[Federal Register Volume 76, Number 193 (Wednesday, October 5, 2011)]
[Proposed Rules]
[Pages 61856-61894]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-25565]



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Vol. 76

Wednesday,

No. 193

October 5, 2011

Part IV





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; 12-Month Finding on a 
Petition To List the Cactus Ferruginous Pygmy-Owl as Threatened or 
Endangered With Critical Habitat; Proposed Rule

  Federal Register / Vol. 76 , No. 193 / Wednesday, October 5, 2011 / 
Proposed Rules  

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

 [FWS-R2-ES-2011-0086; MO 92210-0-0008]


Endangered and Threatened Wildlife and Plants; 12-Month Finding 
on a Petition To List the Cactus Ferruginous Pygmy-Owl as Threatened or 
Endangered With Critical Habitat

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 12-month petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
12-month finding on a petition to list the cactus ferruginous pygmy-owl 
(Glaucidium brasilianum cactorum) as threatened or endangered and to 
designate critical habitat under the Endangered Species Act of 1973, as 
amended (Act). Additionally, the petition requested that we recognize 
and list a western subspecies of the cactus ferruginous pygmy-owl 
(Glaucidium ridgwayi cactorum), or, alternatively, two potential 
distinct population segment (DPS) configurations. After review of all 
available scientific and commercial information, we find that 
Glaucidium ridgwayi cactorum is not a valid taxon, and, therefore, not 
a listable entity under the Act. Additionally, using the currently 
accepted taxonomic classification of the pygmy-owl (Glaucidium 
brasilianum cactorum), we find that listing the pygmy-owl is not 
warranted at this time throughout all or a significant portion of its 
range, including the petitioned and other potential DPS configurations. 
However, we ask the public to submit to us at any time any new 
information concerning the taxonomy or status of the pygmy-owl, as well 
as any new information on the threats to the pygmy-owl or its habitat.

DATES: The finding announced in this document was made on October 5, 
2011.

ADDRESSES: This finding is available on the Internet at http://www.regulations.gov at Docket Number FWS-R2-ES-2011-0086. Supporting 
documentation we used in preparing this finding is available for public 
inspection, by appointment, during normal business hours at the U.S. 
Fish and Wildlife Service, Arizona Ecological Services Office, 2321 
West Royal Palm Road, Suite 103, Phoenix, AZ 85021-4951. Please submit 
any new information, materials, comments, or questions regarding this 
finding to the above address.

FOR FURTHER INFORMATION CONTACT: Steve Spangle, Field Supervisor, 
Arizona Ecological Services Office (see ADDRESSES); telephone 602-242-
0210; or by facsimile 602-242-2513. If you use a telecommunications 
device for the deaf (TDD), please call the Federal Information Relay 
Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Background

    Section 4(b)(3)(B) of the Endangered Species Act (Act) (16 U.S.C. 
1531 et seq.) requires that, for any petition to revise the Federal 
Lists of Endangered and Threatened Wildlife and Plants that contains 
substantial scientific and commercial information that listing a 
species may be warranted, we make a finding within 12 months of the 
date of receipt of the petition. In this finding, we determine whether 
the petitioned action is: (1) Not warranted, (2) warranted, or (3) 
warranted, but immediate proposal of a regulation implementing the 
petitioned action is precluded by other pending proposals to determine 
whether species are threatened or endangered, and expeditious progress 
is being made to add or remove qualified species from the Lists of 
Endangered and Threatened Wildlife and Plants. Section 4(b)(3)(C) of 
the Act requires that we treat a petition for which the requested 
action is found to be warranted but precluded as though resubmitted 
annually on the date of such finding. Therefore, a new finding is to be 
made within 12 months and subsequently thereafter until we take action 
on a proposal to list or withdraw our original finding. We must publish 
these 12-month findings in the Federal Register.

Previous Federal Actions

    On March 20, 2007, we received a petition dated March 15, 2007, 
from the Center for Biological Diversity and Defenders of Wildlife 
(petitioners) requesting that we list the cactus ferruginous pygmy-owl 
(Glaucidium brasilianum cactorum) (pygmy-owl) as a threatened or 
endangered species under the Endangered Species Act (Act) (CBD and DOW 
2007). Additionally, the petition requested the designation of critical 
habitat concurrent with listing. The petition clearly identified itself 
as a petition and included the identification information, as required 
in 50 CFR 424.14(a). We acknowledged the receipt of the petition in a 
letter to the petitioners dated June 25, 2007, stating that we were 
proceeding with a review of the petition.
    The petitioners described three potentially listable entities of 
the pygmy-owl: (1) An Arizona distinct population segment (DPS) of the 
pygmy-owl; (2) a Sonoran Desert DPS of the pygmy-owl; and (3) the 
western subspecies of the pygmy-owl, which they identified as 
Glaucidium ridgwayi cactorum. As an immediate action, the petitioners 
requested that we promulgate an emergency listing rule for the pygmy-
owl. In our June 25, 2007, response letter to the petitioners, we 
described our evaluation of the need for emergency listing and stated 
our determination that emergency listing was not warranted for the 
pygmy-owl. We also stated that the designation of critical habitat 
would be considered if listing of the pygmy-owl was found to be 
warranted.
    In the Federal Register of June 2, 2008 (73 FR 31418), we published 
a 90-day finding in which we determined that the petition presented 
substantial scientific and commercial information to indicate that 
listing the pygmy-owl may be warranted. A more thorough summary of 
previous Federal actions related to the pygmy-owl can be found in the 
June 2, 2008 90-day finding (73 FR 31418).
    Following the publication of our 90-day finding on this petition, 
we initiated a status review to determine if listing of the pygmy-owl 
was warranted. During our status review, we solicited and received 
information from the general public and other interested parties on the 
status of the pygmy-owl. We consulted with experts, agencies, 
countries, and tribes to gather pertinent information, and ensure that 
experts and affected parties were aware of the status review and of the 
opportunity to provide input. We identified, contacted, and consulted 
with a diverse group of experts and interested persons in an effort to 
ensure that we gathered and evaluated the best available scientific and 
commercial information on this subspecies to inform our 12-month 
finding.
    On December 12, 2009, we received a 60-day Notice of Intent to Sue 
from the petitioners for failure to produce a timely 12-month finding 
on their petition. They subsequently filed suit on February 17, 2010, 
in the U.S. District Court for the District of Arizona. That complaint 
was subsequently consolidated in the U.S. District Court for the 
District of Columbia along with another case filed by the Center for 
Biological Diversity and thirteen cases filed by Wild Earth Guardians, 
all related to petition finding deadlines. The court in the 
consolidated case

[[Page 61857]]

approved two settlement agreements between the parties on September 9, 
2011. In re Endangered Species Act Deadline Litigation, Misc. Action 
No. 10-377 (EGS), MDL Docket No. 2165 (D.D.C. Sept. 9, 2011) (Docs. 55 
& 56). The settlement agreements stipulate that the Service will submit 
to the Federal Register a proposed listing rule or a not warranted 
finding for the cactus ferruginous pygmy-owl no later than the end of 
Fiscal Year 2011, which is September 30, 2011.
    This notice constitutes a 12-month finding for the petition to list 
the pygmy-owl as threatened or endangered. We base our finding on a 
review of the best scientific and commercial information available, 
including all substantive information received during our status 
review.
    In this finding, we first provide background information on the 
biology of the pygmy-owl. Included in this background is our analysis 
of the petitioner's request that we recognize a western subspecies of 
the pygmy-owl (Glaucidum ridgwayi cactorum), which represents a 
proposed change in the taxonomic classification of the pygmy-owl. Then, 
we consider each of the five factors listed in section 4(a)(1) of the 
Act. For each factor, we first determine whether any negative impacts 
appear to be affecting the pygmy-owl anywhere in the subspecies' range, 
and whether any of these impacts rise to the level of threats such that 
the pygmy-owl is endangered or threatened throughout its range, 
according to the statutory standard.
    After the rangewide assessment, we evaluate the validity of the 
petitioned distinct population segments (DPSs), as well as other 
potential DPS configurations suggested by information submitted during 
the status review or by the ecology, occurrence, and distribution of 
the pygmy-owl. This analysis determines whether any of the DPS 
configurations meet the criteria for discreteness and significance 
under our DPS policy (see Distinct Vertebrate Population Segment 
section below). We then evaluate whether there is a significant portion 
of the pygmy-owl's range that warrants further evaluation, consistent 
with the Act's definitions for ``endangered species'' and ``threatened 
species,'' which requires analysis of whether a ``species'' is 
endangered or threatened within ``a significant portion of its range'' 
(see Significant Portion of the Range section below). Finally, we make 
our finding with regard to the petitioned action and our evaluation as 
described above.

Species Information

Description
    The pygmy-owl is in the order Strigiformes and the family 
Strigidae. It is a small bird, approximately 17 centimeters (cm) (6.75 
inches (in)) long. Generally, male pygmy-owls average 58 grams (g) to 
66 g (2.0 to 2.3 ounces (oz)) and females average 70 g to 75 g (2.4 to 
2.6 oz) (AGFD 2008b, p. 3; Proudfoot and Johnson 2000, p. 16; Johnsgard 
1988, p. 159). The pygmy-owl is reddish brown overall, with a cream-
colored belly streaked with reddish brown. Color may vary, with some 
individuals being more grayish brown (Proudfoot and Johnson 2000, pp. 
15-16). The crown is lightly streaked, and a pair of dark brown or 
black spots outlined in white occurs on the nape, suggesting ``eyes,'' 
leading to the name ``Cuatro Ojos'' (four eyes), as it is sometimes 
called in Mexico (Oberholser 1974, p. 451). The species lacks ear 
tufts, and the eyes are yellow. The tail is relatively long for an owl 
and is reddish brown in color, with darker brown bars. Pygmy-owls have 
large feet and talons relative to their body size.
Taxonomy
    The petitioners requested that we recognize a change in the 
taxonomic classification of the pygmy-owl (CBD and DOW 2007, pp. 1-2). 
In considering taxonomic data, the Service relies ``on standard 
taxonomic distinctions and the biological expertise of the Department 
and the scientific community concerning the relevant taxonomic group'' 
(50 CFR 424.11(a)) and on ``the best available scientific and 
commercial information'' (50 CFR 424.11(b)). The use of specific 
taxonomic data is at the discretion of the Service, as long as the 
information is reliable and meets the above standards. With regard to 
the pygmy-owl, existing avian checklists attempt to present the most 
current taxonomic classifications, but discrepancies among checklists 
demonstrate that there is scientific debate and disagreement over some 
accepted taxonomic designations. Taxonomic changes within these 
checklists generally occur as a result of a proposal to change the 
existing taxonomy. Lack of reference to a proposed taxonomic change 
within these checklists cannot be interpreted as rejection (or 
acceptance) of a proposed change. It may simply mean a proposal has not 
been submitted or evaluated. Absolute reliance on one or more of these 
avian checklists, absent consideration of recent studies, would be 
arbitrary on the part of the Service. The Service has the 
responsibility for deciding what taxonomic entities are to be protected 
under the Act, based on the best available scientific information. We 
address any conflicting information or conflicting expert opinion by 
carefully evaluating the underlying scientific information and weighing 
its reliability and adequacy according to the considerations of the Act 
and our associated policies and procedures.
    When we previously listed the pygmy-owl as endangered in 1997 (62 
FR 10730; March 10, 1997), and in all subsequent regulatory and legal 
actions, we followed the currently accepted taxonomic classification, 
Glaucidium brasilianum cactorum. We considered G. b. cactorum to occur 
from lowland central Arizona south through western Mexico to the 
Mexican states of Colima and Michoac[aacute]n, and from southern Texas 
south through the Mexican states of Tamaulipas and Nuevo Leon, 
consistent with most of the contemporary literature (Johnsgard 1988, p. 
159; Millsap and Johnson 1988, p. 137; Oberholser 1974, p. 452; 
Friedmann et al. 1950, p. 145), and the last American Ornithologist 
Union (AOU) list that addressed avian classification to the subspecies 
level (AOU 1957) (Figure 1). The AOU checklist is generally accepted as 
the primary authority for avian taxonomic classification, and the 1957 
AOU checklist description is the currently accepted taxonomic 
classification of the pygmy-owl at the subspecies level.

[[Page 61858]]

[GRAPHIC] [TIFF OMITTED] TP05OC11.003

    The petitioners requested a revised taxonomic consideration for the 
pygmy-owl based on Proudfoot et al. (2006a, p. 9; 2006b, p. 946) and 
K[ouml]nig et al. (1999, pp. 160, 370-373), classifying the northern 
portion of Glaucidium brasilianum's range as an entirely separate 
species, G. ridgwayi, and recognizing two subspecies of G. ridgwayi--G. 
r. cactorum in western Mexico and Arizona and G. r. ridgwayi in eastern 
Mexico and Texas (Figure 1). Other recent studies proposing or 
supporting the change to G. ridgwayi for the northern portion of G. 
brasilianum's range have been published in the past 15 years (Heidrich 
et al. 1995, p. 2, 25; Navarro-Siguenza and Peterson 2004, p. 5).
    Groups classified within species, such as subspecies, are important 
in the discussion of biodiversity because they represent the 
evolutionary potential within a species. Recognizing this, a number of 
existing lists of threatened, endangered, or special status species 
include subspecific groups (Haig et al. 2006, p. 1585). We considered 
the information in these existing lists and other literature as we 
evaluated the petitioned taxonomic classification. The 1957 AOU 
checklist is the last AOU checklist that described subspecies. 
Subsequent AOU checklists have limited their descriptions to the 
species level only and are, therefore, not helpful in our evaluation.
    In our 90-day finding for this petition (73 FR 31418), we indicated 
that the petition presented reliable and substantive information that a 
taxonomic revision may be warranted. The suggested taxonomic change is 
based on recently published recommendations (Proudfoot et al. 2006a, p. 
9; 2006b, p. 946; K[ouml]nig et al. 1999, pp. 160, 370-373) to revise 
pygmy-owl taxonomy. Various other publications also provide evidence 
that the taxonomic status of the pygmy-owl has not been resolved 
(Proudfoot and Johnson 2000, pp. 4-5; K[ouml]nig et al. 1999, p. 373; 
Phillips 1966, p. 93; Buchanan 1964, p. 107). Information received 
during our status review also indicates that pygmy-owl taxonomy needs 
additional work to resolve current questions (Johnson and Carothers 
2008b, pp. 5-6; Robbins 2008, p. 1; Voelker 2008, p. 1).
    Taxonomic nomenclature for the pygmy-owl has changed over time. 
Originally called Glaucidium ferrugineum in 1872 by Coues (Coues 1872, 
p. 370), the pygmy-owl has also been known as G. ferrugineus (Aiken 
1937, p. 29) and G. phalo(a)enoides (Fisher 1893, p. 199; Gilman 1909, 
p. 115, Swarth 1914, p. 31; Kimball 1921, p. 57). Since the 1920's, the 
pygmy-owl has been classified as G. brasilianum (van Rossem 1937, p. 
27; Bent 1938, p. 435; Peters 1940, p. 130; Brandt 1951, p. 653; Sutton 
1951, p. 168). We will focus our discussion at the subspecies level 
since the petitioned entity is at the subspecies level of 
classification. As such, we will not evaluate or discuss whether the 
appropriate species classification is G. brasilianum or G. ridgwayi.
    The petitioners asked the Service to recognize a subspecies, 
Glaucidium ridgwayi cactorum, described by

[[Page 61859]]

Proudfoot et al. (2006a, pp. 9-10; 2006b, p. 2, 9) as the listable 
entity in the petition. The primary difference between the petitioned 
subspecies and the currently accepted description of G. brasilianum 
cactorum is the latter's more extensive distribution to the south and 
east (Figure 1). The range of the G. b. cactorum subspecies we 
originally listed in 1997 is Arizona, northwestern Mexico, the Lower 
Rio Grande Valley of Texas, and northeastern Mexico, for a general 
distribution that runs from central Mexico northward on both sides of 
the Sierra Madre mountains into Arizona and Texas. The range of the 
proposed G. r. cactorum does not extend as far south as G. b. cactorum. 
The two G. ridgwayi subspecies proposed by the petition encompass the 
northwestern (G. r. cactorum) and northeastern (G. r. ridgwayi) 
extensions of the range of G. b. cactorum. Specifically, the petition 
describes the range of the suggested subspecies, G. r. cactorum, as 
extending from Arizona on the north through the States of Sonora and 
Sinaloa in Mexico (Figure 2).
[GRAPHIC] [TIFF OMITTED] TP05OC11.004

    Our analysis of whether to accept the petitioners' proposed 
Glaucidium ridgwayi cactorum subspecies as a listable entity includes 
an evaluation of whether there are historical or current descriptions 
or studies of the proposed subspecies that would support the 
description of the petitioned subspecies based on Proudfoot et al. 
(2006a, 2006b). A number of subspecies of G. brasilianum have been 
described or suggested (Proudfoot and Johnson 2000, p. 4; Friedmann et 
al. 1950, pp. 145-147), including various descriptions of a cactorum 
subspecies, the distribution of some of which generally match the 
petitioned subspecies. Therefore, the delineation of a cactorum 
subspecies as petitioned is not a new classification, but one that has 
been described previously in the literature under G. brasilianum.
    With regard to existing literature, van Rossem (1937, pp. 27-28) 
described the earliest cactorum subspecies that approximates the 
distribution of the petitioned subspecies. This was a newly described 
subspecies of ferruginous pygmy-owl and was described from a ``giant 
cactus grove between Empalme and Guaymas * * * Sonora, Mexico'' (van 
Rossem 1937, p. 27). Van Rossem restricted this new subspecies to 
northwestern Mexico and Arizona (Figure 3). Van Rossem also included a 
more southern and eastern subspecies, ridgwayi, that was described as 
occurring in southern Mexico and central America, but also Texas (van 
Rossem, 1937, pp. 27-28). He specifically excluded the Texas population 
from cactorum, about which

[[Page 61860]]

he wrote ``they approximate very closely the measurements and tail 
characters of cactorum * * * in color they are best referred to 
ridgwayi'' (van Rossem 1937, pp. 27-28; italics added). The 1944 AOU 
checklist accepted this classification and described its distribution 
as southern Arizona to Nayarit, in western Mexico (AOU 1944, p. 50) 
(Fig. 3). However, in a later publication van Rossem (1945, p. 111) 
indicated that cactorum extended only to the Sonora and Sinaloa border 
in Mexico (Figure 3), perhaps excluding Nayarit, because his 1937 
publication indicates that the specimen from Nayarit was not typical 
(van Rossem 1937, p. 28). Karalus and Eckert (1971, p. 223) give a 
southern distribution for cactorum of western and northwestern Sonora 
(Figure 3). Proudfoot et al. (2006a, p. 9; 2006b, p. 7) indicate the 
state of Sinaloa is the southern extent of the range, while K[ouml]nig 
et al. (1999, p. 373) extend the distribution of cactorum into Nayarit 
and Jalisco in western Mexico (Figure 3). Freethy (1992, p. 121) simply 
states that western Mexico is the southern limit of cactorum. Clements 
(2007, p. 171) recognizes the cactorum subspecies, but gives no 
distribution.
BILLING CODE 4310-55-P
[GRAPHIC] [TIFF OMITTED] TP05OC11.005


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BILLING CODE 4310-55-C
    The chronology described in the previous paragraph, which excludes 
the currently accepted distribution of Glaucidium brasilianum cactorum, 
focuses on descriptions in the literature which generally approximate 
the petitioned description of G. ridgwayi cactorum, and there is 
consensus that cactorum extended northward into Arizona. However, it is 
evident there is inconsistency regarding the southern extent of the 
subspecies. With the exception of van Rossem (1937, pp. 27-28), who 
uses morphological characteristics to describe the subspecies, most of 
the above descriptions of the cactorum subspecies do not indicate why 
they have ascribed the subspecies to the ranges indicated in these 
publications. K[ouml]nig et al. (1999, p. 373) simply uses the 
morphological characters of van Rossem (1937, pp. 27-28). K[ouml]nig et 
al. (1999, entire) and Proudfoot et al. (2006a; 2006b, entire) do 
classify cactorum using genetic data, but draw different conclusions 
with regard to the southern boundary. The incremental southward 
extension of the various cactorum ranges may provide some support for 
the idea of a clinal pattern of differentiation in which genetic and 
morphological differences occur in an incremental manner, as opposed to 
more abrupt changes that are more likely to represent a boundary 
between two distinct subspecies groupings. The data presented in the 
petition (Proudfoot et al. 2006a; 2006b, entire) are not sufficient to 
clarify the groupings in the literature, nor does it allow us to 
determine if the subspecies ranges are distinct because there is a lack 
of adequate sampling in southern and eastern Mexico. The uncertainty of 
the southern boundary would suggest that additional sampling is needed 
to refine this portion of the range of cactorum. In the presence of 
unresolved inconsistencies, the Service relies upon the ``standard 
taxonomic distinctions (50 CFR 424.11(a)); in this case, the currently 
accepted taxonomic classification (AOU 1957).
    In addition to reviewing historical and current descriptions of the 
subspecies, we requested review and input on the issue of taxonomic 
classification of the petitioned entity from 10 individuals with 
biological expertise and background in this issue. Of the 10 we 
consulted, 5 provided comments on specific questions we asked regarding 
the issues of taxonomic classification, genetic differentiation, and 
genetic diversity based on recent and historical studies and 
publications related to pygmy-owl taxonomic classification. Information 
submitted by all five experts indicated that, while there are certain 
aspects of the information presented in the petition that support 
acceptance of the petitioned entity, there is insufficient information 
regarding how to define a distinct subspecies. Additional work is 
needed to clarify the distribution of the subspecies, especially in 
regards to the southern boundary (Voelker 2008, p. 1; Cicero 2008, p. 
2; Robbins 2008, p. 1; Oyler-McCance 2008, pp. 1-2; Dumbacher 2008, pp. 
2-8). A summary of their comments is presented below.
    Dumbacher (2008, p. 7) provided a summary of considerations in 
response to our request for input on this issue: ``In summary, 
Proudfoot et al. 2006a and 2006b do not provide a critical test for the 
subspecies Glaucidium ridgwayi ridgwayi or G.r. cactorum or their 
geographical ranges. The data are consistent with current subspecies 
names in that they show: (1) Isolation by distance across the range, 
albeit with larger genetic breaks in the region that corresponds with 
the subspecies names [as described by van Rossem 1937]; (2) and 
significant variation among major geographical areas that broadly 
correspond to present subspecies names [van Rossem 1937]. However, it 
is not clear: (1) Where exactly the subspecies boundaries occur; (2) 
whether the boundary will be geographically distinct or correspond to 
characters used in the original subspecies designation, such that the 
two groups would qualify for subspecies under the 75 percent rule [75 
percent of individuals in a new subspecies (or region) are diagnosably 
different from the other possible subspecies]; or (3) whether a broad 
hybrid zone or cline would be discovered that might call the two 
subspecies into question. Further data are needed to critically test 
the validity of the subspecies and to identify the most appropriate 
geographic boundary between them. Proudfoot et al. (2006b) make a plea 
for more data in critical areas, such as between Sonora and Sinaloa, 
and I would argue further south as well.''
    Cicero (2008, p. 2) adds, ``On the basis of these data, I would 
argue that Arizona and Texas populations should be managed as separate 
units. However, further study of the variation in morphology and 
plumage (the characters originally used to describe cactorum) is needed 
before we can reliably apply names to these populations. Thus, in my 
opinion, the molecular data provided by Proudfoot et al. (2006a and 
2006b) do not clarify subspecific limits and ranges in North American 
populations of G. brasilianum''. Similarly, Oyler-McCance (2008, p. 2) 
indicates that, ``within the United States, it is clear that the 
Arizona group is much different from the Texas group and should not be 
considered as one group. What is less clear, however, is where exactly 
to draw the boundary between the two subspecies * * *. It would be 
informative to look at other characteristics (morphology, behavior, 
geographic distribution) and see how well they fit with the patterns 
provided by the genetic data. Only then, using all those 
characteristics, would it be prudent to make a decision.''
    Robbins (2008, p. 1) indicated that work on a molecular-based 
phylogeny of New World pygmy-owls is about to be completed that will 
inform this issue. He suggested that acceptance of the petitioned 
entity be delayed until this work has been published. However, the 
study to which Robbins refers will focus on species-level analyses, and 
it may not provide additional information regarding the distribution of 
subspecies and, as of the date of this finding, has not yet been 
published.
    Recently, the Committee on Classification and Nomenclature on North 
and Middle American birds (the Checklist Committee) of the AOU 
considered a proposal to separate Glaucidium brasilianum ridgwayi as a 
distinct species, but rejected that proposal, citing the need to wait 
for additional work (AOU 2009).
    In fairness to Proudfoot and his collaborators, their two 2006 
studies are more general in nature and did not have the objective of 
defining pygmy-owl classification to the subspecies level. In addition, 
Proudfoot and his fellow authors, similar to the authors of many other 
publications related to pygmy-owl taxonomy, pointed out the need for 
additional work to clarify the taxonomic classification of pygmy-owls. 
Therefore, when we consider the recent information provided by 
Proudfoot et al. (2006a; 2006b, entire) and K[ouml]nig et al. (1999, 
entire), in combination with the historical descriptions of 
distributions for the subspecies cactorum, there is evidence of a 
general nature that the petitioned subspecies may have merit. However, 
after reviewing the best available information, we find that 
uncertainty and inconsistency exists with regard to the delineation of 
the range of these subspecies.
    The peer reviewers who provided information to the Service 
regarding this issue represent respected experts with considerable 
knowledge of the current science regarding avian taxonomy and 
classification. They point out that a combination of factors, including 
morphological, vocal, and genetic, need to be considered in greater 
depth, with

