be as little as between 3 to 5 years (Golet et al. 2008, pp. 
20-22). However, other vegetation used by the western yellow-billed 
cuckoo such as alder, walnut, sycamore, boxelder, ash, or mesquite 
would take several decades for habitat to mature to the point where it 
would be available for use (Strahan 1984, pp. 58-67; Opperman and 
Merenlender 2004, pp. 822-834; Trowbridge et al. 2004, pp. 157-164; 
Morris et al. 2006, pp. 106-116; Griggs 2009, p. 12). In areas where 
conditions are less than optimal (as is the current situation in most 
areas) it may take longer if at all (Briggs 1995, pp. 63-67).
    The exact timeframe for resolving water management and delivery 
issues and their impact on the western yellow-billed cuckoo and its 
habitat would vary on the location, resource demands, sensitive habitat 
or species concerns, stakeholders, and amount of water available. As a 
result, we would expect that resolving water issues for the various 
uses (agriculture, urbanization, wildlife, and tribal interests) in the 
west will be a lengthy ongoing process and not be resolved in the near 
future (next 20 years) and may take substantially longer considering 
the increased demands and the effects of climate change.
    Our review of the best available scientific and commercial 
information identified numerous activities or processes that threaten 
to destroy, modify, or curtail the western yellow-billed cuckoo's 
habitat or range now or are likely to in the near future in any portion 
of the western yellow-billed cuckoo range. These include habitat loss 
from reservoirs and water management, surface and groundwater 
diversion, flood control activities, gravel mining, agriculture, 
livestock grazing, invasive nonnative plants and their control, and 
climate change. We, therefore, conclude that habitat loss under Factor 
A currently constitutes a threat to the western yellow-billed cuckoo, 
and we expect these activities to continue and habitat loss to be a 
threat in the near future.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    There are no known threats to the western yellow-billed cuckoo 
resulting from overutilization for commercial, scientific, or 
educational purposes. Our review of the best available scientific and 
commercial information yielded nothing to indicate that overutilization 
for commercial, recreational, scientific, or educational purposes is 
occurring at this time or is likely to in the near future in any 
portion of the western yellow-billed cuckoo range. We, therefore, 
conclude that such overutilization does not currently constitute a 
threat to the western yellow-billed cuckoo, nor do we expect it to be a 
threat in the future.

C. Disease or Predation

    Little is known about diseases in the western yellow-billed cuckoo. 
West Nile virus has recently spread throughout portions of the western 
United States. It poses a potential threat to many bird species. The 
U.S. Geological Survey's (USGS) National Wildlife Health Center has 
identified the yellow-billed cuckoo as a species that is subject to the 
effects of West Nile virus (USGS-National Wildlife Health Center 2005, 
p. 2). The Centers for Disease Control's (CDC) Vector-Borne Disease Web 
site reports that West Nile virus has been documented in a dead yellow-
billed cuckoo (CDC 2012); however, it is unknown if this yellow-billed 
cuckoo was from the western DPS. Although the population of the western 
yellow-billed cuckoo has been in decline over several decades (see 
Historical and Current Status section, above), no evidence suggests 
that it has undergone a precipitous decline coincident with the 
relatively recent arrival of West Nile virus in western North America. 
Therefore, we conclude, based on the best available scientific and 
commercial information, which is limited, that the adverse effects of 
West Nile virus to the western yellow-billed cuckoo are not significant 
and do not constitute a threat at this time, nor is there any 
information to suggest that this situation will change into the future.
    All bird species, including the yellow-billed cuckoo, are exposed, 
to some extent, to parasites. Greiner et al. (1975, pp. 1762-1787) 
found 5 of 16 yellow-billed cuckoos infected with Leucocytozoon, 
Trypanosoma, and microfilaria blood parasites. No information indicates 
whether these and other parasites (see Hughes 1999, p. 18, for a brief 
review) pose any threat to the western yellow-billed cuckoo.
    Predation is a potential threat to the western yellow-billed 
cuckoo. On the Kern River, red-shouldered hawks (Buteo lineatus) and 
northern harriers (Circus cyaneus) have been observed preying on 
nestlings, and western yellow-billed cuckoos have been observed chasing 
western scrub-jays

[[Page 60027]]

(Aphelocoma californica) and loggerhead shrikes (Lanius ludovicianus) 
away from their nests (Laymon 1998, pp. 12-14); however, we do not have 
any information on the frequency of predation. An inverse relationship 
appears to exist between the presence of western yellow-billed cuckoos 
and western scrub-jays on the Sacramento River, indicating a possible 
aversion by the western yellow-billed cuckoos to nesting at sites 
occupied by western scrub-jays, a known predator of eggs and young 
(Halterman 1991, p. 38). Avian predators such as the Cooper's hawks 
(Accipiter cooperii) or other similarly sized avian predators are 
thought to be the only avian predator capable of taking adult western 
yellow-billed cuckoos (Laymon 1998, pp. 12-13). During migration, adult 
western yellow-billed cuckoo are susceptible to predation by raptors, 
such as the Aplomado falcons (Falco femoralis) (Hector 1985, p. 338); 
however, we have no information to suggest that the rate of adult 
predation is significantly affecting the western yellow-billed cuckoo 
population. In the Sonoran town of Alamos, Mexico, Mackay (David Mackay 
2012, in litt.) witnessed a brown vine snake (Oxybelis aeneus) leaving 
a western yellow-billed cuckoo nest after eating one of four nestlings.
    On the lower Colorado River, McNeil et al. (2011, p. 41) found that 
high nest predation rates (63 percent of nests failed) contributed to 
the much lower average nest productivity at restoration sites (1.25 
young fledged per nest) compared to nests at the Bill Williams River 
NWR (2.14 young fledged per nest). Most of that predation was 
attributed to avian predators; however, for 2 consecutive years a nest 
was preyed upon by a California king snake (Lampropeltis getula 
californiae) (McNeil et al. 2011, p. 41; McNeil et al. 2012, p. 50). 
Nest predation may have been high in restoration sites because most 
were located adjacent to agricultural areas, which may have increased 
the exposure of nests to human-adapted avian predators that thrive in 
agricultural areas. Additionally, these sites did not yet have the 
height, structure, and composition of more complex riparian habitats 
(McNeil et al. 2011, pp. 41, 49; McNeil et al. 2012, p. 56) that may 
serve to hide nests from predators. Nest predation can be partially 
compensated by the ability of western yellow-billed cuckoos to renest 
when a nest fails. In general, despite the instances of nest predation 
listed above, western yellow-billed cuckoos have higher than normal 
nest success and lower nest predation rates than other open-cup nesting 
birds (Laymon et al. 1997, p. 11).
    In summary, western yellow-billed cuckoos, particularly the eggs or 
young in nests, are vulnerable to predation. Predation may be a 
significant threat in some localities and in some years, and may be 
influenced by several factors, such as surrounding land use and size 
and complexity of riparian habitat. As a result, predation may act 
periodically in concert with other stressors that contribute to the 
decline of the species (which we discuss in greater detail under Factor 
E, below). However, we conclude that predation by itself does not pose 
a significant threat to the western yellow-billed cuckoo at this time, 
and we do not have any reason to believe that this situation will 
change substantially in the future.
    We conclude that predation, parasites, and disease are not 
currently significant threats to the western yellow-billed cuckoo, and 
are not expected to become significant threats in the near future.

D. The Inadequacy of Existing Regulatory Mechanisms

    Under this factor, we examine whether existing regulatory 
mechanisms are inadequate to address the threats to the western yellow-
billed cuckoo discussed under other factors. We give strongest weight 
to statutes and their implementing regulations, and management 
direction that stems from those laws and regulations. They are 
nondiscretionary and enforceable, and are considered a regulatory 
mechanism under this analysis. Examples include State governmental 
actions enforced under a State statute or constitution, or Federal 
action under statute.
    Some other programs are more voluntary in nature or dependent on 
available funding; in those cases, we analyze the specific facts for 
that effort to ascertain its effectiveness at mitigating the threat and 
the extent to which it can be relied on in the future. Having evaluated 
the significance of the threat as mitigated by any such conservation 
efforts, we analyze under Factor D the extent to which existing 
regulatory mechanisms adequately address the specific threats to the 
species. Regulatory mechanisms, if they exist, may preclude the need 
for listing if we determine that such mechanisms adequately address the 
threats to the species such that listing is not warranted.
    We have identified a number of significant threats to the western 
yellow-billed cuckoo that are impacting the species now and will 
continue to impact the species in the future. The decline of the 
western yellow-billed cuckoo is primarily the result of the long-
lasting effects of habitat loss and modification from altered hydrology 
resulting from decades of dam construction, channelization, water 
extraction, and other activities, as well as impacts associated with 
climate change. Other threats include loss of habitat to agricultural 
and other land uses, overgrazing, exposure to pesticides (which is 
addressed in Factor E, below), wildfire, and conversion of habitat to 
monotypic stands of nonnative vegetation. Under this factor, we discuss 
whether the existing regulatory mechanisms adequately address impacts 
to the western yellow-billed cuckoo described under Factors A and E, 
based on the best available information.
Federal Regulatory Mechanisms
    In the United States, the Migratory Bird Treaty Act (MBTA) (16 
U.S.C. Sec. 703-712) is the only current Federal protection provided 
for the yellow-billed cuckoo. The yellow-billed cuckoo (the entire 
taxonomically defined species), which includes the western yellow-
billed cuckoo, is considered a ``migratory bird'' under the MBTA. The 
MBTA prohibits ``take'' of any migratory bird. Take is defined as: ``to 
pursue, hunt, shoot, wound, kill, trap, capture, or collect, or attempt 
to pursue, hunt, shoot, wound, kill, trap, capture, or collect.'' 
However, no provisions in the MBTA prevent habitat destruction unless 
direct mortality or destruction of active nests occurs.
    The Federal Land Policy and Management Act of 1976 (FLPMA) (43 
U.S.C. 1701 et seq.) requires that ``the public lands be managed in a 
manner that will protect the quality of scientific, scenic, historical, 
ecological, environmental, air and atmospheric, water resource, and 
archeological values; that . . . will preserve and protect certain 
public lands in their natural condition; (and) that will provide food 
and habitat for fish and wildlife. . . .'' Furthermore, it is the 
policy of the Bureau of Land Management (BLM) ``to manage habitat with 
emphasis on ecosystems to ensure self-sustaining populations and a 
natural abundance and diversity of wildlife, fish, and plant resources 
on public lands'' (BLM manual 6500.06). Similarly, the National Forest 
Management Act of 1976 (NFMA) directs that the National Forest System 
``where appropriate and to the extent practicable, will preserve and 
enhance the diversity of plant and animal communities.'' Additionally, 
section 219.12(g) calls for the maintenance of viable populations of 
native vertebrates in national forests. As such, FLPMA and

