[Federal Register Volume 84, Number 196 (Wednesday, October 9, 2019)]
[Rules and Regulations]
[Pages 54436-54463]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-22096]

[[Page 54435]]

Vol. 84


No. 196

October 9, 2019

Part V

Department of the Interior


Fish and Wildlife Service


50 CFR Part 17

Endangered and Threatened Wildlife and Plants; Removing the Kirtland's 
Warbler From the Federal List of Endangered and Threatened Wildlife; 
Final Rule

Federal Register / Vol. 84 , No. 196 / Wednesday, October 9, 2019 / 
Rules and Regulations

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Fish and Wildlife Service

50 CFR 17

[Docket No. FWS-R3-ES-2018-0005; FXES11130900000]
RIN 1018-BC01

Endangered and Threatened Wildlife and Plants; Removing the 
Kirtland's Warbler From the Federal List of Endangered and Threatened 

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.


SUMMARY: Under the authority of the Endangered Species Act of 1973, as 
amended (ESA), we, the U.S. Fish and Wildlife Service (Service), are 
removing the Kirtland's warbler (Setophaga kirtlandii) from the Federal 
List of Endangered and Threatened Wildlife (List) due to recovery. This 
determination is based on a thorough review of the best available 
scientific and commercial information, which indicates that the threats 
to the species have been eliminated or reduced to the point that the 
species has recovered and no longer meets the definition of endangered 
or threatened under the ESA. This rule also announces availability of a 
post-delisting monitoring plan for Kirtland's warbler.

DATES: This rule is effective November 8, 2019.

ADDRESSES: This final rule and the post-delisting monitoring plan are 
available on the internet at http://www.regulations.gov under Docket 
No. FWS-R3-ES-2018-0005 or https://ecos.fws.gov. Comments and materials 
we received, as well as supporting documentation we used in preparing 
this rule, are available for public inspection at http://www.regulations.gov. Comments, materials, and documentation that we 
considered in this rulemaking will be available by appointment, during 
normal business hours at: U.S. Fish and Wildlife Service, Michigan 
Ecological Services Field Office, 2651 Coolidge Road, Suite 101, East 
Lansing, MI 48823; telephone 517-351-2555.

FOR FURTHER INFORMATION CONTACT: Scott Hicks, Field Supervisor, 
Michigan Ecological Services Field Office, 2651 Coolidge Road, Suite 
101, East Lansing, MI 48823; telephone 517-351-2555. If you use a 
telecommunications device for the deaf (TDD), please call the Federal 
Relay Service at 800-877-8339.


Executive Summary

    Why we need to publish a rule. Under the Endangered Species Act, a 
species may be removed from the List (``delisted'') if it is determined 
that it has recovered and is no longer endangered or threatened. 
Delisting can be completed only by issuing a rule.
    This rule removes the Kirtland's warbler (Setophaga kirtlandii) 
from the List.
    Basis for action. Under the ESA, we determine that a species is an 
endangered or threatened species based on any of five factors: (A) The 
present or threatened destruction, modification, or curtailment of its 
habitat or range; (B) overutilization for commercial, recreational, 
scientific, or educational purposes; (C) disease or predation; (D) the 
inadequacy of existing regulatory mechanisms; or (E) other natural or 
manmade factors affecting its continued existence. We must consider the 
same factors in delisting a species. We have determined that the 
primary threats to the Kirtland's warbler have been reduced or managed 
to the point that the species is recovered.
    Peer review and public comment. We sought comments on the proposed 
delisting rule and draft post-delisting monitoring plan from 
independent specialists to ensure that this rule is based on 
scientifically sound data, assumptions, and analyses. We also 
considered all comments and information we received during the proposed 
delisting rule's comment period.

Previous Federal Actions

    On April 12, 2018, we published a proposed rule to remove 
Kirtland's warbler from the List (83 FR 15758). Please refer to that 
proposed rule for a detailed description of previous Federal actions 
concerning this species.

Species Information


    The Kirtland's warbler is a songbird classified in the Order 
Passeriformes, Family Parulidae. This species was originally described 
in 1852, and named Sylvicola kirtlandii (Baird 1872, p. 207). The 
American Ornithologists' Union Committee on Classification and 
Nomenclature-North and Middle America recently changed the 
classification of the Parulidae, which resulted in three genera 
(Parula, Dendroica, and Wilsonia) being deleted and transferred to the 
genus Setophaga (Chesser et al. 2011, p. 606). This revision was 
adopted by the Service on February 12, 2014 (78 FR 68370; November 14, 


    The Kirtland's warbler is a neotropical migrant that breeds in jack 
pine (Pinus banksiana) forests in northern Michigan, Wisconsin, and 
Ontario. This species has one of the most geographically restricted 
breeding distributions of any mainland bird in the continental United 
States. Breeding habitat within the jack pine forest is both highly 
specific and disturbance-dependent, and likely was always limited in 
extent (Mayfield 1960, pp. 9-10; Mayfield 1975, p. 39). Similarly, the 
known wintering range is primarily restricted to The Bahamas (Cooper et 
al. 2019, p. 83).
    Kirtland's warblers are not evenly distributed across their 
breeding range. Female Kirtland's warblers are often observed with 
singing males; therefore, nesting is generally assumed to occur at most 
sites where singing males are present (Probst et al. 2003, p. 369; 
MDNR, USFWS, USFS, unpubl. data). More than 98 percent of all singing 
males have been counted in the northern Lower Peninsula of Michigan 
since population monitoring began in 1951 (Michigan Department of 
Natural Resources (MDNR), Service (USFWS), U.S. Forest Service (USFS), 
unpubl. data). The core of the Kirtland's warbler's breeding range is 
concentrated in five counties in northern lower Michigan (Ogemaw, 
Crawford, Oscoda, Alcona, and Iosco), where nearly 85 percent of the 
singing males were recorded between 2000 and 2015, with over 30 percent 
counted in Ogemaw County alone and over 21 percent in just one township 
during that same time period (MDNR, USFWS, USFS, unpubl. data).
    Kirtland's warblers have been observed in Ontario periodically 
since 1900 (Samuel 1900, pp. 391-392) and in Wisconsin since the 1940s 
(Hoffman 1989, p. 29). Systematic searches for the presence of 
Kirtland's warblers in States and provinces adjacent to Michigan, 
however, did not begin until 1977 (Aird 1989, p. 32; Hoffman 1989, p. 
1) and have not been conducted consistently across the years. Shortly 
after these searches began, male Kirtland's warblers were found during 
the breeding season in Ontario in 1977 and Quebec in 1978 (Aird 1989, 
pp. 32-35), Wisconsin in 1978 (Tilghman 1979, p. 19), and the Upper 
Peninsula of Michigan in 1982 (Probst 1985, p. 11). Nesting was 
confirmed in the Upper Peninsula in 1996 (Weinrich 1996, p. 2; Weise 
and Weinrich 1997, p. 2), and in Wisconsin and Ontario in 2007 (Richard 
2008, pp. 8-10; Trick et al. 2008, pp. 97-98). Singing males have been 
observed in the

[[Page 54437]]

Upper Peninsula annually since 1993, with the majority of observations 
in the central and eastern Upper Peninsula (MDNR, USFWS, USFS, unpubl. 
data). In Wisconsin, nesting has been confirmed in Adams County every 
year since 2007 and has expanded into Marinette and Bayfield Counties 
(USFWS 2017, pp. 2-4). Scattered observations of mostly solitary birds 
have also occurred in recent years at several other sites in Douglas, 
Vilas, Washburn, and Jackson Counties in Wisconsin. Similarly, in 
Ontario, nesting was confirmed in Renfrew County from 2007 to 2016 
(Richard 2013, p. 152; Tuininga 2017, pers. comm.), and reports of 
Kirtland's warblers present during the breeding season have occurred in 
recent years in both northern and southern Ontario (Tuininga 2017, 
pers. comm.).
    The current distribution of breeding Kirtland's warblers 
encompasses the known historical breeding range of the species based on 
records of singing males observed in Michigan's northern Lower 
Peninsula, Wisconsin, and Ontario (Walkinshaw 1983, p. 23). In 
Michigan's northern Lower Peninsula, the Kirtland's warbler's breeding 
habitat is spread over an approximately 15,540-square-kilometer (km) 
(6,000-square-mile) non-contiguous area. In 2015, the number of singing 
males confirmed in Wisconsin (19), Ontario (20), and the Upper 
Peninsula (37) represented approximately 3 percent of the total singing 
male population (Environment Canada, MDNR, USFS, USFWS, Wisconsin 
Department of Natural Resources (WDNR), unpubl. data), demonstrating 
the species' reliance on their core breeding range in Michigan's 
northern Lower Peninsula. The number of Kirtland's warblers that could 
ultimately exist outside of the core breeding range is unknown; 
however, these peripheral individuals do contribute to a wider 
    On the wintering grounds, Kirtland's warblers are more difficult to 
detect and are infrequently observed. Kirtland's warblers are unevenly 
distributed across the landscape; they tend to hide in low-lying, dense 
vegetation, and males do not generally sing during the winter (Currie 
et al. 2003, pp. 1-2; Currie et al. 2005a, p. 97). Kirtland's warblers 
winter largely within The Bahamas (Mayfield 1996, pp. 36-38; Lee et al. 
1997, p. 21; Stone 1986, p. 2). The Bahamas is an archipelago of 
approximately 700 low-lying islands stretching more than 1,046 km (650 
miles) from near the eastern coast of Florida to the southeastern tip 
of Cuba. The central islands, particularly Eleuthera and Cat Islands, 
support the largest known population of wintering Kirtland's warblers 
(Sykes and Clench 1998, pp. 249-250; Cooper et al. 2019, p. 85). 
Wintering Kirtland's warbler have also been observed in The Bahamas on 
The Abacos, Andros, Cat Island, Crooked Island, Eleuthera, The Exumas, 
Grand Bahama Island, Long Island, and San Salvador (Blanchard 1965, pp. 
41-42; Cooper, unpubl. data; Cooper et al. 2019, p. 85; Ewert and 
Wunderle, unpubl. data; Haney et al. 1998, p. 202; Hundley 1967, pp. 
425-426; Jones et al. 2013, pp. 638-641; Mayfield 1972, pp. 347-348; 
Mayfield 1996, pp. 37-38; Sykes and Clench 1998, p. 250).
    Although the central islands of The Bahamas support the greatest 
number of overwintering Kirtland's warblers, less frequent sightings 
have been reported elsewhere in the Caribbean, including sightings from 
northern Dominican Republic, coastal Mexico (Haney et al. 1998, p. 
205), Bermuda (Amos 2005, p. 3), Cuba (Isada 2006, p. 462; Sorenson and 
Wunderle 2017), Florida (Cooper et al. 2019, p. 85), and Jamaica 
(Weidensaul 2019). These sightings may represent vagrants and do not 
necessarily represent an extension of the overwintering range.
    Recent data from winter playback surveys, citizen scientists, and 
light-level geolocators also indicate that the majority of 
overwintering Kirtland's warblers are found in the central Bahamas, 
with fewer birds overwintering in the western and eastern Bahamas and 
Cuba (Cooper et al. 2017, pp. 209-211; Cooper et al. 2019, pp. 84-85).
    Although the central islands of The Bahamas support the greatest 
number of overwintering Kirtland's warblers, less frequent sightings 
have been reported elsewhere in the Caribbean. Of 107 accessible 
reports, only 3 originated from outside of The Bahamas: Two sightings 
from northern Dominican Republic, and one sighting from coastal Mexico 
(Haney et al. 1998, p. 205). In addition, recent winter reports of 
solitary individuals have originated from Bermuda (Amos 2005, p. 3), 
Cuba (Isada 2006, p. 462; Sorenson and Wunderle 2017), Florida (Cooper 
et al. 2019, p. 85), and Jamaica (Weidensaul 2019), possibly 
representing vagrants and not necessarily representative of an 
extension of the overwintering range.
    Although the known wintering range appears restricted primarily to 
The Bahamas, many of the islands in the Caribbean basin are uninhabited 
by people, may be overgrown and difficult to access, or have had 
limited avian survey efforts, which may constrain our ability to 
comprehensively describe the species' wintering distribution. 
Kirtland's warblers readily shift sites on the wintering grounds based 
on habitat availability and food resources, and they colonize new areas 
following disturbance (Wunderle et al. 2007, p. 123; Wunderle et al. 
2010, p. 134; Wunderle et al. 2014, p. 44). Suitable habitat may exist 
on other islands, both within The Bahamas and elsewhere in the 
Caribbean basin, potentially providing habitat and buffering against 
the effects of catastrophic events such as hurricanes. However, the 
full extent and availability of suitable habitat on the wintering 
grounds has not been measured outside of the more-studied island of 
Eleuthera (Wunderle 2018, pers. comm.).

Breeding Habitat

    The Kirtland's warbler's breeding habitat consists of jack pine-
dominated forests with sandy soil and dense ground cover (Walkinshaw 
1983, p. 36), most commonly found in northern lower Michigan, with 
scattered locations in the Upper Peninsula of Michigan, Wisconsin, and 
Ontario. Jack pine-dominated forests of the northern Great Lakes region 
historically experienced large, frequent, and catastrophic stand-
replacing fires (Cleland et al. 2004, p. 313). These fires occurred 
approximately every 60 years, burned approximately 85,420 hectares (ha) 
(211,077 acres (ac)) per year, and resulted in jack pine comprising 53 
percent of the total land cover (Cleland et al. 2004, pp. 315-317). 
Modern wildfire suppression has since increased the average fire return 
interval within this same landscape to approximately 775 years, 
decreased the amount of area burned to approximately 6,296 ha (15,558 
ac) per year, and reduced the contribution of jack pine to 37 percent 
of the current land cover (Cleland et al. 2004, p. 316). The overall 
effect has been a reduction in the extent of dense jack pine forest, 
and in turn, the Kirtland's warbler's breeding habitat.
    Kirtland's warblers generally occupy jack pine stands that are 5 to 
23 years old and at least 12 ha (30 ac) in size (Donner et al. 2008, p. 
470). The most obvious difference between occupied and unoccupied 
stands is the percent canopy cover (Probst 1988, p. 28). Stands with 
less than 20 percent canopy cover are rarely used for nesting (Probst 
1988, p. 28). Tree canopy cover reflects overall stand structure, 
combining individual structural components such as tree stocking, 
spacing, and height factors (Probst 1988, p. 28). Tree canopy cover, 
therefore, may be an important environmental cue for Kirtland's 
warblers when selecting nesting areas.

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    Occupied stands usually occur on dry, excessively drained, 
nutrient-poor glacial outwash sands (Kashian et al. 2003, pp. 151-153). 
Stands are structurally homogeneous with trees ranging 1.7 to 5.0 
meters (m) (5.5 to 16.4 feet (ft)) in height and are generally of three 
types: Wildfire-regenerated, planted, and unburned-unplanted (Probst 
and Weinrich 1993, p. 258). Wildfire-regenerated stands occur naturally 
following a stand-replacing fire from serotinous seeding (seed cones 
remain closed on the tree with seed dissemination in response to an 
environmental trigger, such as fire). Planted stands are stocked with 
jack pine saplings after a clear cut. Unburned-unplanted stands 
originate from clearcuts that regenerate from non-serotinous, natural 
seeding, and thus do not require fire to release seeds.
    Optimal habitat is characterized as large stands (more than 32 ha 
(80 ac)) composed of 8- to 20-year-old jack pines that regenerated 
after wildfires, with 27 to 60 percent canopy cover, and more than 
5,000 stems per hectare (2,023 stems per acre) (Probst and Weinrich 
1993, pp. 262-263). The poor quality and well-drained soils reduce the 
risk of nest flooding and maintain low shrubs that provide important 
cover for nesting and brood-rearing. Yet as jack pine saplings grow in 
height, percent canopy cover increases, causing self-pruning of the 
lower branches and changes in light regime, which diminishes cover of 
small herbaceous understory plants (Probst 1988, p. 29; Probst and 
Weinrich 1993, p. 263; Probst and Donnerwright 2003, p. 331). 
Kirtland's warblers select nest sites with higher jack pine densities, 
higher percent cover of blueberry, and lower percent cover of woody 
debris than would be expected if nests were placed at random (Bocetti 
1994, p. 122). Due to edge effects associated with low area-to-
perimeter ratios, predation rates may be higher for Kirtland's warblers 
nesting in small patches bordered by mature trees than in large patches 
(Probst 1988, p. 32; Robinson et al. 1995, pp. 1988-1989; Helzer and 
Jelinski 1999, p. 1449). Foraging requirements may also be negatively 
influenced as jack pines mature (Fussman 1997, pp. 7-8).
    Conversely, marginal habitat is characterized as jack pine stands 
with at least 20 to 25 percent tree canopy cover and a minimum density 
of 2,000 stems per hectare (809 stems per acre, Probst and Weinrich 
1993, pp. 261-265; Nelson and Buech 1996, pp. 93-95), and is often 
associated with unburned-unplanted areas (Donner et al. 2010, p. 2). 
The main disadvantage of marginal habitat is reduced pairing success 
(Probst and Haynes 1987, p. 237); however, Kirtland's warblers 
successfully reproduce in areas with smaller percentages of jack pine 
and with significant components of red pine (Pinus resinosa) and pin 
oak (Quercus palustris) in Wisconsin and Canada (Mayfield 1953, pp. 19-
20; Orr 1975, pp. 59-60; USFWS 1985, p. 7; Fussman 1997, p. 5; Anich et 
al. 2011, p. 201; Richard 2013, p. 155; Richard 2014, p. 307). Use of 
these areas in Michigan is rare and occurs for only short durations 
(Huber et al. 2001, p. 10). In Wisconsin, however, breeding has 
occurred primarily in red pine plantations that have experienced 
extensive red pine mortality and substantial natural jack pine 
regeneration (Anich et al. 2011, p. 204). Preliminary investigation 
(Anich et al. 2011, p. 204) suggests that, in this case, a matrix of 
openings and thickets has produced conditions suitable for Kirtland's 
warblers, and that the red pine component may actually prolong the use 
of these sites due to a longer persistence of low live branches on red 
pines. Habitat conditions in documented Kirtland's warbler breeding 
areas in Ontario had ground cover similar to breeding sites in Michigan 
and Wisconsin, although tree species composition was more similar to 
Wisconsin sites than Michigan sites (Richard 2014, p. 306). The tree 
species composition at the Canadian sites also had high levels of red 
pine (up to 71 percent), similar to the plantations in Wisconsin (Anich 
et al. 2011, p. 201; Richard 2014, p. 307).
    Habitat management to benefit Kirtland's warblers began as early as 
1957 on State forest land and 1962 on Federal forest land (Mayfield 
1963, pp. 217-219; Radtke and Byelich 1963, p. 209). Efforts increased 
in 1981, with the establishment of an expanded habitat management 
program to supplement wildfire-regenerated habitat and ensure the 
availability of relatively large patches of early successional jack 
pine forest for nesting (Kepler et al. 1996, p. 16). In the late 1980s, 
maturation of habitat generated through wildfire contributed to a 
higher percentage of the total suitable habitat available to the 
Kirtland's warbler compared to other types of habitat (Donner et al. 
2008, p. 472). By 1992, artificially regenerated plantation habitat was 
nearly twice as abundant as wildfire habitat, and increased to triple 
that of wildfire habitat by 2002 (Donner et al. 2008, p. 472). From 
1979 to 1994, the majority of singing males were found in wildfire-
generated habitat (Donner et al. 2008, p. 474). By 1994, responding to 
a shift in available nesting habitat types, males redistributed out of 
habitat generated by wildfire and unburned-unplanted habitat and into 
plantation (planted) habitat. From 1995 to 2004, males continued 
redistributing into plantations from wildfire habitat, and 85 percent 
of males were found in plantation habitat by 2004 (Donner et al. 2008, 
p. 475). This redistribution of males into plantations also resulted in 
males being more evenly distributed across the core breeding range than 
in previous years. Since 2004, the majority of Kirtland's warblers 
continue to nest in plantations (USFWS, unpubl. data).
    The amount of available suitable habitat has also increased 
significantly in the past 40 years due to these increased efforts by 
land management agencies. The goal for 51,638 ha (127,600 ac) of 
available habitat to support a recovered Kirtland's warbler population 
was initially set out in the 1981 Management Plan for Kirtland's 
Warbler Habitat (USFS and MDNR 1981, p. 18). Of this total, 
approximately 29,987 ha (74,100 ac) of Michigan State forest lands and 
about 21,650 ha (53,500 ac) of Federal forest lands were identified as 
lands suitable and manageable for Kirtland's warbler breeding habitat. 
That plan also provided prescriptions and guidelines to be used in 
protecting and improving identified nesting habitat. Contiguous stands 
or stands in close proximity were grouped into 23 areas referred to as 
Kirtland's Warbler Management Areas (KWMAs). KWMAs are administrative 
boundaries that describe parcels of land dedicated to and managed for 
Kirtland's warbler breeding habitat. The KWMAs were further subdivided 
into cutting blocks containing 200 or more acres of contiguous stands. 
These acreages were determined by factoring an average population 
density of one breeding pair per 12 ha (30 ac) into a 45- to 50-year 
commercial harvest rotation, with the goals of producing suitable 
habitat as well as marketable timber (USFWS 1985, p. 21). Data 
collected from the annual singing male census from 1980 to 1995 
indicated that a breeding pair used closer to 15 ha (38 ac) within 
suitably aged habitat (Bocetti et al. 2001, p. 1). Based on these data, 
in 2002, the Kirtland's Warbler Recovery Team (Recovery Team) 
recommended increasing the total amount of managed habitat to 76,890 ha 
(190,000 ac) (Ennis 2002, p. 2). Habitat management is currently 
conducted on approximately 88,788 ha (219,400 ac) of jack pine forest 
within MDNR (36,705 ha (90,700 ac)), USFS (49,372 ha; 122,000 ac), and 
Service lands (2,711 ha (6,700 ac)) throughout the northern Lower

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Peninsula and Upper Peninsula of Michigan (MDNR et al. 2015, pp. 22-
23), exceeding both the original and revised acreage goals.