[[Page 61862]]

additional sampling, to determine if the petitioned taxonomic 
classification should be accepted, and we are in agreement with these 
comments. Given the uncertainty and lack of clarification found in the 
best available scientific and commercial information, we rely on the 
``biological expertise of the Department and the scientific community 
concerning the relevant taxonomic group'' (50 CFR 424.11(a)).
    In summary, we find that there is considerable uncertainty as to 
whether the genetic differentiation found at the far ends of the pygmy-
owl's distribution represented by Arizona and Texas are adequate to 
define the eastern and western distributions as separate subspecies. 
These differences may simply represent isolation by distance with a 
clinal gradation of genetic differentiation between the two extremes of 
the range, which would be inconsistent with the existence of two 
different subspecies. Therefore, the best available scientific and 
commercial information does not suggest that genetic differentiation 
reported by Proudfoot et al. (2006a; 2006b, entire) and K[ouml]nig et 
al. (1999, entire) supports their proposed Glaucidium ridgwayi cactorum 
subspecies classification at this time. Future work and studies may 
clarify and resolve these issues, but, in the meantime, we will 
continue to use the currently accepted distribution of G. brasilianum 
cactorum as described in the 1957 AOU checklist and various other 
publications (Johnsgard 1988, p. 159; Millsap and Johnson 1988, p. 137; 
Oberholser 1974, p. 452; Friedmann et al. 1950, p. 145). The Service 
accepted this information under the previous listing of the pygmy-owl 
(62 FR 10730). We, therefore, reject the petitioned listing of a 
western subspecies of pygmy-owl, G. r. cactorum, as an insufficiently 
supported taxonomic subspecies at this time.
    The following discussion will examine the potentially listable 
entities of Glaucidium brasilianum cactorum, the currently recognized 
subspecies of pygmy-owl.
Distribution and Status
    The currently accepted distribution of the pygmy-owl is described 
as south central Arizona and southern Texas in the United States, south 
through the Mexican States of Sonora, Sinaloa, Nayarit, Jalisco, 
Colima, and Michoac[aacute]n on the west and Nuevo Leon and Tamaulipas 
on the east (Figure 1). Available information on the specific 
distribution of the pygmy-owl within this general area is not 
comprehensive, especially in the southern portions of Mexico. As 
described below, we have relatively detailed information on pygmy-owl 
distribution in the United States and Sonora, Mexico. The following is 
a description of the available information we have related to the 
distribution of the pygmy-owl.
    The cactus ferruginous pygmy-owl is the northernmost subspecies of 
the ferruginous pygmy-owl. This subspecies was originally described as 
being common in the lower Rio Grande River in southern Texas 
(Oberholser 1974, p. 452) and along the Salt and Gila Rivers in central 
Arizona (Fisher 1893, p. 199; Breninger 1898, p. 128; Gilman 1909, p. 
148). In Arizona and Texas, apparent range and population declines have 
occurred, reducing the current distribution of the pygmy-owl in these 
areas (Oberholser 1974, p. 452; Monson and Phillips 1981, p. 72; 
Proudfoot and Johnson 2000, p. 3). Historical records for the pygmy-owl 
in Arizona span at least five counties in southern and south-central 
Arizona, including Maricopa, Pima, Pinal, Santa Cruz and Yuma Counties 
(Johnson et al. 2003, p. 394). Most of the historical (pre-1900) and 
recent (post-1990) records are from Pima County. Between 1872 and 1971, 
a total of 56 published records or specimens were recorded for Arizona. 
Of those, almost half (27) were from Pima County (Johnson et al. 2003, 
pp. 392-395). Although the pygmy-owl was historically recorded 
primarily from lowland riparian habitats, all recent records are from 
upland and xeroriparian (vegetation community in drainages associated 
with seasonal or intermittent water) Sonoran desertscrub (Abbate et al. 
2000, pp. 15-16, Service 2009b, p. 1: 2011, p. 1).
    Some information provided by the public suggested that the pygmy-
owl is an obligate wet riparian species in south-central Arizona and a 
preferential wet riparian species in southern Arizona, tying its 
distribution to these types of areas. In addition, the information 
states that recent records in upland habitats have occurred primarily 
in areas associated with ``cultivated riparian'' habitats resulting 
from the human influences of irrigation and ornamental plantings, such 
as in suburban areas of Tucson (Johnson and Carothers 2008b, pp. 13-
14). We agree that riparian ecosystems provide important pygmy-owl 
habitat within its range. However, we disagree with the suggestion that 
pygmy-owls are riparian obligates, and thus limited in occurrence to 
these areas. For example, there are numerous recent locations in which 
pygmy-owls were detected in Sonoran desert uplands and semi-desert 
grasslands of southern Pinal County, Avra Valley, Altar Valley, Cabeza 
Prieta National Wildlife Refuge, Organ Pipe Cactus National Monument, 
and northern Sonora that are not in proximity to ``cultivated 
riparian'' or naturally occurring hydro- or mesoriparian (wet riparian) 
habitats.
    Two members of the public provided extensive information in support 
of the idea that pygmy-owls have never been common in Arizona; 
therefore, the current low numbers and reduced distribution are not 
sufficient reason to determine that the pygmy-owl is endangered in 
Arizona (James 2008, pp. 8-10; Parker 2008, pp. 2-10). This conclusion 
is based on the historical records from early naturalists and 
ornithologists regarding their observations or collections of pygmy-
owls or their nests or eggs, or the lack thereof. Specifically, this 
information points out that a number of early naturalists or 
ornithologists that made trips of various lengths and in various 
locations in Arizona where pygmy-owls would have been expected to occur 
did not make mention of observing pygmy-owls in their trip reports 
(James 2008, pp. 46-48; Parker 2008, pp. 6-8). We appreciate the effort 
and research represented by this information. It provides an excellent 
summary of historical ornithological efforts in Arizona. In assessing 
the information provided, we must determine if it is comparable to the 
information currently available on pygmy-owl numbers and distribution 
in Arizona. Current information comes from extensive surveys focused on 
locating only pygmy-owls using tape-playback or call imitation to 
locate the owls. We can find no evidence from the information provided 
that this same effort or methodology was used to locate pygmy-owls in 
the historical record; thus comparison with current surveys is not 
appropriate.
    We do not discount the ability of early naturalists and 
ornithologists to find and identify pygmy-owls. However, finding pygmy-
owls was not the objective of the trips reported in the literature, and 
unfortunately, most of these early reports do not contain enough 
information for us to determine that the effort was adequate to find 
pygmy-owls if they were present or that the absence of documentation of 
pygmy-owls truly means that no pygmy-owls were encountered. Additional 
information received from the public points out the problems in 
interpreting these early reports, ``While certainly instructive as to 
the critical value of surface water diversions, irrigation, and 
agriculture to Cactus ferruginous pygmy owls, lack of necessary 
specific information prevents Breninger's 1898

[[Page 61863]]

account from serving as a source of support for the petitioner's claim 
that this owl was historically common across the lowlands of central 
and southern Arizona. This is because Breninger neither shows how much 
time he spent in the field nor the locations he actually visited along 
either the Salt and Gila Rivers that caused him to conclude that Cactus 
ferruginous pygmy owls were then ``of common occurrence'' ``among the 
growth of cottonwood'' that fringed both on a highly localized basis'' 
(Parker 2008, pp. 3-4).
    While early records provide information that shows the range of the 
pygmy-owl has contracted in Arizona, this conclusion relies on 
information at a large scale and is not dependent on specific 
population numbers, only presence or absence. The logical assumption 
may follow that pygmy-owl numbers are likely reduced as well. However, 
these early records do not have enough specific information for us to 
quantify historical pygmy-owl population numbers in a way that allows 
comparison to our current information. Glinski (1998, p. 3) provides a 
summary of this issue in The Raptors of Arizona, ``From the perspective 
of the variety and numbers of raptors, what did Arizona's landscape 
harbor two centuries ago? Is the answer to this question in the early 
literature? Unfortunately, no. Detailed records that accurately depict 
the status of Arizona raptors before 1970 are entirely lacking. The 
records of early explorers are full of errors, and later 
interpretations of them have added to the problem (G.P. Davis 1982).''
    We received information from various agencies and municipalities 
that contained survey results from Arizona indicating that the pygmy-
owl is likely absent from some areas in Maricopa and Pima Counties. 
Survey data submitted by the USDA Forest Service covering over 4,050 
hectares (ha) (10,000 acres (ac)) in a 6-year period on the Tonto 
National Forest in Maricopa County detected no pygmy-owls (USFS 2008, 
p. 1). Burger (2008, p.1) indicated that the Arizona Game and Fish 
Department (AGFD) had conducted 3 years of surveys in Maricopa County 
without any pygmy-owl detections. Annual pygmy-owl surveys have been 
conducted by the Air Force on the Barry M. Goldwater Range of 
southwestern Arizona from 1993 to the present with no verified pygmy-
owl detections (Uken 2008, p. 1). The Pima County Department of 
Transportation conducts pygmy-owl surveys for their capital improvement 
projects. These pygmy-owl surveys are associated with specific 
projects, and do not represent systematic surveys throughout Pima 
County. To date, they have conducted 383 surveys at 152 locations in 
Pima County with no detections (Pima County 2008, p.1). Some of the 
above surveys, and other negative surveys conducted throughout Arizona 
since 1997, occurred in areas where the pygmy-owl was historically 
located. This provides strong evidence that the current range of the 
pygmy-owl in Arizona has contracted.
    Currently in Arizona, the pygmy-owl is found only in portions of 
Pima and Pinal Counties. The Arizona Breeding Bird Atlas reports 
confirmed occurrences of the pygmy-owl in only three blocks distributed 
in Pima and Pinal Counties (Arizona Breeding Bird Atlas (ABBA) 2005, p. 
219). Twelve other blocks recorded probable (3) or possible (9) 
occurrences, but none occurred outside of Pima and Pinal Counties (ABBA 
2005, p. 219). Recent surveys indicate that probably fewer than 50 
adult pygmy-owls exist in the state, with 10 or fewer nest sites on an 
annual basis (Abbate et al. 2000, pp. 15-16, AGFD unpublished data). 
However, since the pygmy-owl was delisted in 2006 (71 FR 194521; April 
14, 2006), surveys, monitoring, and other research on pygmy-owls has 
declined. Limited survey and monitoring in Arizona from 2009 to 2011 
documented that pygmy-owls still occupy historical locations in the 
Altar Valley, Avra Valley, and Organ Pipe Cactus National Monument, all 
within Pima County (Service 2009b, p. 1; Tibbitts 2011, p. 1; Service 
2011, p. 1). Comprehensive surveys have not been conducted on the 
Tohono O'odham Nation (Nation), which is located in the central portion 
of both the historical and current distribution of pygmy-owls in 
Arizona. However, a number of surveys have been completed for various 
utility projects on the Nation, and the pygmy-owl is known to occur 
there. Distribution of the data from these surveys has been restricted 
by the Nation and is not available for analysis. There are large areas 
of suitable habitat on the Nation, but the information we have 
indicates that pygmy-owls are patchily distributed, just as in other 
areas of the State, and occur at similar densities.
    In summary, because the early records found in the literature 
provide no basis for consistent interpretation, the statements that the 
pygmy-owl was ``not uncommon,'' ``of common occurrence,'' and ``fairly 
numerous'' in lowland central and southern Arizona may be as 
appropriate as the commenter's interpretation that the pygmy-owl was 
never common in Arizona. The bottom line is that these early records 
provided no quantifiable information on which to base trends in pygmy-
owl populations. Consequently, we must base our evaluation of the 
current pygmy-owl status on the best available scientific and 
commercial data, which is the information that does, at least, provide 
some ability to quantify pygmy-owl population numbers. Regardless of 
the lack of quantified historical data, the early records found in the 
literature give us some idea of the historical distribution of the 
pygmy-owl in Arizona that, when compared to the current distribution, 
has unquestionably been reduced.
    In Texas, the pygmy-owl was formerly common in the Rio Grande 
delta. Griscom and Crosby (1926, p. 18) reported that the pygmy-owl was 
considered a ``common breeding species'' in the Brownville region of 
southern Texas. Even as late as 1950, Friedman et al. (1950, p. 145) 
considered the pygmy-owl to be ``a very common breeding bird.'' 
However, Oberholser (1974, pp. 451-452) indicates that agricultural 
expansion and subsequent loss of native woodland and thornscrub 
habitat, beginning in the 1920s, preceded the rapid demise of the 
pygmy-owl populations in the Rio Grande delta. By the 1970s, the pygmy-
owl was encountered only rarely in Texas.
    Nonetheless, Wauer et al. (1993, pp. 1074-1076) indicate that 
private ranches in Kenedy and Brooks Counties in Texas support a 
``large and apparently thriving population of ferruginous pygmy-owls.'' 
Currently, the pygmy-owl is most consistently found only in the 
southernmost counties in Texas, mainly in Starr and Kenedy Counties 
(Tewes 1992, p. 21; Oberholser 1974, p. 451). More recent work 
documents occupancy in Brooks and Kenedy Counties on the King Ranch and 
adjacent ranches in Texas (Proudfoot 1996, p. 6; Mays 1996, p. 29). 
Population estimates in Texas include estimates of greater than 100 
owls in Kleberg County (Tewes 1992, p. 24), 654 pairs in Kenedy, 
Brooks, and Willacy Counties (Wauer et al. 1993, p. 1074), and 745 to 
1,823 pygmy-owls on ranches in Kenedy and Brooks Counties (Mays 1996, 
p. 32).
    Recent concern about the populations in Texas has been raised 
because of an apparent decline in the number of pygmy-owl nestlings 
banded as part of an ongoing nest box study in Texas (Proudfoot 2010, 
p. 1). The numbers of nestlings banded at more than 200 nest boxes in 
2003 and 2004 were 84 and 96 respectively. The numbers suggest a steady 
decline from 2004 to 2010, with 25 and 24 nestlings banded in 2009 and

[[Page 61864]]

2010, respectively (Proudfoot 2010, p. 1). This represents an 
approximate 70 percent decline in the number of nestlings banded over 
an 8-year period. Proudfoot (2011b, p. 1) indicates this decline is 
likely the result of the loss of suitable habitat around nest boxes due 
to recent hurricanes and fires. Without a more comprehensive survey 
effort in southern Texas, we cannot definitively state that the overall 
population of pygmy-owls in south Texas matches the decline of 
nestlings documented during this nest box study. However, it does raise 
our level of concern for this population. More work is needed in Texas 
to determine the overall population status and the extent of habitat 
loss and fragmentation. It may simply be that the pygmy-owls in these 
areas have moved to adjacent suitable habitat as former habitat and the 
associated nest boxes have been destroyed.
    The pygmy-owl occurs in portions of eight States in Mexico. The 
pygmy-owl was thought to be uncommon throughout much of Sonora (Russell 
and Monson 1998, p. 141; Hunter 1988, pp. 1-6). However, recent surveys 
and capture efforts have shown that the pygmy-owl commonly occurs in 
both northern and southern Sonora, but is uncommon or absent in central 
Sonora (Flesch 2003, p. 39; AGFD 2008a, p.6; Service 2009a, p. 1). The 
highest densities of pygmy-owls occurred in the Sinaloan deciduous 
forest of southern Sonora (Flesch 2003, p. 42). Flesch (2003, p. 39) 
documented 438 males, 74 females, and 12 pygmy-owls of unknown sex 
along 1,113 kilometers (km) (1,780 miles (mi)) of transects in Sonora, 
and an additional 112 pygmy-owls incidentally detected.
    During capture efforts in 2008, AGFD (2008a, p. 6) documented 
multiple pygmy-owls commonly responding at capture sites in the 
thornscrub and tropical deciduous forests of southern Sonora. In areas 
of central Sonora sampled by AGFD, some sites had no pygmy-owl 
responses, but responses increased as sampling moved into northern 
Sonora. These results are similar to patterns of occupancy documented 
by Flesch (2003, p. 40). However, it is clear that the number and 
density of pygmy-owls is higher in the thornscrub and deciduous forest 
community types than in the Sonoran desert community type. This 
occurrence and distribution agrees with conclusions found in the 
literature (Hunter 1988, p. 7; Russell and Monson 1988, p. 141; 
Shaldach 1963, p. 40). A total of 119 pygmy-owls were captured by AGFD 
over 15 days of trapping in northern Sinaloa and Sonora (AGFD 2008a, p. 
6). The most recent monitoring of pygmy-owls in northern Sonora showed 
that, in 2010, sites sampled had the highest occupancy rates in the 
past 10 years at nearly 64 percent (Flesch 2011, p. 1). However, early 
results from the 2011 monitoring show occupancy of these same sites at 
around 50 percent, not far from the 10-year low of 45.7 percent (Flesch 
2011, p. 1).
    In summary, recent surveys and research in northwestern Mexico 
indicate that numbers and density of pygmy-owls are higher in 
thornscrub and tropical deciduous forest communities of southern Sonora 
and Sinaloa than in the Sonoran desertscrub and semi-desert grassland 
vegetation communities of the Sonoran Desert Ecoregion (Flesch 2003, 
pp. 39-42; AGFD 2008a, p. 6).
    The best available information we have from the literature for the 
southern portion (areas south of Sonora and northern Sinaloa) of the 
pygmy-owl range indicates that pygmy-owls are one of the most common 
birds collected in these areas (Cartron et al. 2000, p. 5; Enriquez-
Rocha et al. 1993, p. 154; Binford 1989, p. 132; Hunter 1988, p. 7; 
Johnsgard 1988, p. 161; Oberholser 1974, p. 451; Schaldach 1963, p. 
40). It is important to note, however, that most of these references 
apply to the ferruginous pygmy-owl as a species and not to the cactorum 
subspecies specifically. However, the more recent survey, monitoring, 
and capture work discussed above all occurred within the range of the 
cactorum subspecies.
    Tewes (1993, pp. 15-16) provides the most current information on 
pygmy-owls in northeastern Mexico. During surveys in 1991, he estimated 
96 pygmy-owls in association with 142 plots at 12 locations (Tewes 
1993, pp. 15-16). He concludes that no published empirical evidence 
suggests any change in the distribution of this species in Texas or 
northeastern Mexico, although the likelihood of finding pygmy-owls is 
low in some historically occupied areas (Tewes 1993, p. 22).
    In addition, pygmy-owls are not evenly distributed across their 
current range; rather they tend to be patchily distributed across the 
landscape. Pygmy-owl populations, particularly in the northern portion 
of its range, likely function as metapopulations (a group of spatially 
separated populations that act at some levels as a single large 
population). Genetic and population support for individual groups of 
pygmy-owls likely occurs as a result of dispersal. Therefore, habitat 
connectivity among these population groups is important to maintain 
genetic diversity, as well as demographic support. Interaction among 
these population groups likely varies with distance, but pygmy-owls 
have been documented to disperse up to 260 km (161 mi.) (AGFD 2008a, p. 
5). Individual pygmy-owl groups throughout the range are important to 
the survival of the subspecies as a whole in providing metapopulation 
support.
    In conclusion, pygmy-owl distribution in the United States has 
contracted, with pygmy-owls no longer found in Maricopa, Cochise, Yuma, 
and Santa Cruz Counties in Arizona, nor in the Lower Rio Grande Valley 
in Texas. Despite this range contraction in the United States, pygmy-
owls remain in Arizona and Texas. Survey results for Arizona indicate 
that approximately 50 adult pygmy-owls remain. In addition, there are a 
few large expanses of Arizona with suitable pygmy-owl habitat that have 
not been completely surveyed or for which pygmy-owl information is not 
available for evaluation. Pygmy-owl populations in Texas are estimated 
to range up to 1,800 birds, although there have been some declines in 
pygmy-owl nestlings associated with a nest box study in Texas. Pygmy-
owls are still found in Sonora and northern Sinaloa, with higher 
densities reported in thornscrub and dry tropical forested areas 
compared to the arid desert areas. Based on Tewes study (1993, entire), 
pygmy-owls still occupy suitable habitat in northeastern Mexico and the 
pygmy-owl's distribution remains unchanged in Texas and northeastern 
Mexico. In addition, it appears that pygmy-owls still occur in the same 
areas of Mexico reported in the literature, suggesting that the current 
distribution is similar to the historical distribution. The available 
information, although dated, suggests that pygmy-owls remain common in 
the southern portion of their range.
Habitat
    Pygmy-owls are found in a variety of vegetation communities, 
including Sonoran desertscrub and semidesert grasslands in Arizona and 
northern Sonora, thornscrub and dry deciduous forests in southern 
Sonora south to Michoac[aacute]n, and Tamaulipan brushland in Texas and 
northeastern Mexico. However, available information regarding specific 
pygmy-owl habitat elements within these vegetation communities is 
limited to Arizona, Texas, and northern Sonora.
    In Arizona, pygmy-owls rarely occur below 300 meters (m) (1,000 
feet (ft)) or above 1,200 m (4,000 ft) (Proudfoot and Johnson 2000, p. 
5), except perhaps during dispersal (AGFD 2008b, p. 3). Historically, 
in Arizona, the pygmy-owl

[[Page 61865]]

nested in Fremont cottonwood-mesquite forests and mesquite bosques 
(woodlands) associated with major drainages and their tributaries and 
the subspecies is considered by some to be a preferential riparian 
nesting species. The pygmy-owl in Arizona also occupies upland Sonoran 
desertscrub, often associated with xeroriparian areas. Species 
associated with these areas are Prosopis spp. (mesquite), Parkinsonia 
spp. (palo verde), Acacia spp. (acacia), Olneya tesota (ironwood), and 
Carnegiea gigantea (saguaro cactus) (Proudfoot and Johnson 2000, p. 5).
    In Texas, the pygmy-owl was historically found in Prosopis spp., 
Ebenopsis ebano (ebony), and Arundinaria gigantea (cane) along the Rio 
Grande River, and a more general distribution in riparian trees, brush, 
palm, and mesquite thickets (Oberholser 1974, p. 451). It is now found 
primarily in undisturbed live oak-mesquite forests and mesquite brush, 
ebony, and riparian areas of the historical Wild Horse Desert north of 
Brownsville, Texas (Proudfoot and Johnson 2000, p. 5).
    In Mexico, the pygmy-owl occurs from sea level to 1,200 m (4,000 
ft) (Friedmann et al. 1950, p. 145). In Sonora, it was originally 
common in the lower Sonoran and Tropical Zones, primarily in giant 
cactus associations (van Rossem 1945, p. 111). The subspecies is 
resident throughout most of the desertscrub, tropical thornscrub, and 
dry subtropical forests of Sonora, being most common in the latter 
association (Russell and Monson 1998, p. 141). The pygmy-owl is absent 
from tropical deciduous forests and higher vegetation zones in west 
Mexico, where it is replaced by the least pygmy-owl (Glaucidium 
minutissimum) and the northern pygmy-owl (G. gnoma) (Schaldach 1963, p. 
40; Buchanan 1964, pp. 104-105), as well as the Colima pygmy-owl (G. 
palmarum) (Howell and Robbins 1995, pp. 19-20). Dry, subtropical 
forests provide important pygmy-owl habitat elements, as evidenced by 
pygmy-owls being more common in this vegetation community type than in 
other community types in Mexico. The dry, subtropical forests comprise 
the majority of the pygmy-owl's southern range in Mexico. The presence 
of large trees and columnar cacti for nesting, and diversity of cover 
and prey types, contribute to the value of dry subtropical forests as 
pygmy-owl habitat.
    The pygmy-owl is a creature of edges found in semi-open areas of 
thorny scrub and woodlands in association with giant cacti, scattered 
patches of woodlands in open landscapes, mostly dry woods, and 
evergreen secondary growth (K[ouml]nig et al. 1999, p. 373). It is 
often found at the edges of riparian and xeroriparian drainages and 
even habitat edges created by villages, towns, and cities (Proudfoot 
and Johnson 2000, p. 5; Abbate et al. 1999, pp. 14-23). The pygmy-owl 
is a secondary cavity nester, and nests occur within woodpecker holes 
and natural cavities in giant cacti, but also in trees and even in a 
sand bank (Flesch 2003, pp. 130-132; Proudfoot and Johnson 2000, p. 11; 
Russell and Monson 1998, p. 141; Johnsgard 1988, p. 162). Tewes (1992, 
p. 22) contends that status and occurrence of the pygmy-owl is related 
to the availability of nest cavities.
    While native and nonnative plant species composition differs among 
the various locations within the range of the pygmy-owl, there are 
certain unifying characteristics such as the presence of vegetation in 
fairly dense thickets or woodlands; the presence of trees, saguaros, 
Stenocereus thurberi (organ pipe cactus), or other columnar cacti large 
enough to support cavities for nesting; and elevations typically below 
1,200 m (4,000 ft) (Swarth 1914, p. 31; Karalus and Eckert 1974, p. 
218; Monson and Phillips 1981, pp. 71-72; Johnsgard 1988, Enriquez-
Rocha et al. 1993, p. 158; Proudfoot 1996, p. 75; Proudfoot and Johnson 
2000, p. 5). Large trees provide canopy cover and cavities used for 
nesting, and the density of mid- and lower-story vegetation provides 
foraging habitat and protection from predators and contributes to the 
occurrence of prey items (Wilcox et al. 2000, pp. 6-9).
Life History
    Usually, pygmy-owls first nest as yearlings (Proudfoot and Johnson 
2000, p. 13; Abbate et al. 1999, pp. 17-19), and both sexes breed 
annually thereafter. Territories normally contain several potential 
nest and roost cavities from which responding females select a nest. 
Hence, cavities per unit area may be a fundamental criterion for 
habitat selection. Historically, pygmy-owls in Arizona used cavities in 
cottonwood, mesquite, and ash trees, and saguaro cacti for nest sites 
(Millsap and Johnson 1988, pp. 137-138). Recent information from 
Arizona indicates nests were located in cavities in saguaro cacti for 
all but two of the known nests documented from 1996 to 2002 (Abbate et 
al. 1996, p. 15; 1999, p. 41; 2000, p. 13; AGFD 2003, p. 1). Pygmy-owl 
nests in Texas were primarily in mesquite and live oak trees (Proudfoot 
1996, pp. 36-38), and nests in Sonora, Mexico, were nearly always in 
columnar cacti (Flesch and Steidl 2002, p. 6). Pygmy-owls will also use 
nest boxes for nesting (Proudfoot 1996, p. 67).
    Pygmy-owls begin courtship and advertisement calls early in the 
year from January into February. Nest selection then occurs, with eggs 
typically being laid from late March into June. Average clutch size as 
reported by Johnsgard (1988, p. 162) for the United States and Mexico 
was 3.3 (range 2 to 5, n = 43). In Texas, Proudfoot and Johnson (2000, 
p. 11) report an average clutch size of 4.9 (range 3 to 7, n = 58). 
First eggs hatch generally around mid-May, and fledging occurs from 
late-May through June. The first dispersal of fledglings in Arizona and 
Texas was documented as July 24th and August 14th, respectively 
(Proudfoot and Johnson 2000, p. 10). Pygmy-owl juveniles typically 
disperse at 8 weeks post-fledging. Males typically disperse shorter 
distances than females. Dispersal distance ranges from 2.5 to 20.91 km 
(1.55 to 13.00 mi) in Arizona (Abbate et al. 2000, p. 21) and 16 to 31 
km (9.6 to 18.6 mi) in Texas (Proudfoot and Johnson 2000, p. 13). One 
juvenile female pygmy-owl in Arizona recently dispersed a total of 260 
km (161 mi) between August 2003 and April 2004 (AGFD 2008a, p. 5). In 
Sonora, Mexico, Flesch and Steidl (2007, p. 37) documented dispersal 
distances ranging from 1.1 to 19.2 km (0.7 to 11.5 mi).
    Pygmy-owls are considered nonmigratory throughout their range. 
There are winter (November to January) pygmy-owl locations from 
throughout their historical range in Arizona (University of Arizona 
1995, pp. 1-2; Snyder 2005, pp. 4-5; Abbate et al. 1999, pp. 14-17; 
2000, pp. 12-13) and also in Texas (Proudfoot 1996, p. 19; Mays 1996, 
p. 14). These winter records suggest that pygmy-owls are found within 
their home ranges throughout the year and that they do not migrate 
seasonally. The pygmy-owl is primarily diurnal (active during daylight) 
with crepuscular (active at dawn and dusk) tendencies.
    The pygmy-owl is a perch-and-wait hunter. It is largely a 
generalist with regard to prey and diet. Oberholser (1974, p. 451) 
indicated that the pygmy-owl's diet included lizards, large insects, 
rodents, and birds (some as large as the owl). In Texas, insects, 
reptiles, birds, small mammals, and amphibians, to a lesser extent, are 
eaten by pygmy-owls (Proudfoot and Johnson 2000, p. 6). In Arizona, 
reptiles, birds, small mammals, and insects have all been recorded in 
the diet of the pygmy-owl (Abbate et al. 1999, pp. 35-40). Seasonal and 
annual variations in diet occur throughout its range (Proudfoot

[[Page 61866]]

and Johnson 2000, p. 6; Abbate et al. 1999, pp. 35-40).
    The pygmy-owl is commonly mobbed (harassed) by many species of 
passerines, presumably in response to being a regular predator on those 
species (Proudfoot and Johnson 2000, p. 10; Abbate et al. 1999, pp. 25-
26; Hunter 1988, p. 1). The mobbing behavior of birds can often aid in 
locating a well hidden pygmy-owl, as multiple individuals and species 
will often participate in the mobbing and identify the perch of the 
pygmy-owl. The dark eye-spots on the back of the pygmy-owl's head may 
act to fend off mobbing or increase predatory efficiency by confusing 
prey (Heinrich 1987 in Proudfoot and Johnson 2000, p. 10).
    Due to their small size and occurrence in similar habitats as many 
of their predators, pygmy-owls are preyed upon by a variety of species. 
Documented and likely predators in Texas and Arizona include raccoons 
(Procyon lotor), great horned owls (Bubo virginianus), Cooper's hawks 
(Accipiter cooperii), Harris' hawks (Parabuteo unicinctus), western 
screech owls (Megascops kennicottii), bull snakes (Pituophis 
melanoleucus), and domestic cats (Felis domesticus) (Abbate et al. 
1999, p. 27; Proudfoot and Johnson 2000, p. 10). Pygmy-owls may be 
particularly vulnerable to predation and other threats during and 
shortly after fledging (Abbate et al. 1999, p. 50). Lifespan has been 
documented to be 7 to 9 years in the wild (Proudfoot 2009b, p. 1) and 
10 years in captivity (AGFD 2009, p. 1).