[[Page 60028]]

NFMA have the potential to benefit the western yellow-billed cuckoo and 
its habitat. However, given that the BLM and USFS have discretion in 
how these statutes are carried out and measures are implemented, we 
continue to see continued loss and degradation of habitat for the 
western yellow-billed cuckoo on lands that these agencies manage.
    Congress passed the Federal Water Pollution Control Act Amendments 
of 1972 and the Clean Water Act (CWA) of 1977 (33 U.S.C. 1251 et seq.) 
to provide for the restoration and maintenance of the chemical, 
physical, and biological integrity of the Nation's lakes, streams, and 
coastal waters. Primary authority for the implementation and 
enforcement of the CWA now rests with the U.S. Environmental Protection 
Agency (EPA) and, to a lesser extent, the USACE. In addition to the 
measures authorized before 1972, the CWA implements a variety of 
programs, including Federal effluent limitations and State water 
quality standards, permits for the discharge of pollutants and dredged 
and fill materials into navigable waters, and enforcement mechanisms. 
Section 404 of the CWA is the principal Federal program that regulates 
activities affecting the physical integrity of wetlands and other 
waters of the United States.
    Section 404 prohibits the discharge of dredged or fill material in 
jurisdictional waters of the United States, unless permitted by USACE 
under section 404(a) (individual permits) or 404(e) (general permits), 
or unless the discharge is otherwise exempt from regulation as 
designated in section 404(r). Some areas of riparian habitat may be 
considered ``waters of the United States,'' but many areas of riparian 
habitat do not meet the term's strict definition. The Service can 
review permit applications and provide recommendations to the USACE to 
avoid and minimize impacts and to implement conservation measures for 
fish and wildlife resources, including the western yellow-billed 
cuckoo. However, incorporation of Service recommendations into section 
404 permits is at the discretion of the USACE.
    Furthermore, not all activities in wetlands or streams involve 
fill, and not all wetlands or streams fall under the jurisdiction of 
the USACE. For example, in areas where the historical floodplain has 
been cut off from the river by levees, determining the boundaries of 
wetlands subject to USACE jurisdiction becomes complex. The areas 
behind these levees have had their hydrological characteristics 
altered, soil conditions changed, and riparian vegetation removed. As a 
result, these former floodplains, which in some cases would be 
important to protect and restore as habitat for the western yellow-
billed cuckoo, fall outside the jurisdiction of the USACE. 
Additionally, many actions that resulted in adverse hydrological 
modifications, such as channelization and levees, were implemented in 
compliance with the CWA.
    The National Environmental Policy Act (NEPA) (42 U.S.C. 4321 et 
seq.) requires all Federal agencies to formally document, consider, and 
publicly disclose the environmental impacts of major Federal actions 
and management decisions that have significant effects on the human 
environment (including natural resources); however, NEPA does not 
require that mitigation alternatives be implemented. Additionally, NEPA 
applies only to actions by Federal agencies, so private landowners are 
not required to comply with NEPA unless a Federal agency is involved 
through provision of Federal funding or a Federal permit.
    Through the Fish and Wildlife Coordination Act (FWCA) (16 U.S.C. 
661 et seq.), the Service may recommend discretionary conservation 
measures to avoid, minimize, and offset impacts to fish and wildlife 
resources resulting from Federal projects and water development 
projects authorized by the USACE and other Federal agencies such as 
Reclamation. Therefore, the FWCA may provide some protection for the 
western yellow-billed cuckoo and its habitat through avoidance and 
minimization measures that may be incorporated into Federal projects. 
However, these measures are discretionary.
    A majority of dams in the western United States supply hydropower, 
and their construction and ongoing operation is authorized by the 
Federal Energy Regulatory Commission (FERC), under the Federal Power 
Act of 1920, which incorporates by reference the FWCA and NEPA. The 
remainder of hydropower in the western United States is largely 
produced by the USACE and Reclamation. Reclamation also oversees water 
diversion and delivery projects. FERC reconsiders its hydropower 
licenses every 30 to 50 years. Through the various Federal regulations 
under which these agencies implement their water projects, the Service 
has an opportunity to periodically review their permits and relicensing 
applications and provide its recommendations to avoid and minimize 
impacts, and implement conservation measures for fish and wildlife 
resources, including species such as the western yellow-billed cuckoo. 
Implementation of these recommendations by FERC, USACE, and Reclamation 
is discretionary for nonlisted species. We continue to see loss and 
degradation of habitat for the western yellow-billed cuckoo as a result 
of altered hydrology from operation of dams and other water supply 
projects, as described under Factor A.
    The EPA is responsible for regulating pesticides under the Federal 
Insecticide, Fungicide, and Rodenticide Act and the Food Quality 
Protection Act. Before a pesticide can be distributed, sold, and used 
in the United States, it must first go through a registration process 
through the EPA. The EPA conducts short- and long-term toxicity tests 
to evaluate potential adverse effects on humans, wildlife, fish, and 
plants, including endangered species and nontarget organisms, and 
evaluates the potential for possible contamination of surface water or 
ground water from leaching, runoff, and spray drift. The sensitivity of 
any life stages of the western yellow-billed cuckoo or its prey items 
to exposure from common agricultural pesticides that could leach, 
runoff, or migrate from agricultural areas into the habitat of the 
western yellow-billed cuckoo has not been tested. However the EPA does 
evaluate the effects of these factors on surrogate species and has 
determined the use of certain approved pesticides are appropriate in 
areas used by the western yellow-billed cuckoo. Even if approved 
application procedures are followed, pesticides could reduce available 
insect prey for the western yellow-billed cuckoos.
State Regulatory Mechanisms
    The majority of occupied areas for the western yellow-billed cuckoo 
north of Mexico occur within California, Arizona, and New Mexico 
(Hughes 1999, p. 1). Only California classifies the western yellow-
billed cuckoo as endangered (CDFW 2011, p. 10). The California 
Endangered Species Act (CESA) prohibits unpermitted possession, 
purchase, sale, or take of listed species. However, the CESA definition 
of take does not include harm, which under the Federal Act can include 
destruction of habitat that actually kills or injures wildlife by 
significantly impairing essential behavioral patterns (50 CFR 17.3). 
CESA does require consultation between the CDFW and other State 
agencies to ensure that their activities will not jeopardize the 
continued existence of State-listed species; however, the western 
yellow-billed cuckoo continues to decline in California despite its 
status

[[Page 60029]]