Wintering Habitat

    On the wintering grounds, Kirtland's warblers occur in early 
successional scrublands, characterized by dense, low, broadleaf shrubs 
of varied foliage layers with small openings, resulting from natural or 
anthropogenic disturbances (locally known as low coppice) (Maynard 
1896, pp. 594-595; Challinor 1962, p. 290; Mayfield 1972, p. 267; 
Radabaugh 1974, p. 380; Mayfield 1992, p. 3; Mayfield 1996, pp. 38-39; 
Lee et al. 1997, p. 23; Haney et al. 1998, p. 207; Sykes and Clench 
1998, p. 256; Wunderle et al. 2007, p. 123; Wunderle et al. 2010, p. 
133). Kirtland's warblers predominantly overwinter in broadleaf scrub 
habitat, rather than pine-dominated habitats (Cooper et al. 2019, p. 
83). Suitable wintering habitat requires availability of a food source, 
often fruit plants such as Erithalis fruticosa and Lantana involucrata 
(see ``Diet and Foraging,'' below, for additional discussion) that are 
in fruit at the right time of year, as well as availability of water.
    Historically, Kirtland's warbler winter habitat was likely created 
when storm surges or other natural disturbances, such as wildfire, 
removed vegetation and leaf litter (Wunderle and Ewert 2018, p. 1; 
Wunderle 2018, pers. comm.), allowing for establishment of the 
preferred fruit plants (which are shade-intolerant) (Fleming et al. 
2015, p. 588). Human-caused disturbances may also produce suitable 
habitat for Kirtland's warblers. Although goats consume the preferred 
fruit plants, the plants readily regrow in open sunlight and persist, 
indicating goat grazing could be an effective means of setting back 
succession and creating or maintaining Kirtland's warbler habitat 
(Fleming et al. 2016, p. 287). Abandonment of garden plots or other 
cultivated lands are not likely to result in suitable Kirtland's 
warbler habitat, because the important fruit plants are shaded out by 
other, faster-growing plants (Wunderle et al., unpubl. data).
    Kirtland's warblers typically occupy wintering sites 3 to 28 years 
(the mean is approximately 14 years) after human disturbance (Wunderle 
et al. 2010, p. 127). As local food resources diminish in abundance, 
these sites may not be sufficient to sustain an individual for an 
entire winter; therefore, individuals must move widely from patch to 
patch, tracking changes in fruit abundance (Wunderle et al. 2007, p. 
123; Wunderle et al. 2010, p. 134; Wunderle et al. 2014, p. 44).

Migration and Stopover Habitat

    Spring departure from the wintering grounds is estimated to occur 
from late April to early May, and arrival on the breeding grounds 
occurs approximately 15 days later (Cooper et al. 2017, p. 212; 
Rockwell et al. 2012, p. 746; Ewert et al. 2012, p. 11). Male 
Kirtland's warblers have been observed arriving on the breeding grounds 
between May 1 and June 5 (Petrucha 2011, p. 17; Rockwell et al. 2012, 
p. 747), with the first females arriving a week or so after the first 
males (Mayfield 1960, pp. 41-42; Rockwell 2013, pp. 48-49).
    Fall migration of adult males begins in late September through late 
October and ends with arrival on the wintering grounds in mid-October 
to early November (Cooper et al. 2017, p. 212). The earliest recorded 
sighting in The Bahamas was August 20 (Robertson 1971, p. 48). Data 
from recovered geolocators showed that most Kirtland's warblers 
exhibited a loop migration, with fall migration occurring farther east 
than spring migration (Cooper et al. 2017, p. 214). Nearly all males 
departed the breeding grounds and flew in an easterly direction, 
spending time in southeastern Ontario or in the eastern Great Lakes 
region of the United States (Cooper et al. 2017, pp. 211, 213). Fall 
migration proceeded in a general southern direction, departing the 
mainland United States along the Carolina coastline (Cooper et al. 
2017, pp. 211, 213). Spring migration followed a more westerly path, 
with landfall occurring in Florida and Georgia (Cooper et al. 2017, pp. 
213, 216). An additional stopover site was identified in the western 
Lake Erie basin (Cooper et al. 2017, p. 216). An analysis of 562 
records of Kirtland's warblers observed during migration found that 
migration records were spread over most of the United States east of 
the Mississippi River, clustered around the Great Lakes and Atlantic 
Ocean coastlines (Petrucha et al. 2013, p. 383).
    Migrating Kirtland's warblers have been observed in a variety of 
habitats, including shrub/scrub, residential, park, orchard, woodland, 
and open habitats (Petrucha et al. 2013, p. 390). There is some 
evidence that dense vegetation less than 1.5 m (4.9 ft) in height may 
be important to migrating Kirtland's warblers (Stevenson and Anderson 
1994, p. 566). The majority of migration records (82 percent) described 
the habitat as shrub/scrub, similar in structure to what the species 
uses on the breeding and wintering grounds (Petrucha et al. 2013, p. 
Diet and Foraging
    On the breeding grounds, Kirtland's warblers are primarily 
insectivorous and forage by gleaning (plucking insects from) pine 
needles, leaves, and ground cover, occasionally making short sallies, 
hover-gleaning at terminal needle clusters, and gathering flying 
insects on the wing. Kirtland's warblers forage on a wide variety of 
prey items, including various types of larvae, moths, flies, beetles, 
grasshoppers, ants, aphids, spittlebugs, and blueberries (Mayfield 
1960, pp. 18-19; Fussman 1997, p. 33). Similar taxa have been 
identified from fecal samples from Kirtland's warblers, although 
homopterans (primarily spittlebugs), hymenopterans (primarily ants), 
and blueberries were proportionally greater in number than other taxa 
among samples collected from July to September (Deloria-Sheffield et 
al. 2001, p. 385). These differences in the relative importance of food 
items between spring foraging observations and late summer fecal 
samples may be temporal and may reflect a varied diet that shifts as 
food items become more or less available during the breeding season 
(Deloria-Sheffield et al. 2001, p. 386). Within nesting areas, 
arthropod numbers peak at the same time that most first broods reach 
the fledging stage (Fussman 1997, p. 27). Planted and wildfire-
regenerated habitats were extremely similar in terms of arthropod 
diversity, abundance, and distribution, suggesting that current habitat 
management techniques are effective in simulating the effects that 
wildfire has on food resources for Kirtland's warblers (Fussman 1997, 
p. 63).
    On the wintering grounds, Kirtland's warblers rely on a mixed diet 
of fruit and arthropods. During foraging observations, 69 percent of 
Kirtland's warblers consumed fruits, such as snowberry (Chiococca 
alba), wild sage (Lantana involucrata), and black torch (Erithalis 
fruticosa), with wild sage being the overwhelmingly predominant food 
choice (Wunderle et al. 2010, pp. 129-130). Despite variation in food 
availability among sites and winters, the proportion of fruit and 
arthropods in fecal samples of Kirtland's warblers was consistent 
(Wunderle et al. 2014, p. 25). Food abundance was a reliable predictor 
of site fidelity, with birds shifting location to sites with higher 
biomass of ripe fruit and ground arthropods during the late winter 
(Wunderle et al. 2014, p. 31).
    The average life expectancy of adult Kirtland's warblers is 
approximately 2.5

[[Page 54440]]

years (Walkinshaw 1983, pp. 142-143). The oldest Kirtland's warbler on 
record was an 11-year-old male, which, when recaptured in the Damon 
KWMA in 2005, appeared to be in good health and paired with a female 
(USFS, unpubl. data).
    Overall, Kirtland's warbler annual survival estimates are similar 
to those of other wood warblers (reviewed in Faaborg et al. 2010, p. 
12). Survival rates of the Kirtland's warbler varied by sex and age 
classes (Mayfield 1960, pp. 204-207; Walkinshaw 1983, pp. 123-143; 
Bocetti et al. 2002, p. 99; Rockwell et al. 2017, p. 723; Trick, 
unpubl. data). Based on mark-recapture data from 2006-2010 on breeding 
grounds in Michigan and from 2003-2010 on the wintering grounds in The 
Bahamas, the mean annual survival estimates for adults and yearlings 
were 0.58 and 0.55, respectively (Rockwell et al. 2017, pp. 719-721). 
Monthly survival probabilities were relatively high when birds were 
stationary on the wintering and breeding grounds, and were 
substantially lower during the migratory period, which has the highest 
mortality rate out of any phase of the annual cycle, accounting for 44 
percent of annual mortality (Rockwell et al. (2017, p. 722). Survival 
probability was positively correlated to March rainfall in the previous 
year, suggesting the effects of rain on the wintering grounds carried 
over to affect annual survival in subsequent seasons. Late winter 
rainfall in The Bahamas showed a positive effect on Kirtland's warblers 
corrected body mass (Wunderle et al. 2014, p. 47). Reduced rain can 
result in lower available food resources for Kirtland's warblers, which 
could result in poorer body condition, making them less likely to 
survive the subsequent spring migration (Rockwell et al. 2017, pp. 721-
722) and lowering reproductive success during the breeding season 
(Rockwell et al. 2012, p. 745).
    Historically, one of the largest factors influencing Kirtland's 
warbler's reproductive success was brood parasitism from brown-headed 
cowbirds (Molothrus ater). Brown-headed cowbirds are obligate brood 
parasites. Females remove an egg from a host species' nest and lay 
their own egg to be raised by the adult hosts, usually resulting in the 
death of the remaining host nestlings (Rothstein 2004, p. 375). Prior 
to initiation of the brown-headed cowbird management program (discussed 
in more detail under Factor E: Brood Parasitism), Kirtland's warblers 
averaged less than one young fledged per nest (Walkinshaw 1983, p. 
151). After brown-headed cowbird control efforts began in 1972, the 
estimated number of chicks fledged per nest (1972 to 1977) increased to 
2.67, with 63.3 percent nest success (Walkinshaw 1983, pp. 150-152). 
More recently, mean annual reproductive success of 3.3 fledglings per 
year per male has been observed (Rockwell et al. 2012, p. 748).
    From the information available, it appears that Kirtland's warblers 
display winter and breeding-ground panmixia (mixing of individuals 
across locations within the population). In 2007, eight birds examined 
from six different wintering sites on Eleuthera Island were found on 
breeding territories in the Damon KWMA in Ogemaw County, Michigan 
(Ewert, unpubl. data). Additionally, four other birds banded from one 
wintering site on Eleuthera Island were found on breeding territories 
across four counties in northern lower Michigan. Kirtland's warblers 
are also known to regularly move between KWMAs in northern lower 
Michigan during the breeding season (Probst et al. 2003, p. 371). 
Regardless of where they overwintered in The Bahamas (i.e., either Cat 
or Eleuthera Islands), Kirtland's warblers intermixed heavily on the 
breeding grounds and migrated to various sites throughout the breeding 
range, showing a weak connectivity between the breeding and wintering 
grounds (Cooper et al. 2018, pp. 5-6). These data suggest that the 
warbler's population exhibits panmictic (a group of interbreeding 
individuals where all individuals in the population are potential 
reproductive partners) rather than metapopulation (groups of 
interbreeding individuals that are geographically distinct) demographic 
characteristics (Esler 2000, p. 368).
    Analysis of microsatellite DNA markers from Kirtland's warblers in 
Oscoda County, Michigan, over three time periods (1903-1912, 1929-1955, 
and 2008-2009) showed no evidence of a genetic bottleneck in the oldest 
(1903-1912) sample, indicating that any population declines prior to 
that point may have been gradual (Wilson et al. 2012, pp. 7-9). 
Although population declines have been observed since then, there was 
only weak genetic evidence of a bottleneck in the two more recent 
samples (no bottleneck detected in two of three possible models for 
each sample). The study showed a slight loss of allelic richness 
between the oldest and more recent samples, but no significant 
difference in heterozygosity between samples and no evidence of 
inbreeding. Effective population size estimates varied depending on the 
methods used, but none was low enough to indicate that inbreeding or 
rapid loss of genetic diversity were likely in the future (Wilson et 
al. 2012, pp. 7-9). Based on the available data, genetic diversity does 
not appear to be a limiting factor for the Kirtland's warbler or 
indicate the need for genetic management at this time.

Abundance and Population Trends

    Prior to 1951, the size of the Kirtland's warbler population was 
extrapolated from anecdotal observations and knowledge about breeding 
and wintering habitat conditions. The Kirtland's warbler population may 
have peaked in the late 1800s, a time when conditions across the 
species' distribution were universally beneficial (Mayfield 1960, p. 
32). Wildfires associated with intensive logging, agricultural burning, 
and railroads in the Great Lakes region burned hundreds of thousands of 
acres, and vast portions were dominated by jack pine forests (Pyne 
1982, pp. 199-200, 214). Suitable winter habitat consisting of low 
coppice (early-successional and dense, broadleaf vegetation) was also 
becoming more abundant, due to a decrease in widespread commercial 
agriculture in The Bahamas after the abolition of slavery in 1834, 
resulting in former croplands converting to scrub (low coppice) (Sykes 
and Clench 1998, p. 245). During this time, Kirtland's warblers were 
found in greater abundance throughout The Bahamas than were found in 
previous decades, and reports of migratory strays came from farther 
north and west of the known migratory range, evidence of a larger 
population that would produce more migratory strays (Mayfield 1993, p. 
    Between the early 1900s and the 1920s, agriculture in the northern 
Great Lakes forests was being discouraged in favor of industrial tree 
farming, and systematic fire suppression was integrated into State and 
Federal policy (Brown 1999, p. 9). The estimated amount of jack pine on 
the landscape suitably aged for Kirtland's warblers had decreased to 
approximately 40,470 ha (100,000 ac) of suitable habitat in any one 
year (Mayfield 1960, p. 26). This reduction in habitat presumably 
resulted in fewer Kirtland's warblers from the preceding time period, 
and Kirtland's warblers were not observed in all stands of suitable 
conditions (Wood 1904, p. 10). Serious efforts to control forest fires 
in Michigan began in 1927 and resulted in a further reduction of total 
acres burned as the number and size of wildfires decreased (Mayfield 
1960, p. 26; Radtke and Byelich 1963, p.

[[Page 54441]]

210). By this time, brown-headed cowbirds had expanded from the 
shortgrass plains and become common within the Kirtland's warbler's 
nesting range due to clearing of land for settlement and farming in 
northern Michigan (Wood and Frothingham 1905, p. 49; Mayfield 1960, p. 
146), further contributing to the decline of Kirtland's warblers.

    Figure: Kirtland's warbler census results for each year in which a 
full census was completed (1951, 1961, 1971-2013, and 2015) (MDNR 
data). Note: A rangewide census was not conducted in the years 1952-
1960, 1962-1970, 2014, or 2016-2018.
    Comprehensive surveys (censuses) of the entire Kirtland's warbler 
population began in 1951. Because of the warbler's specific habitat 
requirements and the frequent, loud, and persistent singing of 
territorial males during the breeding season, it was possible to 
establish a singing male census (Ryel 1976, pp. 1-2). The census 
consists of an extensive annual survey of all known and potential 
breeding habitat to count singing males.
    Censuses were conducted in 1951, 1961, each year from 1971 to 2013, 
and 2015 (see figure, above). The 1951 census documented a population 
of 432 singing males confined to 28 townships in eight counties in 
northern lower Michigan (Mayfield 1953, p. 18). By 1971, the Kirtland's 
warbler population declined to approximately 201 singing males and was 
restricted to just 16 townships in six counties in northern lower 
Michigan (Probst 1986, pp. 89-90). Over the next 18 years, the 
Kirtland's warbler population level remained relatively stable at 
approximately 200 singing males but experienced record lows of 167 
singing males in 1974 and again in 1987. In response to conservation 
efforts, including artificial regeneration of jack pine habitat (see 
Breeding Habitat, above) and brown-headed cowbird trapping program, the 
population of Kirtland's warbler began to increase dramatically 
starting in the 1990s (see figure, above) and occupy a wider 
distribution across the landscape. The population reached a record high 
of 2,383 singing males in 2015, the year of the last full census (MDNR, 
USFS, USFWS, unpubl. data).
    The census protocol counts singing males, not breeding pairs. Since 
the census began, Kirtland's warbler conservation partners have often 
made the assumption that there is a breeding female for each singing 
male, so the number of singing males has often been used to approximate 
the number of breeding pairs. Likewise, some reports estimate a total 
breeding population by doubling the number of singing males. 
Extrapolating from singing males to breeding pairs or total breeding 
population should be done with caution. Mating success of males may 
vary depending on the quality of habitat, method of regeneration, or 
other factors (Bocetti 1994, pp. 80-85; Rockwell et al. 2013, p. 748; 
Bocetti 2018, pers. comm.). The annual census provides a robust, 
relative index of the Kirtland's warbler population change over time, 
but results should not be interpreted as an absolute count (Probst et 
al. 2005, pp. 50-59).

Population Viability

    Full annual cycle (breeding and wintering) dynamics were 
incorporated into a population viability model to assess the long-term 
population viability of the Kirtland's warbler under five management 
scenarios: (1) Current suitable habitat and current brown-

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headed cowbird removal; (2) reduced suitable habitat and current brown-
headed cowbird removal; (3) current suitable habitat and reduced brown-
headed cowbird removal, (4) current suitable habitat and no brown-
headed cowbird removal; and (5) reduced suitable habitat and reduced 
brown-headed cowbird removal (Brown et al. 2017a, p. 443). The model 
that best simulated recently observed Kirtland's warbler population 
dynamics included a relationship between precipitation in the species' 
wintering grounds and productivity (Brown et al. 2017a, pp. 442, 444), 
which reflects our understanding of carry-over effects (Rockwell et al. 
2012, pp. 748-750; Wunderle et al. 2014, pp. 46-48).
    Under the current management conditions scenario, which includes 
habitat management at existing levels and brown-headed cowbird control 
occurring throughout the northern Lower Peninsula of Michigan, the 
model predicts that the Kirtland's warbler population will be stable 
over a 50-year simulation period. When simulating a reduced brown-
headed cowbird removal effort by restricting cowbird trapping 
activities to the central breeding areas in northern lower Michigan 
(i.e., eastern Crawford County, southeastern Otsego County, Oscoda 
County, western Alcona County, Ogemaw County, and Roscommon County) and 
assuming a 41 percent or 57 percent reduction in Kirtland's warbler 
productivity, the results showed a stable or slightly declining 
population, respectively, over the 50-year simulation period (Brown et 
al. 2017a, p. 447). Other scenarios, including reduced habitat 
suitability and reduced Kirtland's warbler productivity due to 
experimental jack pine management on 25 percent of available breeding 
habitat, had similar results with projected population declines over 
the 50-year simulation period, but mean population numbers remained 
above the population goal of 1,000 pairs (Brown et al. 2017a, p. 446), 
the numerical criterion identified in the Kirtland's warbler recovery 
plan (USFWS 1985).
    Future reductions to Kirtland's warbler productivity rates under 
two reduced cowbird removal scenarios were assumed to be similar to 
historical rates (Brown et al. 2017a, p. 447). This assumption would 
overestimate the negative effects on Kirtland's warbler productivity if 
future parasitism rates are lower than the rates modeled (see Factor E: 
Brood Parasitism, below, for additional information on contemporary 
parasitism rates). Supplementary analysis (Brown et al. 2017b, unpubl. 
report), using the model structure and assumptions of Brown et al. 
(2017a), simulated the impacts of a 5, 10, 20, and 30 percent reduction 
in productivity to take into consideration a wider range of possible 
future parasitism rates. Even small reductions in annual productivity 
had measurable impacts on population abundance, but there were not 
substantial differences in mean population growth rate up to a 20 
percent reduction in productivity (Brown et al. 2017b, p. 3). Even with 
annual reductions in productivity of up to 5 percent for 50 years, the 
population trend (growth rate) projected for the final 30 years of the 
model simulations was 0.998 (range from the 5 simulations 0.993 to 
1.007) or nearly the same as that projected in the simulations with no 
reduction in productivity at 0.999 (range of 0.995 to 1.008) (Brown et 
al. 2017b, p. 3). It is reasonable to infer that the Kirtland's warbler 
population can support relatively small reductions in productivity over 
a long period of time (e.g., the 50-year timeframe of the simulations), 
providing a margin of assurance as management approaches are adaptively 
managed over time, and the species may be able to withstand as much as 
a 20 percent reduction in annual productivity, provided it does not 
extend over several years.
    The results of the model simulations are more helpful in evaluating 
the effect of various management decisions relative to one another, 
rather than providing predictions of true population abundance. In 
other words, the model output provides projections of relative trends, 
rather than identifying specific population abundance thresholds. 
Although there are limitations to all population models based on 
necessary assumptions, input data limitations, and unknown long-term 
responses such as adaptation and plasticity, data simulated by Brown et 
al. (2017a and 2017b, entire) provide useful information in assessing 
relative population trends for the Kirtland's warbler under a variety 
of future scenarios and provide the best available analysis of 
population viability.
    In summary, Kirtland's warbler population numbers have been greatly 
affected by brown-headed cowbird parasitism rates and the extent and 
quality of available habitat on the breeding grounds. The best 
available population model predicts that limited non-traditional 
habitat management and continued low brood parasitism rates will result 
in sustained population numbers above the recovery goal. Monitoring 
population numbers and brood parasitism rates will be important in 
ensuring the Kirtland's warbler population remains stable post-
delisting (see Post-delisting Monitoring, below).