Summary of Information Pertaining to the Five Factors Affecting the 
Pygmy-Owl Throughout Its Range

    Section 4 of the Act (16 U.S.C. 1533) and implementing regulations 
(50 CFR 424) set forth procedures for adding species to, removing 
species from, or reclassifying species on the Federal Lists of 
Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of 
the Act, a species may be determined to be endangered or threatened 
based on any of the following 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.
    In making our 12-month finding on the petition we considered and 
evaluated the best available scientific and commercial information.
    In considering whether the five statutory factors in section 4(a) 
might constitute threats, we must look beyond the mere exposure of the 
species to the factor and determine whether the species responds to the 
factor in a way that causes actual negative impacts to the species. If 
there is exposure to a factor, but no response, or only a positive 
response, that factor is not a threat. If there is exposure and the 
species responds negatively, the factor may be a threat and we then 
attempt to determine how significant a threat it is. If the threat is 
significant, it may drive or contribute to the risk of extinction of 
the species such that the species warrants listing as threatened or 
endangered as those terms are defined by the Act. This does not 
necessarily require empirical proof of a significant threat. The 
combination of exposure and some corroborating evidence of how the 
species is likely impacted could suffice. The mere identification of 
factors that could impact a species negatively is not sufficient to 
compel a finding that listing is appropriate; we require evidence that 
these factors are operative threats that act on the species to the 
point that the species meets the definition of threatened or endangered 
under the Act. A species may be threatened or endangered based on the 
intensity or magnitude of one operative threat alone or based on the 
synergistic effect of several operative threats acting in concert.
    Through our five-factor analysis, we identified a number of factors 
negatively impacting the pygmy-owl or its habitat. To determine whether 
these impacts individually or collectively rise to the level of threats 
such that the pygmy-owl is in danger of extinction throughout its 
range, or likely to become so in the foreseeable future, we first 
considered whether these impacts to the subspecies were causing long-
term, range-wide, population-scale declines in pygmy-owl numbers, or 
were likely to do so in the foreseeable future. Although some of these 
impacts seem significant individually, we found these impacts to be 
localized in their effects, but not placing the pygmy-owl in danger of 
extinction throughout its range now or in the foreseeable future. In 
other words, the severe impacts were restricted to an area that 
constitutes a relatively small portion of the pygmy-owl's range.
    The detailed information we have on impacts covers only about 27 
percent of the pygmy-owl's range. For this area, which includes Arizona 
and Texas in the United States, and Sonora and northern Sinaloa in 
Mexico, information describing the impacts to pygmy-owls was relatively 
complete. For the remaining 73 percent of the pygmy-owl range in 
Mexico, information regarding impacts to pygmy-owls was relatively 
sparse. The best available scientific and commercial information 
indicates that the impacts to pygmy-owls in the northern portion of 
their range are severe. However, the best available information 
indicates that pygmy-owls in the southern portion of their range remain 
common and that some of the threats that are severe in the northern 
portion of the species' range appear to be less severe or non-existent 
in the southern portion. Thus we conclude that pygmy owls are not 
threatened throughout their range, or likely to become so. The details 
supporting our conclusion are found in the following analysis.

Factor A: Present or Threatened Destruction, Modification, or 
Curtailment of Its Habitat or Range

    For this factor, we evaluate available information related to 
impacts to pygmy-owl habitat throughout its range. Our evaluation 
identified general activities affecting or potentially affecting pygmy-
owl habitat that included urbanization, nonnative species invasions, 
fire, agricultural development, wood cutting, improper grazing, border 
issues, and off-highway vehicle use. However, with the exception of the 
United States and Sonora, Mexico, detailed information related to these 
activities is limited, and we were unable to specifically evaluate the 
effects of many of these activities for much of the pygmy-owl's range 
in Mexico. The following discussion presents the best available 
information regarding these activities and their effects to pygmy-owl 
habitat.
Urbanization
    Increasing human populations result in expanding urban areas. 
Urbanization causes permanent impacts on the landscape that potentially 
result in the loss and alteration of pygmy-owl habitat. Residential, 
commercial, and infrastructure development replace and fragment areas 
of native vegetation resulting in the loss of available pygmy-owl 
habitat and habitat connectivity needed to support pygmy-owl dispersal 
and metapopulation function. Increasing human populations require 
additional water, and increasing water consumption can reduce available 
surface and ground water needed to support pygmy-owl and pygmy-owl prey 
habitats. Added human presence on the landscape can potentially lead to 
increased pygmy-owl mortality through

[[Page 61867]]

introduced predators, collisions, etc. The following discussion 
presents the available information related to pygmy-owl habitat impacts 
associated with urbanization.
    Human population growth results in the expansion of urbanization 
(Travis et al. 2005, p. 2). Arizona's population increased by 394 
percent from 1960 to 2000, and was second only to Nevada as the fastest 
growing State during this timeframe (Social Science Data Analysis 
Network (SSDAN) 2000, p. 1). Since 1990, Arizona's population has grown 
by 44 percent. From 1960 to 2000, population growth rates in Arizona 
counties where the pygmy-owl occurs, or recently occurred, have varied 
by county, but all are increasing: Maricopa (463 percent); Pima (318 
percent); Pinal (54 percent); and Santa Cruz (355 percent) (SSDAN 
2000).
    Urban expansion and human population growth trends in Arizona are 
expected to continue into the future. The Maricopa-Pima-Pinal County 
areas of Arizona are expected to grow by as much as 71 percent in the 
next 15 years, creating rural-urban edge effects across thousands of 
acres of pygmy-owl habitat (AIDTT 2000, p. 10; BLM files-Lands 
Livability Initiative). In another projection, the Arizona population 
is expected to more than double within the next 20 years, compared to 
the 2000 population estimate (U.S. Census Bureau 2005, p. 1). Many 
cities and towns within the historical distribution of the pygmy-owl in 
Arizona already experienced substantial growth during the 8-year time 
span from 2000 to 2008: Town of Carefree (30.5 percent); Casa Grande 
(56 percent); Town of Cave Creek (44.2 percent); City of Eloy (22.3 
percent); City of Florence (20.3 percent); City of Mammoth (45 
percent); Town of Marana (139.9 percent); Town of Oro Valley (32.5 
percent); and the Town of Sahuarita (507.3 percent) (U.S. Census Bureau 
2008, pp. 1-4).
    This population growth has spurred a significant increase in 
urbanization and development in these areas. Regional development is 
predicted to be high in certain areas within the distribution of the 
pygmy-owl in Arizona. In particular, a wide area from the international 
border in Nogales, through Tucson, Phoenix, and north into Yavapai 
County (called the Sun Corridor ``Megapolitan'' Area) is predicted to 
have 8 million people by 2030, an 82.5 percent increase from 2000 
(Gammage et al. 2008, pp. 15, 22-23). If build-out occurs as expected, 
it will encompass a substantial portion of the current and historical 
distribution of the pygmy-owl in Arizona.
    Development pressure across Arizona has slowed due to the recent 
economic downturn and decline in the housing market. However, 
development will likely continue in the future, although perhaps at a 
slower pace than in the earlier part of this century. We also recognize 
that economic trends are difficult to predict into the future. The most 
recent draft Pinal County Comprehensive Plan (February 2009) 
acknowledges that the county is in the middle of the Sun Corridor 
Megapolitan and proposes four shorter-term growth areas in defining 
where development will likely occur over the next decade, but does not 
discourage growth outside of these areas (Pinal County Comprehensive 
Plan 2009, p. 109). Areas within two of the four growth areas (West 
Pinal and Red Rock) support historically occupied and recently occupied 
areas.
    Because most of the pygmy-owl habitat in Texas occurs on private 
ranch lands, the impact of habitat loss and fragmentation of the 
remaining pygmy-owl habitat due to urbanization is greatly reduced. 
Some housing, ranch facilities, roadways, and utilities will 
undoubtedly be constructed with changing ranch plans, and this may 
affect individual pygmy-owl territories. However, the overall impact to 
pygmy-owl habitat from current rates of urbanization in Texas is much 
less than that in Arizona and parts of Mexico.
    In Mexico, the greatest increases in population have occurred 
mostly in coastal resort areas, State capitals, and along the United 
States-Mexico border. In the Sonoran Desert Ecoregion of Mexico (a 
relatively homogeneous ecological area defined by similarity of 
climate, landform, soil, potential natural vegetation, hydrology, or 
other ecologically relevant variables), the human population nearly 
doubled between 1970 and 1990, to a total population of 6.9 million 
(Gorenflo 2002, p. 13). The Sonoran capital, Hermosillo, grew by 116 
percent. When considering urban growth within individual biotic 
communities, the human population more than doubled in three of the 
seven major biogeographic communities of Mexico (Arizona Upland and 
Lower Colorado River Valley, Plains of Sonora, and Magdalena Plain) 
(Gorenflo 2002, p. 28), all of which provide important pygmy-owl 
habitat.
    The United States-Mexico border region has a distinct demographic 
pattern of permanent and temporary development related to warehouses, 
exports, and other border-related activities, and patterns of 
population growth in this area of northern Mexico have been accelerated 
relative to other Mexican States (Pineiro 2001, pp. 1-2). This focuses 
development, and potential barriers or impediments to pygmy-owl 
movements, in a region that is important for pygmy-owl metapopulation 
support and other movements such as dispersal. The Arizona-Sonora 
border region's population growth is expected to reach 2.1 million 
(Walker and Pavlakovich-Kochi 2003, p. 1) in an area that will affect 
cross-border movement by pygmy-owls and other important population 
linkages needed to support the pygmy-owl metapopulation structure. 
Based on 1990 human population numbers, the land cover types currently 
most valuable to the pygmy-owl--Mesquite Bosque and Palo Verde-Mixed 
Cactus--were the most heavily human-populated in the Sonoran Desert 
Ecoregion. The Mesquite Bosque type makes up 8.2 percent of the area, 
but supports 10.4 percent of the human population. Similarly, the Palo 
Verde-Mixed Cactus type covers 29 percent of the area, but supports 
49.4 percent of the population (Gorenflo 2002, p. 28).
    Human activity, most notably in the past century, has dramatically 
altered the landscape of the Arizona-Sonora border, affecting both the 
quantity and quality of its ecological resources. Urbanization not only 
reduces the amount of open space, but impacts the biological value of 
areas (Walker and Pavlakovich-Kochi 2003, p. 3). The Sonoran border 
population has been increasing faster than that State's average and 
faster than Arizona's border population; between 1990 and 2000, the 
population in the Sonoran border municipios increased by 33.4 percent, 
compared to Sonora's average (21.6 percent) and the average increase of 
Arizona's border counties (27.8 percent). Urbanization has increased 
habitat conversion and fragmentation, which, along with immigration, 
population growth, and resource consumption, were ranked as the highest 
threats to the Sonoran Desert Ecoregion (Nabhan and Holdsworth 1998, p. 
1).
    Urbanization has also affected pygmy-owl habitat in other parts of 
Mexico. Trejo and Dirzo (2000, p. 133) indicate that areas of dry 
subtropical forests, important habitat for pygmy-owls in southwestern 
Mexico, have been used by humans through time for settlement and 
various other activities. The long-term impact of this settlement has 
converted these dry subtropical forests into shrublands and savannas 
lacking large trees, columnar cacti, and cover and prey diversity that 
are important pygmy-owl habitat elements Trejo and Dirzo (2000, p. 134) 
state that in Mexico dry tropical forest is the major type of tropical 
vegetation in the country,

[[Page 61868]]

covering over 60 percent of the total area of tropical vegetation. 
According to official governmental maps, about 8 percent (approximately 
160,000 square km (61,776 square mi)) of this forest remained intact by 
the late 1970s, and an assessment made at the beginning of the present 
decade suggested that 30 percent of these tropical forests have been 
altered and converted to agricultural lands and cattle grasslands. The 
remaining forests are restricted to steep slopes where it is not likely 
that land will be cleared for additional agricultural or development 
purposes (Allnutt 2001, p.3). However, the information about the 
current actual extension and condition of dry tropical forests in 
Mexico is unclear due to confusion in their classification and 
difficulty using remote sensing to delineate intact dry forest (Allnutt 
2001, p. 3). The best available information indicates that there are 
still expanses of dry tropical forest along the Pacific coast in 
Mexico, including some areas below 1,200 m (4,000 ft) where pygmy-owls 
are found, but there has been loss of this forest type throughout 
Mexico.
    The actual effects of urbanization on biodiversity are many and 
mutually reinforcing, including the aggravation of the ``urban heat 
island effect''; the channelization or disruption of riverine 
corridors; the proliferation of exotic species; the killing of wildlife 
by automobiles, toxins, and pets; and the fragmentation of remaining 
patches of natural vegetation into smaller and smaller pieces that are 
unable to support viable populations of native plants or animals (Ewing 
and Kostyack 2005, pp. 1-2; Nabhan and Holdsworth 1998, p. 2). Human-
related mortality (e.g., shooting, collisions, and predation by pets) 
increases as urbanization increases (Banks 1979, pp. 1-2; Churcher and 
Lawton 1987, p. 439). The above statements, while general in their 
nature, point out the vulnerability of habitats that support pygmy-owls 
and the impacts that urbanization can have on the extent and quality of 
available habitat. We would expect these types of impacts in areas that 
have experienced or are experiencing urban growth in or near pygmy-owl 
habitats. Not all areas in the United States and Mexico are 
experiencing this type of growth, especially in the southern portion of 
the pygmy-owl's range.
    Development of roadways and their contribution to habitat loss and 
fragmentation is a particularly widespread impact of urbanization 
(Nickens 1991, p. 1). Data from Arizona and Mexico indicate that 
roadways and other open areas lacking cover affect pygmy-owl dispersal 
(Flesch and Steidl 2007, pp. 6-7; Abbate et al. 1999, p. 54). Nest 
success and juvenile survival were lower at pygmy-owl nest sites closer 
to large roadways, suggesting that habitat quality may be reduced in 
those areas (Flesch and Steidl 2007, pp. 6-7).
    Currently, most roadways in Sonora are relatively narrow. However, 
the Sonoran government is starting to implement plans to build new 
highways and other infrastructure improvements. Governor Bours of 
Sonora formed the Sonoran Strategic Projects Operator, in conjunction 
with other investors, to carry out the construction of highway 
improvements (Wild Sonora 2009, p. 2). Of specific concern related to 
pygmy-owl impacts is the recent improvement of the road between Saric, 
in the upper Rio Altar valley, and Sasabe, in the heart of the 
distribution of the pygmy-owl in northern Sonora. Instead of just 
paving the existing Altar/Sasabe road, a new highway was constructed 
resulting in an increase of habitat impacts and fragmentation (Wild 
Sonora 2009, p. 2). Another development project proposed for northern 
Sonora is the Quitovac toxic waste dump south of Organ Pipe Cactus 
National Monument that could accept up to 45,000 tons of toxic waste 
per year (Wild Sonora 2009, p. 7). The proposed site for this project 
is located in the vicinity of a rare spring in this very arid region 
that supports pygmy-owl habitat. There are documented pygmy-owls 
nesting at Quitovac (Flesch 2003, pp. 40-41). While this project is 
currently on hold, it represents the potential for impacts to pygmy-
owls related to development and urbanization in Sonora.
    Significant human population expansion and urbanization in the 
Sierra Madre foothill corridor may represent a long-term risk to pygmy-
owls in northeastern Mexico. In Texas, the pygmy-owl occurred in good 
numbers until approximately 90 percent of the mesquite-ebony woodlands 
of the Rio Grande delta were cleared in 1910-1950 (Oberholser 1974, p. 
452). Habitat removal in northeastern Mexico is widespread and nearly 
complete in northern Tamaulipas (Hunter 1988, p. 8). The pygmy-owl 
metapopulation structure is threatened by ongoing loss and 
fragmentation of habitat in this area. Urbanization has the potential 
to permanently alter the last major landscape linkage between the 
pygmy-owl population in Texas and those in northeastern Mexico (Tewes 
1992, pp. 28-29).
    With regard to Mexico, for those areas outside of Sonora and 
northeastern Mexico discussed above, human population growth in 
Sinaloa, Nayarit, Colima, and Jalisco are relatively slow compared to 
Sonora. The Sinaloan population grew at a rate of 0.9 percent over the 
last decade. The population in Nayarit grew at a rate of 1.8 percent 
over the last decade. The Jalisco population grew by 1.6 percent per 
year during 2000-2010. Colima, one of the smallest States in Mexico, 
has a total population of approximately 650,500 and grew annually at a 
rate of 1.9 percent over the last decade. These areas of Mexico are not 
experiencing the high growth rates of Sonora, and likely will not have 
the concurrent spread of urbanization in the foreseeable future. In 
addition, most of the growth is taking place in the large cities, and 
not the rural areas of these countries (http:www.citypopulation.de/
Mexico-Cities.html). Also, some of the large cities of the southern 
Mexican States, such as Guadalajara in Jalisco and Morelia in 
Michoac[aacute]n, are not within the range of the pygmy-owl, so their 
growth would not be affecting pygmy-owl habitat. The rural areas likely 
contain the remaining habitat for the pygmy-owl. It is reasonable to 
assume that slow or stagnant population growth will result in fewer 
developments and infrastructure projects, such as new highways, or 
destruction and fragmentation of habitat on a landscape scale. The 
impacts associated with urbanization are, therefore, much reduced and 
less severe in this portion of the pygmy-owl's range. While the 
magnitude of the impacts associated with urbanization are significant 
in Arizona and northern Mexico, we would expect these impacts to be 
much reduced in the remaining 73 percent of the pygmy-owl's range in 
Mexico and we expect these impacts to remain less significant in this 
part of its range into the foreseeable future because of the difference 
in population growth.
Nonnative Invasive Species
    The invasion of nonnative vegetation, particularly nonnative 
grasses, has altered the natural fire regime over the Sonoran portion 
of the pygmy-owl range. As a result, fire has become a significant 
threat to the native vegetation of the Sonoran Desert. Esque and 
Schwalbe (2002, pp. 180-190) discuss the effect of wildfires in the 
Arizona Upland and Lower Colorado River subdivisions of Sonoran 
desertscrub, which comprise the primary portions of the pygmy-owl's 
range within Sonoran desertscrub. The widespread invasion of nonnative 
annual grasses appears to be largely responsible for altered fire 
regimes that have been observed in these communities, which are not 
adapted to fire (Esque and Schwalbe 2002, p. 165). In areas comprised 
entirely of native

[[Page 61869]]

species, ground vegetation density is mediated by barren spaces that do 
not allow fire to carry across the landscape. However, in areas where 
nonnative species have become established, the fine fuel load is 
continuous, and fire is capable of spreading quickly and efficiently 
(Esque and Schwalbe 2002, p. 175). Nonnative annual plants prevalent 
within the Sonoran range of the pygmy-owl include Bromus rubens and B. 
tectorum (brome grasses) and Schismus spp. (Mediterranean grasses) 
(Esque and Schwalbe 2002, p. 165). Brassica tournefortii (Sahara 
mustard) is an Old World forb that can cover 100 percent of the ground 
under certain conditions (ASDM 2009, p. 1). In 2006, fires that burned 
thousands of acres of Sonoran desertscrub in southwestern Arizona had 
Sahara mustard as the primary fuel. However, the nonnative species that 
is currently the greatest threat to vegetation communities in Arizona 
and northern Sonora, Mexico is the perennial Pennisetum ciliare 
(buffelgrass), which is prevalent and increasing throughout much of the 
Sonoran range of the pygmy-owl (Burquez and Quintana 1994, p. 23; Van 
Devender and Dimmit 2006, p. 5).
    Buffelgrass is an Indo-African grass introduced to Mexico between 
1940 and 1960 (Burquez et al. 1998, p. 25). The distribution of this 
grass has been supported and promoted by governments on both sides of 
the United States-Mexico border as a resource to increase range 
productivity and forage production. Buffelgrass is first established by 
stripping away the native desertscrub and thornscrub (Franklin et al. 
2006, p. 69). Following establishment, it fuels fires that destroy 
Sonoran desertscrub, thornscrub, and, to a lesser extent, tropical 
deciduous forest; the disturbed areas are quickly converted to open 
savannas composed entirely of buffelgrass. Buffelgrass is now fully 
naturalized in most of Sonora, southern Arizona, and some areas in 
central and southern Baja California (Burquez-Montijo et al. 2002, p. 
131), and now commonly spreads without human cultivation (Arriaga et 
al. 2004, pp. 1509-1511; Perramond 2000, p. 131; Burquez et al. 1998, 
p. 26).
    However, buffelgrass is adapted to dry, arid conditions and does 
not grow in areas with high rates of precipitation or high humidity, 
above elevations of 1,265 m (4,150 ft), and in areas with freezing 
temperatures. Areas that support pygmy-owls south of Sonora and 
northern Sinaloa typically are wetter and more humid, and the best 
available information does not indicate that buffelgrass is invading 
the southern portion of the pygmy-owl's range. Buffelgrass is most 
often located on steep, rocky, south-facing slopes, with poor soil 
development (Van Devender and Dimmitt 2006, pp. 25-26). Surveys 
completed in Sonora and Sinaloa in 2006 noted buffelgrass was present 
in Sonora and northern Sinaloa, but the more southerly locations were 
noted as sparse or moderate (Van Devender and Dimmitt 2006, p. 7). This 
was in comparison to northerly sites in Sonora that were rated as dense 
with buffelgrass. As such, this nonnative species only significantly 
affects a portion of the pygmy-owl's range. The best available 
information indicates that buffelgrass is not significantly affecting 
areas in Mexico beyond Sonora, and northern Sinaloa.
    Buffelgrass is not only fire-tolerant (unlike native Sonoran Desert 
plant species), but is actually fire-promoting (Halverson and Guertin 
2003, p. 13). Invasion sets in motion a grass-fire cycle where 
nonnative grass provides the fuel necessary to initiate and promote 
fire. Nonnative grasses recover more quickly than native grass, tree, 
and cacti species and cause a further susceptibility to fire (D'Antonio 
and Vitousek 1992, p. 73; Schmid and Rogers 1988, p. 442). While a 
single fire in an area may or may not produce long-term reductions in 
plant cover or biomass, repeated wildfires in a given area, due to the 
establishment of nonnative grasses, are capable of ecosystem type-
conversion from native desertscrub to nonnative annual grassland, and 
render the area unsuitable for pygmy-owls and other native wildlife due 
to the loss of trees and columnar cacti and reduced diversity of cover 
and prey species (Brooks and Esque 2002, p. 336). Buffelgrass competes 
with neighboring native species for space, water, and nutrients 
(Halverson and Guertin 2003, p. 13; Williams and Baruch 2000, pp. 128-
135; D'Antonio and Vitousek 1992, pp. 68-72). Buffelgrass conversion is 
associated with increased soil erosion and changes in nutrient dynamics 
and primary productivity (Abbot and McPherson 1999, p. 3). These 
changes make it more difficult for native vegetation to reestablish, 
even if the conversion process or fires are discontinued (Franklin et 
al. 2006, p. 69; Rogers and Steele 1980, pp. 17-18).
    Within the past 15 years, the establishment of nonnative grasslands 
has been identified as the most serious threat to the biological 
diversity of the Sonoran Desert (Burquez and Quintana 1994, p. 23). 
Economic subsidies from the State of Sonora and low-interest loans from 
banks made funds available for more widespread plantings of buffelgrass 
in the 1980s (Camou-Healy 1994). By 1997, more than 1 million ha (2.5 
million ac) of desertscrub and thornscrub (both communities occupied by 
the pygmy-owl) had been cleared in central Sonora to plant buffelgrass, 
and more than 2 million ha (5 million ac) were scheduled for future 
vegetation conversion (Burquez and Quintana 1994, p. 23; Johnson and 
Navarro 1992, p. 118), often as part of government programs to support 
the ranching industry (Van Devender et al. 1997, p. 3). Researchers 
during this time period predicted that, if not halted, this practice of 
buffelgrass planting will permanently change the landscape of the 
Sonoran desert and deplete its associated biological diversity (Burquez 
and Quintana 1994, p. 23). Also, given the government subsidies to 
establish exotic grasslands in order to maintain large cattle herds, 
and to support marginal cattle ranching, it is less likely that control 
measures will be implemented, and the desertscrub and thornscrub in 
Sonora will probably be replaced in the near term by ecosystems with 
significantly lower species diversity and reduced structural complexity 
(Burquez and Martinez-Yrizar 1997, p. 387).
    More recent figures indicate that this is indeed occurring, with 
buffelgrass present in more than two-thirds of Sonora, and 1.6 million 
ha (4 million ac) having been deliberately cleared and seeded with the 
species (Burquez-Montijo et al. 2002, p. 132). A 2006 publication 
estimates that 1.8 million ha (4.5 million ac) have been converted to 
buffelgrass in Sonora, and that between 1990 and 2000, there was an 82 
percent increase in buffelgrass coverage (Franklin et al. 2006, pp. 62, 
66). Buffelgrass pastures have doubled in area in Sonora approximately 
every 10 years since 1973 (Franklin et al. 2006, p. 67) and the 
conversion to buffelgrass is expected to continue into the foreseeable 
future.
    It is not only Sonoran desertscrub communities in Sonora and 
northern Sinaloa that are impacted by the spread of buffelgrass. 
Another unique vegetation community in this region, dry subtropical 
forests, are being lost and fragmented due to the planting of 
buffelgrass in association with cattle ranching, which results in vast 
tracts of forest being removed and replaced by buffelgrass (Allnut et 
al. 2001, pp. 3-4).
    Buffelgrass invasion in the United States is such an urgent and 
significant issue that the Governor of Arizona, and nearly all southern 
Arizona municipalities and agencies have joined together to address the 
issue. The Governor formed the Arizona Invasive Species Advisory 
Council in 2005, and

[[Page 61870]]

the Southern Arizona Buffelgrass Working Group developed the Southern 
Arizona Buffelgrass Strategic Plan in 2008 (Buffelgrass Working Group 
2008) in order to coordinate the control of buffelgrass. Because of its 
negative impacts to native ecosystems, buffelgrass was declared a 
noxious weed by the State of Arizona in March 2005. It is not currently 
known whether these programs will be successful in controlling 
buffelgrass invasion.
    The impacts of buffelgrass establishment and invasion are 
substantial for the pygmy-owl in the United States and Sonora because 
conversion results in the loss of all important habitat elements, 
particularly columnar cacti and trees that provide nest sites. 
Buffelgrass invasion and the subsequent fires eliminate most columnar 
cacti, trees, and shrubs of the desert (Burquez-Montijo et al. 2002, p. 
138). This elimination of trees, shrubs, and columnar cacti from these 
areas is a significant negative impact and potentially a threat to the 
survival of the pygmy-owl in the northern portion of its range, as 
these vegetation components are necessary for roosting, nesting, 
protection from predators, and thermal regulation. Because tree canopy 
cover is an important pygmy-owl habitat feature, the fact that 
buffelgrass fires reduce the number of tree-dominated patches and the 
recruitment opportunities for those native species dependent on them 
[such as saguaros] (Burquez and Quintana 1994, p. 11), is significant. 
Franklin et al. (2010, p. 7) report significant changes in vegetation 
structure as a result of creating buffelgrass pastures for grazing. 
There were 90 percent fewer trees and shrubs of the size used by pygmy-
owls (2 to 5 m (6 to 15 ft) tall) in buffelgrass pastures as compared 
to native vegetation communities. Loss of diversity and availability of 
prey species due to conversion are also detrimental (Franklin et al. 
2006, p. 69; Avila Jimenez 2004, p. 18; Burquez-Montijo et al. 2002, 
pp. 130, 135).
    Some information we received from the public downplays the 
significance of the conversion of Sonoran desertscrub to buffelgrass 
savannas on pygmy-owl habitat by stating that there is no indication 
that the conversion is occurring in areas occupied by the pygmy-owl 
(Johnson and Carothers 2003, pp. 6-7). However, when compared to the 
maps of current and predicted buffelgrass invasion in Sonora found in 
Arriaga et al. (2003, Figure 1), the distribution of pygmy-owl 
locations from Flesch (2003, Figure 2), AGFD (2008a, p. 1), and 
Westland Resources (2008, Figure 4), as well as the known pygmy-owl 
locations and the documented occurrence of buffelgrass in Tucson, Avra 
Valley, Altar Valley, Organ Pipe Cactus National Monument, Pinal 
County, the Tohono O'odham Nation, and Sonora and northern Sinaloa show 
that there is almost 100 percent overlap in the areas occupied by 
pygmy-owls and the areas under greatest threat from buffelgrass 
invasion. One of the principle reasons that nonnative plants pose such 
a significant negative impact on the pygmy-owl in its northern range, 
and the native plant communities on which they depend, is because few, 
if any, reasonable methods currently exist to control the ongoing 
invasion of these plants or to remediate areas where they are already 
established. Mechanical removal, herbicides, and fire have all been 
tested for their effectiveness in control of this nonnative grass. 
However, none have proven effective at the scale of the current 
invasion.
BILLING CODE 4310-55-P

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[GRAPHIC] [TIFF OMITTED] TP05OC11.006