as a State-listed species. In Arizona, the western yellow-billed cuckoo 
is listed as a species of concern (Arizona Game and Fish Department 
2002, p. 3), with no protective status. The western yellow-billed 
cuckoo has no special protective status in New Mexico.
    The State of California has an additional layer of pesticide 
regulation through the Department of Pesticide Regulation, whose 
mission is to protect human health and the environment by regulating 
pesticide sales and use. While concentrating on human health and 
exposure to pesticides, the agency has a program (Endangered Species 
Project) that maps sites occupied by federally listed species and 
candidate species and evaluates pesticide exposure risks to the species 
at those sites. This project does not include species like the western 
yellow-billed cuckoo that are listed as endangered by the State but not 
the Federal Government. In addition, the work was carried out in 1997 
prior to the western yellow-billed cuckoo becoming a Federal candidate 
species. As a result the western yellow-billed cuckoo has not been 
included in the project.
    Washington State's Department of Fish and Wildlife considers the 
western yellow-billed cuckoo a candidate for listing. The State 
wildlife agencies in Wyoming, Montana, Colorado, and Texas classify the 
western yellow-billed cuckoo as a species of concern or a sensitive 
species. In Utah, the Utah Division of Wildlife Resources (UDWR) has 
designated the yellow-billed cuckoo as a State-sensitive species and 
the yellow-billed cuckoo has been a priority for the State's Native 
Terrestrial Wildlife Program since the late 1990's. For example, in 
2009, surveys for the species were conducted on National Park Service 
and adjacent lands at Cubs Creek and Jones Hole in northeastern Utah 
(Beason 2009, pp. 1-19). During these surveys no western yellow-billed 
cuckoos were detected on lands managed by the National Park Service in 
Dinosaur National Monument or private land in northwestern Colorado. 
However, suitable habitat is found within Dinosaur National Monument. 
UDWR has implemented additional survey and monitoring efforts over the 
past 2 years. This status allows for enhanced attention for the species 
and potential voluntary conservation, but the status provides no 
conservation assurances or regulatory oversite.
    The western yellow-billed cuckoo is identified as a Species of 
Greatest Conservation Need in Idaho's Comprehensive Wildlife 
Conservation Strategy (Idaho Department of Fish and Game 2005, Appendix 
B, p. 7), and, under Idaho State law, is considered a protected nongame 
species. It is illegal to intentionally take or possess a protected 
nongame species, except as provided in sections 36-106(e) and 36-1107, 
Idaho Code, by Commission rule, or the Idaho Administrative Procedures 
Act 13.01.10, ``Rules Governing the Importation, Possession, Release, 
Sale, or Salvage of Wildlife,'' subsection 100.06.b (Idaho Department 
of Fish and Game 2005, Appendix B, p. 5). While protected status 
extends certain protections to the western yellow-billed cuckoo in 
Idaho, neither this status nor the Species of Greatest Conservation 
Need designation protects its habitat.
    In Nevada, the western yellow-billed cuckoo is identified as 
critically imperiled due to extreme rarity, imminent threats, or 
biological factors, but this designation provides no protection for 
habitat. Western yellow-billed cuckoos have no State status in Oregon 
because it has not been considered an active breeding species since the 
1940s (Oregon Department of Fish and Wildlife 2005, p. 3). State 
Wildlife Action Plans that include the western yellow-billed cuckoo as 
a species of conservation concern are: California, Washington, Arizona, 
Colorado, Montana, Idaho, New Mexico, Utah, Texas, Nevada, and Wyoming. 
These plans identify conservation needs and actions for a broad range 
of species and habitats, but their implementation is discretionary.
    In summary, where the western yellow-billed cuckoo is State-listed 
(CA), a State candidate (WA), a species of concern or sensitive species 
(AZ, ID, WY, MT, CO, TX), or critically imperiled (NV), these 
designations contain no protection for the western yellow-billed cuckoo 
from habitat modification or destruction, as described under Factors A 
and E. Existing State regulatory mechanisms are not specifically 
designed to protect the western yellow-billed cuckoo from habitat loss 
and degradation from altered hydrology from upstream dams and surface 
water and ground water diversions, encroachment into the floodplain by 
agricultural and other development activities, bank stabilization and 
levee construction and maintenance activities, overgrazing, pesticide 
use on adjacent agricultural lands, conversion of habitat to monotypic 
stands of nonnative vegetation, gravel mining, wildfire, drought, and 
climate change across the range of the western yellow-billed cuckoo.
Canadian, Mexican, and Other International Laws
Canada
    The Canadian Government through the Department of the Environment 
(Environment Canada, which was first established by the Department of 
the Environment Act of 1971) administers numerous acts to preserve and 
enhance the quality of Canada's natural environment. Acts identified 
for conservation of wildlife and plant species or their habitat are 
identified below.
    1916 Great Britain-United States Convention for the Protection of 
Migratory Birds. Canada has committed to migratory bird protection 
through the 1916 Great Britain-United States Convention for the 
Protection of Migratory Birds in Canada, which encourages voluntary 
cooperative actions to protect identified migratory birds. The yellow-
billed cuckoo is listed under the 1916 Great Britain-United States 
Convention for the Protection of Migratory Birds in Canada. In 
addition, Canada has enacted the Migratory Birds Convention Act of 1994 
(MBCA). The MBCA is intended to ensure the conservation of migratory 
bird populations by regulating potentially harmful human activities. 
The implementing regulations of the MBCA ban all activities that are 
harmful to migratory birds, their eggs or their nests, but does not 
protect habitat. Also, some activities, such as hunting or scientific 
collection, may be allowed with an appropriate permit.
    The Species at Risk Act of 2002. The purpose of the Species at Risk 
Act (SARA) is to prevent Canadian native wildlife and plant species, 
subspecies, and distinct populations from becoming extirpated or 
extinct, to provide for the recovery of endangered or threatened 
species, and encourage the management of other species to prevent them 
from becoming at risk. SARA establishes the Committee on the Status of 
Endangered Wildlife in Canada (COSEWIC) as an independent body of 
experts responsible for assessing and identifying species at risk. SARA 
also, among other objectives, establishes: Prohibitions to protect 
listed Canadian threatened and endangered species and their critical 
habitat; requirements for use of the best available knowledge on 
assessing threats to and conservation for wildlife and plant species; 
and long- and short-term objectives for development of recovery 
strategies and action plans.
    The yellow-billed cuckoo is not identified as a species that is 
sensitive, threatened, or endangered under Canadian law. Within the 
range of the

[[Page 60030]]

western yellow-billed cuckoo, British Columbia considers the western 
yellow-billed cuckoo as an extirpated breeder, but that the species 
still does occur within the Province (British Columbia Conservation 
Data Centre, 2013).
    Canadian Environmental Protection Act of 1999. The Canadian 
Environmental Protection Act sets out several guiding principles for 
conserving the environment including but not limited to supporting: 
Sustainable development; pollution prevention; elimination of releases 
of substances that are persistent or that bioaccumulate; an ecosystem 
approach and using the precautionary principle on issues related to the 
environment; science-based national standards; and seeking 
intergovernmental cooperation for consistency and avoidance of 
duplication of efforts. Because the yellow-billed cuckoo is not 
considered a species at risk, implementation of environmental 
protection regulations are optional for the species.
Mexico
    The Mexican Government, through its Secretaria de Medio Ambiente y 
Recursos Naturales (SEMARNAT), has authority to designate species as 
threatened or endangered. The western yellow-billed cuckoo is not 
listed by the Mexican Government's Official Mexican Norm NOM-059-
SEMARNAT-2010, Mexico's threatened species law. The yellow-billed 
cuckoo is listed under the 1936 Mexico-United States Convention for the 
Protection of Migratory Birds and Game Mammals (Service 2013b), which 
encourages voluntary cooperative actions to protect identified 
migratory birds and mammals.
    In 1988, the Mexican Government passed the General Law of 
Ecological Equilibrium and Environmental Protection, which is similar 
to NEPA in the United States. This Mexican statute requires an 
environmental assessment of private or government actions that may 
affect wildlife or their habitat. Currently, no known regulatory 
mechanisms or conservation planning are in place that specifically 
targets the conservation of habitat within the range of the western 
yellow-billed cuckoo in Mexico. Therefore, we anticipate continued 
threats in Mexico, with little or no protection to the western yellow-
billed cuckoo.
    The National Natural Protected Areas (NPAs) system is a Mexican 
program to protect sensitive habitats and species. NPA designation is 
supposed to protect areas that have not been significantly altered by 
human activities and that provide diverse ecosystem services. However, 
prior to 1994, most NPAs lacked sound and comprehensive management 
plans. By 2000, approximately 30 percent of new and existing NPAs had 
developed management plans; however, under the NPA model these plans 
lacked detailed information, and in many cases could be considered 
obsolete. NPA goals to promote sustainable natural resources are often 
unattainable because of conflicting land ownership interests (Valdez et 
al. 2006, p. 272). The allocation of funds for management of natural 
reserve areas in Sonora is not assured, and some reserves have not 
received protection other than that given by government edicts or their 
natural isolation (Burquez and Martinez-Yrizar 1997, p. 378). Urban 
development has reduced some of Sonora's natural reserves. Three of the 
reserves have already disappeared, reflecting the tenuous state of many 
nature reserves in Mexico (Burquez and Martinez-Yrizar 2007, p. 546).
    Wildlife management units, or UMAs, were part of a program 
developed and implemented by SEMARANT in 1997 to promote wildlife 
management on private property in Mexico (Weber et al. 2006, p. 1480). 
The UMA program has not been effective in promoting wildlife management 
or biodiversity conservation. It has increased the introduction of 
exotic wildlife species to meet hunting demands. There is a lack of 
technical capability on private lands to conduct proper wildlife 
monitoring and management (Weber et al. 2006, p. 1482). In Mexico, the 
exploitation of minerals and industrial development has not been 
matched by strong measures to protect the environment (Burquez and 
Martinez-Yrizar 2007, p. 547). Surface water and ground water 
management in Mexico is also lacking, and restoring water quality and 
quantity to water bodies is a primary concern (Organisation for 
Economic Co-operation and Development (OECD) 2013, p. 102). In the 
State of Sonora, 30 years of unregulated water extraction from both 
above and below ground has resulted in serious water resource 
overexploitation and degradation (OECD 2013, p. 115). Although 
regulatory measures are in place, they lack consistent implementation 
and oversight (OECD 2013, p. 133).
    Current efforts for protecting the western yellow-billed cuckoo in 
Mexico primarily consist of identifying areas as Important Areas for 
Bird Conservation ([Aacute]reas de Importancia para la 
Conservaci[oacute]n de las Aves), but no specific projects or 
conservation efforts are focused on the western yellow-billed cuckoo or 
its habitat (S[aacute]nchez-Gonz[aacute]lez and Berlanga 2012 in 
litt.).
    Lack of habitat protection for the western yellow-billed cuckoo in 
northwestern Mexico also impacts the western yellow-billed cuckoo in 
the United States because individuals are known to make transitory 
movements up to several hundred miles between the southwestern United 
States and northern Mexico within a single breeding season (Sechrist et 
al. 2012, p. 5), so that individuals that breed in the United States 
also depend to some extent on habitat in northern Mexico. We are not 
aware of any information on the number of western yellow-billed cuckoos 
that utilize habitats in both countries during a given breeding season; 
however, these are also stopover areas between breeding and wintering 
grounds in South America, and are important as foraging habitat. 
Therefore, lack of regulatory protections for habitat of the western 
yellow-billed cuckoo in northwestern Mexico also affects western 
yellow-billed cuckoos in the southwestern United States.
    In regard to potential for pesticide exposure south of the U.S. 
border, Mexico has the second largest pesticide sales in Latin America, 
behind Brazil, which together account for 78 percent of the volume of 
pesticides within 11 Latin American countries (Mora 1997, pp. 3-4). 
While Mexico has laws concerning pesticide use, and import regulations 
on certain pesticides, there is limited enforcement capacity (Behre 
2003, pp. 337-338). The same is true in Paraguay, Bolivia, Brazil, and 
Argentina, where yellow-billed cuckoos winter. For example, in 
Paraguay, at the center of the yellow-billed cuckoo's wintering range, 
importation and use of many pesticides are banned, but it is estimated 
that the amount of pesticides that are imported illegally are double 
the amount that are imported legally (Scribano 2013, entire). For 
additional information on pesticides, see Factor E below.
    Based on the best available information, the regulatory mechanisms 
in Mexico that would protect the western yellow-billed cuckoo from 
threats described under Factors A and E are either lacking or not being 
fully implemented. These include water supply projects, water 
diversions, expansion of agricultural activities and overgrazing, 
conversion of habitat to nonnative vegetation, climate change (Factor 
A), and pesticides, as well as the threat of small, isolated patches of 
western yellow-billed cuckoo habitat (Factor E).
Summary of Factor D
    Various Federal, State, and international regulatory mechanisms in