Recovery and Recovery Plan Implementation

    State and Federal efforts to conserve the Kirtland's warbler began 
in 1957 and were focused on providing breeding habitat for the species. 
The Kirtland's warbler was federally listed as an endangered species in 
1967, under the Endangered Species Preservation Act of 1966 (Pub. L. 
89-669). By 1972, a Kirtland's Warbler Advisory Committee formed to 
coordinate management efforts and research actions across Federal and 
State agencies, and conservation efforts expanded to include management 
of brown-headed cowbird brood parasitism (Shake and Mattsson 1975, p. 
    Efforts to protect and conserve the Kirtland's warbler were further 
enhanced when the Endangered Species Act of 1973 became law and 
provided for acquisition of land to increase available habitat, funding 
to carry out additional management programs, and provisions for State 
and Federal cooperation. In 1975, the Recovery Team was appointed by 
the Secretary of the Interior to guide recovery efforts. A Kirtland's 
Warbler Recovery Plan was completed in 1976 (USFWS 1976), and updated 
in 1985 (USFWS 1985), outlining steps designed to protect and increase 
the species' population.
    Recovery plans provide important guidance to the Service, States, 
and other partners on methods of minimizing threats to listed species 
and measurable objectives against which to measure progress towards 
recovery, but they are not regulatory documents. A decision to revise 
the status of or remove a species from the List is ultimately based on 
an analysis of the best scientific and commercial data available to 
determine whether a species is no longer an endangered species or a 
threatened species, regardless of whether that information differs from 
the recovery plan.
    The Kirtland's warbler recovery plan (USFWS 1985) identifies one 
``primary objective'' (hereafter referred to as ``recovery criterion'') 
that identifies when the species should be considered for removal from 
the List, and ``secondary objectives'' (hereafter referred to as 
``recovery actions'') that are designed to accomplish the recovery 
criterion. The recovery criterion states that the Kirtland's warbler 
may be considered recovered and considered for removal from the List 
when a self-sustaining population has been re-established throughout 
its known range at a minimum level of 1,000 pairs. The

[[Page 54443]]

1,000-pair goal was informed by estimates of the amount of the specific 
breeding habitat required by each breeding pair of Kirtland's warblers, 
the amount of potential habitat available on public lands in Michigan's 
northern Lower Peninsula, and the ability of State and Federal land 
managers to provide suitable nesting habitat on an annual basis. The 
recovery criterion was intended to address the point at which the 
ultimate limiting factors to the species had been ameliorated so that 
the population is no longer in danger of extinction or likely to become 
so within the foreseeable future.
    The recovery plan does not clearly articulate how meeting the 
recovery criterion will result in a population that is at reduced risk 
of extinction. The primary threats to the Kirtland's warbler are 
pervasive and recurring threats, but threat-based criteria specifying 
measurable targets for control or reduction of those threats were not 
incorporated into the recovery plan. Instead, the recovery plan focused 
on specific actions necessary to accomplish the recovery criterion. 
These included managing breeding habitat, protecting the Kirtland's 
warbler on its wintering grounds and along the migration route, 
reducing key factors such as brown-headed cowbird parasitism from 
adversely affecting reproduction and survival of Kirtland's warblers, 
and monitoring the Kirtland's warbler to evaluate responses to 
management practices and environmental changes.
    At the time the recovery plan was prepared, we estimated that land 
managers would need to annually maintain approximately 15,380 ha 
(38,000 ac) of nesting habitat in order to support and sustain a 
breeding population of 1,000 pairs (USFWS 1985, pp. 18-20). We 
projected that this would be accomplished by protecting existing 
habitat, improving occupied and developing habitat, and establishing 
approximately 1,010 ha (2,550 ac) of new habitat each year, across 
51,640 ha (127,600 ac) of State and Federal pine lands in the northern 
Lower Peninsula of Michigan (USFWS 1985, pp. 18-20). We also 
prioritized development and improvement of guidelines that would 
maximize the effectiveness and cost efficiency of habitat management 
efforts (USFWS 1985, p. 24). The MDNR, USFS, and Service developed the 
Strategy for Kirtland's Warbler Habitat Management (Huber et al. 2001, 
entire) to update Kirtland's warbler breeding habitat management 
guidelines and prescriptions based on a review of past management 
practices, analysis of current habitat conditions, and new findings 
that would continue to conserve and enhance the status of the 
Kirtland's warbler (Huber et al. 2001, p. 2).
    By the time the recovery plan was updated in 1985, the brown-headed 
cowbird control program had been in effect for more than 10 years. The 
brown-headed cowbird control program had virtually eliminated brood 
parasitism and more than doubled the warbler's productivity rates in 
terms of fledging success (Shake and Mattsson 1975, pp. 2-4). The 
Kirtland's warbler's reproductive capability had been successfully 
restored, and the brown-headed cowbird control program was credited 
with preventing further decline of the species. Because management of 
brown-headed cowbird brood parasitism was considered essential to the 
survival of the Kirtland's warbler, it was recommended that the brown-
headed cowbird control program be maintained for ``as long as 
necessary'' (USFWS 1985, p. 27).
    Although the recovery plan identifies breeding habitat as the 
primary limiting factor, with brood parasitism as a secondary limiting 
factor, it also suggests that events or factors outside the breeding 
season might be adversely affecting survival (USFWS 1985, pp. 12-13). 
At the time the recovery plan was updated, little was known about the 
Kirtland's warbler's migratory and wintering behavior, the species' 
migratory and wintering habitat requirements, or ecological changes 
that may have occurred within the species' migration route or on its 
wintering range. This lack of knowledge emphasized a need for more 
information on the Kirtland's warbler post-fledging, during migration, 
and on its wintering grounds (Kelly and DeCapita 1982, p. 365). 
Accordingly, recovery efforts were identified to: (1) Define the 
migration route and locate wintering areas; (2) investigate the ecology 
of the Kirtland's warbler and factors that might be affecting mortality 
during migration and on its winter range; and (3) provide adequate 
habitat and protect the Kirtland's warbler during migration and on its 
wintering areas (USFWS 1985, pp. 24-26).
    In correspondence with the Service's Midwest Regional Director, and 
based on more than 20 years of research on the Kirtland's warbler's 
ecology and response to recovery efforts, the Recovery Team helped 
clarify recovery progress and issues that needed attention prior to 
reclassification to threatened status or delisting (Ennis 2002, pp. 1-
4; Ennis 2005, pp. 1-3). From that synthesis, several important 
concepts emerged that continued to inform recovery, including: (1) 
Breeding habitat requirements, amount, configuration, and distribution; 
(2) brood parasitism management; (3) migratory connectivity and 
protection of Kirtland's warblers and their habitat during migration 
and on the wintering grounds; and (4) establishment of credible 
mechanisms to ensure the continuation of necessary management (Thorson 
2005, pp. 1-2).
    Our understanding of the Kirtland's warbler's breeding habitat 
selection and use, and the links between maintaining adequate amounts 
of breeding habitat and a healthy Kirtland's warbler population, has 
continued to improve. As the population has rebounded, Kirtland's 
warblers have become reliant on artificial regeneration of breeding 
habitat, but have also recolonized naturally regenerated areas within 
the historical range of the species and nested in habitat types 
previously considered non-traditional or less suitable. As explained in 
more detail below, recovery efforts have expanded to establish and 
enhance management efforts on the periphery of the species' current 
breeding range in Michigan's Upper Peninsula, Wisconsin, and Canada and 
reflect the best scientific understanding of the amount and 
configuration of breeding habitat (see Factor A discussion, below). 
These adjustments improve the species' ability to adapt to changing 
environmental conditions and to withstand stochastic disturbance and 
catastrophic events, and better ensure long-term conservation for the 
    Along with habitat management, brown-headed cowbird control has 
proven to be a very effective tool in stabilizing and increasing the 
Kirtland's warbler population. To ensure survival of the Kirtland's 
warbler, we anticipate that continued brown-headed cowbird brood 
parasitism management may be needed, at varying levels depending on 
parasitism rates, to sustain adequate Kirtland's warbler productivity. 
As explained in more detail below, brown-headed cowbird control 
techniques and the scale of trapping efforts have adapted over time and 
will likely continue to do so, in order to maximize program 
effectiveness and feasibility (see Factor E: Brood Parasitism 
discussion, below).
    We now recognize that the Kirtland's warbler persists only through 
continual management activities designed to mitigate recurrent threats 
to the species. The Kirtland's warbler is considered a conservation-
reliant species, which means that it requires continuing management to 
address ongoing threats (Goble et al. 2012, p. 869). Conservation of 
the Kirtland's warbler will continue

[[Page 54444]]

to require a coordinated, multi-agency approach for planning and 
implementing conservation efforts into the future. Four elements that 
should be in place prior to delisting a conservation-reliant species 
include a conservation partnership capable of continued management, a 
conservation plan, appropriate binding agreements (such as memoranda of 
agreement (MOAs)) in place, and sufficient funding to continue 
conservation actions into the future (Bocetti et al. 2012, p. 875).
    The Kirtland's warbler has a strong conservation partnership 
consisting of multiple stakeholders that have invested considerable 
time and resources to achieving and maintaining this species' recovery. 
Since 2016, the Recovery Team is no longer active, but instead new 
collaborative efforts formed to help ensure the long-term conservation 
of the Kirtland's warbler regardless of its status under the ESA. These 
efforts formed to facilitate conservation planning through 
coordination, implementation, monitoring, and research efforts among 
many partners and across the species' range. A coalition of 
conservation partners lead by Huron Pines, a nonprofit conservation 
organization based in northern Michigan, launched the Kirtland's 
Warbler Initiative in 2013. The Kirtland's Warbler Initiative brings 
together State, Federal, and local stakeholders to identify and 
implement strategies to secure funds for long-term Kirtland's warbler 
conservation actions given the continuous, recurring costs anticipated 
with conserving the species into the future. The goal of this 
partnership is to ensure the Kirtland's warbler thrives and ultimately 
is delisted, as a result of strong public-private funding and land 
management partnerships. Through the Kirtland's Warbler Initiative, a 
stakeholder group called the Kirtland's Warbler Alliance was developed 
to raise awareness in support of the Kirtland's warbler and the 
conservation programs necessary for the health of the species and jack 
pine forests.
    The second effort informing Kirtland's warbler conservation efforts 
is the Kirtland's Warbler Conservation Team (KWCT). The KWCT was 
established to preserve institutional knowledge, share information, and 
facilitate communication and collaboration among agencies and partners 
to maintain and improve Kirtland's warbler conservation. The current 
KWCT is comprised of representatives from the Service, USFS, MDNR, 
WDNR, U.S. Department of Agriculture's Wildlife Services (USDA-WS), 
Canadian Wildlife Service, Huron Pines, Kirtland's Warbler Alliance, 
The Nature Conservancy, and California University of Pennsylvania.
    Since 2015, conservation efforts for the Kirtland's warbler have 
been guided by the Kirtland's Warbler Breeding Range Conservation Plan 
(Conservation Plan) (MDNR et al. 2015, entire). The Conservation Plan 
outlines the strategy for future cooperative Kirtland's warbler 
conservation and provides technical guidance to land managers and 
others on how to create and maintain Kirtland's warbler breeding 
habitat within an ecosystem management framework. The scope of the 
Conservation Plan currently focuses only on the breeding range of the 
Kirtland's warbler within the United States, although the agencies 
involved (MDNR, USFS, and USFWS; hereafter ``agencies'' or ``management 
agencies'') intend to cooperate with other partners to expand the scope 
of the plan in the future to address the entire species' range (i.e., 
the entire jack pine ecosystem, as well as the migratory route and 
wintering range of the species). The Conservation Plan will be revised 
every 10 years to incorporate any new information and the best 
available science (MDNR et al. 2015, p. 1).
    In April 2016, the management agencies renewed a memorandum of 
understanding (MOU) through December 31, 2020, committing to continue 
collaborative habitat management, brown-headed cowbird control, 
monitoring, research, and education in order to maintain the Kirtland's 
warbler population at or above 1,000 breeding pairs, regardless of the 
species' legal protection under the ESA (USFWS, MDNR, and USFS 2016, 
entire). In addition, Kirtland's warbler conservation actions are 
included in the USFS's Land and Resource Management Plans (Forest 
Plans), which guide management priorities for the Huron-Manistee, 
Hiawatha, and Ottawa National Forests.
    Funding mechanisms that support long-term land management and 
brown-headed cowbird control objectives are in place to assure a high 
level of certainty that the agencies can meet their commitments to the 
conservation of the Kirtland's warbler. MDNR and USFS have replanted 
approximately 26,420 ha (90,000 ac) of Kirtland's warbler habitat over 
the past 30 years. Over the last 10 years, only a small proportion of 
the funding used to create Kirtland's warbler habitat is directly tied 
to the ESA through the use of grant funding (i.e., funding provided to 
MDNR through the Service's section 6 grants to States' program). 
Although there is the potential that delisting could reduce the 
priority for Kirtland's warbler work within MDNR and USFS, as noted in 
the Conservation Plan (MDNR 2015, p. 17), much of the forest management 
cost (e.g., silvicultural examinations, sale preparation, and 
reforestation) is not specific to maintaining Kirtland's warbler 
breeding habitat and would likely be incurred in the absence of the 
Kirtland's warbler. MDNR and USFS have successfully navigated budget 
shortfalls and changes in funding sources over the past 30 years and 
were able to provide sufficient breeding habitat to enable the 
population to recover, and they have agreed to continue to do so 
through the MOU. Additionally, the Service and MDNR developed an MOA to 
set up a process for managing funds to help address long-term 
conservation needs, specifically brown-headed cowbird control (USFWS 
and MDNR 2015). If the annual income generated is greater than the 
amount needed to manage brown-headed cowbird parasitism rates, the 
remaining portion of the annual income may be used to support other 
high priority management actions to directly benefit the Kirtland's 
warbler, including wildlife and habitat management, land acquisition 
and consolidation, and education. The MOA requires that for a minimum 
of 5 years after the species is delisted, MDNR consult with the Service 
on planning the annual brown-headed cowbird control program and other 
high-priority actions. In addition, MDNR recently reaffirmed their 
commitment to the MOA and confirmed their intent to implement and 
administer the brown-headed cowbird control program, even if the 
Kirtland's warbler is delisted (MDNR 2017).
    In summary, the general guidance of the recovery plan has been 
effective, and the Kirtland's warbler has responded well to active 
management over the past 50 years. The primary threats identified at 
listing and during the development of the recovery plan have been 
managed, and commitments are in place to continue managing the threats. 
The status of the Kirtland's warbler has improved, primarily due to 
breeding habitat and brood parasitism management provided by MDNR, 
USFS, and the Service. The population has been above the 1,000 pair 
goal since 2001, above 1,500 pairs since 2007, and above 2,000 pairs 
since 2012. The recovery criterion has been met. Since 2015, efforts 
for the Kirtland's warbler have been guided by a Conservation Plan that 
will continue to be implemented by the management agencies when the 
species is delisted.

[[Page 54445]]

    Since the revision of the recovery plan (USFWS 1985), decades of 
research have been invaluable to refining recovery implementation and 
have helped clarify our understanding of the dynamic condition of the 
Kirtland's warbler, jack pine ecosystem, and factors influencing them. 
The success of recovery efforts in mitigating threats to the Kirtland's 
warbler are evaluated below.

Summary of Changes From the Proposed Rule

    Based upon our review of the comments received on the April 12, 
2018, proposed rule (83 FR 15758), peer review comments, and new 
information that became available since the publication of the proposed 
rule, we reevaluated the information in the proposed rule and made 
changes as appropriate. We made the following changes in this final 
rule: (1) We added detail on the wintering distribution; (2) we 
clarified that wintering habitat is broadleaf scrub rather than pine 
habitat; (3) we added a paragraph on reproductive success; (4) we added 
a discussion on anthropogenic disturbance regimes on the wintering 
grounds; (5) we added information on connectivity between winter and 
breeding grounds; (6) we clarified that census results (number of 
singing males) are a relative index rather than an absolute count; (7) 
we added a section on the effects of insects and disease to jack pine; 
(8) we added a discussion of the effects of recreation; (9) we added a 
discussion of pesticides; (10) we included new data on brown-headed 
cowbird parasitism rates and the suspended trapping program during 
2018; (11) we updated the analysis on effects of climate change on 
breeding grounds; (12) we added a discussion of recent drought on the 
wintering grounds; (13) we included new data on risk of heavy rainfall 
events and extended period of hurricane force winds due to decreasing 
translational speeds; and (14) we added a discussion of the effects of 
hurricanes. In addition, we made efforts to improve clarity, improve 
organization, and correct typographical or other minor errors. Many of 
our edits were based on comments from peer reviewers and public 
comments; additional detail can be found under Summary of Comments and 
Recommendations, below.

Summary of Factors Affecting the Kirtland's Warbler

    Section 4 of the ESA and its implementing regulations (50 CFR part 
424) set forth the procedures for listing species, reclassifying 
species, or removing species from listed status. 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'' (16 U.S.C. 1532(16)). A 
species may be determined to be an endangered species or threatened 
species because of any one or a combination of the five factors 
described in section 4(a)(1) of the ESA: (A) The present or threatened 
destruction, modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) the inadequacy of 
existing regulatory mechanisms; or (E) other natural or manmade factors 
affecting its continued existence. We must consider these same five 
factors in delisting a species. We may delist a species according to 50 
CFR 424.11(d) if the best available scientific and commercial data 
indicate that the species is neither endangered nor threatened for one 
or more of the following reasons: (1) The species is extinct; (2) the 
species has recovered and is no longer endangered or threatened; or (3) 
the original scientific data used at the time the species was 
classified were in error.
    For species that are already listed as endangered or threatened, 
this analysis of threats is an evaluation of both the threats currently 
facing the species and the threats that are reasonably likely to affect 
the species in the foreseeable future following delisting or 
downlisting (i.e., reclassification from endangered to threatened) and 
the removal or reduction of the ESA's protections. A recovered species 
is one that no longer meets the ESA's definition of endangered or 
threatened. A species is ``endangered'' for purposes of the ESA if it 
is in danger of extinction throughout all or a ``significant portion of 
its range'' and is ``threatened'' if it is likely to become endangered 
within the foreseeable future throughout all or a ``significant portion 
of its range.'' The word ``range'' in the ``significant portion of its 
range'' phrase refers to the range in which the species currently 
exists. For the purposes of this analysis, we will evaluate whether the 
Kirtland's warbler should be considered endangered or threatened 
throughout all of its range. Then we will consider whether there are 
any significant portions of the Kirtland's warbler's range where the 
species is in danger of extinction or likely to become so within the 
foreseeable future.
    The ESA does not define the term ``foreseeable future.'' For the 
purpose of this rule, we define the ``foreseeable future'' to be the 
extent to which, given the amount and substance of available data, we 
can anticipate events or effects, or reliably extrapolate threat 
trends, such that we reasonably believe that reliable predictions can 
be made concerning the future as it relates to the status of the 
Kirtland's warbler. We used the anticipated habitat and brown-headed 
cowbird management analyzed over a 50-year timeframe in Brown et al. 
(2017a, b) to define the foreseeable future for the Kirtland's warbler. 
This analysis considered multiple future management scenarios for 
Kirtland's warbler, including reduced suitable habitat (from 
experimental habitat management) and reduced brown-headed cowbird 
removal. Given the length of time for habitat to become suitable and 
the warbler's average life span, a 50-year period takes into account 
multiple rotations of habitat and generations of birds. This is a 
sufficient amount of time to fully evaluate if the current and 
potential future experimental approaches to management warrant further 
refinement. Beyond 50 years, the future conditions become more 
uncertain, such that we cannot make reliable predictions as to how any 
differing management scenarios may affect the status of the species.
    In considering what factors might constitute threats, we must look 
beyond the exposure of the species to a particular factor to evaluate 
whether the species may respond to the factor in a way that causes 
actual impacts to the species. If there is exposure to a factor and the 
species responds negatively, the factor may be a threat, and during the 
status review, we attempt to determine how significant a threat it is. 
The threat is significant if it drives or contributes to the risk of 
extinction of the species, such that the species warrants listing as 
endangered or threatened as those terms are defined by the ESA. 
However, the identification of factors that could impact a species 
negatively may not be sufficient to compel a finding that the species 
warrants listing. The information must include evidence sufficient to 
suggest that the potential threat is likely to materialize and that it 
has the capacity (i.e., it should be of sufficient magnitude and 
extent) to affect the species' status such that it meets the definition 
of endangered or threatened under the ESA. The following analysis 
examines all five factors currently affecting or that are likely to 
affect the Kirtland's warbler in the foreseeable future.