BILLING CODE 4310-55-C
    In Texas and other portions of the pygmy-owl's range in the United 
States, such as semi-desert grasslands, invasive species and fire are 
not as significant in their impact because the vegetation communities 
in these areas are adapted to periodic fire. However, while fire may 
not be a primary issue, nonnative species can cause other effects to 
pygmy-owl habitat elements. For example, in Texas, studies indicate 
that the spread and prevalence of the nonnative grass, Bothriochloa 
ischaemum (King Ranch bluestem), results in this grass dominating 
native grasses, forbs, and endemic species, thus decreasing plant and 
animal species diversity and altering the vegetative structure of the 
community (Davis 2011, p. 4). It is not known if these changes in plant 
community structure affect pygmy-owls.
    The best available scientific and commercial information, as 
presented in the discussion above, leads us to conclude that conversion 
of Sonoran

[[Page 61872]]

desertscrub to nonnative plant pastures composed of buffelgrass, and 
the subsequent change in the fire regime, has resulted in the loss of 
large areas of pygmy-owl habitat in the northern range of the pygmy-
owl, is negatively impacting the remaining areas of pygmy-owl habitat 
in the Sonoran desert and tropical thornscrub/dry deciduous forest 
communities of Arizona, Sonora, and northern Sinaloa, and is expected 
to continue to do so in the foreseeable future. Other areas in Texas 
and the United States, such as semidesert grassland, are not as 
affected by buffelgrass and subsequent changes in fire behavior, but 
may be invaded by other nonnative species. However, the effect, if any, 
on pygmy-owls, has not been studied.
    In contrast to the severity of buffelgrass invasion as a 
significant negative impact to the pygmy-owl in the northern portions 
of its range, it appears to have less impact or no impact at all 
further south. The area in Mexico that is susceptible to buffelgrass 
invasion and planting represents only just over 22 percent of the 
pygmy-owl's range. The magnitude of the impact diminishes in the 
southern portion of the range where buffelgrass has not been reported 
in the dry tropical forests, which comprise the majority of pygmy-owl 
habitat in the southern portion of its range. In addition, buffelgrass 
is not likely to invade and persist in these areas in the foreseeable 
future because it is adapted to dry, arid savannahs and grasslands in 
its native Africa (Burquez et al. 1998, p. 25). The elevational 
conditions, canopy coverage, and precipitation patterns of the dry 
tropical forest communities are not as suitable for the establishment 
of buffelgrass as the arid desert and semi-desert vegetation 
communities (Arriaga et al. 2004, pp. 1508-1510.). The best available 
scientific and commercial information suggests that buffelgrass 
invasion should not be an issue in the southern portions of the pygmy-
owls range, nor should it become an issue in the future.
Agricultural Production and Wood Harvesting
    Agricultural development and wood harvesting can result in 
substantial impacts to the availability and connectivity of pygmy-owl 
habitat. Conversion of native vegetation communities to agricultural 
fields or pastures for grazing has occurred within historical pygmy-owl 
habitat in both the United States and Mexico, and not only removes 
existing pygmy-owl habitat elements, but also can affect the long-term 
ability of these areas to return to native vegetation communities once 
agricultural activities cease. Wood harvesting has a direct effect on 
the amount of available cover and nest sites for pygmy-owls and is 
often associated with agricultural development. Wood harvesting also 
occurs to supply firewood and charcoal, and to provide material for 
cultural and decorative wood carvings. While we do not have detailed 
information regarding the impacts of agricultural development and wood 
harvesting for all areas within the range of the pygmy-owl, the 
following provides a discussion of the extent of the impacts from these 
activities for areas for which we do have sufficient information.
    The extent of agricultural development and woodcutting as a current 
or ongoing impact to pygmy-owl habitat differs between the United 
States and Mexico. For example, in the United States, habitat loss and 
conversion due to agricultural development is more of a historical 
issue because less area is being used currently for agriculture, and 
wood cutting is primarily for personal, rather than commercial use. 
However, impacts to pygmy-owl habitat from historical agricultural use 
and wood harvesting are still evident. The vegetation and soils of many 
valleys in the Sonoran Desert were shaped by the periodic flooding of 
dynamic wash systems, which partially recharged a shallow, fluctuating 
groundwater table. Because of agricultural development, these valleys 
no longer experience these defining processes and there has been a 
permanent loss of meso- and xero-riparian habitat (Jackson and Comus 
1999, pp. 233, 249). These riparian habitats are important pygmy-owl 
habitat, especially within drier upland vegetation communities like 
Sonoran desertscrub and semi-desert grasslands.
    In Arizona, although new agricultural development is limited and is 
expected to remain limited in the foreseeable future, the effects to 
historical habitat are still evident. Jackson and Comus (1999, pp. 249-
250) describe the long-term effects of agricultural development on 
native vegetation communities, ``The groundwater has been mined, river 
flows have been relocated, tributaries have been channelized, and 
smaller waterways are blocked by roads or the canals of the Central 
Arizona Project. Soil-surface characteristics have been greatly altered 
by field leveling and irrigation ditches. Compounding these large-scale 
changes, soil in some areas has increased salinity, pesticide residues, 
or loss of physical structure due to repeated tillage, soil compaction, 
and irrigation.'' There have been important biological losses and 
introductions as well. Seed sources of native plants in these old 
agricultural fields are now rare. Natural regeneration of many of the 
old agricultural fields is unlikely because they are no longer near to 
a native seed source (Jackson and Comus 1999, pp. 243-247, 250).
    It is not known to what extent the loss of certain pollinators, 
predators, detritivores (organisms that obtain nutrients by consuming 
decomposing organic matter), cryptogamic crusts (soil with crusts 
formed by an association of algae, mosses, and fungi; such crusts 
stabilize desert soil, retain moisture, and protect germinating seeds), 
mycorrhizae (a fungus that grows in a symbiotic association with plant 
roots), etc., as well as the addition of exotic species, will have on 
recovery of habitat. Because of these profound changes, we believe that 
habitat recovery, either by natural succession or through various 
attempts at ecological restoration, will be very limited (Jackson and 
Comus 1999, p. 250). The significance of this lies in the fact that 
many acres of pygmy-owl habitat have been lost to agricultural 
development, especially along valley bottoms and drainages that were 
important for pygmy-owls as they supported higher quality meso- and 
xero-riparian habitats. A well-known example of this is the huge 
mesquite bosque (woodland) south of Tucson on the San Xavier District 
of the Tohono O'odham Nation that comprised old-growth mesquites 
supporting cavities for pygmy-owl nests, adequate cover, and prey 
diversity, and which was lost due to groundwater pumping and diversion 
for agriculture and urban growth (Stromberg 1993, pp. 117-119). 
Mesquite bosques provide important pygmy-owl habitat. The viability of 
these bosques is dependent upon the ability of native trees, like 
mesquite, to reach the water table with their taproots. Only then can 
they grow to sizes that provide habitat for pygmy-owls. Even when 
abandoned and left to return to their natural state, there has been 
such extensive alteration of soils, drainage patterns, and 
contamination that these impacted bosques are unlikely to ever regain 
the historical habitat values. Restoration of old agricultural areas 
often meets with either limited success or failure.
    Historically, agriculture in Sonora, Mexico, was restricted to 
small areas with shallow water tables, but it had, nonetheless, 
seriously affected riparian habitats by the end of the nineteenth 
century. Large-scale agriculture was introduced in the 1940s, with the 
construction of dams in the Rio Yaqui and Rio Mayo watersheds. By the 
late 1970s, the delta regions and alluvial

[[Page 61873]]

plains of these rivers were almost entirely converted to field crops. 
Huge expanses of natural vegetation had been cleared. The vast mesquite 
forests of the Llanos de San Juan Bautista in the plains of the Rio 
Sonora disappeared with the development of the Costa De Hermosillo 
irrigation district. In the Rio Mayo and Rio Yaqui coastal plains, 
nearly one million ha (2.5 million ac) of mesquite, cottonwood, and 
willow riparian forests and coastal thornscrub disappeared after dams 
upriver started to operate (Burquez and Martinez-Yrizar 2007, p. 543). 
In 1980, a national food system was initiated and the total area under 
cultivation in northern Mexico increased significantly (Stoleson et al. 
2005, p. 59).
    Based upon the amount of area currently in irrigated agriculture, 
Sonora, with 530,000 ha (1.3 million ac), ranks second among the States 
in Mexico to Sinaloa (747,800 ha (1.85 million ac)), a State which is 
also occupied by pygmy-owls. The area equipped for agricultural 
irrigation in Sonora is 668,900 ha (1.65 million ac), resulting in the 
potential future loss of approximately 139,000 ha (343,000 ac) of 
natural vegetation communities (AQUASTAT 2007, p. 2) if these areas are 
developed for agriculture. Other Mexican States within the range of the 
pygmy-owl show similar potential for habitat loss. For example, in 
Tamaulipas, area under irrigation increased from 174,400 to 494,472 ha 
(431,000 to 1.22 million ac) between 1998 and 2004, with an area of 
668,872 ha (1.65 million ac) equipped for irrigation. Michoac[aacute]n 
supports 24,900 ha (61,500 ac) of irrigated lands with a potential 
infrastructure for 222,800 additional ha (550,600 ac). Although the 
amount of land converted to agriculture seems to be on the increase, we 
do not know where these areas are in relation to pygmy-owl habitat. Dry 
tropical forests on steeper slopes are not likely to be used for 
agricultural production. In addition, agricultural development in the 
States of Colima, Jalisco, Nayarit, and Nuevo Leon had substantial 
decreases in the amount of irrigated lands over the same period. Colima 
dropped from 64,100 ha (158,394 ac) to 37,800 ha (93,406 ac), Jalisco 
went from 161,600 ha (399,322 ac) to 95,600 ha (236,233 ac), Nayarit 
decreased from 55,400 ha (136,896 ac) to 43,200 ha (106,749 ac), and 
Nuevo Leon dropped from 143,000 ha (353,361 ac) to 32,484 ha (80,270 
ac). These numbers indicate that continuing destruction of habitat for 
agricultural production is not occurring with the same intensity 
throughout the range of the pygmy-owl, and may be declining in large 
parts of its southern range (AQUASTAT 2007, p. 2).
    Agricultural development is declining in some parts of the pygmy-
owl's range, but seems concentrated in the northern portion of the 
range. In certain localities in northwestern Mexico, especially Sonora, 
it has remained the same and even increased over the past few decades. 
In the Sonoyta Valley of Sonora flanking Organ Pipe Cactus National 
Monument across the United States-Mexico border, cropland quadrupled in 
extent between 1977 and 1987, due in part to government-supported 
agricultural development. Proximity to U.S. fruit and vegetable 
markets, inexpensive labor, good quality water, and government agency 
interest in increased fruit and vegetable crops in the area mean that 
agricultural production and the associated descent of groundwater 
levels will likely continue in the future (Nabhan and Holdsworth 1998, 
p. 36). Some scientists surveyed noted that clearing for agriculture 
was becoming more severe in portions of the Lower Colorado River 
Valley, Central Gulf Coast, and Viscaino. Current Sonoran Desert 
cropland is most extensive in the border municipality of Mexicali and 
the extreme southern end of the Sonoran Desert where most 
municipalities have from one-quarter to three quarters of their land 
surface as cropland. The central section around Hermosillo, Sonora, is 
15 to 25 percent cropland, and the rest of the area is less than 15 
percent (Nabhan and Holdsworth 1998, p. 36). However, these figures do 
not include the millions of hectares (acres) of abandoned agricultural 
land. While not all the area converted for agriculture was or could be 
suitable pygmy-owl habitat, agricultural development has typically 
occurred along river bottoms and other drainages that support important 
riparian habitat for pygmy-owls (Flores-Villela and Fernandez 1989, p. 
2). Additionally, associated habitat fragmentation exacerbates the 
actual impacts to available pygmy-owl habitat through loss of habitat 
connectivity (Stoleson et al. 2005, p. 60; Saunders et al. 1991, pp. 
23-24).
    Prescribed burning to reduce mesquite invasion into rangelands 
represents another potential threat to pygmy-owl habitat associated 
with agriculture. In general, improved grassland health adjacent to 
pygmy-owl habitat should benefit pygmy-owls through improved hydrology 
and enhance prey habitat. However, if woodlands providing important 
pygmy-owl habitat are not protected during prescribed burns, impacts to 
pygmy-owl habitat can be significant due to the loss of nest 
structures, predator and thermal cover, and prey habitat. For example, 
in Texas, two prescribed burns over the past 3 years have consumed 
1,200 to 1,600 ha (3,000 to 4,000 ac) respectively, including areas 
that supported natural pygmy-owl nests, as well as pygmy-owl nest boxes 
(Proudfoot 2011b, p. 1). Other documented fires on the King Ranch 
consumed from several hundred up to 3,200 ha (8,000 ac) over this same 
time period (Caller 2009, NOAA 2011, Texas-Fire.com 2011, Firerescue 
2008). While the loss of woodlands to fire is often a temporary impact, 
it can take many years for trees to reach adequate size to once again 
support cavities used for nesting by pygmy-owls.
    Mesquite harvesting also has negative impacts on pygmy-owl habitat. 
Mesquite wood is a valuable commodity. Historically in Arizona, 
mesquite trees have been harvested for decades. In the late 1800s 
through the early 1900s, Arizona saw large-scale harvesting for fuel 
and for mining. Fuelwood cutting once had a major impact on the 
riparian forests, mesquite thickets, and evergreen woodlands near most 
of southeastern Arizona's major cities and mining centers (Bahre 1991, 
p. 143). This whole-scale harvest may explain the scarcity of riparian 
trees in early (1890) photographs of southern rivers such as the San 
Pedro (Stromberg 1993, p. 119). In the Sonoran Desert of Mexico, the 
mesquite tree is being harvested in order to fulfill the demand for 
mesquite charcoal, and former mesquite forests have disappeared at an 
alarming rate (Burquez and Martinez Yrizar 2007, p. 545). Ironwood 
trees are also being harvested in Mexico where the wood is cherished 
for its hardness and carving potential for native artwork by groups 
such as the Seri Indians.
    Mesquite and ironwood woodlands provide pygmy-owl habitat elements 
related to tree canopy cover and a diverse prey base. Unfortunately, 
woodcutters and charcoal makers do not use scrubby-type mesquite, but 
rather take advantage of large, mature mesquite and ironwood trees 
growing in riparian areas (Taylor 2006, p. 12), the exact tree class 
that is of most value as pygmy-owl habitat. From the time ``mesquite 
charcoal'' became popular in U.S. restaurants in the early 1980s, both 
mesquite and ironwood have been harvested from the same lands, with as 
much as 15 to 40 percent of each mesquite charcoal bag consisting of 
ironwood prior to 1991. As a result, both trees were locally 
overexploited in Sonora and Baja California Sur (Taylor 2006, p. 12).

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    Sonora supports 1,888,000 ha (4,665,000 ac), or 46 percent of total 
mesquite woodlands in Mexico; more than double that of any other State 
in Mexico. This also means that much of the mesquite harvested in 
Mexico comes from Sonora (Taylor 2006, p. 12). Current estimates 
suggest that ironwood is being rapidly depleted across an area roughly 
equivalent to twice the size of Massachusetts. In northern Mexico, over 
202,000 ha (500,000 ac) of mesquite have been cleared to meet the 
growing demand for mesquite charcoal (Haller 1994, p. 1). Haller (1994, 
p. 3) predicted that, if this trend continued, the entire ecosystem of 
the Sonoran Desert could crumble, and used the examples of the degraded 
ecosystem along the coast of Sonora near Kino Bay where most of the 
mesquite and ironwood had already been removed and virtually all plant 
and animal life has disappeared. Declining tree populations in the 
Sonoran Desert as a result of commercial uses and land conversion 
threatens other plant species, and may alter the structure and 
composition of the vertebrate and invertebrate communities as well 
(Bestelmeyer and Schooley 1999, p. 644). This has implications for 
pygmy-owl prey availability because pygmy-owls rely on a seasonal 
diversity of vertebrate and invertebrate prey species; loss of tree 
structure and diversity reduces prey diversity and availability.
    In the Sonoyta region of Sonora, an area occupied by pygmy-owls, 
more than 193,000 ha (478,000 ac) have been affected by deforestation 
related to charcoal production, brick foundries, tourist crafts, and 
pasture conversion (Nabhan and Suzan 1994, p. 64). The accelerated rate 
of legume tree (trees belonging to the family Leguminosae whose 
characteristic fruit is a seed pod, including the mesquite and 
ironwood) depletion for charcoal and carvings in the Mexican States of 
Sonora and Baja California has clearly affected the health of ironwood 
populations and associated plant communities (Suzan et al. 1997, p. 
955). This is evidenced by an increased number of damaged and dying 
trees, as well as generally small size classes for sampled areas (Suzan 
et al. 1997, pp. 950-955).
    Pressure for fuelwood and crafts materials has been so intense in 
Mexico south of Organ Pipe Cactus National Monument that wood harvest, 
especially ironwood, has been detected more than 500 m (1600 ft) into 
the Monument as supplies have been depleted south of the border (Suzan 
et al. 1999, p. 1499). The structure of both wash and upland habitats 
in the Monument have been affected by this harvest (Suzan et al. 1999, 
p. 1499). Organ Pipe Cactus National Monument is one of four areas in 
Arizona that has been consistently occupied by pygmy-owls. In the arid 
environment of the Monument, tree canopy and structure are particularly 
important pygmy-owl habitat features.
    Mesquite used as fuelwood is a thriving cross-border trade, 
although not on the same scale as charcoal. However, local impacts can 
be significant in the areas where the fuelwood is harvested. For 
example, Mexican trucks loaded with mesquite cross the border to 
Arizona at Sasabe. Interviews with these truck drivers indicated that 
most of the wood they haul comes from ejidos (communally owned lands) 
within a 20-km (12.4-mi) radius of the Town of Sasabe, an area occupied 
by nesting pygmy-owls (Taylor 2006, p. 5; Flesch 2008, p. 2).
    In 2008, during field work in Sonora to gather pygmy-owl genetic 
samples, large areas of charcoal production were observed near 
Hermosillo. Impacts to vegetation were not limited to just the removal 
of the trees, but a significant area around the production sites was 
covered with fine, black charcoal dust covering all native vegetation 
(Service 2009, p. 1). The effects of these production areas are 
verified by reports of the complete removal of a dense mesquite bosque 
to the axe and charcoal pits just east of Hermosillo (Taylor 2006, p. 
5). The immediate area around charcoal pits is often treeless. Walking 
transects away from charcoal pits revealed that all trees within a 1-km 
(0.6-mi) radius bear the scars of the chainsaw (Taylor 2006, p. 7).
    Native woodlands in Sonora are additionally threatened as ranchers 
and charcoal producers team up to first clear the land of native trees 
for planting buffelgrass, and then use the dead trees to produce 
charcoal (Taylor 2006, pp. 6-7). The end result is the incentive to 
clear more native woodlands. Professional woodcutters are only 
permitted to harvest dead wood. However, dead wood to meet export 
demands is hard to come by. A simple solution practiced by many wood 
cutters is to ring trees and let them die; then the dead wood can be 
legally harvested (Taylor 2006, p. 7).
    Impacts to pygmy-owl habitat in northwestern Mexico from these 
activities are resulting in the loss and fragmentation of habitat in 
this part of Mexico, and the inability to recover or restore habitats 
and habitat connectivity in Arizona. Impacts related to surface- and 
groundwater loss and channel diversions are long-term and are 
particularly significant as riparian habitat, both meso- and xero-
riparian, are crucial for maintaining viable pygmy-owl populations in 
the arid portions of their range in Arizona and Sonora, Mexico. Loss of 
leguminous trees results in long-term effects to the soil as they add 
organic matter, fix nitrogen, and add sulfur and soluble salts, 
affecting overall habitat quality and quantity (Rodriguez Franco and 
Aguirre 1996, p. 6-47). Ironwood and mesquite trees are important nurse 
species for saguaros, the primary nesting substrate for pygmy-owls in 
the northern portion of their range (Burquez and Quintana 1994, p. 11). 
Demand for mesquite charcoal and firewood contributes to the loss of 
extensive, mature mesquite forests in riparian areas of northern 
Mexico.
    The harvest of mature mesquites in the Sonoran Desert for charcoal 
and firewood permanently alters desert ecosystems because leguminous 
trees like mesquite and ironwoods are such important anchors for these 
systems and their associated flora and fauna (Taylor 2006, p. 8). Thus, 
ongoing wood harvesting can reduce or eliminate pygmy-owl habitat in 
the Sonoran Desert region of Arizona and Mexico by perpetuating scrubby 
trees that are unsuitable for nest substrates, supporting increased 
fire frequency associated with nonnative grass invasion, eliminating 
important nurse trees for saguaro protection, reducing tall canopy 
coverage important for pygmy-owl cover, and altering prey availability 
through the reduction of structural diversity.
    Once common in areas of the Rio Grande delta, significant habitat 
loss and fragmentation due to woodcutting have now caused the pygmy-owl 
to be a rare occurrence in this area of Texas. Oberholser (1974, p. 
452) concluded that agricultural expansion and subsequent loss of 
native woodland and thornscrub habitat, begun in the 1920's, preceded 
the rapid demise of pygmy-owl populations in the Lower Rio Grande 
Valley of southern Texas. Because much of the suitable pygmy-owl 
habitat in Texas occurs on private ranches, habitat areas are subject 
to potential impacts that are associated with ongoing ranch activities 
such as grazing, herd management, fencing, pasture improvements, 
construction of cattle pens and waters, road construction, and 
development of hunting facilities. Brush clearing, in particular, has 
been identified as a potential factor in present and future declines in 
the pygmy-owl population in Texas (Oberholser 1974, p. 452). However, 
relatively speaking, the current loss of habitat is much reduced

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in comparison to the historic loss of habitat in Texas. Conversely, 
ranch practices that enhance or increase pygmy-owl habitat to support 
ecotourism can contribute to conservation of the pygmy-owl in Texas 
(Wauer et al. 1993, p. 1076). The best available information does not 
indicate that current ranching practices are significantly affecting 
pygmy-owl habitat in Texas.
    Tamaulipan brushland is a unique ecosystem that is found only in 
the Lower Rio Grande Valley of south Texas and northeastern Mexico. 
This vegetation community has historically supported occupancy by 
pygmy-owls. Brush clearing, pesticide use, and irrigation practices 
associated with agriculture have had detrimental effects on the Lower 
Rio Grande Valley (Jahrsdoerfer and Leslie 1988, p. 1). Since the 
1920's, more than 95 percent of the original native brushland in the 
Lower Rio Grande Valley has been converted to agriculture or urban use. 
Along the Rio Grande River below Falcon Dam, 99 percent of the land has 
been cleared for agriculture and development. Cook et al. (2001, p. 3) 
indicated that both banks of the Rio Grande are now completely 
developed with homes or farms, and that the only remaining natural 
habitat areas south of the river are salt marshes and mudflats, both 
communities that are not used by pygmy-owls. A large percentage of 
similar habitat has been cleared in Mexico (Jahrsdoerfer and Leslie 
1988, p. 17). This is supported by Tewes' (1992, p. 29) conclusion that 
most of the Rio Grande delta of Texas and Mexico has been developed 
over the past 60 years. Hunter (1988, p. 8) states, ``Habitat removal 
in Mexico is widespread and nearly complete in northern Tamaulipas.''
    Habitat fragmentation in northeastern Mexico is extensive, with 
only about two percent of the ecoregion remaining intact, and no 
habitat blocks larger than 250 square km (96.5 square mi), and no 
protected areas (Cook et al. 2001, p. 4). This has the potential to 
limit pygmy-owl movements and dispersal, exacerbating the effects of 
small, isolated populations. Fire is often used to clear woodlands for 
agriculture in this area of Mexico, and many of these fires are not 
adequately controlled. There may be fire-related effects to native 
plant communities (Cook et al. 2001, p. 4); however, there is no 
available information of how much area may be affected by this 
activity.
    The best available scientific and commercial information indicates 
that historical land clearing, as a result of wood harvesting and 
agricultural development has caused the loss and alteration of a 
considerable area of pygmy-owl habitat in Arizona, Sonora, Texas, and 
northeastern Mexico. Past impacts continue to affect the extent of 
available pygmy-owl habitat in these areas, because of the extended 
time it takes for these lands to recover, even if negative actions 
cease, and impacts are expected to continue in many of these same areas 
into the foreseeable future. However, based on our review of the best 
available scientific and commercial information, we conclude that these 
impacts are limited in magnitude, because they are significant only in 
the northern portion of the range (Arizona, Texas, northwestern and 
northeastern Mexico). Moreover, the best available scientific and 
commercial data indicate that habitat loss due to woodcutting or 
agriculture is primarily historical in Texas, and these activities are 
not currently impacting habitats occupied by pygmy-owls on the private 
ranches in Texas. Further, the impacts in the southern portion of the 
range are less extensive, both because woodcutting and agricultural 
development appear to have less impact in the southern portion of the 
pygmy-owl's range, and because the pygmy-owl seems to be common 
throughout this area. Therefore, after reviewing and evaluating the 
best available scientific and commercial data, we conclude that 
woodcutting and agricultural development are not threats to the 
continued existence of the pygmy-owl rangewide, and are not likely to 
become so in the future.
Improper Livestock Grazing
    Probably no single land use has had a greater effect on the 
vegetation of southeastern Arizona or has led to more changes in the 
landscape than improper livestock grazing and range-management programs 
(Carothers 1977, p. 4). Undoubtedly, grazing since the 1870s has led to 
soil erosion, destruction of those native plants most palatable to 
livestock, changes in the regional fire ecology, the spread of both 
native and alien plants, and changes in the age structure of evergreen 
woodlands and riparian forests (Bahre 1991, p. 123). Many areas of 
pygmy-owl habitat have recovered from these historical effects of 
grazing; however, other areas are slow to recover and may never recover 
due to the arid nature of the Sonoran Desert.
    Livestock grazing in northwestern Mexico is probably the most 
widespread human use of Sonoran ecoregional landscapes. Grazing by 
cattle, goats, and other livestock has reduced vegetation cover and 
helped change grasslands to shrublands. Livestock grazing in the 
Sonoran Desert has fluctuated greatly in the last few centuries from 
being relatively confined and intensive to being extensive and 
intensive. In the 19th century, repeated Apache raids on ranchers and 
the paucity of water limited cattle production to relatively small 
areas (Bahre 1991, pp. 114-115). However, the late 19th century saw the 
largest stocking rates in history; extensive cattle production played a 
major role in the transformation of grasslands to scrublands, down-
cutting of arroyos, the spread of nonnative plants, and degradation of 
riparian areas. Stocking rates are now much lower than in the 1890s 
because regulations such as those of the Taylor Grazing Act of 1934 
helped improve rangeland quality in the United States. However, 
overstocking still continues in parts of northwestern Mexico, and 
Mexico's COTECOCA (Comisi[oacute]n T[eacute]cnico Consultiva de 
Coeficientes de Agostadero) statistics confirm that 2 to 5 times the 
recommended stocking rates occur with regularity on the Sonoran side of 
the border (Walker and Pavlakovich Kochi 2003, p. 14; Nabhan and 
Holdsworth 1998, p. 2).
    Available information on livestock grazing in Mexico that we 
evaluated was focused primarily on the border areas adjacent to the 
United States and in the arid areas of northwestern Mexico, such as 
Sonora. In Sonora, rangelands are often heavily grazed, with effects 
particularly apparent during drought (Rorabaugh 2008, p. 25). Sonora's 
higher stocking rate is likely due to its greater amounts of private 
and ejidal (communal) land, less regulation, and the greater dependence 
on ranching and farming in Mexico. Demand in North America drives the 
number of cattle in Sonora. The number of cattle in Sonora nearly 
doubled between 1950 and 1960. The Sonoran cattle population was 
1,652,771 in 1990 according to official government statistics (Hawks 
2003, p. 5). Other authors estimate the overstocking at 177 percent 
(Lopez 1992), with 60 to 400 percent overstocking in some areas 
(Burquez-Montijo et al. 2002, p. 134). Excessive grazing of vegetation 
by livestock, especially when combined with conversion of plant cover 
to exotic pasture grasses, ranked as number four on a list of threats 
to the Sonoran Desert Ecoregion (Nabhan and Holdsworth 1998, p. 1).
    One research study showed that overgrazing in Sonora leaves the 
Mexican landscape more exposed and, as a result, it dries out more 
rapidly following summer convective precipitation. After about 3 days, 
depletion of soil moisture evokes a period of higher surface and air