[[Page 60031]]

place provide varying degrees of conservation oversight that may to 
some degree address the threat of ongoing habitat loss and degradation 
resulting from altered hydrology, conversion of habitat to nonnative 
vegetation, climate change, agricultural activities (Factor A), or 
exposure to pesticides and effects of small and isolated habitat 
patches (Factor E). In California, where the species is listed as 
endangered, regulations prohibit unpermitted possession, purchase, 
sale, or take of listed species. Such prohibition of take does not 
include the species' habitat, and the western yellow-billed cuckoo 
continues to decline in California despite its status as a State-listed 
species. In addition, even though the California Department of 
Pesticide Regulations has a program to protect endangered species, the 
western yellow-billed cuckoo has not been included as a covered 
species.
    Because the yellow-billed cuckoo is not a protected or sensitive 
species in Canada, Mexico, or in a majority of the United States, and a 
variety of factors influence the species and its habitat, we have 
determined that the current regulatory regime does not adequately 
address the majority of impacts to the western yellow-billed cuckoo or 
its habitat. As described under Factor A, one of the primary threats 
with the greatest severity and magnitude of impact to western yellow-
billed cuckoo is the loss of habitat as a result of altered hydrologic 
functioning of streams in the West. Although some protections currently 
exist for the species and its habitat as a result of existing 
regulatory mechanisms at the Federal, State, or local level, our 
evaluation suggests these protections are inadequate to address the 
threats associated with the species and its habitat.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

Small and Widely Separated Habitat Patches
    As described in the Background section and under Factor A, the 
habitat of the western yellow-billed cuckoo has undergone significant 
loss and modification within its occupied breeding range as a result of 
widespread multiple human-caused effects. These include altered 
hydrology in watercourses and past loss and degradation from 
agriculture. Past destruction and modification transformed formerly 
large expanses of riparian habitat into a number of smaller patches of 
smaller total area, isolated from each other by a matrix of mostly 
human-altered habitats (McGill, 1975, pp. 1-4; Thompson, 1961, pp. 294-
315; Wilcove et al. 1986, p. 237). The potential natural regeneration 
or restoration of the habitat to reconnect these areas is low due to 
various reasons (see Factor A discussion). Under the best of 
circumstances, for riparian habitat (willows, cottonwoods) to mature to 
the point at which it provides for appropriate food, shelter, and 
breeding conditions for the western yellow-billed cuckoo may take 3-5 
years (Golet et al. 2008, pp. 20-22). However, in areas where 
conditions are less than optimal, habitat may take several decades to 
mature to the point where it would be available for use (Strahan 1984, 
pp. 58-67; Briggs 1995, pp. 63-67; Opperman and Merenlender 2004, pp. 
822-834; Trowbridge et al. 2004, pp. 157-164; Morris et al. 2006, pp. 
106-116; Griggs 2009, p. 12).
    As a result, the western yellow-billed cuckoo now primarily occurs 
in smaller, more widely separated populations. Compared to large 
populations, smaller populations are disproportionately affected by 
natural and manmade factors. These stressors vary in frequency, timing, 
and magnitude across the species' range. They are related or correlated 
to each other or act in combination to result in significant impacts to 
the western yellow-billed cuckoo within all or portions of its range.
    One of the ramifications of smaller, more isolated habitat patches 
is that the smaller the patch, the more edge it has in proportion to 
its area, which increases the percentage of the available habitat 
exposed to the surrounding land uses (Hunter 1996, pp. 186-187). This 
is a particularly prevalent characteristic of the western yellow-billed 
cuckoo's remaining disjunct habitat patches, as many patches are in 
proximity to agricultural and other human-altered landscapes. For 
example, such land use currently dominates much of the riparian 
landscape within many regions, particularly along some reaches of the 
lower Colorado River, Sacramento River, Snake River, Verde River, Gila 
River, Santa Cruz River, San Pedro River, and R[iacute]o Grande; and 
also in parts of northern Mexico in the vicinity of floodplain farming 
along the Sonora, Magdalena, and Moctezuma Rivers (Villase[ntilde]or-
Gomez 2006, p. 111).
    Agricultural activities on adjacent lands affect riparian bird 
communities in ways that may result in lower reproductive success, and 
possible abandonment of the patch, as reviewed by Saab (1999, pp. 136, 
147-148). Saab (1999, p. 147) found that bird species, including the 
western yellow-billed cuckoo, were more likely to occur in riparian 
habitat along the Snake River, Idaho, in sites surrounded by upland 
natural vegetation than in habitat adjacent to agricultural lands. Saab 
found that, compared to habitat patches surrounded by natural habitat, 
patches near agricultural lands supported more avian nest predators 
that prosper in human-altered landscapes and have a greater effect on 
the smaller, fragmented habitats (Saab 1999, p. 147). Increases in 
these predators can result in more nest losses and discourage western 
yellow-billed cuckoos from nesting, thus suppressing local western 
yellow-billed cuckoo population size. Increases in nonnative vegetation 
can displace or degrade suitable nesting and foraging habitat, thereby 
leading to lower utilization of such areas by western yellow-billed 
cuckoos. Together, the effects can lead to western yellow-billed 
cuckoos abandoning these small habitat patches.
    The western yellow-billed cuckoo is currently found in the largest 
contiguous and least-fragmented remaining habitat patches. For example, 
in California, sites larger than 198 ac (80 ha) in extent and wider 
than 950 ft (600 m) provided optimal patch size for western yellow-
billed cuckoos (Laymon and Halterman 1989, p. 275). Nesting western 
yellow-billed cuckoos are sensitive to patch size and seldom use 
patches smaller than 325 x 975 ft (100 x 300 m) (Hughes 1999, p. 20). 
This observed preferential use of large patches strongly suggests that 
the western yellow-billed cuckoo is sensitive to fragmentation and 
reductions in habitat patch size. Moreover, patch-size reduction 
combined with the scarcity of larger patches keeps the western yellow-
billed cuckoo breeding population size depressed. Such effects prevent 
the western yellow-billed cuckoo from reversing its long-term decline 
in population and range (Hunter 1996, pp. 179-187).
    Moreover, isolated breeding sites separated by hundreds of miles of 
nonhabitat also reduce the ease with which dispersing juvenile and 
returning adult western yellow-billed cuckoos are able to find these 
sites. This isolation may result in low colonization and reoccupation 
rates, so that otherwise suitable habitat remains unoccupied or 
occupied at low densities (Laymon and Halterman 1989, p. 274; Hunter 
1996, p. 185). For example, the Sacramento River still appears to have 
sufficient habitat to maintain a self-sustaining population of western 
yellow-billed cuckoos, as more than 25,000 ac (10,117 ha) of riparian 
and associated natural habitat has been protected and other sections 
are in the

[[Page 60032]]