[[Page 54446]]

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

Breeding Habitat
    Historically, wildfires were the most important factor in the 
establishment of natural jack pine forests and Kirtland's warbler 
breeding habitat. However, modern wildfire suppression greatly altered 
the natural disturbance regime that generated Kirtland's warbler 
breeding habitat for thousands of years (USFWS 1985, p. 12; Cleland et 
al. 2004, pp. 316-318). Prior to the 20th century, the historic fire 
recurrence in jack pine forests averaged 59 years, but it is now 
estimated to occur in cycles as long as 775 years (Cleland et al. 2004, 
pp. 315-316).
    In the absence of wildfire, land managers must take an active role 
in mimicking natural processes that regularly occurred within the jack 
pine ecosystem, namely stand-replacing disturbance events. This is 
primarily done through large-scale timber harvesting and human-assisted 
reforestation. Although planted stands tend to be more structurally 
simplified than wildfire-regenerated stands (Spaulding and Rothstein 
2009, p. 2610), land managers have succeeded in selecting KWMAs that 
have landscape features of the natural breeding habitat and have 
developed silvicultural techniques that produce conditions within 
planted stands suitable for Kirtland's warbler nesting. In fact, over 
85 percent of the habitat used by breeding Kirtland's warblers in 2015 
in the northern Lower Peninsula of Michigan (approximately 12,343 ha 
(30,500 ac)) had been artificially created through clearcut harvest and 
replanting. The planted stands supported over 92 percent of the 
warbler's population within the Lower Peninsula during the 2015 
breeding season (MDNR, USFS, USFWS, unpubl. data). The effectiveness of 
these strategies is also evident by the reproductive output observed in 
planted stands, which function as population sources (Bocetti 1994, p. 
95). Thus, in a landscape where natural fire disturbance patterns have 
been reduced, threats to natural breeding habitat are being mitigated 
through large-scale habitat management. Therefore, the status of the 
Kirtland's warbler depends largely on the continued production of 
managed breeding habitat.
    Federal and State laws establish the foundation for managing the 
USFS, USFWS, and MDNR lands that provide the majority of the breeding 
habitat for Kirtland's warbler. These laws require land management 
agencies to develop plans that describe objectives and goals for forest 
    The National Forest Management Act (16 U.S.C. 1600-1640; NFMA) 
requires that Forest Plans shall ``provide for multiple use and 
sustained yield of the products and services . . . and, in particular, 
include coordination of outdoor recreation, range, timber, watershed, 
wildlife and fish, and wilderness'' (16 U.S.C. 1604(e)). All projects 
and activities authorized by the Forest Service must be consistent with 
the established Forest Plans (16 U.S.C. 1604(i)). The Hiawatha, Huron-
Manistee, and Ottawa National Forest Plans include specific goals and 
objectives for maintaining Kirtland's warbler breeding habitat (USFS 
2006a, p. 35; USFS 2006b, p. 82; USFS 2006c, p. 27). The NFMA's 
implementing regulations will apply to any future Forest Plan revisions 
and currently require National Forests to develop plans that include 
standards or guidelines to maintain or restore the ecological integrity 
of terrestrial ecosystems in the plan area (36 CFR 219.8(a)). Further, 
additional species-specific standards or guidelines may be required to 
maintain a viable population of each species of conservation concern 
within the plan area (36 CFR 219.9(b)(1)). The Forest Service plans to 
designate Kirtland's warbler as a Sensitive Species upon delisting for 
a period of at least five years (Hogeboom 2019, pers. comm.). 
Additionally, in accordance with the Forest Service Manual (FSM), any 
significant current or predicted downward trends in population numbers, 
density, or in habitat capability that would reduce a species' existing 
distribution would be triggers for the Regional Forester to designate 
the Kirtland's warbler as a Sensitive Species (FSM 2670.5) in the 
future. Forest Service objectives for Sensitive Species (FSM 2670.22) 
include developing and implementing management practices to ensure that 
species do not become threatened or endangered because of Forest 
Service actions.
    The National Wildlife Refuge System Improvement Act of 1997 
requires the preparation of Comprehensive Conservation Plans for refuge 
lands and maintenance of the biological integrity, diversity, and 
environmental health of the National Wildlife Refuge System. The 
Service's Kirtland's Warbler Wildlife Management Area defines goals, 
objectives, and strategies that support Kirtland's warbler and the jack 
pine ecosystem (USFWS 2009, pp. 31-33).
    In Michigan law, Part 525, Sustainable Forestry on State Forest 
Lands, of the Natural Resources and Environmental Protection Act (1994 
PA 451, as amended) requires the MDNR to manage the State forest lands 
consistent with the principles of sustainable forestry. Part 525 also 
requires the MDNR to maintain third-party certification of the 
management of the State forest that satisfies sustainable forestry 
standards. The MDNR forest lands are certified under the standards of 
the Forest Stewardship Council and the Sustainable Forestry Initiative 
(Kintigh 2019, pers. comm.). These standards also require the MDNR to 
write, implement, and maintain forest management plans. The MDNR has 
developed a Regional State Forest Management Plan for the northern 
Lower Peninsula ecoregion that includes specific plans for 15 units of 
land managed for Kirtland's warbler (MDNR 2013, pp. 337-354). The 
Federal and State forest management planning standards, which will 
remain in effect after delisting, are synthesized and further refined 
for Kirtland's warbler through the Conservation Plan (MDNR et al. 
    The Conservation Plan (MDNR et al. 2015) identifies continued 
habitat management needs and objectives to maintain sufficient suitable 
breeding habitat for Kirtland's warblers. Habitat management is 
currently conducted on approximately 88,626 ha (219,000 ac) of jack 
pine forest within MDNR, USFS, and Service lands throughout the 
northern Lower Peninsula and Upper Peninsula of Michigan (MDNR et al. 
2015, pp. 22-23). The Conservation Plan incorporates some conservative 
assumptions about the area needed to support a breeding pair of 
Kirtland's warblers, as well as how long a stand will be used by the 
species. The density and duration of use estimates were developed by 
data gathered over the last decade. Lands within the Lower Peninsula 
averaged 8 to 9 ha (19 to 22 ac) per pair and had a duration of use 
between 9 and 10 years. Lands within the Upper Peninsula on the 
Hiawatha National Forest required an average of 40 ha (100 ac) per pair 
and had a duration of use averaging 10 years (Huber et al. 2013, cited 
in MDNR et al. 2015, p. 22). Using those measures of average hectares 
per pair and duration of use, 14,593 ha (36,060 ac) of suitable 
breeding habitat would need to be available at all times to maintain a 
minimum population of 1,300 pairs, requiring land management agencies 
to jointly manage 1,550 ha (3,830 ac) of habitat annually (631 ha 
(1,560 ac) on MDNR land and 918 ha (2,270 ac) on USFS land) through 

[[Page 54447]]

regenerated jack pine or managed reforestation (MDNR et al. 2015, pp. 
22-23). Importantly, the more recent observations concerning density of 
Kirtland's warblers in breeding habitat and duration of stand use are 
often greater than the assumptions used for planning purposes and 
explain why the Kirtland's warbler population that is actually observed 
is higher than would be predicted based on the planning assumptions.
    As described previously, the majority of managed breeding habitat 
is currently created through clear cutting and planting jack pine 
seedlings. However, managing jack pine for Kirtland's warbler breeding 
habitat typically results in lower value timber products due to the 
overall poor site quality in combination with the required spacing, 
density, and rotation age of the plantings (Greco 2017, pers. comm.). 
Furthermore, the demand for jack pine products has fluctuated in recent 
years, and long-term forecasts for future marketability of jack pine 
are uncertain. Commercially selling jack pine timber on sites where 
reforestation will occur is critical to the habitat management program. 
Timber receipts offset the cost of replanting jack pine at the 
appropriate locations, scales, arrangements, and densities needed to 
support a viable population of nesting Kirtland's warblers that would 
not otherwise be feasible through conservation dollars. The 
Conservation Plan directs management agencies to develop at least 75 
percent of the Kirtland's warbler's breeding habitat annual acreage 
objectives using traditional habitat management techniques (i.e., 
opposing wave planting with interspersed openings), and no more than 25 
percent of annual acreage objectives should use non-traditional habitat 
management techniques (e.g., reduced stocking density, incorporating a 
red pine component within a jack pine stand, prescribed burning) (MDNR 
et al. 2015, p. 23). Using non-traditional techniques on a maximum of 
25 percent of breeding habitat acreage annually will allow the 
management agencies to evaluate new planting methods that improve 
timber marketability, reduce costs, and improve recreational 
opportunities while sustaining the warbler's population above the 
recovery criterion of 1,000 pairs. The KWCT is currently working on 
developing additional habitat regeneration techniques through adaptive 
management that increase the marketability of the timber at harvest 
while not substantially reducing Kirtland's warbler habitat suitability 
(Kennedy 2017, pers. comm.).
    The land management agencies have maintained adequate breeding 
habitat despite times when their budgets were flat or declining, even 
while costs related to reforestation continued to increase. For 
example, over the last 30 years, MDNR replanted more than 20,000 ha 
(50,000 ac) of Kirtland's warbler habitat, averaging over 680 ha (1,700 
ac) per year. They took this action voluntarily, and within the past 10 
years, they used funding from sources in addition to those available 
under the ESA. Section 6 grants under the ESA have helped support 
MDNR's Kirtland's warbler efforts, but that funding has largely been 
used for population census work in recent years and reflects only a 
small percentage of the funding the State of Michigan spends annually 
to produce Kirtland's warbler breeding habitat. Other funding sources 
used by MDNR include State wildlife grants, competitive State wildlife 
grants, Michigan's Nongame Fund, and the Forest Development Fund.
    Shifting agency priorities and competition for limited resources 
have and will continue to challenge the ability of land managers to 
fund reforestation of areas suitable for Kirtland's warblers. Low jack 
pine timber sale revenues, in conjunction with reduced budgets, 
increased Kirtland's warbler habitat reforestation costs, and 
competition with other programs, are all challenges that the land 
management agencies have met in the past and will need to continue 
addressing to meet annual habitat development objectives. Commitments 
by land managers and the KWCT are in place, as described earlier in 
this document, to ensure recovery of the Kirtland's warbler will be 
sustained despite these challenges.
    The management agencies have agreed through the Conservation Plan 
(MDNR et al. 2015, pp. 24, 43-44) to generally limit or prohibit 
commercial, recreational, or infrastructure (e.g., roads, pipelines, 
communication towers) development within or near areas managed for 
Kirtland's warbler to protect them and provide for the long-term 
integrity of breeding habitat. Additionally, a regulatory mechanism 
that aids in the management of breeding habitat is Executive Order 
(E.O.) 13186, ``Responsibilities of Federal Agencies to Protect 
Migratory Birds'' (66 FR 3853; January 17, 2001), which directs Federal 
agencies to develop a memorandum of understanding (MOU) with the 
Service to promote the conservation of migratory bird populations. USFS 
and the Service signed an MOU (FS Agreement #08-MU-1113-2400-264), 
pursuant to E.O. 13186, with the purpose of strengthening migratory 
bird conservation by identifying and implementing strategies that 
promote conservation and avoid or minimize adverse impacts on migratory 
birds through enhanced collaboration.
    Once planted for Kirtland's warbler habitat, jack pine trees need 
to survive to provide usable habitat. Multiple natural events, such as 
fire, drought, disease, and insect outbreaks, may affect the survival 
of jack pine trees and longevity of suitable habitat. Wildfire can be 
harmful to Kirtland's warblers when it destroys occupied habitat. For 
example, on May 18, 2010, a wildfire started in southeastern Crawford 
County within the Eldorado KWMA. The wildfire eventually burned a total 
of approximately 3,071 ha (7,588 ac), including 146 ha (362 ac) of 
occupied habitat (where 30 singing males were counted in 2009) and 36 
ha (90 ac) of young jack pine habitat that would have likely been 
occupied by Kirtland's warblers in 3 years (USFS 2010, pp. 1, 7, 11). 
The following year on June 7, 2011, lightning ignited a wildfire that 
destroyed approximately 49 ha (120 ac) of 11-year-old habitat in the 
Manistee River KWMA, where seven male Kirtland's warblers were counted 
during the 2011 census (MDNR, unpubl. data). Drought can cause 
mortality of jack pine seedlings (Rajasekaran and Blake 1999, p. 175) 
and reduce the density of jack pine trees (Kintigh 2011, pers. comm.). 
Drought can also stress older jack pines and make them more susceptible 
to insects and diseases (Kintigh 2011, pers. comm.). Fungal pests, 
including Gremmeniella abietina var. abietina, and Sphaeropsis sapinea 
(also known as Diplodia pinea), are known to cause mortality in jack 
pine trees (USFS and MDNR 1981, p. 14; Nicholls and Ostry 1990, p. 55). 
Jack pine budworm (Choristoneura pinus pinus), mountain pine beetle 
(Dendroctonus ponderosae), and jack pine sawfly (Neodiprion swainei) 
can also cause topkill and mortality in jack pine trees (McCullough 
2000, p. 252; Colgan and Erbilgin 2011, p. 426; Wilson 1971, p. 1). 
Generally, past impacts of these natural events on jack pines have had 
little effect on Kirtland's warbler habitat. Severe outbreaks of insect 
or fungal pests can have devastating effects on large areas of forest 
(e.g., the effect of emerald ash borer (Agrilus planipennis Fairmaire) 
on ash species (Fraxinus spp.)). Although there are no known imminent 
threats to Kirtland's warbler, emerging disease and pests warrant 
continued monitoring

[[Page 54448]]

because of the potential to harm significant amounts of managed 
habitat. Jack pine forests that serve as Kirtland's warbler habitat are 
under the oversight of forest-management agencies that closely track 
new forest diseases and pests and will take swift action if a newly 
emerging issue is detected.
    We reviewed available information on the effects to Kirtland's 
warbler habitat from expanded development on private lands in or near 
breeding habitat. Although these factors and forest pests and diseases 
have the potential to affect Kirtland's warblers and their habitat, 
land management agencies have been successful in maintaining sufficient 
amounts of suitable habitat to support historically high numbers of 
Kirtland's warblers. While activities and natural processes (e.g., 
wildfire, drought, development) that affect breeding habitat may still 
have some negative effects on individual Kirtland's warblers, the 
population of Kirtland's warblers appears resilient to these factors 
within the context of the current management regime. Furthermore, 
management efforts to date have been adaptive in terms of the acreage 
and spatial and temporal configuration of habitat needed to mitigate 
the effects associated with natural breeding habitat loss and 
fragmentation. The land management agencies have shown a commitment to 
Kirtland's warbler habitat management through their forest management 
plans as reflected in the 2016 MOU, agreeing to continue habitat 
management, and developing and implementing the Conservation Plan.
Migration Habitat
    Although Kirtland's warblers spend a relatively small amount of 
time each year migrating, the migratory period has the highest 
mortality rate of any phase of the annual cycle, accounting for 44 
percent of annual mortality (Rockwell et al. 2017, p. 722). Migratory 
survivorship levels are, however, above the minimum needed to sustain 
the population (Mayfield 1960, pp. 204-207; Berger and Radabaugh 1968, 
p. 170; Bocetti et al. 2002, p. 99; Rockwell et al. 2017, pp. 721-723; 
Trick, unpubl data). Recent research is refining our knowledge of 
spring and fall migration timing and routes for the Kirtland's warbler. 
Little is currently known about the importance of specific stopover 
sites and any factors affecting them, although coastal areas along the 
Great Lakes and Atlantic Ocean (e.g., western Lake Erie basin and the 
Florida and Georgia coasts) that appear important to migrating 
Kirtland's warblers are also areas where natural habitats have been 
highly fragmented by human development. At stopover sites within these 
highly fragmented landscapes, competition for food sources among long-
distance passerine migrants is expected to be high, especially in 
fallout areas where many migrating birds land to rest, usually due to 
weather events or long flights over open water (Moore and Yong 1991, 
pp. 86-87; Kelly et al. 2002, p. 212; N[eacute]meth and Moore 2007, p. 
373). Increased competition may prolong stopover duration or increase 
the number of stopovers that are needed to complete migration between 
breeding and wintering grounds (Goymann et al. 2010, p. 480).
    The quantity and quality of migratory habitat needed to sustain 
Kirtland's warbler numbers above the recovery goal of 1,000 pairs 
appears to be sufficient, based on a sustained and increasing 
population since 2001. If loss or destruction of migratory habitat were 
limiting or likely to limit the population to the degree that 
maintaining a healthy population may be at risk, it should be apparent 
in the absence of the species from highly suitable breeding habitat in 
the core breeding range. In fact, we have seen just the opposite: 
Increasing densities of breeding individuals in core areas and a range 
expansion into what would appear to be less suitable habitat elsewhere. 
This steady population growth and range expansion has occurred despite 
increased development and fragmentation of migratory stopover habitat 
within coastal areas.
Wintering Habitat
    Similar to the breeding grounds, the quantity and quality of 
wintering habitat needed to sustain Kirtland's warbler numbers above 
the recovery goal of 1,000 pairs appears to be sufficient, based on a 
sustained and increasing population since 2001. Compared to the 
breeding grounds, less is known about the wintering grounds in The 
Bahamas. Factors affecting Kirtland's warblers on the wintering 
grounds, as well as the magnitude of the impacts, remain somewhat 
uncertain. Few of the known Kirtland's warbler wintering sites 
currently occur on protected land. Rather, most Kirtland's warblers 
appear to winter more commonly in early successional habitats that have 
recently been or are currently being used by people (e.g., abandoned 
after clearing, grazed by goats), where disturbance has set back plant 
succession (Wunderle et al. 2010, p. 132). Potential threats to 
wintering habitat include habitat loss caused by human development, 
altered fire regime, changes in agricultural practices, and invasive 
plant species. The potential threats of rising sea level, drought, and 
destructive weather events, such as hurricanes on the wintering 
grounds, are discussed below under Factor E.
    Tourism is the primary economic activity in The Bahamas, accounting 
for 65 percent of the gross domestic product, and The Bahamas' Family 
Islands Development Encouragement Act of 2008 supports the development 
of resorts on each of the major Family Islands (part of The Bahamas) 
(Moore and Gape 2009, p. 72). Residential and commercial development 
could result in direct loss of Kirtland's warbler habitat, especially 
on New Providence and Grand Bahama, which together support 85 percent 
of the population of Bahamian people (Moore and Gape 2009, p. 73; 
Wunderle et al. 2010, p. 135; Ewert 2011, pers. comm.). This loss could 
occur on both private and commonage lands (land held communally by 
rural settlements), as well as generational lands (lands held jointly 
by various family members).
    Local depletion and degradation of the water table from wells and 
other water extraction and introduction of salt water through human-
made channels or other disturbances to natural hydrologies may also 
negatively impact Kirtland's warblers by affecting fruit and arthropod 
availability (Ewert 2011, pers. comm.).
    Fire may have positive or negative impacts on winter habitat, 
depending on the frequency, timing, and intensity of fires and where 
the fires occur. Fires are relatively common and widespread on the pine 
islands in the northern part of the archipelago and have increased 
since settlement, especially during the dry winter season when 
Kirtland's warblers are present (The Nature Conservancy 2004, p. 3). 
Fire may benefit Kirtland's warblers when succession of low coppice to 
tall coppice is set back (Currie et al. 2005b, p. 79) but may 
negatively impact wintering Kirtland's warblers if it results in 
reduced density and fruit production of understory shrubs (Currie et 
al. 2005b, p. 85).
    Invasive plants are another potential factor that could limit the 
extent of winter habitat in The Bahamas. Brazilian pepper (Schinus 
terebinthifolius), jumbie bean (Leucaena leucocephala), Guinea grass 
(Panicum maximum), and Casuarina or Australian pine (Casuarina 
equisetifolia) may be the most important invasive species of immediate 
concern (Ewert 2011, pers. comm.; Wunderle 2018, pers. comm.). These 
aggressive plants colonize patches early after disturbances and may 
form monocultures, which preclude the establishment of fruit plant 
species heavily used by Kirtland's

[[Page 54449]]

warblers. Casuarina pine establishment can increase sand loss by out-
competing native plants that stabilize dunes, resulting in increased 
coastal erosion and habitat loss (Sealey 2011, p. 12).
    Some invasive species, such as jumbie bean, are good forage for 
goats. By browsing on these invasive plants, goats create conditions 
that favor native shrubs and may increase the density of native shrubs 
used by Kirtland's warblers (Ewert 2011, pers. comm.). Goat farming 
could play a role in controlling the spread of some invasive species at 
a local scale, while aiding in the restoration of native vegetation 
patches. Still, many plants such as royal poinciana (Delonix regia), 
tropical almond (Terminalia catappa), and morning glory (Ipomoea 
indica) are commonly imported for landscaping and have the potential to 
escape into the wild (Smith 2010, pp. 9-10; Ewert 2011, pers. comm.) 
and could displace native shrubs that provide fruit for Kirtland's 
    The Bahamas National Trust administers 32 national parks that cover 
more than 809,371 ha (2 million ac) (Bahamas National Trust 2017, p. 
3). Although not all national parks contain habitat suitable for 
Kirtland's warblers, several parks provide suitable wintering habitat, 
including the Leon Levy Native Plant Preserve on Eleuthera Island, 
Harrold and Wilson Ponds National Park on New Providence Island, and 
Exuma Cays Land and Sea Park on Hawksbill Cay (The Nature Conservancy 
2011, p. 2).
    The Bahamas National Trust Act of 1959 and the National Parks 
Ordinance of 1992 established non-government statutory roles to the 
Bahamas National Trust and the Turks and Caicos Islands National Trust, 
respectively. These acts empower these organizations to hold and manage 
environmentally important lands in trust for their respective 
    Simply protecting parcels of land or important wintering habitat, 
however, may be insufficient to sustain adequate amounts of habitat for 
the Kirtland's warbler because of the species' dependence on early 
successional habitat (Mayfield 1972, p. 349; Haney et al. 1998, p. 210; 
Sykes and Clench 1998, pp. 256-257; Wunderle et al. 2010, p. 124), 
which changes in distribution over time. In addition, food availability 
at any one site varies seasonally, as well as between years, and is not 
synchronous across all sites (Wunderle et al. 2010, p. 124). In the 
face of changes in land use and availability, sustaining sufficient 
patches of early-successional habitat for Kirtland's warbler in The 
Bahamas will likely require a landscape-scale approach (Wunderle et al. 
2010, p. 135).
    Although threats to Kirtland's warblers on the wintering grounds 
exist as a result of habitat loss due to succession or development, 
hydrology changes, fire, and invasive species, the current extent and 
magnitude of these threats appears not to be significantly limiting 
Kirtland's warbler population numbers based on the species' continuous 
population growth over the last two decades.
Habitat Distribution
    The Kirtland's warbler has always occupied a relatively limited 
geographic range on both the breeding and wintering grounds. This 
limited range makes the species naturally more vulnerable to 
catastrophic events compared to species with wide geographic 
distributions, as having multiple populations in a wider distribution 
reduces the likelihood that all individuals will be affected 
simultaneously by a catastrophic event (e.g., large wildfire in 
breeding habitat, hurricane in The Bahamas). Since the species was 
listed, the geographic area where the Kirtland's warbler occurs has 
increased, reducing the risk to the species from catastrophic events. 
As the population continues to increase and expand in new breeding and 
wintering areas, the species will become less vulnerable to 
catastrophic events. The Conservation Plan, which land management 
agencies agreed to implement under the 2016 MOU, includes a goal to 
improve distribution of habitat across the breeding range to reduce 
this risk by managing lands in the Upper Peninsula of Michigan and in 
Wisconsin in sufficient quantity and quality to provide breeding 
habitat for 10 percent (100 pairs) or more of the goal of 1,000 pairs 
(MDNR et al. 2015, p. 23).