[[Page 61876]]

temperatures in northwestern Mexico (Bryant et al. 1990, pp. 254-258). 
These drier soils and higher temperatures can result in impacts to 
vegetation survival and persistence. Effects of poorly managed 
livestock grazing in Sonora include changes in plant species 
composition and vegetation cover and structure, soil compaction, 
erosion, altered fire regimes, and nonnative plant species 
introductions and invasions (Stoleson et al. 2005, pp. 61-62). With 
regard to pygmy-owl habitat, improper stocking rates can result in 
reduced saguaro reproduction through trampling and alteration of 
microclimates (Abouhaider 1989, pp. 40-48), reduced tree cover and 
reproduction through grazing of seedlings and seed pods, and impacts to 
prey availability from reduced vegetation structural diversity and 
species composition.
    One of the most significant adverse impacts within western riparian 
systems has been the perpetuation of improper grazing practices. Belsky 
et al. (1999, p. 419) found that grazing by livestock has damaged 80 
percent of the streams and riparian ecosystems in the arid regions of 
the western United States. The initial deterioration of western 
riparian systems began with the severe overgrazing in the late 
nineteenth century. Livestock grazing can affect four general 
components of riparian systems: (1) Streamside vegetation; (2) stream 
channel morphology; (3) shape and quality of the water column; and (4) 
structure of streambank soil. Vegetation impacts include: (1) 
Compaction of soil, which increases runoff and decreases water 
availability to plants; (2) herbage removal, which allows soil 
temperatures to rise, thereby increasing evaporation; (3) physical 
damage to vegetation by rubbing, trampling, and browsing; and (4) 
alteration of growth form of plants by removing terminal buds and 
stimulating lateral branching (Fleischner 1994, p. 635).
    In a summary of studies investigating the impacts of livestock 
grazing on riparian areas, Belsky et al. (1999, p. 425) found that none 
of the studies showed positive impacts or ecological benefits that 
could be attributed to livestock activities when grazed areas were 
compared to protected areas. It was mostly negative effects that were 
reported, and there was little debate about those effects. Most of 
these studies tended to agree that improper livestock grazing can 
damage stream and riparian ecosystems. All types of riparian habitats 
provide important pygmy-owl habitat elements due to the increased size, 
diversity, and structure associated with riparian communities and 
enhanced moisture availability. Larger trees provide substrates for 
nest cavities. Structure diversity provides important predator and 
thermoregulatory cover, as well as an increased number and diversity of 
prey species. A reduction of the extent or quality of riparian habitats 
within the range of the pygmy-owl represents direct impacts on the 
availability and quality of pygmy-owl habitat.
    Although proper management has greatly improved riparian 
communities in some areas, field data compiled in the last decade 
showed that riparian areas throughout much of the West were in the 
worst condition in history due mainly to the complications initiated by 
improper grazing techniques (Krueper 1993, p. 322). However, 
information submitted during the public comment period supports the 
idea that, in certain areas, riparian habitat has returned and, 
perhaps, even increased in certain areas in Arizona, including areas 
that are being grazed by livestock. Parker (2008, p. 13) points out 
that Webb et al. (2007, pp. 388-389, 404-408) conclude that, in the 
drainages they studied, increases in riparian vegetation from 24 
percent to 49 percent had occurred since the late 1800s and early 
1900s, and that increases in the density of riparian plants appear to 
have accelerated in the 1970s. We are encouraged by this positive 
information indicating that riparian habitats in some areas may become 
suitable for pygmy-owls in the future if grazing continues to be 
properly managed. It is not our contention that grazing per se has a 
negative effect on riparian areas, but that improper or overgrazing can 
have detrimental effects. Parker (2008, p. 14) reiterates this by 
stating, ``While there is little question that overgrazing can degrade 
riparian ecosystems, the question here is whether grazing has had long-
term negative effects on woody riparian vegetation in Arizona.'' We 
acknowledge that, with proper management, riparian areas can recover 
and provide habitat for the pygmy-owl.
    In Mexico, increasing human population numbers and the extent of 
subsistence agriculture threatens the future of Mexico's extensive 
riparian systems. Grazing impacts include contamination and an 
increasing demand for agricultural and forage production (Deloya 1985, 
pp. 9-11). Riparian destruction is evident throughout Mexico, but 
especially in areas of denser human population. Of particular relevance 
to the pygmy-owl has been the loss and destruction of virtually all of 
the dense woodlands within the Rio Grande River valley. Despite the 
evident destruction of riparian systems, little information exists on 
the problem and there is apparently no strategy at a national level to 
solve the problem. The present trends pose serious concerns for the 
future of Mexico's riparian ecosystems (Deloya 1985, pp. 11-12).
    In Texas, areas occupied by pygmy-owls are primarily on large, 
private ranches where livestock production is a primary objective. 
However, alternative sources of revenue for these ranches also include 
hunting and ecotourism. As a result, habitat management for the benefit 
of wildlife is also a high priority for these ranchers. Livestock 
management is often conducted with consideration of impacts to 
wildlife.
    Pygmy-owls are known to exist in areas that are grazed. Grazing, 
itself, does not appear to negatively affect pygmy-owls. Properly 
managed grazing can enhance certain pygmy-owl habitat elements (Loeser 
et al. 2007, p. 96; Holechek et al. 1982, p. 208). Climatic variation 
is important in determining the ecological effects of grazing practices 
in arid rangelands (Loeser et al. 2007, pp. 93-96). However, improper 
grazing at inappropriate stocking rates or during seasons or years when 
drought and other conditions reduce forage availability can affect 
pygmy-owls directly through the loss of important habitat elements 
(e.g., saguaros, tree cover, riparian vegetation, vegetation 
reproduction) and prey availability. No studies specifically related to 
the effects of livestock grazing on pygmy-owls have been conducted; 
however, impacts to pygmy-owls can be determined indirectly from 
studies on related species or issues. For example, studies in Arizona 
and Sonora show that the number of lizard species and abundance of 
lizards declined significantly in heavily grazed areas (Jones 1981, p. 
111); there is also a likely loss of lizard species in areas invaded by 
buffelgrass. Lizards are an important food resource for pygmy-owls; 
therefore, impacts to lizard abundance can affect pygmy-owls.
    An additional concern related to grazing lands is that, faced with 
rising land prices, unstable markets, and unpredictable climate, many 
ranchers in the United States are choosing or are forced to sell their 
private lands to real estate developers or subdivide it themselves. 
This results in these lands being subject to the threats described 
above related to urbanization. There was no available information to 
determine if these same pressures apply to grazing lands in Mexico.
    Improper livestock grazing has a negative impact on pygmy-owl 
habitat under some circumstances in Arizona and Sonora. While we expect 
that

[[Page 61877]]

continued implementation of improved grazing-management techniques will 
reduce grazing impacts on pygmy-owls in Arizona and Texas, we expected 
that overgrazing will continue to negatively impact pygmy-owls in 
Sonora and other parts of northern Mexico. Within the Sonoran desert, 
over grazing can result in loss of structural habitat components 
important to pygmy-owls, as well as reducing prey availability and 
diversity. Additionally, improper grazing during droughts can affect 
the long-term viability of riparian habitats, which are an important 
habitat type for pygmy-owls in Arizona and Sonora. However, there is no 
indication that livestock grazing precludes occupancy by pygmy-owls in 
any part of its range. While improper livestock grazing can have 
negative impacts to local pygmy-owl populations, we do not believe 
livestock grazing is significantly affecting pygmy-owl populations 
throughout its range. The best available scientific and commercial 
information does not appear to indicate that improper grazing is 
affecting pygmy-owl populations in Texas. We have no readily-available 
information to determine whether the effects of livestock grazing on 
pygmy-owl habitat in Mexico outside of Sonora are greater or more 
harmful than in Arizona and Sonora, but we suspect impacts are similar. 
Based on the best available scientific and commercial data, we conclude 
that improper livestock grazing is not a threat to the continued 
existence of the pygmy-owl rangewide, nor is it likely to become so.
Border Issues
    One of the most pressing issues for the Arizona-Sonora border is 
the impact of illegal human and vehicular traffic through these unique 
and environmentally sensitive areas. Many of these locations now bear 
the scars of wildcat trails, abandoned refuse, and trampled vegetation 
(Marris 2006, p. 339; Walker and Pavlakovich-Kochi 2003, p. 15). 
Monitoring activities by the U.S. National Park Service (NPS) estimate 
that, annually, 300,000 individuals illegally cross through Organ Pipe 
Cactus National Monument in southwestern Arizona. Video surveillance 
equipment erected at Coronado National Memorial, in southeastern 
Arizona, indicates traffic volumes ranging from 100 to 150 immigrants 
per night (Walker and Pavlakovich-Kochi 2003, p. 15). In the Cabeza 
Prieta National Wildlife Refuge, located in southwestern Arizona, which 
supports resident pygmy-owls, there are over 640 km (400 mi) of illegal 
roads plus another 1,280 km (800 mi) of unauthorized foot trails as a 
result of illegal border activities (Cohn 2007, p. 96). These 
activities result in direct impacts to pygmy-owl habitat.
    Additional information from the NPS indicates a significant issue 
``* * * is the increasing drug smuggling, illegal immigrants, and law 
enforcement activity which results in much greater human disturbance of 
the birds.'' Further elaboration shows that the NPS believes ``* * * 
that cactus ferruginous pygmy-owls within the Monument have been 
subject to repeated disturbance events and some habitat degraded as a 
result of long-term drought and impacts associated with illegal 
migration, drug smuggling, and law enforcement interdiction efforts'' 
(Snyder 2005, pp. 1-3). Trails and roadways remove pygmy-owl habitat 
features, noise and disturbance from people and vehicles disrupt 
important behaviors, and there is an increased risk of fire in 
important habitats resulting from cooking and warming fires, as well as 
signal fires used by cross-border immigrants and smugglers. Areas 
occupied by pygmy-owls in Organ Pipe Cactus National Monument have been 
abandoned by the owls, likely due, at least in part, to heavy illegal 
immigrant traffic and associated enforcement actions.
    There is fear that efforts to curb illegal border activities 
through the construction of infrastructure such as fences and barrier 
will fragment the Sonoran Desert ecosystem, damage the desert's plant 
and animal communities, and prevent free movement of wildlife between 
the United States and Mexico (Cohn 2007, p. 96). During the time the 
pygmy-owl was listed under the Act, we consulted on the effects of 
Federal border infrastructure projects and identified a number of 
potential impacts (Service 2003, pp. 66-85). The construction of new 
border infrastructure in the form of pedestrian fences, vehicle 
barriers, and patrol roads create impediments to pygmy-owl movement 
across the border due to pygmy-owl flight patterns and behavior (Marris 
2006, p. 239; Vacariu 2005, p. 354). The fences and vehicle barriers, 
when considered in conjunction with patrol roads, drag roads, and 
vegetation removal, result in a combination of nonvegetated area with a 
raised structure in the middle causing an impediment to pygmy-owl 
movement, particularly given their normal flight patterns, where normal 
flights are generally less than 30 m (100 ft) and typically only 1.5 to 
3.0 m (5 to 11 ft) above the ground (Flesch and Steidl 2007, p. 35; 
AGFD 2008b, p. 5). Flesch et al. (2009, pp. 7-9) show that the 
vegetation gaps, in association with the tall fences, may limit 
transboundary movements by pygmy-owls. Raptors are often attracted to 
artificial hunting perches, especially in areas that lack tall trees 
(Oles 2007, p. 1; Heintzelman 2004, p. 35; Askham 1990, p. 147). Border 
fences can provide open hunting areas and improved hunting perches for 
a variety of raptors that are potential predators of pygmy-owls. This 
combination of perches, open area, and an impediment to movement may 
result in increased predation of pygmy-owls, particularly dispersing 
juvenile pygmy-owls. Because the overall population of pygmy-owls 
likely functions as a metapopulation, the pygmy-owl depends on 
dispersal, emigration, and immigration to maintain the genetic and 
demographic fitness of regional populations. To the extent that border 
infrastructure and activities reduce or prevent such movements, and 
increase the likelihood of pygmy-owl predation, it follows that 
population-level impacts may result.
    Impacts to pygmy-owls from border infrastructure and illegal 
activities are likely limited to the immediate border areas of Arizona 
and northern Sonora. Information was not readily available so that we 
could determine the extent of these impacts in Texas and northeastern 
Mexico, although they are likely to be similar (habitat gaps, perches 
for raptors, etc.). Nevertheless, these impacts are restricted to the 
border regions of Arizona and Texas, and only affect a relatively-small 
portion of the pygmy-owl range. This localized effect reduces the 
magnitude of this impact to the overall pygmy-owl population. 
Therefore, based on the best available scientific and commercial data, 
we conclude that effects associated with border activities are not a 
threat to the continued existence of the pygmy-owl rangewide, and are 
not likely to become so in the future.
Off-Highway Vehicle (OHV) Use
    The information we have on impacts to the pygmy-owl from OHV use 
relates primarily to Arizona. Information was not readily available on 
any potential OHV impacts to pygmy-owls or pygmy-owl habitat in Texas 
and Mexico.
    OHV use is widespread in Arizona and occurs on lands under a 
variety of management entities including the Forest Service, Bureau of 
Land Management, State Land Department, Tribes, and private 
individuals. The use of OHVs has grown considerably. For example, as of 
2007, 385,000 OHVs were registered in Arizona (a 350 percent increase 
since 1998) and 1.7 million people (29 percent of Arizona's population) 
engaged in off-road activity from 2005 to 2007 (Sacco 2007). Over

[[Page 61878]]

half of OHV users reported that merely driving off the paved road was 
their primary activity, versus using the OHV for the purpose of seeking 
a destination to hunt, fish, or hike (Sacco 2007). Specific impacts to 
the pygmy-owl or its habitat from OHV use when driving off road include 
disturbance from noise and human activity, vegetation damage, changes 
in plant abundance and species composition, reduced habitat 
connectivity, soil compaction, soil erosion, reduced water 
infiltration, higher soil temperatures, destruction of cryptogamic 
soils (soil with crusts formed by an association of algae, mosses, and 
fungi; such crusts stabilize desert soil, retain moisture, and protect 
germinating seeds), and increased fire-starts (Boarman 2002, pp. 46-47; 
Ouren et al. 2007, pp. 6-7, 11, 16).
    Of specific concern is the regular use by OHV operators to utilize 
xero-riparian washes as travel ways. These washes provide important 
habitat elements for pygmy-owls due to the increased structure and 
productivity of vegetation resulting from the presence of increased 
moisture. Pygmy-owls use these wash areas for foraging, dispersal, 
thermal and predator cover, and for movements within their home range. 
Wash areas are often narrow and constrained, resulting in OHV impacts 
to vegetation and concentrated noise and disturbance, affecting the use 
and suitability of these areas as pygmy-owl habitat.
    Pygmy-owls may be affected by OHV use in riparian areas. However, 
this effect is temporary and not continuous. Pygmy-owls may leave the 
area if disturbed by noise and return once the activity has ceased. 
Pygmy-owl habitat destruction in Arizona may result from OHV activity, 
but the magnitude and severity of this impact is relatively minor. 
Based on our evaluation of the best available scientific and commercial 
data, we conclude that OHV use does not threaten the continued 
existence of pygmy-owl, and is not likely to do so in the future.
Summary of Factor A
    In summary, pygmy-owls require habitat elements such as mature 
woodlands that include appropriate cavities for nest sites, adequate 
structural diversity and cover, and a diverse prey base. A number of 
negative impacts described in Factor A are affecting pygmy-owl habitat 
within portions of its range. However, the best available scientific 
and commercial information indicates that most of these impacts are 
either restricted to or are greater in a smaller subset of the pygmy-
owl's range (approximately 27 percent). For instance, we have detailed 
information that in the Arizona and Sonoran Desert Ecoregion, pygmy-owl 
habitat loss and fragmentation resulting from urbanization, changing 
fire regimes due to the invasion of buffelgrass, agricultural 
development and woodcutting, overgrazing, and border issues have had 
significant negative impacts on pygmy-owl habitat in these areas and 
will likely continue to do so to varying degrees in the foreseeable 
future. In Texas, which comprises approximately five percent of the 
pygmy-owl's range, historical loss of habitat has reduced the pygmy-owl 
range, but current impacts, such as livestock grazing and the invasion 
of nonnative plants, are reduced in their magnitude and severity.
    For the larger part of the pygmy-owl's ranger in Mexico (the 
remaining 73 percent south of Sonora), the best available data 
indicates that many impacts to pygmy-owl habitat are reduced in their 
magnitude and severity or absent altogether. The rate of growth in 
these southern Mexican States is relatively slow compared with growth 
in Sonora and the Arizona border region and is expected to remain that 
way. Agricultural development has decreased in these areas, and 
buffelgrass is not a known threat to pygmy-owl habitat in this area and 
is not expected to become a threat in the future because of unfavorable 
growth conditions for buffelgrass. Historical loss of pygmy-owl habitat 
in northeastern Mexico has occurred, but there is no available evidence 
that significant habitat destruction is currently taking place. In 
addition, pygmy-owls are still considered common in the southern 
portion of their range. This information indicates that the negative 
impacts to pygmy-owl habitat discussed herein have different levels of 
effects on the populations of pygmy-owls throughout their range, and 
are much reduced or absent in the southern portion of the pygmy-owl's 
range. Based on the best available scientific and commercial 
information, we conclude that the present or threatened destruction, 
modification, or curtailment of its habitat or range is not a threat to 
the pygmy-owl rangewide now or in the foreseeable future.

Factor B: Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    We are unaware of any overutilization of pygmy-owls for commercial, 
scientific, or educational purposes. However, the pygmy-owl is highly 
sought after by birders, who concentrate at several of the remaining 
known locations of pygmy-owls in the United States. For example, in 
1996, a resident in Tucson reported a pygmy-owl sighting (documented 
pair) that subsequently was added to a local birding hotline, and the 
location was added to their website on the internet. Several carloads 
of birders were later observed in the area of the reported location 
(AGFD 1999, p. 12). As recently as 2003, property owners in Tucson have 
expressed concerns that birders and others have been documented trying 
to get photos or see pygmy-owls at occupied sites (AGFD 2003, p. 1).
    In Texas, Tewes (1992, p. 28) states, ``Frequent disruption by 
well-intentioned bird enthusiasts with call imitations may produce a 
local risk to the pygmy-owls, especially during breeding season.'' We 
believe this disturbance problem is most significant in southern Texas. 
Oberholser (1974, p. 452) made a similar observation: ``They [pygmy-
owls] are considerably disturbed by hordes of bird watchers, some of 
whom keep their portable tape recorders hot for hours at a time in 
hopes that one of these rare birds will answer.'' Recreational 
disturbance of pygmy-owls in Texas is particularly an issue in the side 
patches of mesquite, ebony, and cane in Starr and Hidalgo Counties 
(Oberholser 1974, p. 452). Oberholser (1974, p. 452) and Hunter (1988, 
p. 6) suggest that recreational birding may disturb pygmy-owls in 
highly visited areas, affecting their occurrence, behavior, and 
reproduction. Tewes (1992, p. 12) indicates that many amateur and 
professional ornithologists have strictly controlled or eliminated 
their use of taped calls to locate pygmy-owls because of the potential 
to affect the pygmy-owl's behavior.
    Currently, a number of ranches in Texas offer the opportunity to 
view and photograph pygmy-owls. An internet search revealed invitations 
to birders to view pygmy-owls on the Canelo, King, and San Miguelito 
ranches. Additionally, both the AGFD and the Service continue to get 
requests to view and photograph pygmy-owls in Arizona.
Summary of Factor B
    In summary, impacts to pygmy-owls from over-zealous birdwatchers 
have been documented in some areas within the range of the pygmy-owl. 
While pygmy-owls continue to be a highly sought after species by 
birders, there is some indication that compliance with etiquette 
related to use of tape-playback or call imitation has improved. We were 
unable to find any information on the effects of birding on pygmy-owls 
in Mexico, but we do not believe that it is a significant issue in 
Mexico, except

[[Page 61879]]

perhaps on local ranches or ejidos where ecotourism and bird watching 
are promoted. While the above impacts may negatively affect individual 
pygmy-owls on a local basis, landowners in areas that promote 
ecotourism are also likely to implement actions that have positive 
effects for the pygmy-owl. We conclude, based upon our review of the 
best commercial and scientific data available, that overutilization for 
commercial, recreational, scientific, or educational purposes is not a 
threat to the pygmy-owl now or likely to become so.

Factor C: Disease or Predation

    Documentation of disease or predation as a significant mortality 
factor within a wildlife population requires extensive monitoring and 
the ability to observe individuals in hand. With regard to pygmy-owls, 
monitoring and capture has only occurred with any regularity in Arizona 
and Texas within the United States. This has included the capture of 
hundreds of individual pygmy-owls and subsequent monitoring using radio 
telemetry. Consequently, all of the available information on disease 
and predation is from Arizona and Texas. We are aware of only limited, 
anecdotal information related to predation for northwestern Mexico 
(Flesch 2010, pers. comm.). The following discussion outlines our 
evaluation of the information related to disease and predation that we 
have available from Arizona and Texas.
    Little is known about the rate or causes of mortality in pygmy-
owls; however, they are susceptible to predation from a wide variety of 
species. Recent research indicates that natural predation likely plays 
a key role in pygmy-owl population dynamics, particularly after 
fledging and during the postbreeding season (AGFD 2003, p. 2). AGFD 
telemetry monitoring in 2002 indicated at least three of the nine young 
produced that year were killed by predators prior to dispersal during a 
year when tree species failed to leaf out due to drought conditions 
(AGFD 2003, p. 2). Increased predation during a particularly harsh 
drought year (2004) in Arizona prompted a rescue effort by the AGFD and 
the Service during which two hatch-year pygmy-owls were temporarily 
brought into captivity to increase their chances of survival. They were 
subsequently released when habitat conditions improved (Service 2004, 
p. 1). Pygmy-owl predation by screech owls has been identified as a 
potential factor contributing to the decline of regional pygmy-owl 
population groups (AGFD 2008b, p. 9). However, there is not enough 
information to conclusively support this hypothesis. Predation is a 
significant pygmy-owl nest mortality factor associated with nest boxes 
and tree cavities in Texas. Proudfoot (2011a, p. 1) indicates that 
predation rates on natural cavities and unprotected nest boxes have 
been as high as 40 to 60 percent, with an average of 25 to 30 percent.
    Domestic cat predation of pygmy-owls has been documented in both 
Texas and Arizona (AGFD 2003, p. 1; Proudfoot 1996, p. 79). Human 
population growth can increase the numbers of subsidized predators, 
such as household cats, that can affect pygmy-owl populations. As the 
number of potential predators increases, the chance of predation on 
pygmy-owls increases. In addition, domestic house cats consume 
considerable quantities of birds, reptiles, insects, and small mammals, 
reducing available pygmy-owl prey availability (Barratt 1995, p. 185; 
Coleman et al. 1997, p. 2; Evans 1995, p. 4). This introduction of 
additional potential predators and a reduction in prey availability 
negatively affects pygmy-owls.
    Ectoparasites have recently been identified as a potential threat 
to pygmy-owl populations (Proudfoot et al. 2005, pp. 186-187; Proudfoot 
et al. 2006c, pp. 874-875). These recent investigations in Texas and 
Arizona have indicated the regular occurrence of avian parasites in the 
materials inside of pygmy-owl nest cavities. The numbers of parasites 
may be high enough to affect nestling pygmy-owl health and survival. 
Blood parasites have been implicated in reduced body condition and 
impacts to survival and dispersal in small raptors (Dawson and 
Bortolotti 2000, pp. 3-5). Proudfoot et al. (2005, pp. 186-187) could 
not rule out that blood loss from external parasites, in combination 
with other factors, may have contributed to the loss of an entire 
clutch of pygmy-owls in Arizona.
    The West Nile virus has been identified as the cause of a number of 
raptor mortalities throughout the United States, including Arizona. A 
number of North American owl species have documented mortality from 
West Nile virus, including the northern pygmy-owl (Gancz et al. 2004, 
p. 2139). However, the West Nile virus has not been documented in 
cactus ferruginous pygmy-owls in either the United States or Mexico, 
and no pygmy-owl mortalities have been suspected to be the result of an 
infection with the West Nile virus.
Summary of Factor C
    In summary, our review of the best available information suggests 
that disease and predation clearly have the potential to affect pygmy-
owl individuals and populations, and have done so in local populations. 
However, information related to these factors is limited to pygmy-owl 
populations in the United States. We have only limited, anecdotal 
information related to predation on pygmy-owls in Mexico. Even in the 
United States, where predation has been documented, we conclude that it 
is not resulting in significant effects to the status of the pygmy-owl, 
because no disease or predation effects have been identified as having 
population-level effects on pygmy-owls. Based upon our review of the 
best commercial and scientific data available, we conclude that disease 
and predation are not threats to the pygmy-owl now or in the future.

Factor D: Inadequacy of Existing Regulatory Mechanisms

    Regulations that could potentially address conservation of the 
pygmy-owl or pygmy-owl habitat in both the United States and Mexico may 
occur at a number of different levels of government, from Federal to 
local. The following discussion addresses the existing regulatory 
mechanisms related to the conservation of pygmy-owls and pygmy-owl 
habitat based on the best available information.
    Although the pygmy-owl in Arizona is considered nonmigratory, it is 
protected under the Migratory Bird Treaty Act (MBTA) (16 U.S.C. 703-
712). The MBTA prohibits ``take'' of any migratory bird; however, 
unlike take under the Endangered Species Act, some Federal courts have 
concluded that the MBTA does not apply to indirect forms of take such 
as habitat destruction, unless direct mortality or destruction of an 
active nest occurs during the activity that causes the habitat 
destruction. Other Federal and State regulations and policies, such as 
the Clean Water Act, the Department of Defense's Integrated Natural 
Resources Management Plans (Barry M. Goldwater Range) (Uken 2008, p.1), 
National Park Service policy, the inclusion of the pygmy-owl on the 
State of Arizona's list of Species of Special Concern (AGFD 1996, p. 
15), and various municipal planning documents (Oro Valley 2008, p. 1) 
provide varying levels of protection, but have not been effective in 
protecting the pygmy-owl in Arizona from further decline. As a result 
of the implementation of the 2005 Real ID Act, the U.S. Department of 
Homeland

[[Page 61880]]

Security has waived application of the Endangered Species Act and other 
environmental laws in the construction of border infrastructure, 
including areas occupied by the pygmy-owl (73 FR 5271). Some local 
conservation mechanisms, such as habitat conservation plans, are in 
development in southern Arizona. These plans include conservation 
measures for pygmy-owls, but are at least a year from completion, and 
as drafts, do not afford the pygmy-owl any level of protection or 
conservation (although some pygmy-owl habitat has been conserved 
through acquisitions related to these plans). There are currently no 
statutory or regulatory provisions under Arizona law addressing the 
destruction or alteration of pygmy-owl habitat.
    One member of the public provided information indicating that, 
because the current distribution of pygmy-owls occurs primarily on 
lands under Federal, State, or Tribal control, these lands are not at 
risk for the primary threats that have been identified (James 2008, p. 
8). However, activities occur on all these lands that can result in all 
of the negative impacts to pygmy-owls identified in our 90-day finding 
and this document. None of these types of lands are immune to or 
restricted from impacts of facilities development, nonnative invasive 
species, changing fire regimes, drought, climate change, wood 
harvesting, bird watching, avian disease and predation, border issues, 
or any of the other impacts discussed above. In fact, it is on these 
very lands that many of these impacts, such as border issues, nonnative 
species invasions, fire, and recreation are concentrated. As discussed 
above, existing regulations governing these lands do not specifically 
protect pygmy-owls or their habitats, particularly absent protection 
under the Act.
    A potential regulatory effect not specifically related to 
protection of the pygmy-owl, but which will affect our ability to 
conserve the pygmy-owl, has recently come to light with regard to 
Arizona State Trust lands. The Arizona State Land Department is 
considering restricting access to State Trust Lands for the purposes of 
conducting wildlife studies. Such access restrictions might prohibit 
further surveys, research, and monitoring of pygmy-owls on State Trust 
lands, due to new permit requirements and substantial cost. This has 
not been formally adopted and may be changed prior to finalization 
(Latimer 2010, p. 1). However, if implemented as described by Latimer 
(2010, p. 1), these proposed procedures and fees would likely limit 
pygmy-owl research on State Trust lands because of our and other 
biologists' inability to meet the requirements or pay the fees. This 
would have a substantial negative effect on our ability to conserve 
pygmy-owls within Arizona.
    The State of Texas lists the pygmy-owl as threatened (TPWD 2009, p. 
1). This designation requires permits for take of individuals for 
propagation, zoological gardens, aquariums, rehabilitation purposes, 
and scientific purposes (Texas Parks and Wildlife Code Chapters 67 and 
68; Texas Administrative Code Sections 65.171-65.176, Title 31). There 
are no provisions for habitat protection. The pygmy-owl is also on the 
Texas Organization for Endangered Species (TOES) ``watch list,'' but 
this list provides no regulatory protection for the species or its 
habitat (TOES 1995, p. 1).
    The establishment of protected areas of habitat and management to 
enhance or restore habitat are important to the conservation of pygmy-
owl populations in both the United States and Mexico. In the United 
States, this could potentially be accomplished on lands managed by 
Federal agencies such as the Park Service, Bureau of Land Management, 
Department of Defense, and the Service. However, many of these lands 
have a multiple-use mandate and do not focus solely on pygmy-owl 
conservation, or even wildlife conservation in general. Similar issues 
exist in Mexico as well. Goals and objectives of wildlife management in 
Mexico have primarily focused on huntable or harvestable species.
    A Mexican program to protect sensitive habitats and species is the 
National Natural Protected Areas (NPAs) system. 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 were 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 precarious, 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 taken its toll on Sonora's natural reserves. Three of 
the reserves have already disappeared, which reflects the tenuous state 
of many nature reserves in Mexico during the 1990s (Burquez and 
Martinez-Yrizar 2007, p. 546).
    Another program set up to promote wildlife management on private 
property in Mexico is the development of wildlife management units, or 
UMAs. The UMA program in Mexico 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). Riparian management in particular seems 
to lack sufficient efforts (Kusler 1985, p. 6).
Summary of Factor D
    In summary, Federal laws such as the Migratory Bird Treaty Act and 
Arizona and Texas State laws do address direct take of pygmy-owls 
within the United States. Existing regulations in Mexico do not protect 
or conserve pygmy-owls. Laws and regulations within the range of the 
pygmy-owl in both the United States and Mexico do not address the loss 
of or impacts to pygmy-owl habitat. However, within the majority of the 
range of the pygmy-owl, the inadequacy of existing regulations does not 
appear to affect the frequency or magnitude of impacts to pygmy-owls 
and their habitat. Therefore, based on the best scientific and 
commercial information available, we find that, despite the lack of 
specific laws or regulations addressing impacts to and conservation and 
protection of pygmy-owls and their habitat, the inadequacy of 
regulatory mechanisms does not threaten the pygmy-owl rangewide, and is 
not likely to do so in the future.