process of being restored. However, not all suitable patches are 
occupied or may only be occupied in very low densities, and the western 
yellow-billed cuckoo population remains much lower than its potential 
(Dettling and Howell 2011, pp. 20-21).
    On the Colorado River (between Lake Mead and the Mexico border), 
habitat restoration efforts are being implemented as a result of the 
Lower-Colorado River Multi-species Conservation Plan (LCR MSCP). The 
LCR MSCP permittees are in the process of creating and maintaining up 
to 4,050 ac (1,639 ha) of western yellow-billed cuckoo habitat, 
reducing the risk of loss of created habitat to wildfire, replacing 
created habitat affected by wildfire, and avoiding and minimizing 
operational and management impacts to western yellow-billed cuckoos 
over the 50-year life of the permit (2005 to 2055) (Lower Colorado 
River Multi-Species Conservation Program 2004, pp. 5-30-5-36, Table 5-
10, 5-58-5-60). Not all of the habitat has been created, and as a 
result, the restoration sites are not contiguous along the entire river 
reach. Monitoring and survey efforts for the western yellow-billed 
cuckoo have shown an increase in detections, but the majority of 
detections were confined to only a few of the larger areas (McNeil et 
al. 2011, pp. 1-16).
    In summary, despite efforts to protect and restore riparian habitat 
along the Sacramento River and Colorado River and elsewhere in the 
range of the western yellow-billed cuckoo, these efforts offset only a 
small fraction of historical habitat that has been lost. Therefore, the 
threats resulting from the species' behavioral response to the 
multiple, combined effects of small and widely separated habitat 
patches exacerbate the effect of other threats within a large portion 
of the range of the western yellow-billed cuckoo. Moreover, because the 
threats that create small and isolated patches are ongoing (see Factor 
A) and maturation of regenerated or restored habitat may take several 
decades to fully provide for the needs of the species, we expect the 
effects of the species' response to small patch size to continue to 
adversely impact the western yellow-billed cuckoo into the future.
Pesticides
    Exposure to pesticides may also be a threat to western yellow-
billed cuckoos because it negatively impacts populations of insect prey 
(Groschupf 1987, p. 29; Hughes 1999, p. 2). The effects of pesticides 
on western yellow-billed cuckoos can be from intentional aerial 
spraying of habitat for mosquito or forest pest control, or from 
overspray or drift when the species' foraging habitat is located next 
to agricultural fields. Pesticides can affect western yellow-billed 
cuckoos foraging for grasshoppers at the field-forest interface or 
foraging for caterpillars in riparian habitat adjacent to the sprayed 
fields. Accumulation of chlorinated hydrocarbon pesticides, 
particularly dichlorodiphenyltrichloroethane (DDT), has affected other 
bird species, particularly top predators (Robinson and Bolen 1989, pp. 
269-275). Pesticides may affect behavior (for example, loss of balance) 
or cause death by direct contact. Pesticide use may indirectly affect 
western yellow-billed cuckoos by reducing prey numbers, or by poisoning 
nestlings if sprayed directly in areas where the birds are nesting 
(Laymon and Halterman 1987b, p. 23; Lehman and Walker 2001, p. 12).
    Western yellow-billed cuckoo prey populations were affected by 
aerial spraying of larvicides for control of mosquitoes at Caswell 
State Park in California (Laymon 1998, p. 12) and in Colorado to 
control an outbreak of caterpillars on box elders near Durango (Colyer 
2001, pp. 1-6). The available evidence suggests that a reduction in 
prey availability results in reduced nesting success (Laymon 1980, p. 
27; Hughes 1999, pp. 19-20), and pairs may even forgo breeding in years 
with inadequate food supplies (Veit and Petersen 1993, pp. 258-259). 
Therefore, the application of pesticides directly onto areas of 
riparian habitat may indirectly affect the reproductive success of the 
western yellow-billed cuckoo, leading to nest failure and lowered 
population size. Additionally, because breeding site fidelity is in 
part dependent on previous successful nesting (see the Breeding Site 
Fidelity section of the proposed rule), western yellow-billed cuckoos 
may abandon otherwise suitable nest sites where prey availability is 
limited by pesticide use, resulting in curtailment of its occupied 
range.
    Effects from overspray of pesticides are more pronounced in smaller 
patches next to agricultural fields (because they have more edges, 
which allows for increased chances of exposure), but the effects of 
pesticides could also affect larger habitat patches as well. In many 
areas riparian habitat borders agricultural lands, such as California's 
Central Valley, the lower Colorado River, Snake River, Gila River, 
R[iacute]o Grande Valley, and rivers in northern Mexico, including the 
Sonora, Yaqui, Mayo, and Moctezuma, where western yellow-billed cuckoos 
are vulnerable to pesticide exposure. Laymon (1980, pp. 11-12) reported 
sublethal poisoning of young western yellow-billed cuckoos caused by 
spraying active nests in walnut orchards in California.
    Although DDT use has been banned in the United States since 1972, 
and in Mexico since 1999, yellow-billed cuckoos may be exposed to DDT 
in Mexico or on wintering grounds where DDT is still used despite any 
bans on its use. The soil half-life for DDT is from 2 to 15 years. 
However, in some cases, half of the DDT initially present will remain 
for 20, 30, or more years (U.S. Department of Human Health & Human 
Services, Agency for Toxic Substances and Disease Registry 1994, pp. 3-
4).
    For example, yellow-billed cuckoos (most likely of the eastern 
population) collected during the spring and fall migration in Florida 
had unusually high concentrations of DDT, suggesting exposure on the 
wintering grounds in South America (Grocki and Johnston 1974, pp. 186-
188). Analysis of two eggs collected in California in 1979 showed very 
low levels of dichlorodiphenyldichloroethylene (DDE), a stable 
metabolite of DDT, but eggshell fragments collected in 1985 from three 
nests along the South Fork Kern River in California averaged 19 percent 
thinner than pre-DDT era eggshells (Laymon and Halterman 1987b, pp. 22-
23). DDT has caused eggshell thinning in other bird species, and this 
percentage of thinning in other species has allowed eggs to be crushed 
during incubation, but there is no information showing that western 
yellow-billed cuckoo eggs have been crushed during incubation because 
of shell thinning.
    A recent study in southern Sonora, Mexico, tested for the presence 
of a group of agricultural pesticides banned in the United States, 
known as organochlorine pesticides (beta-hexachlorocyclohexane (BHC), 
lindane, aldrin, endrin, b-endosulfan, methoxychlor, p, p0-DDE, p, p0-
Dichlorodiphenyldichloroethane (DDD), p, p0-DDT). Collectively called 
OCPs, these pesticides are persistent in the environment. Soil samples 
collected from 24 localities in the Yaqui and Mayo Valleys of southern 
Sonora, Mexico, watersheds in which the western yellow-billed cuckoo is 
known to breed, were found to have higher OCP levels than other regions 
of the world. The OCPs were predominantly DDT (Cantu-Soto et al. 2011, 
p. 559), despite its having been discontinued in Mexico in 1999 after 
decades of heavy use in agriculture and for malaria control 
(Ya[ntilde]ez et al. 2004, p. 18). This finding may indicate recent 
applications of DDT in agricultural soils (Cantu-Soto et al.

[[Page 60033]]

2011, p. 559). Because of the proximity of habitat for western yellow-
billed cuckoos to these valleys and the prevalence of floodplain 
agriculture in northern Mexico, these pesticides, especially DDT, may 
be having widespread long-lasting effects on the western yellow-billed 
cuckoo. These include direct and indirect exposure through ingestion of 
contaminated prey items, and reduction in prey availability from direct 
exposure and pesticide runoff into habitat that supports western 
yellow-billed cuckoos.
    Neonicotinoid pesticides are systemic chemicals that are taken up 
through various plant parts and can be distributed through a plant's 
tissues. These chemicals can be applied to a plant as a seed coating, 
soil contact, irrigation water, or as a foliar spray. Many of these 
chemicals are long acting with half-lives up to 2 years. Plant tissues 
that have been treated are toxic to both sap-sucking (e.g., aphids and 
true bugs) and foliage-eating insects (e.g., caterpillars, katydids, 
grasshoppers, and beetles). Many of these foliage-eating insects are 
potential prey of the western yellow-billed cuckoo. These chemicals 
have the potential to reduce prey abundance if intentionally or 
accidentally applied to foliage on which western yellow-billed cuckoos 
forage. To date no scientific studies have been done on western yellow-
billed cuckoos and their prey, but additional reports and research on 
these chemicals discuss the potential adverse effects (Mineau and 
Whiteside 2013; Hopwood et al. 2013; Mineau and Palmer 2013).
    In summary, pesticide use is widespread in agricultural areas in 
the western yellow-billed cuckoo breeding range in the United States 
and northern Mexico. Yellow-billed cuckoos have been exposed to the 
effects of pesticides on their wintering grounds, as evidenced by DDT 
found in their eggs and eggshell thinning in the United States. Because 
much of the species' habitat is in proximity to agriculture, the 
potential exists for direct and indirect effects to a large portion of 
the species in these areas through altered physiological functioning, 
prey availability, and, therefore, reproductive success, which 
ultimately results in lower population abundance and curtailment of the 
occupied range. While agricultural pesticides can kill prey of the 
yellow-billed cuckoo, and documentation exists of pesticide exposure in 
the wild, described above, no known data are available to determine 
specifically how often agricultural chemicals may be affecting yellow-
billed cuckoo prey availability, locations where it may be particularly 
significant, or the extent to which pesticides may be responsible for 
population-level effects in the western yellow-billed cuckoo. However, 
based on the close proximity of agricultural areas to where the western 
yellow-billed cuckoo breeds, the threat is potentially significant.
Collisions With Communication Towers, Wind Turbines, Solar Power 
Towers, and Other Tall Structures
    Yellow-billed cuckoos are vulnerable to collision with 
communication towers and other tall structures, particularly during 
their migration. For example, several hundred yellow-billed cuckoo 
mortalities were documented at a single television tower in Florida 
over a 29-year period (Crawford and Stevenson 1984, p. 199; Crawford 
and Engstrom 2001, p. 383), and at an airport ceilometer in the east 
(Howell et al. 1954, p. 212). Lesser numbers of yellow-billed cuckoos 
have been reported as killed at other sites with both television towers 
and wind turbines in Wisconsin, West Virginia, and northern Texas 
(Kemper 1996, p. 223; Schechter 2009, p. 1; Bird Watching 2011, p. 1), 
Although these mortalities were in the eastern segment of the 
population, with the number of tall towers that have been constructed 
in recent years in the western United States, the potential exists for 
collisions with the western yellow-billed cuckoo. Remains of a yellow-
billed cuckoo along with 70 other species of birds have been recovered 
at the Ivanpah solar power tower facility (California) during its first 
year of operation (Kagan et al. 2014, p. 10). Without further study, we 
anticipate this to be a minor, but ongoing, effect to individual 
yellow-billed cuckoos, but in combination with all the other effects to 
this species, as described under Factors A and E, mortality from 
collision would have an additive effect to the threats facing the 
western yellow-billed cuckoo.
Conservation Efforts To Reduce Other Natural or Manmade Factors 
Affecting Its Continued Existence
    Active and hydrological process-based restoration of riparian 
habitat on the Colorado, Kern, and Sacramento Rivers and elsewhere will 
help reduce habitat fragmentation, small patch size, and overall lack 
of habitat. In some restoration plans, reduction of fragmentation is a 
stated goal, and restoration sites are planned for sites adjacent to 
existing habitat. The Colorado River riparian habitat restoration work 
is just beginning and is part of the Lower Colorado River Multi-Species 
Conservation Plan. This habitat conservation plan calls for the 
creation of 5,940 ac (2405 ha) of riparian habitat through active 
restoration of which 4,050 ac (1,640 ha) will be suitable for western 
yellow-billed cuckoos (Reclamation 2004, Sec. 5, p. 58). Active 
restoration work began on the South Fork Kern River in California, in 
1986. To date, 340 ac (138 ha) of riparian habitat have been restored 
(Audubon California 2012, pp. 1-10). Along the Sacramento River, the 
Sacramento River National Wildlife Refuge has implemented an active 
riparian restoration program. Riparian habitat restoration activities 
have been conducted on 4,513 ac (1,826 ha) with 2,400 ac (738 ha) 
slated for additional restoration (Hammond 2011, p. 14). In Utah, from 
2008-2013, the State's Watershed Restoration Initiative (WRI) has 
invested funding with partners toward collaborative habitat enhancement 
efforts in lowland riparian habitats. The efforts were distributed 
across 35 different projects and totaled more than 8,000 ac (3,200 ha).
    At present, restoration occurs on a relatively small scale in 
comparison to the need to reduce habitat fragmentation and increase the 
overall extent of suitable habitat. Future process-based restoration 
projects that restore natural river hydrology show great promise for 
large-scale restoration of riparian habitat for western yellow-billed 
cuckoos.
    To date, conservation efforts, though helpful, have been inadequate 
to significantly reduce the effects of natural or manmade factors 
affecting the western yellow-billed cuckoo.
Summary of Factor E
    As noted in Factor A, habitat for the western yellow-billed cuckoo 
has been modified and curtailed, resulting in only remnants of formerly 
large tracts of native riparian forests, many of which are no longer 
occupied by western yellow-billed cuckoos. Despite recent efforts to 
protect existing, and restore additional, riparian habitat in the 
Sacramento, Kern, and Colorado Rivers, and other rivers in the range of 
the western yellow-billed cuckoo, these efforts offset only a small 
fraction of historical habitat that has been lost. Therefore, we expect 
the threat resulting from the combined effects associated with small 
and widely separated habitat patches to continue to affect a large 
portion of the range of the western yellow-billed cuckoo. This threat 
is particularly persistent where small habitat patches are in proximity 
to human-altered landscapes, such as near agricultural fields that 
dominate the landscape in many areas where the