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

    The Kirtland's warbler is a non-game species, and no commercial 
harvest is known to occur in either the breeding or wintering grounds. 
Land management agencies within the Kirtland's warbler's breeding range 
previously had, and will continue to have, the ability to implement 
seasonal closures to specific areas for a variety of reasons and, when 
necessary, could limit access outside of designated roads and trails to 
further protect the species. Within the 23 KWMAs in the northern Lower 
Peninsula of Michigan and designated lands in Michigan's Upper 
Peninsula, approximately 71 km (44 miles) of routes are designated for 
off-road vehicle (ORV), all-terrain vehicle (ATV), or motorcycle use. 
In addition, approximately 151 km (94 miles) of trails are designated 
for hiking, biking, and horseback riding (USFWS, unpubl. data). 
Additionally, approximately 3,510 km (2,181 miles) of authorized 
ungraded and graded roads occur within the KWMAs (USFWS, unpubl. data). 
As described in the Conservation Plan (MDNR et al. 2015, p. 16), 
existing forest roads and trails have not typically been closed or 
otherwise restricted specifically because of the presence of adjacent 
Kirtland's warbler habitat.
    On a few occasions (Enger 2007, pers. comm.; Kaiser 2014, pers. 
comm.), motor vehicles used on roads open to such use have collided 
with and killed Kirtland's warblers. In addition, the noise from roads 
has been shown to reduce breeding success of other passerines 
(Schroeder et al. 2012, pp. 6-7; Proppe et al. 2013, pp. 1080-1082) and 
could have similar negative effects to Kirtland's warblers. Any past 
direct and indirect effects of road use have not hindered progress 
toward recovering the Kirtland's warbler, however, and we do not 
anticipate a greater extent of effects related to recreation post-
delisting. Because Kirtland's warblers occupy large blocks of habitat 
over long periods of time (Donner et al. 2010, p. 5), maintaining 
larger areas of habitat is a primary management goal (MDNR 2015, pp. 
33-34). Managing for larger blocks of breeding habitat reduces the 
effects of roads and trails that are on the edges of the habitat 
    A variety of State, national, and international laws protect 
Kirtland's warblers independent of their status under the ESA. Laws 
outside of the U.S. played an important role in helping to recover the 
species, and State laws will in some cases provide additional 
protections after delisting. The Kirtland's warbler is protected by the 
Migratory Bird Treaty Act of 1918 (MBTA; 16 U.S.C. 703-712). The MBTA 
prohibits take, capture, killing, trade, or possession of Kirtland's 
warblers and their parts, as well as their nests and eggs. The 
regulations implementing the MBTA further define ``take'' as to 
``pursue, hunt, shoot, wound, kill, trap, capture, or collect'' or 
attempt those activities (50 CFR 10.12).
    The States of Florida, Georgia, Indiana, Michigan, North Carolina, 
Ohio, Virginia, and Wisconsin list the Kirtland's warbler as 
endangered, under their respective State endangered species 
regulations. In Michigan, where the majority of the population breeds, 
part 365 of Public Act 451 of 1994 prohibits take, possession,

[[Page 54450]]

transportation, importation, exportation, processing, sale, offer for 
sale, purchase, or offer to purchase, transportation or receipt for 
shipment by a common or contract carrier of Kirtland's warblers or 
their parts.
    The Kirtland's warbler was declared federally endangered in Canada 
in 1979. Canada's Species at Risk Act of 2003 (SARA) is the primary law 
protecting the Kirtland's warbler in Canada. SARA bans killing, 
harming, harassing, capturing, taking, possessing, collecting, buying, 
selling, or trading of individuals that are federally listed. SARA also 
extends protection to the residence (habitat) of individuals that are 
federally listed. In addition, the Kirtland's warbler is listed as 
endangered under Ontario's Endangered Species Act of 2007. Canada's 
Migratory Bird Convention Act of 1994 also provides protections to 
Kirtland's warblers. Under Canada's Migratory Bird Convention Act, it 
is unlawful to be in possession of migratory birds or nests, or to buy, 
sell, exchange, or give migratory birds or nests, or to make them the 
subject of commercial transactions.
    In The Bahamas and the Turks and Caicos Islands, the Kirtland's 
warbler is recognized as a globally ``Near Threatened'' species but has 
no federally listed status. In The Bahamas, the Wild Birds Protection 
Act (chapter 249) allows the Minister of Wild Animals and Birds 
Protection to establish and modify reserves for the protection of any 
wild bird. The species is also protected in The Bahamas by the Wild 
Animals (Protection) Act (chapter 248) that prohibits the take or 
capture, export, or attempt to take, capture, or export any wild animal 
from The Bahamas. The Bahamas regulates scientific utilization of the 
Kirtland's warbler, based on recommendations previously provided by the 
Kirtland's Warbler Recovery Team (Bocetti 2011, pers. comm.).
    Through the MBTA, SARA, laws in The Bahamas, and State laws, the 
species remains protected from pursuit, wounding, or killing that could 
potentially result from activities focused on the species in breeding, 
wintering, and migratory habitat (e.g., wildlife photography without 
appropriate care to ensure breeding birds can continue to feed and care 
for chicks and eggs normally and without injury to their offspring).

C. Disease or Predation

    There is no information of any disease impacting the Kirtland's 
    For most passerines, nest predation has the greatest negative 
impact on reproductive success and can affect entire populations 
(Ricklefs 1969, p. 6; Martin 1992, p. 457). Nest predation may be 
particularly detrimental for ground-nesting bird species in shrublands 
(Martin 1993, p. 902). Predation rates of Kirtland's warbler nests have 
ranged from 3 to 67 percent of nests examined (Mayfield 1960, p. 204; 
Cuthbert 1982, p. 1; Walkinshaw 1983, p. 120); however, few predation 
events have been directly observed, and, in general, evidence regarding 
the importance of certain nest or adult predators lack quantitative 
support (Mayfield 1960, p. 182; Walkinshaw 1972, p. 5; Walkinshaw 1983, 
pp. 113-114).
    Overall, nest predation rates for Kirtland's warblers are similar 
to other passerines and are below levels that would compromise 
population replacement (Bocetti 1994, pp. 125-126; Cooper et al., 
unpubl. data). The increasing numbers of domestic cats (Felis catus) in 
the breeding and wintering habitats is recognized (Lepczyk et al. 2003, 
p. 192; Horn et al. 2011, p. 1184), but there is not sufficient 
evidence to conclude at this time that predation from cats is currently 
having population-level impacts to the Kirtland's warbler.

D. Inadequacy of Existing Regulatory Mechanisms

    Under this factor, we examine the threats identified within the 
other factors as ameliorated or exacerbated by any existing regulatory 
mechanisms or conservation efforts. Section 4(b)(1)(A) of the ESA 
requires that the Service take into account ``those efforts, if any, 
being made by any State or foreign nation, or any political subdivision 
of a State or foreign nation, to protect such species.'' In relation to 
Factor D under the ESA, we interpret this language to require the 
Service to consider relevant Federal, State, and Tribal laws, 
regulations, and other such binding legal mechanisms that may 
ameliorate or exacerbate any of the threats we describe in threat 
analyses under the other four factors or otherwise enhance the species' 
conservation. Our consideration of the regulatory mechanisms addressing 
the threats to the species, is described where applicable in the 
relevant factor section (see discussion under Factors A, B, and E).

E. Other Natural or Manmade Factors Affecting Its Continued Existence

    Pesticides have the potential to cause direct and indirect effects 
to non-target species, but we are not aware of any pesticides that are 
negatively affecting the Kirtland's warbler population. Kirtland's 
warblers could be exposed to pesticides on the breeding or wintering 
grounds or during migration. On the breeding grounds, forest managers 
are not routinely using any pesticides within occupied jack pine stands 
(Huber 2018, pers. comm.; Kintigh 2018, pers. comm.). For Kirtland's 
warbler, exposure to pesticides would be most likely through dietary 
exposure (treatment of insects or fruit plants) or accidental spray 
drift on the edges of suitable habitat.
    The U.S. Environmental Protection Agency used Kirtland's warbler as 
a case study during the re-registration process for two organophosphate 
pesticides, chlorpyrifos and malathion (Moore et al. 2017, p. 1). A 
probabilistic model was developed to assess the risks of the two 
pesticides to the birds during the breeding season and migration. The 
model results predicted very low acute and chronic risk for these 
pesticides for Kirtland's warbler (Moore et al. 2017, p. 265). This 
conclusion is unsurprising, as Moore et al. (2017, p. 267) found that 
treatments do not occur on Kirtland's warbler breeding grounds and only 
rarely would warblers be exposed during migration.
Brood Parasitism
    Brood parasitism can depress reproduction of avian hosts in several 
ways, including the direct removal or predation of eggs or young, 
facilitating nest predation by other nest predators, reducing hatching 
or fledging success, altering host population sex ratios, and 
increasing juvenile and adult mortality beyond the nest (Elliot 1999, 
p. 55; Hoover 2003, pp. 928-929; Smith et al. 2003, pp. 777-780; 
Zanette et al. 2005, p. 818; Hoover and Reetz 2006, pp. 170-171; Hoover 
and Robinson 2007, p. 4480; Zanette et al. 2007, p. 220).
    The brown-headed cowbird is the only obligate brood parasite within 
the Kirtland's warbler's breeding range and the only species documented 
parasitizing Kirtland's warbler nests. Two facultative interspecific 
nest parasite species, the black-billed cuckoo (Coccyzus 
erythropthalmus) and the yellow-billed cuckoo (Coccyzus americanus), 
may occur within the Kirtland's warbler's breeding range, but 
parasitism of a Kirtland's warbler nest has not been documented for 
these species and is not believed to be a threat.
    Although brown-headed cowbirds were historically restricted to 
prairie ecosystems, forest clearing and agricultural development of 
Michigan's Lower Peninsula in the late 1800s

[[Page 54451]]

facilitated the brown-headed cowbird's range expansion into Kirtland's 
warbler nesting areas (Mayfield 1960, p. 145) such that brown-headed 
cowbirds were common within the Kirtland's warbler's breeding range by 
the early 1900s (Wood and Frothingham 1905, p. 49). The first known 
instance of brood parasitism of a Kirtland's warbler nest occurred in 
Crawford County, Michigan, in 1908 (Strong 1919, p. 181). Shortly 
thereafter, the scarcity of Kirtland's warblers was attributed to 
brown-headed cowbird parasitism (Leopold 1924, p. 57), which later data 
confirmed as significantly affecting the survival of the Kirtland's 
warbler (Mayfield 1960, pp. 180-181).
    The Kirtland's warbler is particularly sensitive to brown-headed 
cowbird brood parasitism. The warbler's limited breeding range likely 
exposes the entire population to brown-headed cowbird parasitism 
(Mayfield 1960, pp. 146-147; Trick, unpubl. data). In addition, the 
peak egg-laying period of the brown-headed cowbird completely overlaps 
with that of the Kirtland's warbler, and the majority of Kirtland's 
warblers produce only one brood each year (Mayfield 1960, pp. 151-152; 
Radabaugh 1972, p. 55; Rockwell, unpubl. data). Kirtland's warblers 
have limited evolutionary experience with brown-headed cowbirds 
compared to other hosts and have not developed effective defensive 
behaviors to thwart brood parasitism (Walkinshaw 1983, pp. 157-158).
    Between 1903 and 1971, observed parasitism rates of Kirtland's 
warbler nests ranged from 48 percent to 86 percent (reviewed in Shake 
and Mattson 1975, p. 2). Brown-headed cowbirds also appear to exert 
greater pressure on Kirtland's warbler nests than other passerines 
within the same breeding habitat, with 93 percent of brown-headed 
cowbird eggs found in jack pine habitat placed in Kirtland's warbler 
nests compared to all other host species combined (Walkinshaw 1983, p. 
154). Kirtland's warbler fledging rates averaged less than one young 
per nest prior to the initiation of brown-headed cowbird control 
(Walkinshaw 1972, p. 5).
    The effect of brown-headed cowbird parasitism exacerbated negative 
impacts associated with habitat loss in the decline of the Kirtland's 
warbler population (Rothstein and Cook 2000, p. 7). Once trapping of 
brown-headed cowbirds within Kirtland's warbler nesting areas was 
demonstrated to decrease parasitism rates and increase Kirtland's 
warbler nesting success (Cuthbert 1966, pp. 1-2), intensive brown-
headed cowbird removal was recommended on major Kirtland's warbler 
nesting areas as one of the necessary steps for the recovery of the 
Kirtland's warbler (Shake and Mattsson 1975, p. 2).
    Starting in 1972, the Service, in conjunction with the USDA-WS, 
MDNR, and USFS, implemented an intensive brown-headed cowbird control 
program within Kirtland's warbler nesting areas in Michigan's Lower 
Peninsula. On average, the control program annually removes 
approximately 3,573 brown-headed cowbirds from occupied Kirtland's 
warbler habitat in northern lower Michigan (USDA-WS 2016, unpubl. 
report). Recent trap rates, however, have been below 1,500 brown-headed 
cowbirds per year (USDA-WS, unpubl. data).
    Following the initiation of brown-headed cowbird control in 
northern lower Michigan in 1972, brood parasitism rates decreased to 
6.2 percent, and averaged 3.4 percent between 1972 and 1981 (Kelly and 
DeCapita 1982, p. 363). Kirtland's warbler fledging rates 
simultaneously increased from less than one per nest to 2.8 per nest, 
and averaged 2.78 young fledged per nest between 1972 and 1981 (Kelly 
and DeCapita 1982, pp. 364-365). Had brown-headed cowbird parasitism 
not been controlled, the Kirtland's warbler population may have been 
reduced to only 42 pairs by 1974 (Mayfield 1975, p. 43).
    Brood parasitism of Kirtland's warbler nests also occurs in 
Wisconsin, and brown-headed cowbird trapping is conducted in select 
Kirtland's warbler breeding areas. The trapping program in Wisconsin 
started in 2008, and is run using similar methods to the program in 
Michigan, with an average of 238 brown-headed cowbirds captured per 
year (USDA-WS, USFWS unpubl. data). In 2007, two of three Kirtland's 
warbler nests were parasitized (USFWS, unpubl. data). After the 
initiation of brown-headed cowbird control in 2008, brood parasitism 
rates in Wisconsin have fluctuated substantially among years, from 10 
percent to 66 percent (USFWS, unpubl. data; Trick, unpubl. data). 
However, in the same time period (2008-2017), overall nest success has 
ranged from 19 to 80 percent, and the average fledge rate was estimated 
to be between 1.51 to 1.92 chicks per nest (USFWS 2017, pp. 2-3).
    Limited studies on the effectiveness of the brown-headed cowbird 
control program in relation to Kirtland's warbler nest productivity in 
Michigan have been conducted since the early 1980s. Brown-headed 
cowbirds were nearly eliminated in areas directly adjacent to a trap, 
and brown-headed cowbird densities increased 5 km (3 miles) and greater 
from brown-headed cowbird removal areas (De Groot and Smith 2001, p. 
877). Brown-headed cowbird densities also significantly increased at 
distances greater than 10 km (6 miles) from brown-headed cowbird 
removal areas, further demonstrating the localized effect of brown-
headed cowbird control (De Groot and Smith 2001, p. 877). Although 
brown-headed cowbird density increased with distance beyond 5 km (3 
miles) of brown-headed cowbird traps, brown-headed cowbird densities 
were still low in those areas compared to other parts of North America 
(De Groot and Smith 2001, p. 877). Anecdotal observations of brood 
parasitism rates within Kirtland's warbler nesting areas during periods 
of brown-headed cowbird control indicated very low levels of brood 
parasitism; parasitism rates have been reduced to less than 1 percent 
of all nests in areas where trapping occurred (Bocetti 1994, p. 96; 
Rockwell 2013, pp. 80, 93; Rockwell, unpubl. data).
    A study is currently underway in Michigan to evaluate the effective 
range of a brown-headed cowbird trap and to determine the brood 
parasitism rate of Kirtland's warbler nests when traps are not operated 
during the warbler's breeding season. Beginning in 2015, 12 brown-
headed cowbird traps (out of 55 total) were closed for two breeding 
seasons. In 2015, only one nest out of 157 was parasitized, 
approximately 4.6 km (2.9 miles) away from the nearest brown-headed 
cowbird trap. In 2016, similar low rates of parasitism were observed, 
with only 2 parasitized nests out of 128. Due to the low levels of 
brood parasitism observed, an additional 6 traps were closed in 2017, 
and none of the 100 nests observed between 0.5 and 22.1 km (0.3 and 
13.7 miles) from a brown-headed cowbird trap in 2017 were parasitized 
(Cooper et al., unpubl. data). In total, only 3 of 385 Kirtland's 
warbler nests were parasitized in areas with a spatially reduced 
trapping program from 2015 to 2017. These preliminary data corroborate 
similar findings that the effective range of a brown-headed cowbird 
trap is likely much larger than the range (i.e., 1.6 km (1 mile) 
radius) traditionally used in planning and implementing the brown-
headed cowbird control program. Following these results, all brown-
headed cowbird trapping in Michigan's northern Lower Peninsula was 
suspended for the 2018 nesting season. Only 1 of 129 Kirtland's warbler 
nests was found to be

[[Page 54452]]

parasitized (Cooper et al., unpubl. data) in 2018.
    Trend estimate data from Breeding Bird Survey routes between 2005 
and 2015 show decreasing brown-headed cowbird populations in Michigan 
and the Upper Great Lakes (Sauer et al. 2017, p. 169). Reduced brown-
headed cowbird abundance within Kirtland's warbler nesting areas is 
supported by results from point count surveys conducted between 2015 
and 2018 in Kirtland's warbler nesting areas in Michigan's northern 
Lower Peninsula where brown-headed cowbird traps were not being 
operated. Only 67 brown-headed cowbirds were observed during 1,134 
point count surveys (Cooper et al., unpubl. data).
    However, in similar experiments where brown-headed cowbird trapping 
was reduced or brought to an end following a lengthy period of 
trapping, brood parasitism rates elevated or returned to pre-trapping 
rates. Research at Fort Hood Military Reservation in Texas showed that 
after 3 years of decreased brown-headed cowbird trapping levels, 
parasitism rates increased from 7.9 percent to 23.1 percent and 
resulted in black-capped vireo (Vireo atricapilla) nest survival 
decreasing to unsustainable levels (Kostecke et al. 2009, p. 1). Other 
studies have found similar results with parasitism frequency and host 
bird productivity returning to pre-trapping levels quickly upon 
discontinuing cowbird removal (Kosciuch and Sandercock 2008, p. 546).
    After 45 years of brown-headed cowbird trapping in Michigan, the 
threat of brood parasitism on the Kirtland's warbler has been greatly 
reduced but not eliminated. Brown-headed cowbirds remain present, but 
potentially in lower numbers, in jack pine habitat away from brown-
headed cowbird traps, even if that area had been trapped in previous 
years (DeGroot and Smith 2001, p. 877; Bailey 2007, pp. 97-98; Cooper 
et al., unpubl. data). Female brown-headed cowbirds are highly 
prolific, estimated to produce up to 40 eggs in a breeding season 
(Scott and Ankney 1980, p. 680). Successful brown-headed cowbird 
reproduction outside of trapped areas may maintain a population of 
adult brown-headed cowbirds that could return in subsequent years with 
the ability to parasitize Kirtland's warbler nests. It is unclear if 
reduced parasitism rates are a permanent change to the landscape of 
northern lower Michigan. The best available information, however, 
indicates that cowbird removal efforts can be reduced, at least 
temporarily, without adversely impacting Kirtland's warbler 
productivity rates. Given the historical impact that the brown-headed 
cowbird has had on the Kirtland's warbler, and the potential for the 
brown-headed cowbird to negatively affect the warbler, a sustainable 
Kirtland's warbler population depends on monitoring the magnitude and 
extent of brood parasitism and subsequently adjusting the level of 
cowbird trapping appropriately.
    The MOA (see Recovery and Recovery Plan Implementation, above) 
established in 2015 between the Service and MDNR addresses the 
commitment and long-term costs associated with future efforts to 
control brown-headed cowbirds. The MOA established a dedicated account 
from which income can be used to implement cowbird management and other 
conservation actions for the Kirtland's warbler. To date, the account 
has greater than $2.1 million invested for long-term growth. The MDNR 
has re-confirmed their commitment to implement and administer the 
brown-headed cowbird management program once the species is delisted 
(MDNR 2017). Given our understanding of the status of brown-headed 
cowbirds in northern lower Michigan, the $2.1 million investment, 
coupled with the MDNR's commitment, is sufficient to provide an 
effective brown-headed cowbird management program into the foreseeable 
Climate Change
    Our analyses under the ESA include consideration of ongoing and 
projected changes in climate. A recent compilation of climate change 
and its effects is available from reports of the Intergovernmental 
Panel on Climate Change (IPCC) (IPCC 2014, entire). In our analyses, we 
use our expert judgment to weigh relevant information, including 
uncertainty, in our consideration of various aspects of climate change.
    The effects of climate change on Kirtland's warblers were not 
identified as a threat to the species in the listing rule (32 FR 4001; 
March 11, 1967) or in the updated recovery plan (USFWS 1985, entire). 
Potential effects of climate change to the Kirtland's warbler could 
occur as a result of changes on the breeding or wintering grounds and 
include a decrease and shift in suitable breeding habitat outside of 
the species' current range (Prasad et al. 2007, unpaginated), increase 
in pests or pathogens of jack pine, a decrease in the extent of 
wintering habitat, and decoupling of the timing of migration from food 
resource peaks that are driven by temperature and are necessary for 
migration and feeding offspring (van Noordwijk et al. 1995, p. 456; 
Visser et al. 1998, pp. 1869-1870; Thomas et al. 2001, p. 2598; Strode 
2003, p. 1142).
    Breeding Grounds: On the breeding grounds, climate change 
projections, based on low (B1) and high (A1FI) emission scenarios, 
predict shifts in mean temperature and precipitation as well as altered 
timing and extremes (Handler et al. 2014, pp. 68-84; Janowiak et al. 
2014, pp. 66-85; GLISA 2018, unpaginated). In the core breeding area, 
temperatures are expected to increase across all seasons, with more 
dramatic increases during winter months (Handler et al. 2014, p. 72). 
Precipitation is projected to increase in winter and spring but may 
decrease in the summer (Handler et al. 2014, pp. 73-75), with more 
extreme precipitation events representing a larger proportion of the 
total annual and seasonal rainfall (Handler et al. 2014, p. 82).
    The extent and availability of suitable Kirtland's warbler habitat 
within jack pine forests on the breeding grounds could change based on 
projected changes to temperature and precipitation. The Forest 
Service's Forest Ecosystem Vulnerability Assessments considered impacts 
to above-ground biomass for 26 tree species, and projected stable (in 
Wisconsin) or slight reductions (in Michigan) in the biomass of jack 
pine over the next 50 years, with more significant declines projected 
by the end of the 21st century (Handler et al. 2014, p. 94; Janowiak et 
al. 2014, p. 99). In addition to a possible reduction in the biomass of 
jack pine, the spatial distribution of the species may also shift in 
response to changing climate.
    The projections of how jack pine will be affected by climate change 
vary based on the model used and emission scenario considered. Overall, 
models predict that jack pine occurrence will contract in the northern 
Lower Peninsula and shift out of peripheral breeding areas. Scenarios 
using both low (B1) and high (A1F1) greenhouse gas emissions predicted 
a reduction of the extent of jack pine in Michigan but an expansion of 
jack pine in western Wisconsin and Minnesota (Prasad et al. 2007, 
unpaginated). More recent models using emission scenarios with 
Representative Concentration Pathways (RCPs) of 4.5 and 8.5 similarly 
projected a decline in jack pine occurrence in Michigan and indicated 
declines in northern Minnesota, northern Wisconsin, and the Upper 
Peninsula of Michigan (Donner et al. 2018, pp. 270-273). However, 
conditions were projected to remain suitable for jack pine occupancy in 
northern lower Michigan (Donner et al. 2018, pp. 271).