Factor E: Other Natural or Man-Made Factors Affecting Its Continued 
Existence

    We briefly discussed the effects of introduced predation on pygmy-
owls by domestic house cats in our Factor C analysis above. While this 
is a manmade factor affecting pygmy-owls, for Factor E we will discuss 
human-caused mortality that is not associated with any of the other 
factors, for example, collisions with fences, cars, and windows, and 
shooting. Natural factors affecting pygmy-owl habitat availability and 
suitability not related to Factor A will

[[Page 61881]]

also be discussed under Factor E. These include drought, climate 
change, hurricanes, and the effects of small populations.
Human-Caused Mortality
    Direct and indirect human-caused mortalities (e.g., collisions with 
cars, glass windows, fences, power lines, introduced competitors and 
predators, etc.), while likely uncommon, are often underestimated, and 
probably increase as human interactions with pygmy-owls increase (Banks 
1979, pp. 13-14; Klem 1979, pp. 1-2; Churcher and Lawton 1987, p. 439). 
This may be particularly important in areas of the pygmy-owl's range 
where pygmy-owls are located in proximity to urban development. 
Documentation exists of pygmy-owls flying into windows and fences, 
resulting in serious injuries or death to the birds. In one incident, a 
pygmy-owl collided with a closed window of a parked vehicle; it 
eventually flew off, but had a dilated pupil in one eye, indicating 
neurological injury as a result of this encounter (Abbate et al. 1999, 
p. 58). In another incident, an adult pygmy-owl was found dead at a 
wire fence; apparently it flew into the fence and died (Abbate et al. 
2000, p. 18). AGFD also has documented an incident of individuals 
shooting BB guns at birds perched on a saguaro that contained an active 
pygmy-owl nest. The information we have related to human-caused 
mortality is limited to the United States and does not generally appear 
to be a significant effect on pygmy-owl populations. Information from 
Mexico does not indicate that these activities are affecting pygmy-owls 
in a manner different than the United States.
Drought and Climate Change
    ``Climate'' refers to an area's long-term average weather 
statistics (typically for at least 20- or 30- year periods), including 
the mean and variation of surface variables such as temperature, 
precipitation, and wind, whereas ``climate change'' refers to a change 
in the mean and/or variability of climate properties that persists for 
an extended period (typically decades or longer), whether due to 
natural processes or human activity (Intergovernmental Panel on Climate 
Change (IPCC) 2007a, p. 78). Although changes in climate occur 
continuously over geological time, changes are now occurring at an 
accelerated rate. For example, at continental, regional and ocean basin 
scales, recent observed changes in long-term trends include: a 
substantial increase in precipitation in eastern parts of North 
American and South America, northern Europe, and northern and central 
Asia, and an increase in intense tropical cyclone activity in the North 
Atlantic since about 1970 (IPCC 2007a, p. 30); and an increase in 
annual average temperature of more than 2[deg] F (1.1[deg]C) across US 
since 1960 (Global Climate Change Impacts in the United States (GCCIUS) 
2009, p. 27). Examples of observed changes in the physical environment 
include: An increase in global average sea level, and declines in 
mountain glaciers and average snow cover in both the northern and 
southern hemispheres (IPCC 2007a, p. 30); substantial and accelerating 
reductions in Arctic sea-ice (e.g., Comiso et al. 2008, p. 1), and a 
variety of changes in ecosystem processes, the distribution of species, 
and the timing of seasonal events (e.g., GCCIUS 2009, pp. 79-88).
    The IPCC used Atmosphere-Ocean General Circulation Models and 
various greenhouse gas emissions scenarios to make projections of 
climate change globally and for broad regions through the 21st century 
(Meehl et al. 2007, p. 753; Randall et al. 2007, pp. 596-599), and 
reported these projections using a framework for characterizing 
certainty (Solomon et al. 2007, pp. 22-23). Examples include: (1) It is 
virtually certain there will be warmer and more frequent hot days and 
nights over most of the earth's land areas; (2) it is very likely there 
will be increased frequency of warm spells and heat waves over most 
land areas, and the frequency of heavy precipitation events will 
increase over most areas; and (3) it is likely that increases will 
occur in the incidence of extreme high sea level (excludes tsunamis), 
intense tropical cyclone activity, and the area affected by droughts 
(IPCC 2007b, p. 8, Table SPM.2). More recent analyses using a different 
global model and comparing other emissions scenarios resulted in 
similar projections of global temperature change across the different 
approaches (Prinn et al. 2011, pp. 527, 529).
    All models (not just those involving climate change) have some 
uncertainty associated with projections due to assumptions used, data 
available, and features of the models; with regard to climate change 
this includes factors such as assumptions related to emissions 
scenarios, internal climate variability and differences among models. 
Despite this, however, under all global models and emissions scenarios, 
the overall projected trajectory of surface air temperature is one of 
increased warming compared to current conditions (Meehl et al. 2007, p. 
762; Prinn et al. 2011, p. 527). Climate models, emissions scenarios, 
and associated assumptions, data, and analytical techniques will 
continue to be refined, as will interpretations of projections, as more 
information becomes available. For instance, some changes in conditions 
are occurring more rapidly than initially projected, such as melting of 
Arctic sea ice (Comiso et al. 2008, p. 1; Polyak et al. 2010, p. 1797), 
and since 2000 the observed emissions of greenhouse gases, which are a 
key influence on climate change, have been occurring at the mid- to 
higher levels of the various emissions scenarios developed in the late 
1990's and used by the IPPC for making projections (e.g., Raupach et 
al. 2007, Figure 1, p. 10289; Manning et al. 2010, Figure 1, p. 377; 
Pielke et al. 2008, entire). Also, the best scientific and commercial 
data available indicates that average global surface air temperature is 
increasing and several climate-related changes are occurring and will 
continue for many decades even if emissions are stabilized soon (e.g., 
Meehl et al. 2007, pp. 822-829; Church et al. 2010, pp. 411-412; 
Gillett et al. 2011, entire).
    Changes in climate can have a variety of direct and indirect 
impacts on species, and can exacerbate the effects of other threats. 
Rather than assessing ``climate change'' as a single threat in and of 
itself, we examine the potential consequences to species and their 
habitats that arise from changes in environmental conditions associated 
with various aspects of climate change. For example, climate-related 
changes to habitats, predator-prey relationships, disease and disease 
vectors, or conditions that exceed the physiological tolerances of a 
species, occurring individually or in combination, may affect the 
status of a species. Vulnerability to climate change impacts is a 
function of sensitivity to those changes, exposure to those changes, 
and adaptive capacity (IPCC 2007, p. 89; Glick et al. 2011, pp. 19-22). 
As described above, in evaluating the status of a species, the Service 
uses the best scientific and commercial data available, and this 
includes consideration of direct and indirect effects of climate 
change. As is the case with all potential threats, if a species is 
currently affected or is expected to be affected by one or more 
climate-related impacts, this does not necessarily mean the species is 
a threatened or endangered species as defined under the Act. If a 
species is listed as threatened or endangered, this knowledge regarding 
its vulnerability to, and impacts from, climate-associated changes in 
environmental conditions can be used to help devise appropriate 
strategies for its recovery.
    While projections from global climate model simulations are 
informative and

[[Page 61882]]

in some cases are the only or the best scientific information 
available, various downscaling methods are being used to provide 
higher-resolution projections that are more relevant to the spatial 
scales used to assess impacts to a given species (see Glick et al, 
2011, pp. 58-61). With regard to the area of analysis for the pygmy-
owl, downscaled models predict that the Sonoran Desert Ecoregion will 
be drier through the 21st century and that the transition to a more 
arid climate is likely already under way (Seager et al. 2007, p. 1181). 
Future drought is projected to occur under warmer temperature 
conditions as climate change progresses. Seager et al. (2007, p. 1181) 
predict that the recent multiyear droughts, the Dust Bowl, and 1950s 
drought conditions will become the new climatology of the American 
Southwest with a timeframe of years to decades. Already, the current, 
multiyear drought in the western United States, including most of the 
Southwest, is the most severe drought recorded since 1900 (Overpeck and 
Udall 2010, p. 1642).
    Although specifically looking at pinyon-juniper communities, 
Breshears et al. (2005, pp. 15147-15148) showed that a particular 
concern under these drought conditions is regional-scale mortality of 
overstory trees, which rapidly alters ecosystem type, associated 
ecosystem properties, and land-surface conditions for decades. 
Woodlands providing important pygmy-owl habitat, including meso- and 
xeroriparian trees, thornscrub, and tropical deciduous forests may 
respond in a similar manner. Gitlin et al. (2006, p. 1482) documented 
increased mortality of Populus fremontii (Fremont cottonwood) (an 
important riparian tree in Sonoran Desert mesoriparian communities) 
during the recent drought.
    Northern areas of Mexico are most vulnerable to droughts and 
desertification because erosion and drought severity will increase with 
higher temperatures and rainfall variations in these arid and semi-arid 
regions (Conde and Gay 1999, p. 2). The three Mexican regions most 
vulnerable to climate change are, in order of importance, Central, 
Northern (in areas occupied by pygmy-owls), and the Tabasco Coast 
(Conde and Gay 1999, p. 2). Magana and Conde (2000, p. 183) showed the 
vulnerability of northern Mexico, specifically Sonora, to interannual 
climate variability and climate change. They found that future major 
challenges that will result from climate change are increasing demand 
for water, competition among water users, and decline in water quality, 
along with the resultant loss or reduction of riparian woodlands and 
other pygmy-owl habitat elements. Smith et al. (2000, p. 79) noted the 
following with regard to nonnative grass invasions and climate change, 
``This shift in species composition in favor of exotic annual grasses, 
driven by global [climate] change, has the potential to accelerate the 
fire cycle, reduce biodiversity, and alter ecosystem function in the 
deserts of western North America.''
    Changes in the timing of precipitation due to climate change may 
have effects related to pygmy-owl prey availability and abundance. 
Flesch (2008, p. 8) found that timing and quantity of precipitation 
affected both lizard and rodent abundance in ways that suggested 
rainfall is an important driver of population and community dynamics. 
In general, cool-season rainfall had a positive correlation with rodent 
populations and warm-season rainfall was positively correlated with 
lizard populations. Because various climate change models predict that 
climate conditions will become more variable, lizard species that are 
most affected by variations in precipitation will tend to decline in 
abundance across time. This is an important finding given that lizards 
are the primary prey item for pygmy-owls during the summer.
    The majority of the current range of the pygmy-owl occurs in 
tropical or subtropical vegetation communities that may be reduced in 
coverage if climate change results in hotter, more arid conditions. The 
Sonoran Desert Ecoregion is already characterized by hot, arid 
conditions, and pygmy-owls in this portion of the range are already 
adapted to the hotter, more arid conditions that may prevail in the 
future. This adaptation may be important to the continued existence of 
the subspecies as desertification spreads in response to climate 
change, but may be offset as some future model scenarios predict a 
reduction in columnar cacti densities, the primary pygmy-owl nesting 
substrate within the Sonoran Desert Ecoregion (Weiss and Overpeck 2005, 
p. 2074). Already studies have documented a noticeable shift north of 
bird species in association with changing climates. Christmas Bird 
Count data show a shift northward in 56 percent of the 305 most 
widespread, regularly occurring wintering bird species (NABCI 2010). 
This same report indicates that bird species that are rare or 
nonexistent in the United States at present will expand their ranges 
into our country from the south (NABCI 2009, p. 15).
    Climate change may have a negative impact on some pygmy-owl 
populations because it will exacerbate the current and ongoing effects 
discussed above. For example, drought has been documented in Arizona 
and northern Sonora to reduce juvenile pygmy-owl survival. Under the 
predicted climate change scenarios, drought will occur more frequently 
and increase in severity. The invasion of nonnative species has been 
documented in the loss of pygmy-owl habitat and native vegetation 
communities. A common prediction under climate change is for conditions 
that will favor the increased occurrence and distribution of nonnative 
species. Riparian areas, both permanent and ephemeral, support 
important pygmy-owl habitat elements such as thermal and predator 
cover, and increased prey availability. Precipitation events under most 
climate change scenarios will decrease in frequency and increase in 
severity. This may reduce available cover and prey for pygmy-owls by 
affecting riparian areas through scouring flood events and reduced 
moisture retention. However, the extent to which changing climatic 
patterns will affect the pygmy-owl is not known with certainty at this 
time.
Hurricanes
    Although not generally considered a historical impact to pygmy-owl 
habitat, the loss of habitat and nest structures as a result of 
hurricanes has recently been identified as a potential contributor to 
an apparent decline in pygmy-owl nestlings documented as part of an 
ongoing pygmy-owl nest box study in south Texas (Proudfoot 2011b, p. 1; 
Proudfoot 2010, p. 1). Hurricanes within the past five years have 
impacted thousands of acres of occupied pygmy-owl habitat by removing 
trees and reducing cover and structural diversity. Within the current 
range of the pygmy-owl, hurricanes are most likely to affect pygmy-owl 
habitat in southern Texas and northeastern Mexico, although hurricanes 
in the Pacific Ocean also have the potential to affect pygmy-owl 
habitat in western Mexico. Historically, major hurricanes have made 
landfall in southern Texas on average about once every decade. However, 
more recently, hurricanes (Erika in 2003, Dolly in 2008, and Alex in 
2010) have occurred more often than in the past, suggesting that major 
hurricanes may be occurring more frequently now. If hurricanes continue 
to occur every few years, this frequency of hurricanes resulting in 
loss of woodlands may not allow some areas of previously suitable 
pygmy-owl habitat to regenerate trees of adequate size to support the 
cavities needed for nesting by pygmy-owls. However, the effects are 
expected to be localized.

[[Page 61883]]

Scattered, Small Population Groups
    An important principle of conservation genetics is that small, 
isolated populations will experience reductions in the health of the 
population due to the expression of negative population characteristics 
as a result of inbreeding. Loss of individual adaptation can also occur 
and may adversely affect population demography and increase the risk of 
population extinction (Caughley 1994, p. 217). Inbreeding in small, 
isolated populations often occurs because of a lack of mates to choose 
from, not from preferential mating among related individuals. This can 
lead to increased chances that both parents will contribute genes 
containing harmful traits, some of which may affect important adaptive 
and physiological characteristics, such as survival, fertility, and 
physiological vigor (Soule and Mills 1998, p. 1658).
    Inbreeding has been documented within the small pygmy-owl 
population in Arizona (Abbate et al. 2000, p. 21). Lack of genetic 
diversity has also been documented during recent genetics studies 
(Proudfoot and Slack 2001, pp. 5-7). Loss of isolated population groups 
has occurred in Arizona due to lack of productivity and inadequate 
dispersal (AGFD 2008, p. 1). In 2008, a possible genetic heart 
condition was diagnosed in the mortality of three related pygmy-owls in 
the captive breeding research project, a possible expression of the 
detrimental effects of the inbreeding of pygmy-owls in Arizona (Fox 
2008, p. 1).
    In addition to genetic factors, habitat degradation or human-caused 
mortality can cause shifts in population characteristics that drive 
population decline. Genetic factors may simply hasten the extinction 
process once a population is small (Miller and Waits 2003, p. 4334). In 
the face of ongoing loss and fragmentation of habitat, the potential 
for inbreeding increases as populations or groups of pygmy-owls are 
increasingly isolated. This increases the need for management that 
maintains, restores, or substitutes for historical patterns of between-
population gene flow (Hogg et al. 2006, p. 1491). In addition to 
inbreeding, genetic drift (a change in the gene pool of a population 
that takes place strictly by chance) in small populations can depress 
population fitness and increase extinction risk (Tallmon et al. 2004, 
p. 489), as well as diminish future adaptations to a changing 
environment (Lande 1988, p. 1455). A significant loss in genetic 
variation within small populations may decrease population health or 
limit the long-term capacity of a population to respond to 
environmental challenges (Keller et al. 1994).
    Similarly, chance environmental and demographic events may pose a 
more substantial threat to small populations than to large populations 
(Westemeier et al. 1998, p. 1695). Caughley and Gunn (1996, p. 166) 
noted that small populations can become extinct entirely by chance even 
when their members are healthy and the environment favorable. 
Demographic characteristics of small populations can be significant 
contributors in determining minimum viable population sizes. Viability 
of small populations is likely dependent on both demography and 
population genetics and should not be considered independently (Keller 
et al. 2002, p. 356; Lande 1988, p. 1459). Consequently, for those 
areas of the pygmy-owl's range where local small population size is an 
issue, if the result of any of the above factors negatively affects 
pygmy-owl demography or genetics, effects, at least at the local 
population scale, may be significant.
    Genetic rescue within a metapopulation structure can occur through 
periodic immigration into small, inbred, at-risk populations and can 
alleviate inbreeding depression and boost fitness, but habitat 
connectivity and adequate dispersal opportunities must be present. 
However, immigration of genetically divergent individuals can lead to 
the opposite effect--a reduction in population fitness due to 
outbreeding depression (when crosses between individuals from different 
populations have lower fitness than progeny from crosses between 
individuals within the same population) (Tallmon et al. 2004, p. 489).
    In conclusion, small population size and inadequate dispersal, as 
well as a reduced ability to adapt due to low genetic diversity, can 
result in increased vulnerability of extinction for pygmy-owls in 
small, isolated populations. The best information we have indicates 
that small, isolated populations probably occur in Arizona, Texas, and 
northeastern Mexico. We know of no small, isolated populations in 
southern Mexico, and thus conclude that small population size is not 
likely to be a threat in that area.
Summary of Factor E
    In summary, direct, human-caused mortality of pygmy-owls can occur 
and may, locally, have some impact on isolated population segments. 
However, it is unlikely that direct human-caused mortality will have 
significant population-level impacts on the pygmy-owl throughout its 
range. Impacts to pygmy-owl populations from factors related to drought 
and small population size have been documented in portions of the 
pygmy-owl's range, specifically Arizona. All but one model evaluating 
changing climatic patterns for the southwestern United States and 
northern Mexico predict a drying trend for the region (Seager et al. 
2007, pp. 1181-1184), which will negatively affect riparian and other 
plant communities that provide habitat for pygmy-owls. The extent to 
which changing climatic patterns will affect the pygmy-owl is not known 
with certainty at this time. However, predicted impacts of climate 
change may exacerbate and intensify the effects of long-term drought 
and other negative impacts within the range of the pygmy-owl identified 
under Factor A. One concern in the northwestern portion of the species' 
range is the potential decline in large columnar cacti, an essential 
pygmy-owl habitat element that provides nest sites. However, given the 
persistence of pygmy-owl populations in the more arid areas of its 
range (northwestern Mexico and Arizona), pygmy-owls in these areas may 
provide the genetic adaptations necessary to adapt to changing 
conditions.
    Given the current pygmy-owl population status, the effects of small 
population size are likely to continue, especially in the northern 
portion of the range. Reduced population connectivity as a result of 
habitat impacts identified under Factor A will likely continue to 
increase the potential for inbreeding and the associated loss of 
genetic diversity. At least in Arizona, lack of dispersing juveniles 
and floating nonbreeding individuals in the population due to low 
numbers of breeding pygmy-owls will also affect long-term occupancy of 
breeding territories and further erode the metapopulation structure in 
Arizona and northern Sonora. However, these effects appear to be 
localized, and we do not find that impacts under Factor E are 
significantly affecting pygmy-owls rangewide. Based upon our review of 
the best commercial and scientific data available, we conclude that 
other natural and manmade factors are not immediate threats to the 
pygmy-owl rangewide, and are not likely to become so in the future.

Pygmy-Owl Finding Throughout Its Range

    As required by the Act, we conducted a review of the status of the 
species and considered the five factors from section 4(a) in assessing 
whether the pygmy-owl is threatened or endangered throughout all of its 
range. We examined the best scientific and commercial information

[[Page 61884]]

available regarding the past, present, and future threats faced by the 
species. We reviewed the petition, information available in our files, 
other available published and unpublished information, and we consulted 
with species and subject experts, including peer review, and other 
Federal, State, Tribal, and local agencies.
    In considering what factors might constitute threats, we must look 
beyond the mere exposure of the species to the factor and determine 
whether the species responds to the factor in a way that causes actual 
impacts to the species. If there is exposure to a factor, but no 
response, or only a positive response, that factor is not a threat. If 
there is exposure and the species responds negatively, the factor may 
be a threat and we then attempt to determine how significant a threat 
it is. If the threat is significant, it may drive or contribute to the 
risk of extinction of the species such that the species warrants 
listing as threatened or endangered as those terms are defined by the 
Act. This does not necessarily require empirical proof of a threat. The 
combination of exposure and some corroborating evidence of how the 
species is likely impacted could suffice. The mere identification of 
factors that could impact a species negatively is not sufficient to 
compel a finding that listing is appropriate; we require evidence that 
these factors are operative threats that act on the species to the 
point that the species meets the definition of threatened or endangered 
under the Act.
    Through our five-factor analysis, we identified a number of factors 
that are negatively affecting the pygmy-owl, including the following: 
(1) Habitat loss and fragmentation due to urbanization, improper 
grazing, nonnative-species invasions and associated changes in fire 
regimes, OHV use, agricultural development, and wood cutting; (2) 
border issues; (3) inadequate regulatory mechanisms; (4) drought and 
climate change; and (5) small size of some local populations. To 
determine whether these factors individually or collectively rise to a 
``threat'' level such that the pygmy-owl is in danger of extinction 
throughout its range, or likely to become so in the foreseeable future, 
we first considered whether these negative factors to the subspecies 
were causing long-term, range-wide, population-scale declines in pygmy-
owl numbers, or were likely to do so in the foreseeable future.
    While range-wide surveys have not been conducted for the pygmy-owl, 
information from surveys that have been conducted in Texas and Arizona 
in the United States, and in Sinaloa and Sonora in Mexico can be used 
to help us determine the general population status of the pygmy-owl 
throughout its range. The best available information we have indicates 
that local populations of pygmy-owls in Arizona, northern Sonora, and 
Texas have likely experienced population declines; however, the pygmy-
owl is still found in these areas. Pygmy-owls are still found in 
southern Mexico, and the best available information indicates that they 
may remain relatively common throughout this area. Based on the level 
of information we do have, it appears pygmy-owls persist in most areas 
where they have been historically documented in the literature and 
during recent survey efforts. The most recent IUCN (International Union 
for Conservation of Nature) Red List (an international standard for 
species extinction risk) contains the following statement with regard 
to the status of the ferruginous pygmy-owl, ``Despite the fact that the 
population trend appears to be decreasing, the decline is not believed 
to be sufficiently rapid to approach thresholds for Vulnerable under 
the population trend criterion (greater than a 30 percent decline over 
ten years or three generations).'' (IUCN 2008, p. 2). So, while this 
statement may be an indication of a range-wide population decline, it 
does not appear that such a decline is significant enough to place the 
pygmy-owl in a category of concern for IUCN. In addition, this 
statement applies to ferruginous pygmy-owls as a species, and does not 
separate status for the individual subspecies. Therefore, based on the 
best available scientific and commercial information, we do not find 
evidence of a sufficient declining trend in the subspecies' population 
to indicate it is in danger of range-wide extinction now, or in the 
foreseeable future. In other words, based on a review of the best 
available data, the data do not suggest that the combined effects of 
the negative impacts discussed in our five-factor analysis are 
resulting in an overall, long-term reduction in the distribution of the 
pygmy-owl, or an associated significant range-wide decline in pygmy-owl 
numbers, such that the subspecies is currently in danger of extinction 
or likely to become so.
    There are severe impacts to certain portions of the pygmy-owl's 
range. However, those impacts are restricted to a relatively small (27 
percent) portion of the entire range. We found no evidence that these 
impacts are of sufficient magnitude and severity to affect the 
rangewide population of pygmy-owls. Although it appears there are 
localized declines in pygmy-owl populations in Arizona and, possibly 
Texas and northern Sonora, there does not appear to be an ongoing, 
significant, long-term decline in range-wide pygmy-owl numbers that 
would lead us to believe the subspecies is currently in danger of 
extinction or likely to become so throughout its range due to factors 
identified in our five-factor analysis.
    We also considered whether any of the negative impacts began 
recently enough that their effects are not yet manifested in current 
subspecies' population numbers, but are likely to have an effect in the 
foreseeable future. Impacts from climate change are a particular impact 
that has recently been accelerating. These effects are so recent that 
we have no information on the long-term effects to pygmy-owl 
populations. However, drought is predicted to become more prevalent 
within the Sonoran range of the pygmy-owl, and drought has had a 
historically-negative impact on pygmy-owl populations in this area. The 
predictions of drought throughout the remainder of the range are 
uncertain; however, as discussed under Factor E, pygmy-owls in the 
northern portion of their range may be more resilient and better 
adapted to drought conditions. Other impacts are largely limited to 
specific portions of the subspecies' range, and we do not believe they 
would manifest their future effects as range-wide population declines. 
Therefore, the pygmy-owl is not currently in danger of extinction, or 
likely to become so, due to potential threats that began recently 
enough that their long-term effects are not yet manifest.
    Next, we considered whether any of the current negative factors are 
likely to increase within the foreseeable future, such that the species 
is likely to become in danger of extinction in the foreseeable future. 
We do believe that some of the negative factors identified will 
increase in the foreseeable future including urbanization, nonnative 
invasions and fires, agricultural development, woodcutting, grazing, 
and climate extremes. However, as discussed above in our five-factor 
analysis, these impacts occur in a limited portion of the range, 
primarily Arizona, Texas, and Sonora. For the remaining portions of 
Mexico, the best available information indicates that the negative 
factors are less severe or that there is no evidence of the negative 
impact. The best available information also indicates that pygmy-owls 
are relatively common in this portion, which is 73 percent of their 
range. Therefore, we conclude that there is no

[[Page 61885]]

evidence that negative factors, such as urbanization, agricultural 
development, or woodcutting, will increase in the foreseeable future in 
the majority of the pygmy-owl's range.
    Finally, we considered whether stochastic events might decrease the 
long-term viability of the species (species viability requires a 
naturally-reproducing population large enough to maintain sufficient 
genetic variation to provide for its continued evolution and response 
to natural environmental changes). We considered whether, given a 
currently stable population range-wide, is the pygmy-owl likely to 
become in danger of extinction in the foreseeable future because 
stochastic events might reduce its current numbers to a point where its 
long-term viability would be in question. Current information suggests 
that stochastic events such as hurricanes, extreme drought, and 
catastrophic fires could reduce the viability of local pygmy-owl 
populations in Arizona, Texas, and northern Sonora. However, because of 
the pygmy-owl's wide distribution and historical indications of 
relatively higher numbers throughout most of its range, even if a 
stochastic event were to occur within the foreseeable future that 
negatively affected this subspecies, the range-wide population would 
still be unlikely to fall to such a low level that it would be in 
danger of extinction.
    Despite some regional declines in pygmy-owl population numbers, the 
subspecies has been able to maintain what appears to be range-wide 
population viability. Negative factors affecting pygmy-owls seem to be 
restricted, for the most part, to a relatively small portion of its 
range. The areas where we have detailed information to evaluate 
potential threats and pygmy-owl population status (Arizona, Texas, and 
Sonora) represent approximately 27 percent of the overall pygmy-owl 
range. The best available information suggests that the range-wide 
pygmy-owl population is not significantly declining, despite regional 
changes in population numbers, and that most of the immediate impacts 
to the pygmy-owl and its habitats are geographically concentrated. In 
summary, based on our review of the best available scientific and 
commercial information pertaining to the five factors, we find that 
threats throughout the majority of the pygmy-owl's range are not of 
sufficient imminence, severity, or magnitude to indicate that the 
pygmy-owl is in danger of extinction (endangered), or likely to become 
endangered within the foreseeable future (threatened), throughout all 
of its range.
    After determining the subspecies is not currently in danger of 
extinction or likely to become so in the foreseeable future throughout 
its range, we next consider whether a distinct vertebrate population 
segment (DPS) or whether any significant portion of the pygmy owl's 
range is in danger of extinction or is likely to become so in the 
foreseeable future.