[[Page 60034]]

western yellow-billed cuckoo occurs. As a result, the potential exists 
for pesticides to directly affect (poisoning individual cuckoos) and 
indirectly affect (reducing the prey base) a large portion of the 
species. These effects could ultimately result in lower population 
abundance and curtailment of its occupied range. Mortality from 
collisions with tall structures is also an ongoing but largely 
unquantified effect.
Cumulative Impacts
    Habitat loss and degradation occurs throughout the range of the 
western yellow-billed cuckoo (see Background section and Factor A 
above), and many of the threats under Factor A have worked and are 
working in combination to reduce the amount, configuration, and quality 
of the riparian habitat that remains.
    This array of Factor A threats, working in combination, creates the 
situation that then allows threats from the other listing factors to 
markedly affect the species. These other-factor threats may not be 
significant in and of themselves, but because they are not occurring in 
isolation they, in combination, are contributing to the population 
decline of the species. For example, as discussed in the Small and 
Widely Separated Habitat Patches section of Factor E, above, small 
habitat patches (resulting from the effects of Factor A threats) are 
more likely to have a larger number and a wider range of nest predators 
(see the Predation section of Factor C, above) because more nest 
predators occur in ecological edges. Additionally, habitat patches near 
areas of agricultural or urban development can foster higher densities 
of potential nest predators. Thus, any western yellow-billed cuckoo 
nesting in a small habitat patch near development may be subject to 
higher levels of nest predation and thus lower productivity. Moreover, 
the mere presence of certain nest predators in a habitat patch may 
elicit a behavioral response from western yellow-billed cuckoos such 
that they do not even attempt to nest in such habitat patches, even if 
other aspects of the habitat would suggest that it is suitable for 
nesting.
    Similarly, riparian habitat patches that occur near urban and 
agricultural development may be subject to intentional or accidental 
pesticide spraying, as discussed in the Pesticide section under Factor 
E. This spraying would be unlikely to occur but for the habitat patch's 
proximity to development. This development likely occurs close to the 
riparian habitat through a process similar to the generalized scenario 
described above (see also specific details under Factor A).
    Much of the available habitat is now in small patches with only a 
relatively few patches regularly occupied by nesting western yellow-
billed cuckoos. Thus, the species' intolerance of small patch size in 
combination with extensive habitat loss has resulted in much less 
suitable habitat and a greatly reduced western yellow-billed cuckoo 
population size. In areas at the edge of the western yellow-billed 
cuckoo's current range (e.g., the Sacramento River), restoration of 
riparian habitat has not been accompanied by an increase in the 
species' population indicating that other factors may be limiting the 
population in those areas. Moreover, large areas of suitable habitat 
are unlikely to naturally regenerate within the range of the species 
into the future because western yellow-billed cuckoos need riparian 
habitat in a range of ages, including older, more structurally diverse 
areas for nesting, and nearly all of the areas where riparian habitat 
could grow in western North America are modified by dams, 
channelization, water extraction, and other activities that disrupt 
natural processes to allow good-quality riparian habitat to grow in a 
mosaic of different ages (see Factor A). Climate change is likely to 
further add to these impacts.
Summary of Factors
    The primary factors threatening the western DPS of the yellow-
billed cuckoo are the loss and degradation of habitat for the species 
from altered watercourse hydrology and natural stream processes, 
livestock overgrazing, encroachment from agriculture, and conversion of 
native habitat to predominantly nonnative vegetation as identified in 
Factor A. Additional threats to the species under Factor E include the 
effects of climate change, pesticides, wildfire, and small and widely 
separated habitat patches. The cumulative impact from various threats 
is also a factor that will exacerbate multiple existing threats to the 
western yellow-billed cuckoo and its habitat.
    Various Federal, State, and international regulatory mechanisms in 
place provide varying degrees of conservation oversight that may to 
some degree address the threat of ongoing habitat loss and degradation; 
however, because the yellow-billed cuckoo is not a protected or 
sensitive species in a majority of the United States or in Canada and 
Mexico, the application of these regulatory mechanisms to conserve the 
western yellow-billed cuckoo or its habitat is unknown and the 
effectiveness of these regulatory mechanisms is uncertain.
    These factors pose current and future threats to the species 
because they are ongoing and likely to continue in the near future.

Determination

    We have carefully assessed the best scientific and commercial data 
available regarding the past, present, and reasonably anticipated 
future threats to the western yellow-billed cuckoo. In assessing the 
status of the western yellow-billed cuckoo, we applied the general 
understanding of ``in danger of extinction'' discussed in the December 
22, 2010, Memorandum to the polar bear listing determination file, 
``Supplemental Explanation for the Legal Basis of the Department's May 
15, 2008, Determination of Threatened Status for the Polar Bear,'' 
signed by then Acting Director Dan Ashe (Service 2010, pp. 1-18). 
Threats to the western yellow-billed cuckoo exist for two of five 
threat factors. Threats also occur in combination, resulting in 
synergistically greater effects.
    Factor A threats result from habitat destruction, modification, and 
degradation from dam construction and operations, water diversions, 
riverflow management; stream channelization and stabilization; 
conversion to agricultural uses, such as crops and livestock grazing; 
urban and transportation infrastructure; and increased incidence of 
wildfire. Continuing ramifications of actions that caused habitat loss 
in the past have resulted in ongoing curtailment of the habitat of the 
western yellow-billed cuckoo throughout its range. These factors also 
contribute to fragmentation and promote conversion to nonnative plant 
species, particularly tamarisk. The threats affecting western yellow-
billed cuckoo habitat are ongoing and significant and have resulted in 
curtailment of the range of the species. Loss of riparian habitat leads 
not only to a direct reduction in western yellow-billed cuckoo numbers 
but also leaves a highly fragmented landscape, which in combination 
with other threats (see below), can reduce breeding success through 
increased predation rates and barriers to dispersal by juvenile and 
adult western yellow-billed cuckoos.
    Factor E threats, including habitat rarity and small and isolated 
population sizes, cause the remaining western yellow-billed cuckoo 
populations to be increasingly susceptible to further declines through 
lack of immigration, reduced populations of prey species (food items), 
pesticides, and collisions with tall vertical structures during