[[Page 54453]]

    Insect pests may become more problematic to jack pine under future 
climatic changes, with increasing damage and spread of new jack pine 
pests in the Kirtland's warbler's habitat areas. A warmer climate may 
increase the susceptibility of current jack pine forests to damage from 
pests and diseases (Bentz et al. 2010, pp. 606-610; Cudmore et al. 
2010, pp. 1040-1042; Safranyik et al. 2010, p. 432) and may allow for 
new pests such as western bark beetle to arrive (Handler et al. 2014, 
p.130). Forest managers will continue to monitor pest and pathogen 
outbreaks in jack pine forests.
    Competition with deciduous forest species is also expected to favor 
an expansion of the deciduous forest into the southern portions of the 
boreal forest (USFWS 2009, p. 14) and affect interspecific 
relationships between the Kirtland's warbler and other wildlife 
(Colwell and Rangel 2009, p. 19657; Wiens et al. 2009, p. 19729). 
However, warmer weather and increased levels of carbon dioxide could 
also lead to an increase in tree growth rates on marginal forestlands 
that are currently temperature-limited (NAST 2000, p. 57). Higher air 
temperatures will cause greater evaporation and, in turn, reduce soil 
moisture, resulting in conditions conducive to forest fires (NAST 2000, 
p. 57) that favor jack pine propagation. Too much change in the fire 
regime could have a negative effect on jack pine regeneration and 
result in a shift to barrens (Handler et al. 2014, p. 130). 
Additionally, warmer temperatures could also lead to greater moisture 
stress, through accelerated litter layer decomposition leading to lower 
water-holding capacity (Handler et al. 2014, p. 130). Alternatively, 
warmer conditions and longer growing seasons could benefit pine 
forests, if carbon dioxide fertilization boosts long-term water-use 
efficiency and productivity (Handler et al. 2014, pp. 102, 114-115, 
    Recent vulnerability analyses estimate moderate potential impacts 
to jack pine forests as a result of the effects of climate change and 
low-moderate adaptive capacity of jack pine, based on its high 
tolerance for disturbance and existing management practices (Handler et 
al. 2014, p. 130). A climate change vulnerability assessment for 
wildlife species by MDNR (Hoving et al. 2013, p. 40), using 
NatureServe's Climate Change Vulnerability Index, categorized 
Kirtland's warbler as ``Presumed Stable,'' with the caveat that while 
the population may remain stable, its range may shift outside of 
    In summary, there may be a reduction or a shift in available 
suitable jack pine habitat over the next 50 years, but these reductions 
may be offset to some degree by other ecosystem processes, such as an 
altered fire regime and adaptive habitat management (harvest of jack 
pines and techniques, such as the use of containerized saplings rather 
than bare-root stock, for planting jack pine plantations). Jack pine 
may also adapt to changing climatic conditions. As suitable habitat 
shifts, Kirtland's warblers could also adapt by utilizing more marginal 
habitat, or increasing in density in high-quality habitat. The KWCT 
will continue to analyze the extent and distribution of suitable 
habitat, and the effects of pests and disease on jack pine.
    Wintering Grounds: On the wintering grounds, effects of climate 
change to the Kirtland's warbler could occur as a result of changing 
temperature and precipitation, rising sea levels, and storm events. For 
migratory species, unfavorable changes on the wintering grounds can 
result in subsequent negative effects on fitness later in the annual 
life cycle (Marra et al. 1998, p. 1885; Sillett et al. 2000, pp. 2040-
2041; Rockwell et al. 2012, pp. 747-748; Rockwell et al. 2017, p. 721). 
For the Kirtland's warbler, wintering habitat condition affects 
survival and reproduction (Rockwell et al. 2012, pp. 747-748; Rockwell 
et al. 2017, p. 721). These effects likely result from limited resource 
availability on the wintering grounds that reduces body condition and 
fat reserves necessary for successful migration and reproduction 
(Wunderle et al. 2014, pp. 47-49). The availability of sufficient food 
resources is affected by the amount of habitat for arthropods and 
fruiting plants, temperature, and precipitation (Brown and Sherry 2006, 
pp. 25-27; Wunderle et al. 2014, p. 39).
    Temperatures in the Caribbean have shown strong warming trends 
across all regions, particularly since the 1970s (Jones et al. 2016, 
pp. 3325, 3332), and are likely to continue to warm. A climate model 
with a high emission scenario (A2) predicted an increase in temperature 
of almost 2.5 to 3.0 degrees Celsius (4.5 to 6.3 degrees Fahrenheit) 
above the mean temperatures of 1970-1989 by the 2080s (Karmalkar et al. 
2013, p. 301). Climate change models using a lower emissions scenario 
(RCP4.5) project an increase in surface temperature in the Caribbean 
ranging from 1.2 to 1.9 degrees Celsius (2.2 to 3.4 degrees Fahrenheit) 
for 2081-2100 when compared to 1986-2005 (Nurse et al. 2014, p. 1628). 
Other models, using high (A2) and low (B2) emission scenarios, also 
predicted an increase in the number of warm days and nights and a 
decrease in the frequencies of cool days and nights, in addition to 
higher mean daily temperatures, for 2071-2099 relative to 1961-1999 
(Stennett-Brown et al. 2017, pp. 4838-4840). Increased temperatures 
could affect food availability by altering food supply (arthropod and 
fruit availability), although it is unknown to what extent the 
predicted increases in temperature would increase or decrease food 
supply for the Kirtland's warbler. Other effects of increasing 
temperature related to sea level and precipitation are described below.
    Increasing temperatures can contribute to sea level rise from the 
melting of ice over land and thermal expansion of seawater. A wide 
range of estimates for future global mean sea level rise is found in 
the scientific literature (Church et al. 2013, entire; IPCC 2013a, 
entire; Simpson et al. 2010, pp. 55-61; Sweet et al. 2017, entire). By 
2070, global mean sea level is projected to increase by 0.35 m (1.15 
ft) to 0.42 m (1.38 ft) under RCP4.5 and RCP8.5 scenarios (IPCC 2013a, 
p. 1445). Another model predicts increases in sea level ranging from 
0.35 m (1.15 ft) to 0.79 m (2.59 ft) by 2070 under comparable emission 
scenarios (Sweet et al. 2017, p. 23). An increase in sea level could 
reduce the availability of suitable habitat due to low-elevation areas 
being inundated, resulting in a reduction in the size of the islands on 
which Kirtland's warblers winter (Amadon 1953, p. 466; Dasgupta et al. 
2009, pp. 21-23). The Bahamas archipelago is mainly composed of small 
islands, and more than 80 percent of the landmass is within 1.5 m (4.9 
ft) of mean sea level (The Bahamas Environment, Science and Technology 
Commission 2001, p. 43). This makes The Bahamas particularly vulnerable 
to future rises in sea level (Simpson et al. 2010, p. 74), which could 
result in a reduction of the extent of winter habitat and negatively 
impact the Kirtland's warbler. Estimates of total landmass loss 
throughout The Bahamas due to a 1-meter (3.3 ft) rise in sea level vary 
from 5 percent (Simpson et al. 2010, p. 77) to 11 percent (Dasgupta et 
al. 2007, p. 12; 2009, p. 385). However, not all of the land that may 
be inundated is potentially suitable for Kirtland's warbler (e.g., 
developed land, closed-canopy forest). To assess how climate change 
scenarios may affect Kirtland's warbler's wintering habitat, we 
considered a recent estimate of potential Kirtland's warbler habitat 
loss due to sea level rise (Wolcott et al. 2018, entire). Loss of open-
land habitat varied across the archipelago, based on elevational 
differences (Wolcott et al. 2018, p. 10). There have historically

[[Page 54454]]

been few observations of Kirtland's warblers on the northern islands 
(Cooper et al. 2019, p. 84), where elevations are lower and where 
projections indicate the greatest loss of open land (Wolcott et al. 
2018, p. 10). On Eleuthera, the island with the greatest known density 
of overwintering Kirtland's warblers, a rise in sea level of 1 meter 
(3.3 ft) or 2 meters (6.6 ft) would result in a loss of potential 
Kirtland's warbler wintering habitat of 0.8 percent and 2.6 percent, 
respectively (Wolcott et al. 2018, p. 9). Given that the projected rise 
in sea level in the foreseeable future is less than 1 meter (3.3 ft), 
we anticipate the loss of potential Kirtland's warbler winter habitat 
on Eleuthera due to sea level rise will be less than 0.8 percent.
    Generally, climate models predict a drying trend in the Caribbean, 
but there is considerable temporal and spatial variation and often 
disagreement among models regarding specific predictions that make it 
difficult to determine the extent to which reduced rainfall or timing 
of rainfall may affect the Kirtland's warbler in the future. We 
reviewed available literature examining precipitation trends and 
projections in the Caribbean, and specifically The Bahamas, to assess 
the potential effects of changes in precipitation.
    Precipitation patterns in the Caribbean from 1979 to 2012 did not 
show statistically significant century-scale trends across regions, but 
there were periods of up to 10 years when some regions were drier or 
wetter than the long-term averages (Jones et al. 2016, p. 10). In the 
northern Caribbean (which includes The Bahamas, Cuba, Jamaica, Haiti, 
Dominican Republic, and Puerto Rico), some years were more wet than the 
average, and other years were more dry across all seasons (Jones et al. 
2016, p. 3314), with higher precipitation totals since about 2000. 
Within The Bahamas, precipitation trends during the dry season 
(November through April) showed a significant drying trend for 1979-
2009 (Jones et al. 2016, pp. 3328, 3331).
    Model projections under two emission scenarios (RCP4.5 and 8.5) 
found that the projected precipitation varied seasonally and spatially 
throughout the islands of The Bahamas, both in the mid-term (2050) and 
long-term (2100) (Wolcott et al. 2018, pp. 4-6). The northern and 
north-central islands are likely to have increased precipitation in 
March (compared to baseline conditions), whereas the central islands 
are likely to become drier (Wolcott et al. 2018, p. 7-8) under both 
emission scenarios, with the magnitude of projected changes greater in 
    Accurately projecting future precipitation trends in the Caribbean 
is difficult due to the complex interactions between sea surface 
temperatures, atmospheric pressure at sea level, and predominant wind 
patterns. Further, some models have difficulty accurately simulating 
the semi-annual seasonal cycle of precipitation observed in the 
Caribbean (Karmalkar et al. 2013, pp. 300-302). Recent models using 
statistical downscaling techniques have improved resolution but still 
show limitations for predicting precipitation (Stennett-Brown et al. 
2017, p. 4840). Thus, rainfall projections where Kirtland's warblers 
overwinter have limited certainty and should be interpreted with 
caution. Understanding the likely projected precipitation in The 
Bahamas and Caribbean is important because of the strong link between 
late winter rainfall and fitness of Kirtland's warblers. A drying trend 
on the wintering grounds will likely cause a corresponding reduction in 
available food resources (Studds and Marra 2007, pp. 120-121; Studds 
and Marra 2011, pp. 4-6). Rainfall in the previous month was an 
important factor in predicting fruit abundance (both ripe and unripe 
fruit) for wild sage and black torch in The Bahamas (Wunderle et al. 
2014, p. 19), which is not surprising given the high water content (60-
70 percent) of their fruit (Wunderle, unpubl. data, cited in Wunderle 
et al. 2014, p. 4). Carry-over effects of weather on the wintering 
grounds, particularly late-winter rainfall, have been shown to affect 
spring arrival dates, reproductive success, and survival rates of 
Kirtland's warblers (reviewed in Wunderle and Arendt 2017, pp. 5-12; 
Rockwell et al. 2012, p. 749; Rockwell et al. 2017, pp. 721-722).
    Decreases in rainfall and resulting decreases in food availability 
may also result in poorer body condition prior to migration. The need 
to build up the necessary resources to successfully complete migration 
could, in turn, result in delays to spring departure in dry years 
(Wunderle et al. 2014, p. 16) and may explain observed delays in 
arrival times following years with less March rainfall in The Bahamas 
(Rockwell et al. 2012, p. 747). Delays in the spring migration of 
closely related American redstarts (Setophaga ruticilla) have also been 
directly linked to variation in March rainfall and arthropod biomass 
(Studds and Marra 2007, p. 120; Studds and Marra 2011, p. 4), and have 
also resulted in fewer offspring produced per summer (Reudink et al. 
2009, p. 1624). These results strongly indicate that environmental 
conditions modify the timing of spring migration, which likely carries 
a reproductive cost. If The Bahamas experience a significant winter 
drying trend, Kirtland's warblers may be pressured to delay spring 
departures, while simultaneously contending with warming trends in 
their breeding range that pressure them to arrive earlier in the 
spring. Projection population modeling (Rockwell et al. 2017, p. 2) 
estimated a negative population growth in Kirtland's warbler as a 
result of a reduction of more than 12.4 percent from the current mean 
levels in March rainfall.
    A recent drought in the Caribbean from 2013 to 2016, due in part to 
El Ni[ntilde]o, resulted in some of the highest temperatures and 
potential evapotranspiration anomalies observed in the region (Herrera 
and Ault 2017, p. 7822). As a result, it has been characterized as the 
most severe drought in the region since at least 1950 (Herrera and Ault 
2017, p. 7822) and may have been appreciably more severe because of 
anthropogenic warming (i.e., 15 to 17 percent of the drought's severity 
and approximately 7 percent of its spatial extent could be attributed 
to the anthropogenic effects of climate change) (Herrera et al. 2018, 
pp. 4-5). Future droughts are predicted to be increasingly severe 
because of higher temperatures, which played an important role in the 
2013-2016 drought, regardless of changes in precipitation (Herrera et 
al. 2018, p. 7). For the period during and following the 2013-2016 
drought, the Kirtland's warbler population remained stable or 
increased, indicating at least some level of resilience to severe, 
short-term drought.
    Extreme weather events, such as tropical storms and hurricanes, 
will continue to occur with an expected reduction in the overall 
frequency of weaker tropical storms and hurricanes and an increase in 
the frequency of the most intense hurricanes (category 4 and 5 
hurricanes), based on several dynamical climate-modeling studies of 
Atlantic basin storm frequency and intensity (Bender et al. 2010, p. 
456; Knutson et al. 2010, pp. 159-161; Murakami et al. 2012a, pp. 2574-
2576; Murakami et al. 2012b, pp. 3247-3253; Knutson et al. 2013, pp. 
6599-6613; Knutson et al. 2015, pp. 7213-7220). Although very intense 
hurricanes are relatively rare, they inflict a disproportionate impact 
in terms of storm damage (e.g., approximately 93 percent of damage 
resulting from hurricanes is caused by only 10 percent of the storms 
(Mendelsohn et al. 2012,

[[Page 54455]]

p. 3)). An increasing trend for hurricanes to have decreased forward or 
translational speeds may increase the future risk of heavy rainfall 
events and extended period of hurricane-force winds over an island 
(Kossin 2018, p. 105). This could result in future increased risks to 
Kirtland's warblers and their winter habitat.
    Hurricanes have the potential to result in direct mortality of 
Kirtland's warblers during migration and while on the wintering grounds 
(Mayfield 1992, p. 11), but most birds do not arrive in The Bahamas 
until mid-October to early November, after peak hurricane season 
(Wunderle and Ewert 2018, p. 1). There is a high risk of short-term 
effects following the hurricane due to altered shelter and food (Wiley 
and Wunderle 1993, pp. 331-336). During recent observations of 
hurricane effects on the island of San Salvador, post-hurricane 
declines of Kirtland's warblers relative to previous winters may have 
been due to food resource loss resulting from salt spray that killed 
leaves and possibly arthropods and fruit (Wunderle and Ewert 2018, p. 
1). Because Kirtland's warblers readily shift sites on the wintering 
grounds based on food availability, Kirtland's warblers would likely be 
able to shift locations within and possibly between nearby islands as 
an immediate post-hurricane response (Wunderle et al. 2007, p. 124). 
Further, hurricanes likely produce new wintering habitat for Kirtland's 
warblers by opening up closed canopy habitat of tall coppice and may 
also help set back succession for existing suitable habitat (Wunderle 
et al. 2007, p. 126). Coastal areas at most risk to storm surges (and 
thus less suitable for development) may provide future habitat for 
Kirtland's warblers (Wunderle and Ewert 2018, p. 1).
    In summary, uncertainties in modeling the projected effects of 
climate change in The Bahamas, both spatially and temporally, create 
some uncertainty in effects on the Kirtland's warbler's wintering 
habitat and food availability. There is more confidence that 
temperatures are likely to increase, and it is possible that there will 
be a drying trend over much of the Caribbean. However, it is not clear 
whether all islands will be equally affected by less precipitation. The 
Kirtland's warbler population has increased dramatically during the 
past drying trend (1979-2009) and recent drought (2013-2016) at its 
wintering grounds. In addition, individual warblers have been reported 
wintering outside of The Bahamas (see Distribution, above). Although 
the extent of behavioral plasticity and adaptive capacity at the 
species level to shift locations in response to the effects of climate 
change in the Caribbean remains unknown, as a long-distance migrant, 
the Kirtland's warbler is well suited, in terms of its movement 
patterns and dispersal ability, to reach other locations both within 
and outside of its current winter range where suitable winter habitat 
and food resources may be more available under future temperature and 
precipitation conditions.
Collision With Lighted and Human-Made Structures
    Collision with human-made structures (e.g., tall buildings, 
communication towers, wind turbines, power lines, and heavily lighted 
ships) kills or injures millions of migrating songbirds annually 
(Bocetti 2011, pp. 177-178; reviewed in Drewitt and Langston 2008, p. 
259; Longcore et al. 2008, pp. 486-489). Factors that influence the 
likelihood of avian collisions with human-made structures include size, 
location, use of lighting, and weather conditions during migratory 
periods (reviewed in Drewitt and Langston 2008, p. 233). The presence 
of artificial light at night and plate-glass windows are the most 
important factors influencing avian collisions with existing human-made 
structures (Ogden 1996, p. 4).
    There are five confirmed reports of Kirtland's warblers colliding 
with human-made structures, all of which resulted in death. Two of 
these deaths resulted from collisions with windows (Kleen 1976, p. 78; 
Kramer 2009, pers. comm.), and three resulted from collisions with a 
lighted structure, including a lighthouse (Merriam 1885, p. 376), an 
electric light mast (Jones 1906, pp. 118-119), and a lighted monument 
(Nolan 1954). Another report of a Kirtland's warbler that flew into a 
window and appeared to survive after only being stunned by the 
collision (Cordle 2005, p. 2) was not accepted as an official 
documented observation of a Kirtland's warbler (Maryland Ornithological 
Society 2010, unpaginated).
    Some bird species may be more vulnerable to collision with human-
made structures than others due to species-specific behaviors. 
Particularly vulnerable species include: Night-migrating birds that are 
prone to capture or disorientation by artificial lights because of the 
way exposure to a light field can disrupt avian navigation systems; 
species that habitually make swift flights through restricted openings 
in dense vegetation; and species that are primarily active on or near 
the ground (reviewed in Ogden 1996, p. 8; Gauthreaux and Belser 2006, 
p. 67). Of the avian species recorded, the largest proportion of 
species (41 percent) that suffer migration mortality at human-made 
structures belong to the wood warbler subfamily (Parulinae), of which 
many species exhibit the above-mentioned behaviors (Ogden 1996, p. 14).
    The Kirtland's warbler belongs to the Parulidae family, migrates at 
night, typically occupies dense vegetation, and is often active on or 
near the ground. Although Kirtland's warblers exhibit behavioral traits 
that may contribute to vulnerability to collision with human-made 
structures, little is known regarding how prone this species is to 
collision. The majority of bird collisions go undetected because 
corpses land in inconspicuous places or are quickly removed by 
scavengers, postmortem (Klem 2009, p. 317). Additionally, while most 
avian collisions take place during migration, detailed information 
about Kirtland's warbler migration is still limited. The Kirtland's 
warbler population is also small, reducing the probability of collision 
observations by chance alone, compared to other species. These factors 
have inhibited the gathering of information, and in turn, a more 
comprehensive understanding of the hazards human-made structures pose 
to the Kirtland's warbler. It is reasonable to presume, however, that 
more Kirtland's warblers collide with human-made structures than are 
    Solutions to reduce the hazards that cause avian collisions with 
human-made structures are being implemented in many places. 
Extinguishing internal lights of buildings at night, avoiding the use 
of external floodlighting, and shielding the upward radiation of low-
level lighting such as street lamps are expected to reduce attraction 
and trapping of birds within illuminated urban areas, and in turn, 
reduce injury and mortality caused by collision, predation, starvation, 
or exhaustion (reviewed in Ogden 1996, p. 31). The Service's Urban 
Conservation Treaty for Migratory Birds program has worked with several 
cities to adopt projects that benefit migrating birds flying through 
urban areas between breeding and wintering grounds. For example, some 
cities within the Kirtland's warbler's migration corridor, such as 
Chicago, Indianapolis, Columbus, Detroit, and Milwaukee, have ``Lights 
Out'' or similar programs, which encourage the owners and managers of 
tall buildings to turn off or dim exterior decorative lights, as well 
as interior lights, during spring and fall migration periods (National 
Audubon Society 2019,