Distinct Vertebrate Population Segment

    Under the Service's Policy Regarding the Recognition of Distinct 
Vertebrate Population Segments Under the Endangered Species Act (61 FR 
4722, February 7, 1996), three elements are considered in the decision 
concerning the establishment and classification of a possible DPS. 
These are applied similarly for additions to or removal from the 
Federal List of Endangered and Threatened Wildlife. These elements 
include:
    (1) The discreteness of a population 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. delisting, or reclassification (i.e., is 
the population segment endangered or threatened).

Discreteness

    Under the DPS policy, a population segment of a vertebrate taxon 
may be considered discrete if it satisfies either one of these 
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.
    (2) It is delimited by international governmental boundaries within 
which 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.

Significance

    If a population segment is considered discrete under one or more of 
the conditions described in the Service's DPS policy, its biological 
and ecological significance will be considered in light of 
Congressional guidance that the authority to list DPSs be used 
``sparingly'' while encouraging the conservation of genetic diversity. 
In making this determination, we consider available scientific evidence 
of the discrete population segment's importance to the taxon to which 
it belongs. Since precise circumstances are likely to vary considerably 
from case to case, the DPS policy does not describe all the classes of 
information that might be used in determining the biological and 
ecological importance of a discrete population. However, the DPS policy 
describes four possible classes of information that provide evidence of 
a population segment's biological and ecological importance to the 
taxon to which it belongs. As specified in the DPS policy (61 FR 4722), 
this consideration of the population segment's significance may 
include, but is not limited to, the following:
    (1) Persistence of the discrete population segment in an ecological 
setting unusual or unique to the taxon;
    (2) Evidence that loss of the discrete population segment would 
result in a significant gap in the range of a taxon;
    (3) Evidence that the discrete 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 other populations of the species in its genetic characteristics.
    A population segment needs to satisfy only one of these conditions 
to be considered significant. Furthermore, other information may be 
used as appropriate to provide evidence for significance.

Analysis of Potential Distinct Population Segments

    The petitioners requested that we consider two potential DPS's of 
the pygmy-owl for protection under the Act, a Sonoran Desert DPS and an 
Arizona DPS. The petitioners did not suggest any additional DPS 
configurations to be evaluated. However, in order to be complete in our 
analysis of potentially listable pygmy-owl entities, we also considered 
other potential DPS configurations including an eastern/western DPS and 
a Texas DPS. Our analysis of these two other potential DPS 
configurations follows our evaluation of the petitioned DPS 
configurations.
Potential Sonoran Desert DPS
    As described, none of the boundaries of the petitioner's Sonoran 
Desert DPS include an international border or boundary (CBD and DOW 
2007, pp. 4-6) (Figure 4). Therefore, the petitioned DPS must meet the 
first condition for discreteness in order to be considered a valid DPS, 
because it does not meet the second condition. The eastern and

[[Page 61886]]

western portions of the range of the pygmy-owl are separated by the 
Sierra Madre and other mountain ranges in north-central Mexico 
(Proudfoot et al. 2006a, p. 9). However, there are no obvious physical 
or geographic barriers that separate the petitioned Sonoran Desert DPS 
from the rest of the pygmy-owl's range to the south. There is a 
documented area in central Sonora, near Hermosillo, Mexico, that may 
act as an impediment to pygmy-owl movements and dispersal, because of 
the lack of contiguous suitable habitat resulting from natural and 
artificial conditions (Flesch 2003, pp. 40, 100). However, the extent 
of this band of unsuitable habitat does not prevent regular or 
occasional movements by pygmy-owls between northern and southern 
Sonora. This is supported by genetic sampling and analysis that has 
recently been completed, that indicates that there is likely gene flow 
between the two groups (Proudfoot 2009a, p. 1).
    Proudfoot's earlier assessment of mitochondrial DNA (mtDNA) and 
microsatellite DNA of pygmy-owls from Arizona, Sonora, and Sinaloa 
implied restricted gene flow between the Sonoran and Sinaloan 
populations (Proudfoot et al. 2006a, p. 10; Proudfoot et al. 2006b, p. 
9). However, the authors implied that limited sampling and geographic 
distance between sample sites in Sonora and Sinaloa may have influenced 
the results of these studies. To verify the inference of restricted 
gene flow, a joint effort among Proudfoot, AGFD, and the Service 
resulted in the collection and analysis of an additional 119 samples 
collected in areas not previously sampled (Proudfoot 2009, p. 1; AGFD 
2008a, pp. 1-10). Analysis of the genotypic variation revealed 
isolation by distance with significant gene flow between pygmy-owl 
populations. Estimates of migrants per generation time for pygmy-owl 
populations were 8.62 (Arizona-Sonora), 6.65 (Arizona-Sinaloa) and 
23.46 (Sonora-Sinaloa) (Proudfoot 2009, p. 1).
    So, while no haplotypes from Arizona, Sonora, or Sinaloa are shared 
with the remainder of Mexico and Texas, there are shared haplotypes 
among Arizona, Sonora, and Sinaloa, indicating there is exchange of 
genetic material within this grouping (Proudfoot et al. 2006a, p. 7). 
This would argue against the Sonoran Desert Ecoregion being markedly 
separate from the remainder of Sonora and Sinaloa. Based on 
observations of pygmy-owls during survey and capture activities in 
Arizona, and in both northern and southern Sonora as described above, 
the best available scientific and commercial data does not indicate 
that there is any evidence that there are marked behavioral, 
morphological, or physiological differences within the petitioned DPS 
(AGFD 2008a, pp. 1-4). As a result, this study indicates that there is 
no marked genetic or morphological separation between the petitioned 
Sonoran Desert DPS and southern Sonora populations (Proudfoot 2009a, p. 
1; AGFD 2008a, p. 10).
    The Sonoran Desert Ecoregion does differ ecologically from the 
remainder of the areas within its range. Despite the fact that 
occurrence of some plant species overlaps with other ecoregions to the 
south and east, the Sonoran Desert is a unique dry desert area that 
does function ecologically in a different way when compared to adjacent 
ecoregions. However, as described above, the best available scientific 
and commercial data do not indicate that this ecological difference has 
resulted in any morphological, physiological, or genetic 
differentiation within pygmy-owl populations in the Sonoran Desert. 
Environmental characteristics within the Sonoran Desert have likely 
resulted in the reduced numbers and densities of pygmy-owls found in 
this area. However, this does not appear to have resulted in any 
physical differentiation, at least anecdotally, from adjacent pygmy-owl 
populations.
    We find that there is no evidence that the Sonoran Desert 
population of pygmy-owl is markedly separated in any way from the 
remainder of the taxon. Therefore, we determine, based on a review of 
the best available information, that the petitioned Sonoran Desert DPS 
of the pygmy-owl does not meet the discreteness conditions of the 1996 
DPS policy. As such, this population segment does not qualify as a DPS 
under our policy and is not a listable entity under the Act.
    The DPS policy indicates that significance should be analyzed only 
if a population segment has been identified as discrete. Because we 
found that the Sonoran Desert population segment did not meet the 
discreteness element and, therefore, does not qualify as a DPS under 
the Service's DPS policy, we will not conduct an evaluation of 
significance.
Potential Arizona DPS
    Because we are evaluating this petitioned entity based on the 
currently accepted taxonomic classification of the pygmy-owl (see 
Description and Taxonomy section above), the taxon considered in this 
finding is the same as for our 1997 listing of the pygmy-owl (62 FR 
10730). Consequently, the petitioned Arizona DPS is exactly the same 
DPS configuration that was the subject of litigation and, ultimately, 
the same DPS configuration that the Service removed from the Federal 
List of Endangered and Threatened Wildlife in 2006 (71 FR 19452; April 
24, 2006) (Figure 4). That final rule presents our analysis showing 
that, while the discreteness criteria for the DPS were met, we could 
not show that this DPS was significant to the taxon as a whole. The 
petition states that ``the Arizona DPS occurs in a unique ecological 
setting and differs markedly in its genetic characteristics from pygmy-
owls in Sinaloa and elsewhere in the species range. Loss of the Arizona 
DPS would also create a significant gap in the species' range, 
resulting in loss of roughly a third of the subspecies' range, and half 
of the species' range in the Sonoran Desert. The Arizona DPS is also 
significant because it represents the entire range of G. ridgwayi 
cactorum in the United States'' (CBD and DOW 2007, p. 12).
    Our analysis in the final rule to delist the pygmy-owl showed that 
the then-listed Arizona DPS of the pygmy-owl was not markedly different 
in its genetic characteristics from pygmy-owls in northern Sonora, 
Mexico; did not occur in a unique ecological setting; nor would loss of 
the DPS represent a significant gap in the range of the taxon (71 FR 
19452). We are unaware of any scientific information compiled since the 
delisting that would alter the conclusions made in that final rule. 
Therefore, we determine, based on a review of the best available 
information, that the petitioned Arizona DPS of the pygmy-owl does not 
meet the significance conditions of the 1996 DPS policy. Therefore, 
this population segment does not qualify as a DPS under our policy and 
is not a listable entity under the Act.
Potential Texas DPS
    We have reviewed new information regarding the status of the pygmy-
owl in Texas (Proudfoot 2010, p. 1; 2011b, p. 1). In addition, the peer 
reviewers of the current genetic information provided insight and 
recommendations regarding the genetic diversity and management of 
pygmy-owls in Arizona and Texas. Upon consideration of this new 
information, we concluded that it was appropriate to evaluate a 
potential Texas DPS that includes the current range of the pygmy-owl in 
Texas to the international border with Mexico.
Discreteness
    The use of the international border to define discreteness of the 
Arizona pygmy-owl DPS was upheld by the courts (No. 02-15212, CV00-0903 
SRB

[[Page 61887]]

at 11586, 2003) because of the differences in status and management of 
the pygmy-owl between Arizona and Mexico. Defining the discreteness of 
the Texas DPS is appropriate using the same rationale. For example, 
Mexico has no regulations or laws specifically protecting the pygmy-
owl. In Texas, the pygmy-owl is listed as threatened, and State law 
prohibits take without the appropriate permit. Therefore, we determine 
that the Texas DPS is discrete due to differences in status and 
management of the pygmy-owl between the United States, in Texas, and 
Mexico.
Significance
    The best available scientific and commercial information does not 
indicate that the Texas population of pygmy-owls occurs in an 
ecological setting that is unusual or unique to the taxon. For example, 
the vegetation community that supports pygmy-owls in Texas is 
classified as Tamaulipan brushland (Jahrsdoerfer and Leslie 1988, p. 
1). This vegetation community and the associated pygmy-owl habitat 
elements are found in southern Texas and northeastern Mexico 
(Jahrsdoerfer and Leslie 1988, pp. 1-9; Hunter 1988, p. 8; Cook et al. 
2001, pp. 1-2) and comprise most of the eastern portion of the pygmy-
owl's current range. Texas represents approximately 15 percent of the 
eastern portion of the range of the pygmy-owl. In other words, 
approximately 85 percent of the pygmy-owl habitat that is characterized 
as Tamaulipan brushland occurs outside of Texas. Therefore, the Texas 
population of pygmy-owls does not occur in an unusual or unique setting 
for the taxon.
    Texas represents approximately 5 percent of the overall range of 
the pygmy-owl. From a geographic perspective, loss of this portion of 
the range does not represent a significant gap in the range of the 
pygmy-owl. However, we must also consider where the loss of the 
contribution of this population segment to overall population numbers 
would represent a significant gap in the range. Pygmy-owl population 
estimates for Texas range from 100 owls in Kleberg County (Tewes 1992, 
p. 24), to 654 pairs in Kenedy, Brooks, and Willacy Counties (Wauer et 
al. 1993, p. 1074), and 745 to 1,823 pygmy-owls on ranches in Kenedy 
and Brooks Counties (Mays 1996, p. 32). This is considerably higher 
than population estimates in Arizona (approximately 50 owls (Abbate et 
al. 2000, pp. 15-16)), but likely similar to the densities occurring in 
thornscrub and dry tropical forest habitats further south in Mexico. 
Field data indicate that pygmy-owls in the southern portions of Sonora 
(within thornscrub and tropical deciduous forests) are common and 
likely number on the order of thousands, while further north within the 
Sonoran Desert Ecoregion, they are fewer in number, more patchily 
distributed, and likely number on the order of hundreds (Flesch 2003, 
pp. 39-42; AGFD 2008a, p. 6). Given that the majority of the pygmy-
owl's range appears to support similar numbers and densities of pygmy-
owls as Texas, we do not believe that the loss of the population in 
Texas would represent a significant gap from the perspective of 
contribution to overall pygmy-owl population numbers.
    While there is some evidence that the Texas population of pygmy-
owls contributes key genetic diversity to the overall population of 
pygmy-owls and is, to some extent, genetically unique (Proudfoot 2006a, 
p. 7; Cicero 2008, p. 2; Oyler-McCance 2008, pp. 1-2; Dumbacher 2008, 
p. 9), the best available scientific and commercial information 
suggests that pygmy-owls in Texas are genetically similar to pygmy-owls 
across the international border in Mexico (Proudfoot 2006a, pp. 9-10). 
This lack of genetic differentiation from adjacent pygmy-owl 
populations suggests that the Texas population segment does not differ 
markedly from adjacent populations of pygmy-owls. Proudfoot et al. 
(2006a, p. 7) indicated that Texas is characterized by a single 
haplotype; and that one haplotype is shared with pygmy-owls from 
Tamaulipas, Mexico, indicating there has been some exchange of genetic 
material. Based on the best available scientific and commercial 
information, we do not find that the Texas DPS is significant to the 
taxon as a whole, and is, therefore, not a listable entity under the 
Act. No further analysis of the Texas DPS is warranted at this point.
Potential Western and Eastern DPSs
Discreteness
    The current range of the pygmy owl, as discussed above, is defined 
as occurring from lowland central Arizona south through western Mexico 
to the States of Colima and Michoac[aacute]n, and from southern Texas 
south through the Mexican States of Tamaulipas and Nuevo Leon 
(Johnsgard 1988, p. 159; Millsap and Johnson 1988, p. 137; Oberholser 
1974, p. 452; Friedmann et al. 1950, p. 145), consistent with the last 
American Ornithologist Union (AOU) list that addressed avian 
classification to the subspecies level (AOU 1957). In the United 
States, the eastern and western portions of the pygmy-owl's range are 
separated by over 1,600 km (1,000 mi) of unsuitable habitat (Chihuahuan 
desert and grasslands, oak and pine forests) and elevations greater 
than 1,200 m (4,000 ft) associated with various mountain ranges. There 
has never been any record of occurrence for pygmy-owls in the area 
between south Texas and Tucson, Arizona. In Mexico, this distribution 
is separated throughout its entirety by the Sierra Madre Occidental and 
the Sierra Madre Oriental. These mountain ranges extend south beyond 
the southern boundary of the described range of this subspecies and 
represent a significant geographical barrier between the eastern and 
western segments of the distribution (Cartron et al. 2000, p. 6). The 
elevational range of peaks in these mountain ranges is from 1,880 m to 
over 3,600 m (6,000 ft to over 12,000 feet). Given the elevational 
limits of the pygmy-owl's distribution within its range (Freidman et 
al. 1950, pp. 145-147), and the fact that pygmy-owls are replaced by 
the least pygmy-owl (G. minutissimum), Colima pygmy-owl (G. palmarum), 
and the northern pygmy-owl (G. gnoma) at higher elevations (Schaldach 
1963, p. 40; Howell and Robbins 1995, pp. 19-20), mountains with 
elevations as significant as those separating the eastern and western 
portions of the pygmy-owl's distribution in Mexico represent a 
significant physical barrier, as discussed in the Service's DPS policy 
(61 FR 4725). The eastern and western portions of the current 
distribution of cactorum never meet (Figure 1).
    Recent evaluation of genetic characteristics appears to indicate 
that the eastern and western portions of the pygmy-owl's current 
distribution differ from each other genetically (Proudfoot et al. 
2006b, pp. 7-9). As we have discussed previously in this document, this 
genetic differentiation may not be adequate to define a subspecies, but 
it does provide further evidence that the eastern and western portions 
of the pygmy-owl's range are markedly separate. There is genetic 
evidence that the western group containing this portion of the range 
does group closer together than it does to owls in the eastern portion 
of the overall range. Proudfoot (2006a, p. 7) indicates that pygmy-owls 
in this portion of the range share no haplotypes with populations in 
Texas or in the remainder of Mexico. Additionally, in considering the 
work of Proudfoot et al. (2006a and 2006b), expert review concluded 
that, based on evidence of restricted gene flow between the Arizona/
western Mexico and Texas/eastern Mexico populations, Arizona and Texas 
should be managed as separate units and should be

[[Page 61888]]

considered genetically distinct (Cicero 2008, p. 2; Oyler-McCance 2008, 
pp. 1-2; Dumbacher 2008, p. 9), indicating that Arizona and Texas, as 
portions of the western and eastern distributions of the pygmy-owl, 
contribute to the respective genetic diversity of each of these 
regions. Therefore, we find that the eastern and western portions of 
the range of Glaucidium brasilianum cactorum are markedly separated 
from each other as a consequence of physical and ecological factors. As 
such, we determine that the eastern and western portions of the current 
distribution of the pygmy-owl are discrete (Figure 4).
Significance
    The Service's DPS policy indicates that one of the ways a DPS may 
be significant to the taxon as a whole is if the loss of the DPS would 
result in a significant gap in the range of the taxon (61 FR 4725). A 
gap in the range can be interpreted as a physical gap, but may also be 
considered to be a gap in the continuous cline of genetic variation 
found within the distribution of the species. With regard to the pygmy-
owl, the western portion of the range comprises approximately 68 
percent of the entire range of the taxon and, consequently, the eastern 
portion of the range represents approximately 32 percent of the range. 
Physically, the loss of either of these geographic areas represents a 
significant gap in the distribution of the taxon. In addition, 
Proudfoot et al. (2006a and 2006b) indicate that the genetic 
characteristics of the pygmy-owl may vary from Texas to Arizona as a 
cline of variation based on distance of separation. Loss of either the 
western or eastern portion of this cline represents a significant gap 
in the distribution of genetic variation within the overall pygmy-owl 
population. Therefore, the loss of the current range of the pygmy-owl 
as represented by the western and eastern portions of the current 
range, and the loss of a substantial portion of the genetic variation 
represented within the taxon as a whole, would result in a significant 
gap in the range of the pygmy-owl. As such, we find that the eastern 
and western population segments are significant, based on evidence that 
loss of the discrete population segment would result in a significant 
gap in the range of a taxon.
Determination for the Potential Western DPS
    Of the negative impacts we identified in our 5-factor analysis 
above, the following occur within western portions of the pygmy-owl's 
range: (1) Habitat loss and fragmentation due to urbanization, improper 
grazing, nonnative species invasions, fire, agricultural development, 
and wood cutting; (2) border issues; (3) inadequacy of existing 
regulatory mechanisms; (4) drought and climate change; (5) predation; 
and (6) small population size. Therefore, within the potential western 
DPS configuration, impacts to pygmy-owls and their habitat discussed 
under factors A, C, and E may be affecting this pygmy-owl population 
segment.
    Despite the potential effects of these impacts within the western 
portion of the pygmy-owl's range, low population numbers, and apparent 
population declines in local pygmy-owl populations in the northern 
portion of this population segment, the best available scientific and 
commercial data indicate that pygmy-owls remain common in the majority 
of the western portion of the pygmy-owl's range. Recent survey and 
monitoring in Sonora indicated that the highest densities of pygmy-owls 
occurred in the Sinaloan deciduous forest of southern Sonora (Flesch 
2003, p. 42). During capture efforts in 2008, AGFD (2008, p. 6) 
documented multiple pygmy-owls commonly responding at capture sites in 
the thornscrub and tropical deciduous forests of southern Sonora and 
northern Sinaloa, an occurrence which only rarely happened further 
north in Sonoran desertscrub habitats. While anecdotal, it appears that 
the number and density of pygmy-owls is higher in the thornscrub and 
deciduous forest community types than in the Sonoran Desert community 
type. This occurrence and distribution agrees with past conclusions 
found in the literature (Hunter 1988, p. 7; Russell and Monson 1988, p. 
141; Shaldach 1963, p. 40). Because pygmy-owl habitat in the southern 
portion of the western population segment is primarily thornscrub and 
dry tropical forests, it logically follows that pygmy-owls are more 
common in this portion of the population segment. Based upon our review 
of the best available commercial and scientific data, we conclude that 
pygmy-owl population numbers are not being significantly affected by 
the identified negative impacts in most of the western portion of the 
pygmy-owl's range such that the population is in danger of extinction 
or likely to become so in the foreseeable future. Therefore, we find 
that listing a western DPS of the overall pygmy-owl population is not 
warranted under the Act.
Determination for the Potential Eastern DPS
    Of the negative impacts we identified in our 5-factor analysis 
above, the following occur within the eastern portion of the pygmy-
owl's range: (1) Habitat loss and fragmentation due to urbanization, 
improper grazing, nonnative species invasions, fire, agricultural 
development, and wood cutting; (2) loss or alteration of habitat as a 
result of hurricanes; (3) lack of adequate regulatory mechanisms; (4) 
drought and climate change; (5) predation; and (6) small population 
size. Therefore, within the potential eastern DPS configuration, 
impacts to pygmy-owls and their habitat discussed under factors A, C, E 
may be affecting this pygmy-owl population segment.
    The historical loss of pygmy-owl habitat in the eastern portion of 
its range has had significant effects on the pygmy-owl. As discussed 
above, the pygmy-owl was once a common breeding species in Texas and 
northeastern Mexico (Griscom and Crosby 1926, p. 18; Friedmann et al. 
1950, p. 145), but is now extirpated or extremely rare in the area of 
the Rio Grande Delta (Oberholser 1974, pp. 451-452). However, a 
disjunct population generally occurring in the area of Kenedy County, 
Texas, has been estimated at 100 pygmy-owls (Tewes 1992, p. 24), 654 
pairs (Wauer et al. 1993, p. 1074), and up to 1,823 pygmy-owls (Mays 
1996, p. 32). It should be noted that these studies used different 
methodologies and study areas, and are not directly comparable, but do 
provide estimates for the general area. A recent concern about the 
populations in Texas has been raised because of an apparent decline in 
the number of pygmy-owl nestlings banded in this population as part of 
an ongoing nest box study in Texas (Proudfoot 2010, p. 1). However, 
comprehensive pygmy-owl surveys throughout southern Texas have not 
occurred for over a decade, and, without a more comprehensive survey 
effort in southern Texas, we cannot definitively state that the overall 
population of pygmy-owls in southern Texas matches the decline of 
nestlings documented during this nest box study. Pygmy-owls may simply 
have moved to other areas supporting suitable nesting habitat 
(Proudfoot 2011b, p. 1).
    While the literature indicates that significant areas of pygmy-owl 
habitat have been lost and fragmented throughout the eastern portion of 
the pygmy-owl's range, there is no indication that, where areas of 
suitable habitat remain, numbers and densities of pygmy-owls would not 
be similar to those found in the same type of habitat in Texas. Numbers 
of pygmy-owls in Texas remain substantially higher than those in the 
northwestern portion of the pygmy-owl's range, and similar to the

[[Page 61889]]

apparently higher numbers found in the southwestern portion of the 
range in thornscrub and dry tropical forests.
    Additionally, while urbanization and agricultural development and 
woodcutting may be ongoing negative impacts in northeastern Mexico 
(AQUASTAT 2007, p. 2; Cook et al. 2001, p. 4; Jahrsdoerfer and Leslie 
1985, p. 17; Tewes1993, pp. 28-29), the occurrence of the majority of 
suitable pygmy-owl habitat in Texas on private ranches may reduce the 
potential for these impacts to significantly affect pygmy-owl 
populations in this area. Wauer et al. (1993, p. 1076) state, ``Changes 
in the ranch land habitats of Kenedy and Brooks Counties have been 
relatively limited, suggesting that rancher landowners, at least in 
south Texas, are being good land stewards.'' At least currently, the 
Texas population of pygmy-owls appears to be viable (Wauer et al. 1993, 
p. 1071) and the primary recruitment base for pygmy-owl populations in 
this area (Wauer et al. 1993, p. 1076).
    The best available scientific and commercial information 
demonstrates that, despite the ongoing negative impacts to pygmy-owl 
habitat in the eastern portion of its range, numbers and densities have 
remained relatively high. Therefore, we find that listing an eastern 
DPS of the overall pygmy-owl population is not warranted under the Act.