[[Page 60035]]

migration. The serious and ongoing threat of small overall population 
size, which is the result of other threats in combination, leads to an 
increased chance of local extirpations.
    The threats that affect the western yellow-billed cuckoo are 
important on a threat-by-threat basis, but are even more significant in 
combination. Habitat loss has been extensive throughout the range of 
the western yellow-billed cuckoo. The remaining riparian habitat is 
fragmented into small patches, which the species does not normally 
select as breeding habitat. Additionally, western yellow-billed cuckoos 
need riparian habitat in a range of ages, including older structurally 
diverse areas for nesting. This diversity of tree ages within the 
riparian vegetation (western yellow-billed cuckoo's habitat) is largely 
dependent on disturbances that affect some but not all of the 
vegetation within that habitat patch at one time. A number of threats, 
working in combination or individually, prevent such disturbance from 
happening now and will continue to do so in the future.
    For example, dams and other flood control modifications to a 
watercourse may prevent floods from being severe enough to affect that 
habitat patch; channelization may restrict floodwaters to a narrow 
channel, allowing floodwaters to cause too much damage to habitat 
within the channel and not enough (or no) damage to habitat outside the 
channel; altered flood regimes may allow dead wood to accumulate, 
allowing fires, when they occur, to be severe and affect most of the 
patch; development and other human activities next to habitat patches 
may allow more wildfires to be ignited; and the reduction in patch 
size, through neighboring development, alteration of hydrology, or 
encroachment by nonnative plants, makes it more likely that a larger 
proportion of that patch will be affected during any given disturbance 
event. Moreover, nearly all areas where riparian habitat could 
potentially grow are modified by dams or water withdrawal and disrupted 
by other activities, often in combination, that prevent the 
reestablishment of riparian habitat. Patch size, when coupled with 
habitat loss and Factor C and E threats, including proximity to 
incompatible land uses, which increases exposure to predators and 
pesticides, is a significant cumulative threat to the western yellow-
billed cuckoo now and in the future.
    Per section 4(b)(1)(A) of the Act, prior to making our 
determination, we must first ``[take] into account those efforts, if 
any, being made by any State or foreign nation, or any political 
subdivision of a State or foreign nation, to protect such species, 
whether by predator control, protection of habitat and food supply, or 
other conservation practices, within any area under its jurisdiction, 
or on the high seas.'' Restoration of riparian habitat on the Colorado, 
Kern, and Sacramento Rivers and elsewhere will help reduce habitat 
fragmentation, small patch size, and overall lack of habitat. However, 
at present, restoration is being done on a relatively small scale in 
comparison to the need to reduce habitat fragmentation and increase the 
overall extent of suitable habitat. DDT has been banned in the United 
States for several decades, but use of DDT continues in Central and 
South America, thus potentially exposing western yellow-billed cuckoos 
during migration and winter.
    Through our analysis of the best available scientific and 
commercial information on the species' abundance, life history, current 
population status and trends, and the response of the species and its 
habitat to natural and anthropogenic threats, we have determined that 
the western yellow-billed cuckoo meets the definition of a threatened 
species under the Act, rather than endangered. The Act defines an 
endangered species as any species that is ``in danger of extinction 
throughout all or a significant portion of its range'' and a threatened 
species as any species ``that is likely to become endangered throughout 
all or a significant portion of its range within the foreseeable 
future.''
    The geographic extent of the western yellow-billed cuckoo remains 
rather widespread through much of its historic range, conferring some 
measure of ecological and geographic redundancy and resilience. 
Although there is a general decline in the overall population trend and 
its breeding range has been reduced, the rate of the population decline 
and contraction of its breeding range is not so severe to indicate 
extinction is imminent for the western yellow-billed cuckoo. This 
current downward trend is slow and not expected to increase in the near 
future. The majority of large-scale habitat losses and conversions 
through dam building and agricultural development have already 
occurred, and we are not aware of any large-scale projects that would 
affect the species to the extent that the current trend of decline 
would change. Therefore, threats to the species and population declines 
do not currently reach the level typical of an endangered species.
    Because the western yellow-billed cuckoo does not face any known 
sudden and calamitous threats, it is not a narrowly endemic species 
vulnerable to extinction from elevated or cumulative threats, is not 
yet restricted to a critically small range or critically low numbers, 
and currently does not show any substantial reduction in numbers, it 
would not meet the definition of ``endangered'' as determined by the 
Act. More appropriately, we find that the western yellow-billed cuckoo 
is likely to become endangered throughout all or a significant portion 
of its range within the foreseeable future, based on the timing, 
severity, and scope of the threats described above. Therefore, on the 
basis of the best available scientific and commercial information, we 
are listing the western distinct population segment of the yellow-
billed cuckoo as a threatened species in accordance with sections 3(6), 
3(20), and 4(a)(1) of the Act.

Significant Portion of the Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is an endangered or threatened species throughout 
all or a significant portion of its range. The Act defines ``endangered 
species'' as any species which is ``in danger of extinction throughout 
all or a significant portion of its range,'' and ``threatened species'' 
as any species which is ``likely to become an endangered species within 
the foreseeable future throughout all or a significant portion of its 
range.'' The definition of ``species'' is also relevant to this 
discussion. The Act defines ``species'' as follows: ``The term 
`species' includes any subspecies of fish or wildlife or plants, and 
any distinct population segment [DPS] of any species of vertebrate fish 
or wildlife which interbreeds when mature.'' The phrase ``significant 
portion of its range'' (SPR) is not defined by the statute, and we have 
never addressed in our regulations: (1) The consequences of a 
determination that a species is either endangered or likely to become 
so throughout a significant portion of its range, but not throughout 
all of its range; or (2) what qualifies a portion of a range as 
``significant.''
    In determining whether a species is threatened or endangered in a 
significant portion of its range, we first identify any portions of the 
range of the species that warrant further consideration. The range of a 
species can theoretically be divided into portions an infinite number 
of ways. However, there is no purpose to analyzing portions of the 
range that are not reasonably likely to be both (1) significant and (2) 
threatened or endangered. To identify only those portions that warrant 
further consideration, we determine whether

[[Page 60036]]

there is substantial information indicating that: (1) The portions may 
be significant, and (2) the species may be in danger of extinction 
there or likely to become so within the foreseeable future. In 
practice, a key part of this analysis is whether the threats are 
geographically concentrated in some way. If the threats to the species 
are essentially uniform throughout its range, no portion is likely to 
warrant further consideration. Moreover, if any concentration of 
threats applies only to portions of the species' range that are not 
significant, such portions will not warrant further consideration.
    If we identify portions that warrant further consideration, we then 
determine whether the species is threatened or endangered in these 
portions of its range. Depending on the biology of the species, its 
range, and the threats it faces, the Service may address either the 
significance question or the status question first. Thus, if the 
Service considers significance first and determines that a portion of 
the range is not significant, the Service need not determine whether 
the species is threatened or endangered there. Likewise, if the Service 
considers status first and determines that the species is not 
threatened or endangered in a portion of its range, the Service need 
not determine if that portion is significant. However, if the Service 
determines that both a portion of the range of a species is significant 
and the species is threatened or endangered there, the Service will 
specify that portion of the range as threatened or endangered under 
section 4(c)(1) of the Act.
    We evaluated the current range of the western yellow-billed cuckoo 
to determine if there is any apparent geographic concentration of 
threats for the species. The western yellow-billed cuckoos are highly 
restricted to riparian habitat in their ranges, and the threats occur 
throughout the species' range. We considered the potential threats due 
to altered watercourse hydrology and natural stream processes, 
livestock overgrazing, encroachment from agriculture, conversion of 
native habitat to predominantly nonnative vegetation, pesticides, 
wildfire, small and widely separated habitat patches, and the effects 
of climate change. We found no concentration of threats because of the 
species' limited and curtailed range, and uniformity of the threats 
throughout its entire range. Having determined that the western yellow-
billed cuckoo is threatened throughout its entire range, we must next 
consider whether there are any significant portions of the range where 
the western yellow-billed cuckoo is in danger of extinction or is 
likely to become endangered in the foreseeable future.
    The western yellow-billed cuckoo is highly restricted to riparian 
habitat, and the threats to the species and its habitat occur 
throughout its breeding range. Therefore, we assessed the status of the 
western yellow-billed cuckoo throughout its entire breeding range. The 
threats to the survival of the species occur throughout the western 
DPS' breeding range and are not restricted to any particular 
significant portion of that range. We conclude that what affects the 
entire breeding portion of the western DPS' range affects the status of 
the entire western yellow-billed cuckoo throughout its breeding range, 
including migration corridors and stopover areas. Accordingly, our 
assessment and proposed determination applies to the western yellow-
billed cuckoo throughout its entire breeding range.
    We found no portion of the western yellow-billed cuckoo's range 
where threats are significantly concentrated or substantially greater 
than in other portions of their range and that factors affecting the 
species are essentially uniform throughout its range, indicating no 
portion of the range of the species warrants further consideration of 
possible endangered or threatened status under the Act. Therefore, we 
find there is no significant portion of the range of the western 
yellow-billed cuckoo that may warrant a different status.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness and 
conservation by Federal, State, and local agencies; private 
organizations; and individuals. The Act encourages cooperation with the 
States and requires that recovery actions be carried out for all listed 
species. The protection measures required of Federal agencies and the 
prohibitions against certain activities are discussed, in part, below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate goal of such conservation efforts is the recovery of these 
listed species, so that they no longer need the protective measures of 
the Act. Subsection 4(f) of the Act requires the Service to develop and 
implement recovery plans for the conservation of endangered and 
threatened species. The recovery planning process involves the 
identification of actions that are necessary to halt or reverse the 
species' decline by addressing the threats to its survival and 
recovery. The goal of this process is to restore listed species to a 
point where they are secure, self-sustaining, and functioning 
components of their ecosystems.
    Recovery planning includes the development of a recovery outline 
shortly after a species is listed and preparation of a draft and final 
recovery plan. The recovery outline guides the immediate implementation 
of urgent recovery actions and describes the process to be used to 
develop a recovery plan. Revisions of the plan may be done to address 
continuing or new threats to the species, as new substantive 
information becomes available. The recovery plan identifies site-
specific management actions that set a trigger for review of the five 
factors that control whether a species remains endangered or may be 
downlisted or delisted, and methods for monitoring recovery progress. 
Recovery plans also establish a framework for agencies to coordinate 
their recovery efforts and provide estimates of the cost of 
implementing recovery tasks. Recovery teams (composed of species 
experts, Federal and State agencies, nongovernmental organizations, and 
stakeholders) are often established to develop recovery plans. When 
completed, the recovery outline, draft recovery plan, and the final 
recovery plan will be available on our Web site (http://www.fws.gov/endangered), or from our Sacramento Fish and Wildlife Office (see FOR 
FURTHER INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribal, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include habitat 
restoration (e.g., restoration of native vegetation), research, captive 
propagation and reintroduction, and outreach and education. The 
recovery of many listed species cannot be accomplished solely on 
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires 
cooperative conservation efforts on private, State, and Tribal lands.
    Following publication of this final listing rule, funding for 
recovery actions will be available from a variety of sources, including 
Federal budgets, State programs, and cost share grants for non-Federal 
landowners, the academic community, and nongovernmental organizations. 
In addition, pursuant to