[[Page 54456]]

entire). These programs are estimated to reduce general bird mortality 
by up to 83 percent (Field Museum 2007, p. 1).
    Additionally, migrating birds are not equally attracted to various 
lighting patterns, and modifying certain types of lighting systems 
could significantly reduce collision-related mortality. Removing 
steady-burning, red L-810 lights and using only flashing, red L-864 or 
white L-865 lights on communication towers and other similarly lit 
aeronautical obstructions could reduce mortality rates by as much as 50 
to 70 percent (Gehring et al. 2009, p. 509). On December 4, 2015, the 
Federal Aviation Administration (FAA) revised its advisory circular 
that prescribes tower lighting to eliminate the use of L-810 steady-
burning side lights on towers taller than 107 m (350 ft) (FAA Advisory 
Circular 70/7460-1L), and on September 28, 2016, it released 
specifications for flashing L-810 lights on towers 46-107 m (150-350 
ft) tall. These lighting changes should significantly reduce the risk 
of migratory bird collisions with communication towers.
    As noted previously concerning potential threats to migratory 
habitat, if mortality during migration were limiting or likely to limit 
the population to the degree that maintaining a healthy population may 
be at risk, it should be apparent in the absence of the species from 
highly suitable breeding habitat in the core breeding range. In fact, 
we have seen just the opposite with increasing densities of breeding 
individuals in core areas and a range expansion into what would appear 
to be less suitable habitat elsewhere. This steady population growth 
and range expansion occurred while the potential threats to the species 
during migration were all increasing on the landscape (e.g., new 
communication towers and wind turbines).

Synergistic Effects of Factors A Through E

    When threats occur together, one may exacerbate the effects of 
another, causing effects not accounted for when threats are analyzed 
individually. Many of the threats to the Kirtland's warbler and its 
habitat discussed above under Factors A through E are interrelated and 
could be synergistic, and thus may cumulatively impact Kirtland's 
warbler beyond the extent of each individual threat. For example, 
increases in temperature and evaporation could reduce the amount of 
jack pine habitat available and increase the level of brood parasitism. 
Historically, habitat loss and brood parasitism significantly impacted 
the Kirtland's warbler and cumulatively acted to reduce its range and 
abundance. Today, these threats have been ameliorated and adequately 
minimized such that the species has exceeded the recovery goal. The 
best available data show a positive population trend over several 
decades and record high population levels. Continued habitat management 
and brown-headed cowbird control at sufficient levels, as identified in 
the Conservation Plan and at levels consistent with those to which 
management agencies committed in the MOU and MOA, will assure continued 
population numbers at or above the recovery criterion with the current 
magnitude of other threats acting on the Kirtland's warbler.

Summary of Comments and Recommendations

    In the proposed rule published on April 12, 2018 (83 FR 15758), we 
requested that all interested parties submit written comments on the 
proposal by July 11, 2018. We also contacted appropriate Federal and 
State agencies, scientific experts and organizations, and other 
interested parties and invited them to comment on the proposal. 
Newspaper notices inviting general public comment were published in The 
Milwaukee Journal Sentinel on April 16, 2018, and in The Detroit Free 
Press on April 23, 2018. We did not receive any requests for a public 
hearing. The draft Post-delisting Monitoring Plan (PDM) was made 
available on our website on June 7, 2018. During the comment period for 
the proposed rule, we received a total of 42 comment letters or 
statements directly addressing the proposed action. These included 
comments from seven peer reviewers and 34 comments from the public 
during the open comment period; all comments are posted on http://www.regulations.gov under Docket No. FWS-R3-ES-2018-0005. Many 
commenters expressed their support or opposition to the proposed rule 
without offering substantive information.
    In accordance with our peer review policy published on July 1, 1994 
(59 FR 34270), we solicited expert opinion from 10 knowledgeable 
individuals with scientific expertise that included familiarity with 
Kirtland's warbler and its habitat, biological needs, and threats, as 
well as familiarity with conservation biology, ornithology, climate 
change, and population ecology. We received responses from seven peer 
reviewers. Almost all of the peer reviewers supported the proposed 
delisting rule, although one peer reviewer suggested that a more 
cautious approach would be to downlist the species to provide a 
``buffer'' of protection. Many peer reviewers commented that the 
current status of Kirtland's warbler is accurately presented in the 
proposed rule.
    We reviewed all comments we received from the peer reviewers and 
the public for substantive issues and new information regarding the 
delisting of Kirtland's warbler. Substantive comments we received 
during the comment period are addressed below and, where appropriate, 
are incorporated directly into this final rule. Comments that we 
received on the PDM without reference to or comment on the proposed 
rule are addressed separately in the PDM.
    Comment (1): Several peer reviewers and public commenters expressed 
concern that additional funding will be needed to support the species 
post-delisting. They discussed the need for sufficient funding to 
ensure habitat management and brown-headed cowbird control will 
continue at levels necessary to support the population above the 
recovery goals. Several peer reviewers also mentioned that funding will 
be necessary to support monitoring efforts to ensure any significant 
changes to the species' population levels are detected. A reviewer also 
stated that an income-producing fund has been created and appears to be 
successful, but they were concerned over the uncertainty as to whether 
it will be adequate to support conservation efforts post-delisting.
    Our Response (1): We acknowledge that the long-term survival of 
Kirtland's warbler is dependent upon the continued implementation of 
conservation programs that require agency commitment and sufficient 
funding. The vast majority of conservation programs (with the exception 
of brown-headed cowbird management) were previously funded through 
agency appropriations and grants, and not funded through ESA recovery 
funding. Thus, delisting Kirtland's warbler will not eliminate a major 
source of funding that is tied to its listing status. In the 2016 MOU, 
the MDNR, USFS, and Service reaffirmed their commitment to continue 
managing and monitoring Kirtland's warblers if the species is delisted. 
To supplement agency funding, which can fluctuate, the Kirtland's 
Warbler Alliance has been working with partners to establish additional 
funding sources for future conservation efforts. Recently, the American 
Bird Conservancy (ABC) was awarded a grant to help establish a long-
term Kirtland's warbler endowment that would offset some of the 
agencies' costs and support future Kirtland's warbler

[[Page 54457]]

conservation throughout the bird's full life cycle (Graff 2018, 
    Previous funding of brown-headed cowbird management was provided 
through ESA funding; therefore, a new funding source is needed to 
secure brown-headed cowbird management efforts post-delisting. To 
address this, the MDNR and Service developed a dedicated fund to be 
used for brown-headed cowbird management and other high priority 
conservation needs. At the time the proposed delisting rule was 
published (83 FR 15758; April 12, 2018), the dedicated fund had greater 
than $1 million. Since then, an additional $1.1 million was added, 
increasing our certainty that sufficient funding for brown-headed 
cowbird management will be available in the future. This account is 
invested for long-term growth, and income generated will be used to 
ensure sufficient brown-headed cowbird management to adequately reduce 
brood parasitism of the Kirtland's warbler.
    Comment (2): Several peer reviewers discussed the issue of brown-
headed cowbird control. The majority expressed support of continuing 
the brown-headed cowbird management program and asked for more detail 
regarding how the agencies will monitor the rates of parasitism to know 
when parasitism rates change, how the agencies will respond to 
increases in parasitism rates, and whether sufficient funding exists to 
continue to support the brown-headed cowbird program at historical 
levels of trapping.
    Our Response (2): Brood parasitism has historically been one of the 
primary threats to Kirtland's warbler, and thus the brown-headed 
cowbird management program has been a critical component of the 
recovery program. Recent research has shown a reduced brown-headed 
cowbird population throughout the Kirtland's warbler's core range in 
the northern Lower Peninsula. An experiment was initiated in 2015 to 
evaluate the effect of a reduced trapping program on Kirtland's warbler 
nest success. During a 3-year period (2015-2017), 3 of 385 Kirtland's 
warbler nests were parasitized in areas with a spatially reduced 
trapping program. Following these results, all trapping in the northern 
Lower Peninsula was suspended for the 2018 nesting season. In 2018, 
only one nest of over 140 was found to be parasitized. Additional 
information and data have been added to this final rule to reflect the 
most recent information on parasitism rates, including data from the 
2018 nesting season.
    We fully expect brood parasitism rates to fluctuate and recognize 
that permanent reductions to the brown-headed cowbird management 
program are not prudent. Rather, an adaptive management approach is 
appropriate to ensure adequate brown-headed cowbird management into the 
future. We have included the need for continued research and monitoring 
in the PDM to help inform future efforts.
    Based on the ongoing research, we do not expect that trapping 
levels will need to return to previous levels for several years, and 
may never return to historic levels. Through ongoing research, the KWCT 
hopes to establish trigger points that would dictate when trapping 
would be resumed and at what level. Through the MOA, and reaffirmed in 
a letter dated November 9, 2017, the MDNR has agreed to assume 
responsibility for the brown-headed cowbird management program. Funding 
for the brown-headed cowbird management program will be available 
through interest accrued from the brown-headed cowbird dedicated fund 
(see our response to Comment (1)), or other agency funds through the 
    External funding has been secured for the Smithsonian Migratory 
Bird Center to continue monitoring brown-headed cowbird presence and 
brood parasitism for the 2019 and 2020 nesting seasons. The results 
from the cowbird monitoring research conducted during 2015-2020 will be 
used to develop specific monitoring protocols that will be conducted in 
accordance with the PDM. We also expect the KWCT to continue assessing 
the need for further monitoring or research.
    Comment (3): Several peer reviewers discussed the importance of 
continued habitat management for the Kirtland's warbler population. A 
reviewer asserted that we made a major assumption in stating that 
management agencies will continue to create habitat post-delisting. 
Another comment discussed the uncertainty regarding timber 
marketability and the importance of timber receipts in offsetting the 
cost of Kirtland's warbler habitat management, and asked that this 
topic be more explicitly addressed in the rule. Further, a reviewer 
recommended a better plan on developing forestry techniques that 
increase marketability of the timber, as well as finding creative ways 
to fund future habitat management efforts. Many of the comments 
received regarding continued habitat management related to ensuring 
management would continue and how habitat management will be funded.
    Our Response (3): The management agencies have a long-standing 
history of providing habitat for the Kirtland's warbler and have 
described their commitment to continuing management for the Kirtland's 
warbler in the Conservation Plan and the MOU. We recognize the 
uncertainty over future timber markets and the impact that timber 
receipts may have in offsetting the costs of habitat management. The 
land managers and the KWCT have also recognized this uncertainty and 
have started the process to develop and test alternative planting 
techniques that would reduce costs and improve the marketability of 
jack pine through increased growth rates while still providing 
Kirtland's warbler nesting habitat. Currently, the Conservation Plan 
indicates up to 25 percent of future habitat management, annually, may 
incorporate non-traditional regeneration techniques designed to address 
the marketability and regeneration of jack pine.
    Specific plans are not yet available, as the habitat management 
planning process is dynamic. Alternative management techniques will 
evolve over time and be adaptable to changing circumstances. A 
subcommittee of the KWCT has routinely met over the last several years 
to develop alternative techniques. Additional information regarding 
timber marketability and future jack pine regeneration techniques has 
been added to this rule.
    Habitat management will continue to be funded through appropriated 
funds provided to the land management agencies for timber harvest and 
reforestation. Additional funds may be available through the endowment 
being developed by the Kirtland's Warbler Alliance and ABC, which is 
described earlier in this rule.
    Comment (4): Several peer reviewers provided comments on the 
Conservation Plan's allowance of up to 25 percent of habitat management 
to be non-traditional habitat regeneration techniques. They stated that 
the quality of Kirtland's warbler breeding habitat created through new 
techniques is not known and could result in a loss of up to 25 percent 
of breeding habitat and potentially a substantial decrease in the 
abundance of Kirtland's warbler. The reviewers recommend any non-
traditional techniques be used as part of the annual habitat goals only 
after they have been shown to be effective. They clarified that both 
density of breeding pairs and fledgling production are important 
metrics for evaluating the quality of non-traditional breeding habitat. 
Another peer reviewer asked us to emphasize that the 25 percent 
experimental habitat regeneration is a maximum and should not be 
interpreted as an annual requirement. This reviewer also pointed out 
that the 75 percent of

[[Page 54458]]

breeding habitat created using traditional methods is enough to support 
the population above the recovery goal of 1,000 pairs and reflects the 
best available science regarding breeding habitat use by the species.
    Our Response (4): We have clarified in this rule that the 25 
percent experimental habitat amount is a maximum amount annually. 
Managing habitat with traditional techniques at a minimum of 75 percent 
of the annual objective will still provide enough breeding habitat to 
maintain the species well above the recovery goal. Additionally, we 
expect that the experimental habitat will still provide breeding 
habitat for Kirtland's warbler but at potentially lower densities or 
reduced nest success. These experimental designs will be closely 
monitored to evaluate their effectiveness in regenerating jack pine and 
providing Kirtland's warbler breeding habitat.
    Comment (5): Several peer reviewers also commented on the agencies' 
commitment to continue conservation actions for Kirtland's warbler and 
whether the level of commitment provided via the current MOA and MOU 
are sufficient to support delisting. A peer reviewer expressed concern 
regarding the level of commitment to continuing habitat management and 
pointed out that the MOU indicates that management will occur ``only as 
appropriated funds are available'' and that ``additional funds will be 
necessary to meet these commitments.'' They also pointed out that the 
MOU can be terminated at any time by any agency and asked whether the 
agreements are legally binding. Multiple peer reviewers and several 
public commenters indicated that the levels of commitment in the 
existing MOU and MOA are sufficient to support delisting. One reviewer 
asked if the MOU had expired and, if so, when it might be renewed. 
Regarding conservation agreements on the wintering grounds, one 
reviewer commented that they are not necessary prior to delisting, 
given our understanding of threats to winter habitat.
    Our Response (5): The MOU is a synthesis of the land management 
agencies' commitments to forest management, developed under the 
requirements of Federal and State law that will remain in effect after 
delisting, to sustain Kirtland's warbler. The MOU was first signed in 
2011, was renewed in 2016, and currently expires in 2020. Prior and 
subsequent to the MOU, habitat management and other conservation 
programs were always dependent on annual appropriated funds provided to 
the land management agencies. Further, MDNR did not have any legal 
obligations under the ESA to conduct habitat management during the last 
40 years while the species was listed, but MDNR adopted into their 
forest plans the habitat management goals set forth by the Kirtland's 
Warbler Recovery Team and later by the KWCT. The MOA is specific to 
cowbird management and the development of a dedicated funding source 
primarily for that activity, but possibly other activities in the 
future if excess funding resources become available. The MOA was signed 
in 2015 with no expiration date and stipulates that the Service and 
MDNR will review progress under the MOA every 5 years to determine 
whether any modifications are warranted. While not fully legally 
binding, the MOU and MOA are built on a foundation of Federal and State 
law guiding land management and further express the agencies' 
commitments to continue managing for the species, regardless of the 
species' status under the ESA.
    Comment (6): Several peer reviewers asked for additional detail 
regarding the intensity and extent of population monitoring post-
delisting. A peer reviewer expressed concern over the lack of full 
surveys (censuses) in recent years, noting that the last full 
population survey was in 2015. Several reviewers questioned the recent 
(2016) shift from full census to the less intensive survey effort and 
requested that the MDNR sampling method be better explained. Several 
peer reviewers indicated that MDNR should continue with the full census 
until the proposed survey technique undergoes peer review and 
publication in a reputable journal. One peer reviewer emphasized that 
any reduced survey effort should be capable of providing a reliable 
extrapolation of total breeding male abundance, so as to allow 
comparison with past total singing/territorial male counts from 
previous population censuses. Another reviewer commented that the 
census techniques should be improved to assure accuracy, reduce 
uncertainty, and improve ability to detect small population-level 
changes. In addition, a reviewer noted that in areas where reduced 
brown-headed cowbird trapping occurs (as compared to previous levels) 
or experimental habitat management techniques are used, more intensive 
population monitoring is necessary. Some reviewers also suggested that 
the PDM should include monitoring of survival and reproductive success 
in addition to the number of singing males. Furthermore, one peer 
reviewer mentioned the possibility of using mist-netting as an 
alternative to nest searching to estimate productivity.
    Our Response (6): We appreciate the comments regarding the need for 
further details on how the Kirtland's warbler population will continue 
to be monitored post-delisting. Our knowledge of the Kirtland's warbler 
population and its response to habitat management has greatly been 
informed by conducting an annual census using similar protocols over 
several decades. We recognize that the complexity of conducting an 
annual census has changed as the species has expanded from its core 
breeding range. Further, the intensity of a monitoring effort should be 
continually reevaluated in accordance with adaptive management needs 
and the population size (e.g., for a smaller population, intensive 
monitoring is more feasible and potentially more important). For a 
recovered population, unless new information or concerns suggest 
otherwise, a less-intensive monitoring effort (when compared to when 
populations were critically imperiled) helps ensure staffing and 
funding resources are used most effectively. Monitoring of the 
Kirtland's warbler has routinely been coordinated by the respective 
land management agencies in coordination with the Service and Recovery 
Team, or more recently, the KWCT. As the species' population and range 
has expanded, so has the time and resources needed to conduct a full 
census. While the KWCT recognizes how critically important it is to 
continue monitoring the species, it has also recognized that there may 
be more efficient ways to monitor the species' status than a full 
    In 2016, Michigan State University, in conjunction with MDNR, 
developed a survey protocol designed to detect a 20 percent change in 
the population. The recommended survey would randomly select 50 percent 
of occupied stands on which the standard census protocol would be 
conducted. By incorporating stand size and age with the observed number 
of singing males, the survey would provide an estimate of the singing 
male population with enough confidence to detect a 20 percent reduction 
in individual singing males. The survey design was tested by using 
previous census results from 2010, 2011, 2012, and 2013. In each case, 
the reported census number fell within the survey protocols' 95% 
confidence interval. Other land management agencies, including USFS and 
WDNR, plan to continue periodic full censuses.
    We recognize that there may be instances where more precise 
population monitoring is warranted.