Significant Portion of the 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 the 
term ``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 
explicitly addressed it in our implementing regulations either: (1) The 
consequences of a determination that a species is 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.''
    Two recent district court decisions have addressed whether the SPR 
language allows the Service to list or protect less than all members of 
a defined ``species'': Defenders of Wildlife v. Salazar, 729 F. Supp. 
2d 1207 (D. Mont. 2010), concerning the Service's delisting of the 
Northern Rocky Mountain gray wolf (74 FR 15123; Apr. 12, 2009); and 
WildEarth Guardians v. Salazar, 2010 U.S. Dist. LEXIS 105253 (D. Ariz. 
Sept. 30, 2010), concerning the Service's 2008 finding on a petition to 
list the Gunnison's prairie dog (73 FR 6660; Feb. 5, 2008). The Service 
had asserted in both of these determinations that it had authority 
under the Act to protect only some members of a ``species,'' as that 
term is defined by the Act (i.e., species, subspecies, or DPS). Both 
courts ruled that the determinations were arbitrary and capricious on 
the grounds that this approach violated the plain and unambiguous 
language of the Act. The courts concluded that reading the SPR language 
to allow protecting only a portion of a species' range is inconsistent 
with the Act's definition of ``species.'' The courts concluded that, 
once a determination is made that a species (i.e., species, subspecies, 
or DPS) meets the definition of ``endangered species'' or ``threatened 
species,'' it must be placed on the list in its entirety and the Act's 
protections applied consistently to all members of that species 
(subject to modification of protections through special rules under 
sections 4(d) and 10(j) of the Act).
    Consistent with that interpretation, and for the purposes of this 
finding, we interpret the phrase ``significant portion of its range'' 
in the Act's definitions of ``endangered species'' and ``threatened 
species'' to provide an independent basis for listing; thus there are 
two situations (or factual bases) under which a species would qualify 
for listing: A species may be endangered or threatened throughout all 
of its range (which we have determined is not the case with the pygmy-
owl); or a species may be endangered or threatened in only a 
significant portion of its range. If a species is in danger of 
extinction throughout an SPR, the species is an ``endangered species.'' 
The same analysis applies to ``threatened species.'' Based primarily on 
existing case law, the consequence of finding that a species is 
endangered or threatened in only a significant portion of its range is 
that the entire species shall be listed as endangered or threatened, 
respectively, and the Act's protections shall be applied across the 
species' entire range.
    We conclude, for the purposes of this finding, that interpreting 
the SPR phrase as providing an independent basis for listing is the 
best interpretation of the Act because it is consistent with the 
purposes and the plain meaning of the key definitions of the Act. This 
interpretation does not conflict with established past agency practice 
(prior to the 2007 Solicitor's Opinion, which interpreted language in 
section 4(c) as limiting the application of ESA protections to the 
significant portion of a species' range where it is endangered or 
threatened, rather than throughout its range) because no consistent, 
long-term agency practice has been established, and it is consistent 
with the most recent judicial opinions that have most closely examined 
this issue. Having concluded that the phrase ``significant portion of 
its range'' provides an independent basis for listing and protecting 
the entire species, we next turn to the meaning of ``significant'' to 
determine the threshold for when such an independent basis for listing 
exists.
    Although there are potentially many ways to determine whether a 
portion of a species' range is ``significant,'' we conclude, for the 
purposes of this finding, that the significance of the portion of the 
range should be determined based on its biological contribution to the 
conservation of the species. For this reason, we describe the threshold 
for ``significant'' in terms of an increase in the risk of extinction 
for the species. We conclude that a biologically-based definition of 
``significant'' best conforms to the purposes of the Act, is consistent 
with judicial interpretations, and best ensures species conservation. 
Thus, for the purposes of this finding, a portion of the range of the 
pygmy-owl is ``significant'' if its contribution to the viability of 
the species is so important that, without that portion, the pygmy-owl 
would be in danger of extinction. Therefore, if we determine that the 
pygmy-owl is endangered or threatened in a significant portion of its 
range, and it would be in danger of extinction in the rest of its range 
without that portion, that portion is significant and we will list the 
entire species according to its status there.
    We evaluate biological significance based on the principles of 
conservation biology using the concepts of redundancy, resiliency, and 
representation. Resiliency describes the characteristics of a species 
that allow it to recover from periodic disturbance. Redundancy (having 
multiple populations distributed across the landscape) may be needed to 
provide a margin of safety for the species to withstand catastrophic 
events. Representation (the range of variation found in a species) 
ensures that the species' adaptive capabilities are conserved. 
Redundancy, resiliency, and representation are not independent of

[[Page 61890]]

each other, and some characteristic of a species or area may contribute 
to all three. For example, distribution across a wide variety of 
habitats is an indicator of representation, but it may also indicate a 
broad geographic distribution contributing to redundancy (decreasing 
the chance that any one event affects the entire species), and the 
likelihood that some habitat types are less susceptible to certain 
threats, contributing to resiliency (the ability of the species to 
recover from disturbance). None of these concepts is intended to be 
mutually exclusive, and a portion of a species' range may be determined 
to be ``significant'' due to its contributions under any one of these 
concepts.
    For the purposes of this finding, we determine if a portion's 
biological contribution is so important that the portion qualifies as 
``significant'' by asking whether, without that portion, the 
representation, redundancy, or resiliency of the species would be so 
impaired that the species would have an increased vulnerability to 
threats to the point that the overall species would be in danger of 
extinction (i.e., would be ``endangered''). Conversely, we would not 
consider the portion of the range at issue to be ``significant'' if 
there is sufficient resiliency, redundancy, and representation 
elsewhere in the species' range that the species would not be in danger 
of extinction throughout its range if the population in that portion of 
the range in question became extirpated (extinct locally).
    We recognize that this definition of ``significant'' establishes a 
threshold that is relatively high. On the one hand, given that the 
consequences of finding a species to be endangered or threatened in an 
SPR would be listing the species throughout its entire range, it is 
important to use a threshold for ``significant'' that is robust. It 
would not be meaningful or appropriate to establish a very low 
threshold whereby a portion of the range can be considered 
``significant'' even if only a negligible increase in extinction risk 
would result from its loss. Because nearly any portion of a species' 
range can be said to contribute some increment to a species' viability, 
use of such a low threshold would require us to impose restrictions and 
expend conservation resources disproportionately to conservation 
benefit; listing would be rangewide, even if only a portion of the 
range of minor conservation importance to the species is imperiled. On 
the other hand, it would be inappropriate to establish a threshold for 
``significant'' that is too high. This would be the case if the 
standard were, for example, that a portion of the range can be 
considered ``significant'' only if threats in that portion result in 
the entire species being currently endangered or threatened. Such a 
high bar would not give the SPR phrase independent meaning, as the 
Ninth Circuit held in Defenders of Wildlife v. Norton, 258 F.3d 1136 
(9th Cir. 2001).
    The definition of ``significant'' used in this finding carefully 
balances these concerns. By setting a relatively high threshold, we 
minimize the degree to which restrictions will be imposed or resources 
expended that do not contribute substantially to species conservation. 
But we have not set the threshold so high that the phrase ``in a 
significant portion of its range'' loses independent meaning. 
Specifically, we have not set the threshold as high as it was under the 
interpretation presented by the Service in the Defenders litigation. 
Under that interpretation, the portion of the range would have to be so 
important that current imperilment there would mean that the species 
would be currently imperiled everywhere. Under the definition of 
``significant'' used in this finding, the portion of the range need not 
rise to such an exceptionally high level of biological significance. 
(We recognize that if the species is imperiled in a portion that rises 
to that level of biological significance, then we should conclude that 
the species is in fact imperiled throughout all of its range, and that 
we would not need to rely on the SPR language for such a listing.) 
Rather, under this interpretation we ask whether the species would be 
endangered everywhere without that portion, i.e., if that portion were 
completely extirpated. In other words, the portion of the range need 
not be so important that even being in danger of extinction in that 
portion would be sufficient to cause the remainder of the range to be 
endangered; rather, the complete extirpation (in a hypothetical future) 
of the species in that portion would be required to cause the remainder 
of the range to be endangered.
    The range of a species can theoretically be divided into portions 
in an infinite number of ways. However, there is no purpose to 
analyzing portions of the range that have no reasonable potential to be 
significant and threatened or endangered. To identify only those 
portions that warrant further consideration, we determine whether 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. Depending 
on the biology of the species, its range, and the threats it faces, it 
might be more efficient for us to address the significance question 
first or the status question first. Thus, if we determine that a 
portion of the range is not ``significant,'' we do not need to 
determine whether the species is endangered or threatened there; if we 
determine that the species is not endangered or threatened in a portion 
of its range, we do not need to determine if that portion is 
``significant.'' In practice, a key part of the portion status 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 individual 
consideration. Moreover, if any concentration of threats applies only 
to portions of the species' range that clearly would not meet the 
biologically-based definition of ``significant,'' such portions will 
not warrant further consideration.
    Therefore, having determined that the pygmy-owl does not meet the 
definition of a threatened or endangered species throughout its range 
or within any considered DPS configuration, we next considered whether 
there are any significant portions of the range where the pygmy-owl is 
in danger of extinction or is likely to become endangered in the 
foreseeable future. We engaged in a systematic process that began with 
identifying any portions of the range of the pygmy-owl that may warrant 
further consideration.
    To determine whether any portions of the pygmy-owl's range 
warranted further consideration as possible threatened or endangered 
significant portions of the range, we reviewed the entire supporting 
record for the status review of this species with respect to the 
geographic concentration of threats, and the significance of portions 
of the range to the conservation of the species. We chose to first 
identify any portions of the pygmy-owl's range where the species may be 
in danger of extinction or likely to become so within the foreseeable 
future. We found that documented and potential population declines are 
occurring in some parts of the pygmy-owl's range, but not throughout 
the range of the pygmy-owl, indicating the possibility that threats 
affect the species to varying degrees across the range of the pygmy-
owl. Additionally, the best available data indicates that the impacts 
identified above do not occur uniformly throughout the range of the 
pygmy-owl.

[[Page 61891]]

Analysis of Potential Significant Portions of the Range

    We identified one area of the pygmy-owl's range that warrants 
further consideration as a possible threatened or endangered 
significant portion of the range. Based on our five-factor analysis of 
threats throughout the range of the pygmy-owl, we found that the 
Sonoran Desert Ecoregion was an area where documented and potential 
declines in pygmy-owl populations have occurred, indicating the species 
may be threatened or endangered there.
Sonoran Desert Ecoregion SPR Analysis
    We identified the Sonoran Desert Ecoregion as a portion of the 
pygmy-owl's range that was potentially significant, and that could 
potentially meet the criteria for threatened or endangered (Figure 3). 
The decision to use this area to define the boundaries of that portion 
of the overall pygmy-owl range that may be significant was based on 
factors related to pygmy-owl ecology and information available related 
to the status of the pygmy-owl. This portion of the pygmy-owl's range 
is characterized by a generally unique vegetation community. The 
Sonoran Desert has the greatest diversity and vegetative growth of any 
desert worldwide. It is the most tropical of the three North American 
warm deserts (Sonoran, Mojave, and Chihuahuan) (Williams et al. 2001, 
pp. 1-2; MacMahon and Wagner 1985, pp. 105-202). The boundaries of this 
vegetation community have been consistently described in a number of 
papers (Marshall et al. 2000, pp. 4-7; McLaughlin and Bowers 1999, pp. 
3-7; Dimmitt 2000, pp. 13-15; Brown 1994, p. 181; Leopold 1950, p. 513; 
Shreve 1951, pp. 1-3; and Nabhan and Holdsworth 1998, pp. 1-5). 
Finally, number and density estimates from formal studies and 
incidental observations from the field show that this area has markedly 
lower numbers and densities of pygmy-owls than the other areas of its 
range, and that population declines have occurred within the area (AGFD 
2008a, p. 2; Flesch and Steidl 2006, p. 869).
    For the purposes of this analysis, the current range of the pygmy-
owl within the Sonoran Desert Ecoregion includes those areas of the 
ecoregion within the Arizona Counties of Pima and Pinal, and the 
Mexican State of Sonora, from the area immediately south of the western 
border of Pima County, east to Nogales, and south from Nogales to 
Guaymas and then back northwest to the western coast of Sonora.

Pygmy-Owl Population Status Within the Sonoran Desert Ecoregion

    Within the Arizona portion of the Sonoran Desert Ecoregion, the 
pygmy-owl occurs in very low numbers in widely scattered population 
groups within the State. Historically (i.e., late 1800s and early 
1900s), pygmy-owls occupied areas of south-central Arizona, from New 
River, about 56 km (35 mi.) north of Phoenix, south to the United 
States and Mexico border, west to Agua Caliente near Gila Bend and 
Cabeza Prieta Tanks, and east to Tucson, and, rarely, the San Pedro 
River (Bent 1938, pp. 435-438; Monson and Phillips 1981, pp. 71-72; 
Johnson et al. 2003, pp. 390-391). The geographic area historically 
occupied by pygmy-owls in Arizona includes portions of Gila, Pima, 
Pinal, Maricopa, Graham, Santa Cruz, Cochise, Greenlee, and Yuma 
Counties. Currently, the known locations of pygmy-owls in Arizona are 
restricted to two counties, Pima and Pinal (Service 2011, p. 1; Service 
2009b, p. 1; Abbate et al. 2000, pp. 15-16). The current distribution 
of pygmy-owls within Arizona is significantly reduced from its 
historical distribution.
    Historically, the pygmy-owl was found as far north as New River in 
Maricopa County, and, prior to the mid-1900s, early naturalists 
considered the pygmy-owl ``not uncommon,'' ``of common occurrence,'' 
and a ``fairly numerous'' resident of the areas in which they traveled 
in Arizona (Breninger 1898, p. 28; Gilman 1909, p. 148; Swarth 1914, p. 
31). Recent data indicate that there are fewer than 50 adult pygmy-owls 
and fewer than 10 nest sites in Arizona in any given year (Abbate et 
al. 2000, pp. 15-16). Limited surveys and monitoring conducted in 2009 
indicate that pygmy-owls in Arizona still occupy the areas of Avra 
Valley, Altar Valley, and Organ Pipe Cactus National Monument (Service 
2009b, p. 1; 2011, p. 1). However, populations of pygmy-owls in Arizona 
are in an ongoing decline (AGFD 2008a, p. 2). Comprehensive surveys 
have not been conducted on the Tohono O'odham Nation in Arizona. A 
number of surveys have been completed on the Nation with respect to 
various utility and roadway projects, and some of these surveys did 
document the presence of pygmy-owl. But distribution of the data from 
these surveys has been restricted by the Nation and is not readily 
available for analysis. There are large areas of suitable habitat on 
the Nation, but the information we have indicates that pygmy-owls are 
patchily distributed in those areas as in other areas of the State and 
occur in similar densities.
    Within the Mexico portion of the Sonoran Desert Ecoregion, pygmy-
owl numbers are higher, but, similar to their distribution in Arizona, 
pygmy-owls also occur here as scattered population groups throughout 
the occupied area (Flesch 2003, pp. 123-124). Recent surveys and 
research in northwestern Mexico indicate that numbers and density of 
pygmy-owls are higher in thornscrub and tropical deciduous forest 
communities of southern Sonora and Sinaloa than in the Sonoran 
desertscrub and semi-desert grassland vegetation communities of the 
Sonoran Desert Ecoregion (Flesch 2003, pp. 39-42; AGFD 2008a, p. 6). 
Long-term monitoring of pygmy-owl sites in northern Sonora indicates 
that the extended drought has resulted in reduced occupancy at 
monitored sites (Flesch 2008, pp. 4-5). Pygmy-owl survivorship is tied 
to precipitation (Flesch 2008, pp. 5-6; Service 2004, p. 1). As in 
Arizona, drought has negatively affected the numbers and distribution 
of pygmy-owls on the landscape within the analysis area (Flesch 2008, 
pp. 5-6). While data adequate to define population trends in Sonora, 
Mexico, are lacking, field data indicate that pygmy-owls in the 
southern portions of the State (within thornscrub and tropical 
deciduous forests) are common and likely number on the order of 
thousands, while further north within the Sonoran Desert Ecoregion, 
they are fewer in number, more patchily distributed, and likely number 
on the order of hundreds (Flesch 2003, pp. 39-42; AGFD 2008a, p. 6).

Significance of the Sonoran Desert Ecoregion

    This part of the pygmy-owl's range contains habitat that meet the 
needs of the pygmy-owl for reproduction and survival, and can support 
self-sustaining population groups. It also provides a mosaic of 
connected habitat maintaining dispersal and genetic exchange among 
subpopulations. The habitat found in this portion of the range may 
become increasingly important if the predictions about climate change 
prove correct. As hotter, drier conditions prevail, this area, which 
already provides habitat under these conditions, may provide the 
largest, most contiguous blocks of higher quality habitat if the 
wetter, more tropical habitats (thornscrub and tropical deciduous 
forests) are reduced due to climate change. Conditions in the Sonoran 
desert are also likely to become hotter and drier. However, the 
population groups of pygmy-owls found

[[Page 61892]]

in the Sonoran Desert Ecoregion are already adapted to the drier 
climate that is likely to become more widespread under current climate 
change scenarios and, therefore, this shift in temperature and 
precipitation may have a reduced effect on pygmy-owls in this area. 
Saguaros and other columnar cacti may experience range-shifts 
associated with climate change, however, there is much uncertainty 
associated with the current models of individual species responses to 
climate change. Therefore, predictions about the decline of columnar 
cacti are too speculative to consider in this finding. This population 
group of pygmy-owls is likely to become a more significant contributor 
to the long-term viability of this species.
    Given the presumed adaptation of this segment of the population to 
drier, more extreme conditions, we considered whether the demographic 
characteristics of this population might be important for the species 
to recover from predicted changes in the ecosystem due to climate 
change. Although birds in every terrestrial habitat will be affected by 
climate change, birds in arid lands show lower overall vulnerability to 
the effects of climate change (NABCI 2010). Pygmy-owls in the Sonoran 
Desert Ecoregion may be more likely to be able to provide population 
support for the remainder of its range. Therefore, demographic 
characteristics and population size within this portion of the range 
might allow for at least partial recovery of pygmy-owl populations 
within this portion of the range following disturbance events.
    Pygmy-owls are secondary cavity nesters, using cavities excavated 
in trees and cacti. Within the Sonoran Desert Ecoregion, pygmy-owls 
typically nest in large, columnar cacti found throughout the area. The 
Sonoran Desert Ecoregion contains the greatest concentration of large 
columnar cacti (saguaro, organ pipe, hecho) anywhere in the range of 
the pygmy-owl. While other areas to the south of this portion of the 
range also contain large, columnar cacti, they do not occur in as high 
of densities, nor are they as extensively distributed. In other 
portions of its range, the pygmy-owl nests in tree cavities; therefore, 
this aspect of the pygmy-owl's life history requirements is not 
exclusive to columnar cacti, but it is an important and necessary 
element in this part of its range because nesting in saguaros reduces 
the impacts to eggs and nestlings from the temperature extremes and 
predation found in this portion of the range.
    There is some information indicating that this subdivision of the 
western part of the range is different genetically than the remainder 
of the range. Proudfoot (2006a, p. 7) indicates that pygmy-owls in this 
portion of the range share no haplotypes with populations in Texas or 
in the remainder of Mexico. Using information in Proudfoot et al. 
(2006a, pp. 6-9 and 2006b, pp. 5-7), we have determined that the 
Arizona/Sonora pygmy-owls contribute approximately 10 percent of the 
species total mitochondrial DNA (mtDNA) variation and 5 percent of the 
total alleles (gene types) detected in their study (Service 2009c, p. 
1). This data analysis indicates that this part of the range does have 
unique alleles and contributes to the genetic variation within the 
range of the pygmy-owl. There is evidence of restricted gene flow 
between the Arizona/western Mexico and Texas/eastern Mexico populations 
(Cicero 2008, p. 2; Oyler-McCance 2008, pp. 1-2; Dumbacher 2008, p. 9).
    We have found that the Sonoran Desert Ecoregion has unique habitat 
characteristics and the pygmy-owls in this area possess some unique 
behavioral and genetic adaptations to this area. Next, we evaluated 
whether, should this portion of the range theoretically be extirpated, 
the remaining portion of the pygmy-owl's current range would be in 
danger of extinction. This evaluation focused on the pygmy-owl's 
rangewide population status and the importance of this part of the 
range to the entire range.
    There is general consensus in the literature and other reports that 
pygmy-owls remain common throughout most of the areas of Mexico south 
of Sonora and Texas. As noted above, the population of pygmy-owls in 
this ecoregion is small and scattered, and thus represents only a small 
portion of the overall pygmy-owl population. The best available 
information does not indicate that, under the theoretical removal of 
the Sonoran Desert Ecoregion from the current range of the pygmy-owl, 
the remaining portion of the range is likely to become extinct. 
Therefore, we do not find the Sonoran Desert Ecoregion of the pygmy-owl 
to be significant, and thus it is not an SPR.
Sonoran Desert Ecoregion SPR Analyses in Relation to the Eastern and 
Western DPS's
    We determined that the eastern and western portions of the pygmy-
owl's current range represent DPSs; that is, we found that they are 
discrete and significant to the taxon as a whole (see DPS discussion 
above). We found that the best scientific and commercial information 
did not indicate that the negative impacts in these DPSs affect the 
pygmy-owl's status such that these DPSs warrant listing under the Act. 
However, because we found that these DPS configurations were 
appropriate under our DPS policy, we next evaluated whether the Sonoran 
Desert Ecoregion represents significant portions of the western and 
eastern DPSs respectively.

Potential Sonoran Desert Ecoregion SPR of the Western DPS

    The portion of the Sonoran Desert Ecoregion currently occupied by 
pygmy-owls represents approximately 33 percent of the Western DPS 
(Figure 3). Even though this is only approximately one-third of the 
Western DPS, this portion of the DPS may provide important 
contributions to population numbers, genetic diversity, and status of 
the pygmy-owls within this DPS.
    In considering the portion of the western DPS outside of the 
Sonoran Desert Ecoregion and whether it may be in danger of extinction, 
we find it is likely that the population of pygmy-owls in this area is 
large enough to withstand environmental catastrophes and random 
perturbations. This is because the area outside of the Sonoran Desert 
Ecoregion represents approximately 67 percent of the DPS, and it likely 
supports a higher proportion of the overall population than the Sonoran 
Desert Ecoregion, because this portion of the DPS is characterized by 
thornscrub and tropical deciduous forest communities, which have been 
documented to support higher numbers and densities of pygmy-owls than 
Sonoran desertscrub communities (Swarth 1914, p. 31; Karalus and Eckert 
1974, p. 218; Monson and Phillips 1981, pp. 71-72; Johnsgard 1988, 
Enriquez-Rocha et al. 1993, p. 158; Proudfoot 1996, p. 75; Proudfoot 
and Johnson 2000, p. 5). The production and population growth of the 
pygmy-owls outside the Sonoran Desert Ecoregion are likely high enough 
to maintain viability of the population under current conditions. 
Because the Sonoran Desert Ecoregion occurs at the northern end of the 
Western DPS, the theoretical loss of that portion would not result in 
fragmentation of the DPS in a way that would affect movements and 
connectivity of the pygmy-owl population.
    However, the theoretical loss of a third of the range might 
represent a significant loss of important habitat and genetic 
diversity, affecting the redundancy and representation of the overall 
pygmy-owl population, and possibly affect the remaining portion of the 
population by reducing metapopulation support including

[[Page 61893]]

genetic adaptation and demographic rescue. The current genetic 
structure of the western DPS indicates that there is population 
movement within the DPS and, as a consequence, exchange of genetic 
material among population groups, even though the distribution of 
pygmy-owls on the landscape is patchy. Removal of approximately 33 
percent of the DPS might reduce the viability and potential for long-
term survival of the remaining portion of the DPS. For example, the 
Sonoran Desert Ecoregion supports the portion of the DPS population 
that is adapted to the unique environment of the Sonoran Desert. Loss 
of this segment of the population might substantially decrease the 
genetic diversity of the overall DPS to the point that the pygmy-owl 
may not be able to adapt to what may be the predominant vegetation 
community under the predicted effects of climate change. However, the 
thornscrub and tropical deciduous forest communities have already been 
substantially reduced, and this reduction and fragmentation is likely 
to continue. Sonoran desertscrub will likely expand to the north and 
south as climates to the north become warmer and climates to the south 
become drier (Weiss and Overpeck 2005, p. 2074).
    Pygmy-owl adaptations documented in the Sonoran Desert Ecoregion 
include the use of saguaro cavities as nest sites, paler plumage 
coloration, ability to obtain moisture from prey rather than free-
standing water, and the ability to select nest locations that maintain 
productivity during drought conditions (AGFD 2008a, pp. 1-2 and b, pp. 
3-7; Flesch 2008, p. 3; Flesch and Steidl 2010, p. 1021). The ability 
of the western DPS to adapt to impacts from climate change may be 
substantially reduced with the theoretical loss of the Sonoran Desert 
Ecoregion.
    The Sonoran Desert Ecoregion population is characterized by lower 
numbers and density of pygmy-owls. This is likely the result of reduced 
habitat quality and location of this population group at the northern 
extent of the Western DPS. While this population may be considered 
marginal, it is important to recognize that marginal populations may 
have a high adaptive significance to the species as a whole, and 
marginal habitat conservation, preservation and management is one of 
the best ways to conserve genetic diversity and resources (Scudder 
1989, p. 1). The portion of the western DPS outside of the Sonoran 
Desert Ecoregion may lack sufficient resiliency to meet future 
environmental changes that are already manifesting themselves within 
this DPS. However, the pygmy-owl is somewhat of a habitat generalist 
and, if impacts to habitat occur over an extended period of time, these 
populations may still be able to adapt to environmental changes in this 
DPS.
    The primary vegetation communities found outside of the Sonoran 
Desert Ecoregion in the Western DPS, thornscrub and subtropical dry 
forests, are under significant stress. As discussed above, thornscrub 
and subtropical dry forests are among the most threatened vegetation 
communities in Mexico. Loss of dry tropical forest occurs on as great, 
or greater, scale than the loss of tropical rain forests (Trejo and 
Dirzo 2000, p. 133). Only approximately two percent of the original 
distribution of subtropical dry forests remains in Mesoamerica, 
including Mexico. Some areas of intact dry tropical forest remain on 
steep slopes within the western DPS (Allnutt 2001, p. 3; Lugo 1999, p. 
4). However, the topography of such slopes, above 1,200 m (4,000), 
renders these areas unsuitable for occupancy by pygmy-owls. In areas 
occupied by pygmy-owls, dry tropical forests are threatened by 
woodcutting, clearing for agriculture, urbanization, and impacts from 
invasive species. Urbanization is increasing, particularly in the 
southern portion of the Western DPS (Lugo 1999, p. 2; Trejo and Dirzo 
2000, p. 133). In Mexico specifically, only approximately 27 percent of 
the original cover of seasonally dry forest remains intact (Trejo and 
Dirzo 2000, p. 139).
    In addition, increasing temperatures due to climate change pose a 
serious threat to subtropical dry forests due to the transitional 
nature of the community, and the narrow temperature and precipitation 
requirements of many of its native species (Allnutt 2001, p. 4). Trejo 
and Dirzo (2000, p. 140) predicted that, under current rates of 
deforestation, by the year 2030, intact seasonally dry forests would be 
reduced to 10 percent of their original area. Additionally, the 
remaining 10 percent would likely be characterized by small, vegetation 
islands separated from each other, causing significant ecological 
repercussions at the genetic, ecological, and ecosystem function levels 
of the ecoregion. Protected areas in Mexico that include seasonally dry 
forests are few and total less than 10 percent of the remaining, intact 
forest areas in Mexico (Trejo and Dirzo 2000, p. 140). This loss and 
fragmentation of habitat, and the influence of climate change on the 
remaining areas of native habitat, may substantially reduce the 
availability of pygmy-owl habitat and, consequently, pygmy-owl 
populations in the foreseeable future.
    We acknowledge that the Sonoran Desert Ecoregion represents an 
important portion of the Western DPS, and of the taxon as a whole. 
However, in order to find that the portion of the western DPS in the 
Sonoran Desert Ecoregion is significant under our SPR policy, our 
position is that its contribution to the viability of the species must 
be so important that, without that portion, the pygmy-owl would be in 
danger of extinction. As noted above in the discussion under Sonoran 
Desert Ecoregion SPR Analysis, even though pygmy-owls in this area 
possess some unique behavioral and genetic adaptations, the population 
of pygmy-owls in this ecoregion is small and scattered, and thus 
represents only a small portion of the overall pygmy-owl population. 
The best available information does not indicate that, if the Sonoran 
Desert Ecoregion portion of the pygmy-owl's range is extirpated, the 
remaining portion of the Western DPS is likely to become extinct. 
Therefore, we do not find the Sonoran Desert Ecoregion of the pygmy-owl 
to be significant, and thus it is not an SPR.
SPR Conclusion
    In summary, we have thoroughly analyzed all potentially-listable 
entities of the pygmy-owl. For the reasons described above, we find 
that the pygmy-owl is not in danger of extinction now, nor is it likely 
to become endangered within the foreseeable future, throughout all or 
any significant portion of its range. Therefore, listing the pygmy-owl 
as endangered or threatened under the Act is not warranted at this 
time.
    We request that you submit any new information concerning the 
status of, or threats to, the pygmy-owl to our Arizona Ecological 
Services Office (see ADDRESSES) whenever it becomes available. New 
information will help us monitor the pygmy-owl and encourage management 
of this subspecies and its habitat. If an emergency situation develops 
for the pygmy-owl or any other species, we will act to provide 
immediate protection.

References Cited

    A complete list of all references cited in this document is 
available on the Internet at http://www.regulations.gov and upon 
request from the Arizona Ecological Services Office (see ADDRESSES).

Authors

    The primary authors of this notice are the staff members of the 
Arizona

[[Page 61894]]

Ecological Services Office (see FOR FURTHER INFORMATION CONTACT).

Authority

    The authority for this action is section 4 of the Endangered 
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: September 27, 2011.
Rowan W. Gould,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2011-25565 Filed 10-4-11; 8:45 am]
BILLING CODE 4310-55-P