[[Page 60037]]

section 6 of the Act, the States of Washington, Idaho, Montana, Oregon, 
California, Nevada, Wyoming, Utah, Colorado, Arizona, New Mexico, and 
Texas would be eligible for Federal funds to implement management 
actions that promote the protection or recovery of the yellow-billed 
cuckoo. Information on our grant programs that are available to aid 
species recovery can be found at: http://www.fws.gov/grants.
    Please let us know if you are interested in participating in 
recovery efforts for the yellow-billed cuckoo. Additionally, we invite 
you to submit any new information on this species whenever it becomes 
available and any information you may have for recovery planning 
purposes (see FOR FURTHER INFORMATION CONTACT).
    Section 7(a) of the Act requires Federal agencies to evaluate their 
actions with respect to any species that is proposed or listed as 
endangered or threatened and with respect to its critical habitat, if 
any is designated. Regulations implementing this interagency 
cooperation provision of the Act are codified at 50 CFR 402. Section 
7(a)(4) of the Act requires Federal agencies to confer with the Service 
on any action that is likely to jeopardize the continued existence of a 
species proposed for listing or result in destruction or adverse 
modification of proposed critical habitat. If a species is listed 
subsequently, section 7(a)(2) of the Act requires Federal agencies to 
ensure that activities they authorize, fund, or carry out are not 
likely to jeopardize the continued existence of the species or destroy 
or adversely modify its critical habitat. If a Federal action may 
affect a listed species or its critical habitat, the responsible 
Federal agency must enter into formal consultation with the Service.
    Federal agency actions within or affecting the species' habitat 
that may require conference or consultation or both as described in the 
preceding paragraph include, but are not limited to, projects that will 
result in removal or degradation of riparian vegetation, altered 
streamflow or fluvial dynamics, or other habitat-altering activities on 
Federal lands or as a result of issuance of section 404 CWA permits by 
the USACE; construction and management of energy and power line rights-
of-way by the FERC; construction and maintenance of roads, highways, or 
bridges by the Federal Highway Administration; grazing leases by the 
USFS or the BLM; and projects funded through Federal loan programs. 
Such projects may include, but are not limited to, construction or 
modification of reservoirs, levees, bank stabilization structures, 
water diversion and withdrawal projects, roads and bridges, utilities, 
recreation sites, and other forms of development, and livestock 
grazing.
    Under section 4(d) of the Act, the Service has discretion to issue 
regulations that we find necessary and advisable to provide for the 
conservation of threatened species. The Act and its implementing 
regulations set forth a series of general prohibitions and exceptions 
that apply to threatened wildlife. The prohibitions of section 9(a)(1) 
of the Act, as applied to threatened wildlife and codified at 50 CFR 
17.31 make it illegal for any person subject to the jurisdiction of the 
United States to take (which includes harass, harm, pursue, hunt, 
shoot, wound, kill, trap, capture, or collect; or to attempt any of 
these) threatened wildlife within the United States or on the high 
seas. In addition, it is unlawful to import; export; deliver, receive, 
carry, transport, or ship in interstate or foreign commerce in the 
course of commercial activity; or sell or offer for sale in interstate 
or foreign commerce any listed species. It is also illegal to possess, 
sell, deliver, carry, transport, or ship any such wildlife that has 
been taken illegally. Certain exceptions apply to employees of the 
Service, the National Marine Fisheries Service, other Federal land 
management agencies, and State conservation agencies.
    We may issue permits to carry out otherwise prohibited activities 
involving threatened wildlife under certain circumstances. Regulations 
governing permits are codified at 50 CFR 17.32. With regard to 
threatened wildlife, a permit may be issued for the following purposes: 
For scientific purposes, to enhance the propagation or survival of the 
species, and for incidental take in connection with otherwise lawful 
activities. There are also certain statutory exemptions from the 
prohibitions, which are found in sections 9 and 10 of the Act.
    It is our policy, as published in the Federal Register on July 1, 
1994 (59 FR 34272), to identify to the maximum extent practicable at 
the time a species is listed, those activities that would or would not 
constitute a violation of section 9 of the Act. The intent of this 
policy is to increase public awareness of the effect of a final listing 
on proposed and ongoing activities within the range of a listed 
species. However, at this time, we are unable to identify specific 
activities that would not be considered to result in a violation of 
section 9 of the Act because the western yellow-billed cuckoo occurs in 
riparian habitat across numerous western States that exhibit a variety 
of habitat conditions across its range, and it is likely that site- and 
project-specific conservation measures may be needed for activities 
that may directly or indirectly affect the species.
    Based on the best available information, the following activities 
may potentially result in a violation of section 9 the Act; this list 
is not comprehensive: (1) Handling or collecting of the species; (2) 
destruction/alteration of the species' habitat by discharge of fill 
material, draining, ditching, tiling, pond construction, stream 
channelization or diversion, or diversion or alteration of surface or 
ground water flow; (3) livestock grazing that results in direct or 
indirect destruction of riparian habitat; (4) activities such as 
continued presence of cattle and fragmentation of riparian habitat; (5) 
pesticide applications in violation of label restrictions; and (6) 
release of biological control agents that modifies or destroys habitat 
used by the species.
    Questions regarding whether specific activities would constitute a 
violation of section 9 of the Act should be directed to the Sacramento 
Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT).

Required Determinations

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.), need not be 
prepared in connection with regulations pursuant to section 4(a) of the 
Act. We published a notice outlining our reasons for this determination 
in the Federal Register on October 25, 1983 (48 FR 49244).

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994 
(Government-to-Government Relations with Native American Tribal 
Governments; 59 FR 22951), Executive Order 13175 (Consultation and 
Coordination With Indian Tribal Governments), and the Department of the 
Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with recognized Federal 
Tribes on a government-to-government basis. In accordance with 
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights, 
Federal-Tribal Trust Responsibilities, and the Endangered

[[Page 60038]]

Species Act), we readily acknowledge our responsibilities to work 
directly with tribes in developing programs for healthy ecosystems, to 
acknowledge that tribal lands are not subject to the same controls as 
Federal public lands, to remain sensitive to Indian culture, and to 
make information available to tribes. During the development of this 
final rule, we contacted, held meetings with, or otherwise coordinated 
with all known tribal entities within the range of the species within 
the United States. Information solicited or gathered as result of this 
coordination has been incorporated into this final determination as 
appropriate. We will conduct further coordination during our 
designation of critical habitat for the species.

References Cited

    A complete list of all references cited in this rule is available 
on the Internet at http://www.regulations.gov or upon request from the 
Field Supervisor, Sacramento Fish and Wildlife Office (see ADDRESSES).

Authors

    The primary authors of this final rule are the staff members from 
the Service's Sacramento Fish and Wildlife Office and the Pacific 
Southwest Regional Office (Region 8) with assistance from staff from 
the Pacific Northwest Region (Region 1), the Southwest Region (Region 
2), and the Mountain-Prairie Region (Region 6).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Regulation Promulgation

    Accordingly, we amend part 17, subchapter B of chapter I, title 50 
of the Code of Federal Regulations, as follows:

PART 17--[AMENDED]

0
1. The authority citation for part 17 continues to read as follows:

    Authority:  16 U.S.C. 1361-1407; 1531-1544; 4201-4245, unless 
otherwise noted.


0
2. Amend Sec.  17.11(h) by adding an entry for ``Cuckoo, yellow-billed 
(Western DPS)'' to the List of Endangered and Threatened Wildlife in 
alphabetical order under Birds, to read as follows:


Sec.  17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                        Species                                                    Vertebrate
--------------------------------------------------------                        population where                                  Critical     Special
                                                            Historic Range       endangered or         Status      When listed    habitat       rules
           Common name                Scientific name                              threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
              Birds
 
                                                                      * * * * * * *
Cuckoo, yellow-billed............  Coccyzus americanus.  U.S.A., Canada,      Western DPS: U.S.A.  T                       850           NA           NA
                                                          Mexico.              (AZ, CA, CO
                                                                               (western), ID, MT
                                                                               (western), NM
                                                                               (western), NV, OR,
                                                                               TX (western), UT,
                                                                               WA, WY (western));
                                                                               Canada (British
                                                                               Columbia
                                                                               (southwestern);
                                                                               Mexico (Baja
                                                                               California, Baja
                                                                               California Sur,
                                                                               Chihuahua, Durango
                                                                               (western),
                                                                               Sinaloa, Sonora).
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * *

    Dated: September 24, 2014.
Daniel M. Ashe,
Director, U. S. Fish and Wildlife Service.
[FR Doc. 2014-23640 Filed 10-2-14; 8:45 am]
BILLING CODE 4310-55-P