[[Page 54459]]

When experimenting with alternative habitat regeneration techniques or 
reduced brown-headed cowbird management levels, a higher level of 
monitoring would need to be conducted in order to accurately determine 
the warbler's response to those activities. The need for additional 
monitoring will be determined by the management agencies, researchers, 
and KWCT. This need is also addressed within the PDM.
    We believe that the monitoring proposed in the PDM is sufficient to 
detect population-level trends, and MDNR's proposed sampling technique 
will provide a sufficient estimate of the singing male population. The 
KWCT will continue to evaluate monitoring protocols and may determine 
that a periodic full census may be warranted as time and resources 
    Comment (7): A peer reviewer asked for clarification on the 
population level that will trigger intensified conservation efforts 
necessary to ensure the population remains above the numerical recovery 
goal of 1,000 pairs. Another emphasized that maintaining population 
numbers above the recovery goal provides flexibility (and a buffer) if 
new threats emerge.
    Our Response (7): In development of the Conservation Plan, the 
agencies agreed that if the population drops below 1,300 singing males, 
they would discuss the population decline, decide whether their 
objectives and actions need to be changed, and implement these 
recommended changes. The primary objective remains to keep the 
Kirtland's warbler population above the numerical recovery goal of 
1,000 pairs. However, any noted decline from current population levels 
will be discussed amongst the agencies and the KWCT, and any 
appropriate action will be taken.
    Comment (8): Several reviewers commented that a better 
understanding of wintering habitat needs should be a high priority for 
the KWCT and recommended fully mapping the extent of wintering habitat, 
as well as further research on how various activities and land uses on 
the wintering grounds impact the species.
    Our Response (8): Although threats to Kirtland's warblers on the 
wintering grounds exist, the current extent and magnitude of these 
threats are not significantly limiting Kirtland's warbler population 
numbers, based on the species' continuous population growth over the 
last two decades. If the population shows signs of decline in the 
future, we will coordinate with the KWCT to assess all potential 
stressors, including those occurring on the wintering grounds. The KWCT 
and its Non-breeding Range Subcommittee recognize the importance of 
continued research on the needs of the Kirtland's warbler on the 
wintering grounds, specifically delineating wintering habitat and 
assessing how land use may impact the species.
    Comment (9): Multiple peer reviewers commented on the species' 
wintering distribution, and provided citations to incorporate into the 
rule. One reviewer added that occasional vagrant Kirtland's warbler 
sightings outside of the core islands should not give the impression 
that suitable habitat is widespread elsewhere in the Caribbean; the 
rule should be explicit about our ignorance regarding suitable habitat 
elsewhere (outside of the core), as habitat suitability has not yet 
been measured except for on Eleuthera Island.
    Our Response (9): The text under Distribution in this rule has been 
updated to more clearly reflect this uncertainty regarding wintering 
    Comment (10): Several comments received were related to our 
analysis of the effects of climate change on the Kirtland's warbler's 
breeding and wintering grounds. Two reviewers stated that the analysis 
of climate change in the proposed rule was thorough and relied on the 
best available science. One reviewer stated that delisting will not 
prohibit the ongoing research to improve our understanding of future 
potential threats. Another peer reviewer commented that current climate 
change projections indicate that habitat suitability within the core 
breeding range will remain suitable for supporting jack pine in this 
century; another commenter stated that climate change could result in a 
shift in the range toward Wisconsin. One reviewer mentioned that on the 
wintering grounds, Kirtland's warbler could be negatively affected by 
climate change, but added that there is much uncertainty and currently 
a lack of strong evidence to suggest a major loss or degradation of 
wintering grounds habitat will occur in the near future. Another 
reviewer emphasized the importance of acquiring baseline data on 
wintering habitat availability and quality to provide a context for 
future climate change analysis. A reviewer commented that climate 
change projections that predict an increased drought for the central 
islands of The Bahamas may represent risk to the main wintering area 
and recommended protecting drought-tolerant sites (e.g., freshwater 
lens near the ground surface) where the Kirtland's warbler's preferred 
fruit plants occur. Another reviewer provided the citation for a 
recently published paper regarding future risks of heavy rainfall 
events and extended periods of hurricane-force winds due to an 
increasing trend for hurricanes to have decreased forward or 
translational speeds (Kossin 2018, entire). Further, the reviewer asked 
that the rule be updated to add observations of hurricane effects on 
the island of San Salvador, where post-hurricane declines of Kirtland's 
warblers have been observed.
    Our Response (10): Climate change predictions are variable and in 
many cases uncertain. We reviewed the best available data using 
multiple models and emission scenarios to evaluate the impact of 
climate change on the Kirtland's warbler in the foreseeable future. On 
the breeding grounds, temperature will very likely increase, and 
precipitation will increase for parts of the year but may decrease at 
the end of the growing season (Handler et al. 2014, pp. 72-75; Janowiak 
et al. 2014, pp. 66-85). On the wintering grounds, temperatures will 
also increase, which could result in rising sea level. The Caribbean is 
experiencing a general drying trend, but there is temporal and spatial 
    We will remain engaged with the KWCT and its Non-breeding Range 
Subcommittee to monitor climate conditions and how they may impact the 
Kirtland's warbler. We will also work with the KWCT as they engage The 
Bahamas National Trust and other groups in an effort to identify and 
protect critical sites in The Bahamas for Kirtland's warbler 
    Additional discussion regarding the potential for climate change 
has been added to this rule under Factor E: Climate Change.
    Comment (11): Almost all of the peer reviewers indicated their 
support of delisting the Kirtland's warbler and stated that the 
analysis in the proposed rule was sufficient to support delisting. Many 
heralded the Kirtland's warbler as a success story of the ESA. One peer 
reviewer, however, recommended we apply a more cautious approach and 
instead reclassify (i.e., downlist) Kirtland's warbler as a threatened 
species. Several public commenters had similar comments indicating that 
the proposed delisting rule was premature, and we should maintain 
protections to ensure we more fully understand proposed and recent 
changes to habitat management and brown-headed cowbird control programs 
before changing the status of the Kirtland's warbler.
    Our Response (11): During our analysis, we evaluated the status of 

[[Page 54460]]

Kirtland's warbler to determine if the species met the definition of an 
endangered or threatened species based on any of five factors: (A) The 
present or threatened destruction, modification, or curtailment of its 
habitat or range; (B) overutilization for commercial, recreational, 
scientific, or educational purposes; (C) disease or predation; (D) the 
inadequacy of existing regulatory mechanisms; or (E) other natural or 
manmade factors affecting its continued existence. Based on the status 
of the species and the known and foreseeable threats, we determined 
that the species has recovered and does not meet the ESA's definition 
of an endangered or a threatened species. Thus, the Kirtland's warbler 
does not warrant listing under the ESA. While we appreciate the concern 
and suggestion of a more cautious approach, delisting Kirtland's 
warbler is warranted based on the best available information.
    Comment (12): One peer reviewer expressed concern over potential 
forest pests causing a catastrophic loss of suitable habitat; the 
reviewer acknowledges that the currently known insect or fungal threats 
to jack pine or red pine are possible to manage, and forests in this 
region are under the oversight of forest management agencies. The 
reviewer added that the Kirtland's warbler may be less vulnerable to 
catastrophic loss due to pests or disease outbreaks when compared to 
historically lower population levels. One commenter expressed concern 
over the effects of pesticides on the Kirtland's warbler and its insect 
    Our Response (12): Our review of the best available science did not 
identify any known threats to the status of the Kirtland's warbler from 
forest pests, disease, or the use of pesticides. We acknowledge that 
new threats from insects, fungi, other pests, or the use of a new 
pesticide may emerge in the future, but our analysis concluded that the 
species has good redundancy, representation, and resiliency, which 
should allow the species to withstand potential future stressors.
    We agree with the reviewer that the management of forest pests and 
disease primarily falls under the authority of the forest management 
agencies. Through collaborative efforts, the KWCT and its Breeding 
Range Subcommittee, the land management agencies' silviculturists, and 
the forest product industry can collectively monitor these potential 
threats and respond accordingly if the threats are determined to impact 
Kirtland's warbler nesting habitat.
    We added additional discussion and references regarding forest 
pests, disease, and pesticides to this rule (see discussions under 
Factors A and E).
    Comment (13): A peer reviewer requested that additional discussion 
be added regarding recreation, access, and development, including 
current restrictions in areas occupied by the Kirtland's warbler, and 
regarding changes that would occur if the Kirtland's warbler is 
delisted. The reviewer expressed concern that unrestricted recreational 
activity and nearby development could have unforeseen impacts on the 
population and that this should be more explicitly considered in our 
    Our Response (13): Currently, only a portion of the Kirtland's 
warbler's nesting habitat in the northern Lower Peninsula is posted 
closed during the species' breeding season by the respective land 
management agency. Many of the recreational uses of the Kirtland's 
warbler's nesting habitat (e.g., hunting, blueberry picking) are 
typically conducted at times when impacts to the species are limited. 
Further, in areas that are not posted closed, we have not seen evidence 
of impacts to the species. Delisting Kirtland's warbler would not limit 
the authority of the land management agencies to close areas as needed 
to limit resource damage or protect sensitive species. We added 
additional information and discussion related to other uses of the 
Kirtland's warbler's nesting habitat to this rule (see Factor B 
    Comment (14): Several peer reviewers provided additional 
information and suggested additional references to support statements 
in the proposed rule. This included information regarding mortality due 
to lighted cruise ships in the Caribbean, presence of other avian brood 
parasites (i.e., cuckoo species) in the Kirtland's warbler breeding 
range, and new information on wintering habitat and distribution.
    Our Response (14): We appreciate the additional information 
provided by the reviewers. We reviewed the additional information and 
corresponding references, and we updated this final rule accordingly.
    Comment (15): A peer reviewer suggested adding a discussion of 
reproductive rates to the ``Demographics'' section of the rule.
    Our Response (15): We added this discussion as suggested.
    Comment (16): A peer reviewer commented that the assumption 
regarding number of singing males equating to number of breeding pairs 
needs clarification and suggested caution when interpreting the number 
of singing males as an indication of number of breeding pairs.
    Our Response (16): We added additional clarification to this rule 
under Abundance and Population Trends.
    Comment (17): One commenter requested peer review and a public 
comment period greater than or equal to 90 days.
    Our Response (17): The proposed rule was open for public comments 
for 90 days, from April 12, 2018, through July 11, 2018, and we 
solicited peer review on the proposal.
    Comment (18): One commenter asked for additional detail on State 
regulatory protections if the Kirtland's warbler is delisted.
    Our Response (18): The Kirtland's warbler is currently protected by 
State law in a number of States in the species' breeding and migratory 
ranges under the respective State endangered species regulations. 
Changing the Federal status of the Kirtland's warbler will not 
automatically change the listing status of the Kirtland's warbler under 
State law. Each State evaluates the current status of a species to 
determine whether it warrants protection under the State's respective 
statutes. We expect that each State will evaluate the State listing 
status of the Kirtland's warbler at some point in the next several 
years, but we cannot speculate as to their decisions under State law. 
Similarly, the Kirtland's warbler is also protected as endangered under 
Canada's Species at Risk Act of 2003. Canadian officials will decide 
whether to retain protected status for the Kirtland's warbler based on 
their laws and regulations.
    Comment (19): One commenter asked if we were proposing delisting to 
benefit the wind industry and suggested the proposed rule was motivated 
by reducing regulatory burden to make it easier to get ``wind towers in 
place in rural Ohio.''
    Our Response (19): Our determination is based solely on the status 
of the species utilizing the best available science, and our status 
review was initiated due to the species' population and range expansion 
in recent years, the development of the Kirtland's Warbler Conservation 
Plan and MOU, and development of a long-term endowment and MOA to 
conduct brown-headed cowbird management.


    Section 4 of the ESA (16 U.S.C. 1533), and its implementing 
regulations at 50 CFR part 424, set forth the procedures for 
determining whether a species is an endangered species or threatened 
species and should be included on the Federal Lists of Endangered and 
Threatened Wildlife and Plants. The

[[Page 54461]]

ESA defines an endangered species as any species that is ``in danger of 
extinction throughout all or a significant portion of its range'' and a 
threatened species as any species that is ``likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range.''
    Under section 4(a)(1) of the ESA, we determine whether a species is 
an endangered species or threatened species because of any of the 
following 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. These same factors apply whether we 
are analyzing the species' status throughout all of its range or 
throughout a significant portion of its range.

Determination of Status Throughout All of the Kirtland's Warbler's 

    We have carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
to the Kirtland's warbler. We assessed the five factors to evaluate 
whether the species is in danger of extinction, or likely to become so 
in the foreseeable future, throughout all of its range. The size of the 
Kirtland's warbler population is currently at its known historical 
maximum, which is nearly 10 times larger than it was at the time of 
listing and more than double the recovery goal. The population's 
breeding range also expanded outside of the northern Lower Peninsula to 
areas in Michigan's Upper Peninsula, Wisconsin, and Ontario. This 
recovery is attributable to successful interagency cooperation in the 
management of habitat and brood parasitism. The amount of suitable 
habitat has increased by approximately 150 percent since listing, 
primarily due to the increased amount of planted habitat generated from 
adaptive silvicultural techniques. Brown-headed cowbird control has 
been conducted on an annual basis within the majority of Kirtland's 
warbler nesting areas since 1972, and has greatly reduced the impacts 
of brood parasitism.
    During our analysis, we found that impacts believed to be threats 
at the time of listing have been eliminated or reduced, or are being 
adequately managed since listing, and we do not expect any of these 
conditions to substantially change after delisting and into the 
foreseeable future. Population modeling that assessed the long-term 
population viability of Kirtland's warbler populations showed stable 
populations over a 50-year simulation period with current habitat 
management and maintaining sufficient brown-headed cowbird removal (see 
Population Viability, above). Brood parasitism and availability of 
sufficient suitable breeding habitat are adequately managed through the 
Kirtland's Warbler Breeding Range Conservation Plan and the 2016 MOU. 
The Conservation Plan and the MOU acknowledge the conservation-reliant 
nature of the Kirtland's warbler and the need for continued habitat 
management and brown-headed cowbird control, and affirm that the 
necessary long-term management actions will continue. The species is 
resilient to threats including changing weather patterns and sea level 
rise due to the effects of climate change, collision with lighted and 
human-made structures, impacts to wintering and migratory habitat, and 
cumulative effects, and existing information indicates that this 
resilience will not change in the foreseeable future. These conclusions 
are supported by the available information regarding the species' 
abundance, distribution, and trends. Thus, after assessing the best 
available information, we conclude that the Kirtland's warbler is not 
in danger of extinction throughout all of its range, nor is it likely 
to become so within the foreseeable future.

Determination of Status Throughout a Significant Portion of the 
Kirtland's Warbler's Range

    Under the ESA and our implementing regulations, a species may 
warrant listing if it is in danger of extinction or likely to become so 
in the foreseeable future throughout all or a significant portion of 
its range (SPR). Where the best available information allows the 
Service to determine a status for the species rangewide, that 
determination should be given conclusive weight because a rangewide 
determination of status more accurately reflects the species' degree of 
imperilment and better promotes the purposes of the ESA. Under this 
reading, we should first consider whether the species warrants listing 
``throughout all'' of its range and proceed to conduct a ``significant 
portion of its range'' analysis if, and only if, a species does not 
qualify for listing as either an endangered or a threatened species 
according to the ``throughout all'' language.
    Having determined that the Kirtland's warbler is not in danger of 
extinction or likely to become so in the foreseeable future throughout 
all of its range, we now consider whether it may be in danger of 
extinction or likely to become so in the foreseeable future in an SPR. 
The range of a species can theoretically be divided into portions in an 
infinite number of ways, so we first screen the potential portions of 
the species' range to determine if there are any portions that warrant 
further consideration. To do the ``screening'' analysis, we ask whether 
there are portions of the species' range for which there is substantial 
information indicating that: (1) The portion may be significant; and 
(2) the species may be, in that portion, either in danger of extinction 
or likely to become so in the foreseeable future. For a particular 
portion, if we cannot answer both questions in the affirmative, then 
that portion does not warrant further consideration and the species 
does not warrant listing because of its status in that portion of its 
range. We emphasize that answering these questions in the affirmative 
is not a determination that the species is in danger of extinction or 
likely to become so in the foreseeable future throughout a significant 
portion of its range--rather, it is a step in determining whether a 
more detailed analysis of the issue is required.
    If we answer these questions in the affirmative, we then conduct a 
more thorough analysis to determine whether the portion does indeed 
meet both of the SPR prongs: (1) The portion is significant; and (2) 
the species is, in that portion, either in danger of extinction or 
likely to become so in the foreseeable future. Confirmation that a 
portion does indeed meet one of these prongs does not create a 
presumption, prejudgment, or other determination as to whether the 
species is an endangered species or threatened species. Rather, we must 
then undertake a more detailed analysis of the other prong to make that 
determination. Only if the portion does indeed meet both SPR prongs 
would the species warrant listing because of its status in a 
significant portion of its range.
    At both stages in this process--the stage of screening potential 
portions to identify any portions that warrant further consideration 
and the stage of undertaking the more detailed analysis of any portions 
that do warrant further consideration--it might be more efficient for 
us to address the ``significance'' question or the ``status'' question 
first. Our selection of which question to address first for a 
particular portion depends on the biology of the species, its range, 
and the threats it faces. Regardless of which question we address 
first, if we reach a negative answer with respect to the first question

[[Page 54462]]

that we address, we do not need to evaluate the second question for 
that portion of the species' range.
    For the Kirtland's warbler, we chose to evaluate the status 
question (i.e., identifying portions where the Kirtland's warbler may 
be in danger of extinction or likely to become so in the foreseeable 
future) first. To conduct this screening, we considered whether the 
threats are geographically concentrated in any portion of the species' 
range at a biologically meaningful scale.
    Kirtland's warblers occupy different geographic areas (breeding 
grounds, migratory routes, wintering grounds) throughout the course of 
a year. Although there are different threats acting on the species on 
the breeding grounds, migratory routes, and wintering grounds (see 
discussion under Factors A through E, above), the threats associated 
with these areas are uniformly spread across each area (e.g., threats 
on the breeding grounds are uniform across the breeding range, threats 
on the wintering grounds are uniform across the winter range). The 
entire population moves through the full annual cycle (breeding, 
migration, and wintering) and functions as a single panmictic 
population (see discussion under ``Genetics,'' above); therefore, these 
different geographic areas do not represent biologically separate 
populations that could be exposed to different threats.
    We examined the following threats: Availability and distribution of 
breeding, migration, and wintering habitat; pesticides; brood 
parasitism; the effects of climate change; collision with lighted and 
human-made structures; and the cumulative effects of these threats. We 
found no concentration of threats in any portion of the Kirtland's 
warbler's range at a biologically meaningful scale. If both (1) a 
species is not in danger of extinction or likely to become so in the 
foreseeable future throughout all of its range and (2) the threats to 
the species are essentially uniform throughout its range, then the 
species could not be in danger of extinction or likely to become so in 
the foreseeable future in any biologically meaningful portion of its 
range. For the Kirtland's warbler, we found both: The species is not in 
danger of extinction or likely to become so in the foreseeable future 
throughout all of its range, and there is no geographical concentration 
of threats so the threats to the species are essentially uniform 
throughout its range. Therefore, no portions warrant further 
consideration through a more detailed analysis, and the species is not 
in danger of extinction or likely to become so in the foreseeable 
future in any significant portion of its range. Our approach to 
analyzing SPR in this determination is consistent with the court's 
holding in Desert Survivors v. Department of the Interior, No. 16-cv-
01165-JCS, 2018 WL 4053447 (N.D. Cal. Aug. 24, 2018).
    Our review of the best available scientific and commercial 
information indicates that the Kirtland's warbler is not in danger of 
extinction or likely to become an endangered species within the 
foreseeable future throughout all or a significant portion of its 
range. Therefore, we find that listing the Kirtland's warbler as an 
endangered species or a threatened species under the ESA is not 
warranted at this time.


    We have carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
to the Kirtland's warbler. The threats that led to the species being 
listed under the ESA (i.e., primarily loss of the species' habitat 
(Factor A) and effects of brood parasitism by brown-headed cowbirds 
(Factor E)) have been removed, have been ameliorated, or have been 
appropriately managed by the actions of multiple conservation partners 
over the past 50 years. These actions include habitat management, 
brown-headed cowbird control, monitoring, research, and education. 
Given commitments shown by the cooperating agencies entering into the 
Kirtland's warbler MOU and the long record of engagement and proactive 
conservation actions implemented by the cooperating agencies over a 50-
year period, we expect conservation efforts will continue to support a 
healthy, viable population of the Kirtland's warbler post-delisting and 
into the foreseeable future. Furthermore, there is no information to 
conclude that, at any time over the next 50-year window (as we define 
the foreseeable future for this species), the species will be in danger 
of extinction. Thus, we have determined that none of the existing or 
potential threats, either alone or in combination with others, is 
likely to cause the Kirtland's warbler to be in danger of extinction 
throughout all or a significant portion of its range, nor are any of 
the existing or potential threats likely to cause the species to become 
endangered within the foreseeable future throughout all or a 
significant portion of its range. On the basis of our evaluation, we 
conclude that, due to recovery, the Kirtland's warbler is not an 
endangered or threatened species. We, therefore, remove the Kirtland's 
warbler from the Federal List of Endangered and Threatened Wildlife at 
50 CFR 17.11(h) due to recovery.

Effects of This Rule

    This rule revises 50 CFR 17.11(h) by removing the Kirtland's 
warbler from the Federal List of Endangered and Threatened Wildlife. On 
the effective date of this rule (see DATES, above), the prohibitions 
and conservation measures provided by the ESA, particularly through 
sections 7 and 9, no longer apply to this species. Federal agencies are 
no longer required to consult with the Service under section 7 of the 
ESA in the event that activities they authorize, fund, or carry out may 
affect the Kirtland's warbler. There is no critical habitat designated 
for this species; therefore, this rule does not affect 50 CFR 17.95. 
Removal of the Kirtland's warbler from the List of Endangered and 
Threatened Wildlife does not affect the protection given to all 
migratory bird species under the MBTA.

Post-Delisting Monitoring

    Section 4(g)(1) of the ESA requires us, in cooperation with the 
States, to implement a system to monitor for not less than 5 years the 
status of all species that have been recovered and delisted. The 
purpose of this requirement is to develop a program that detects the 
failure of any delisted species to sustain itself without the 
protective measures provided by the ESA. If, at any time during the 
monitoring period, data indicate that protective status under the ESA 
should be reinstated, we can initiate listing procedures, including, if 
appropriate, emergency listing.
    The PDM for the Kirtland's warbler was developed in coordination 
with our Federal, State, and other partners. The PDM is based upon 
current research and effective management practices that have improved 
the status of the species since listing. Ensuring continued 
implementation of proven management strategies, such as brown-headed 
cowbird control and habitat management, that have been developed to 
sustain the species is a fundamental goal of the PDM. The PDM 
identifies measurable management thresholds and responses for detecting 
and reacting to significant changes in the Kirtland's warbler's 
numbers, distribution, and persistence. If declines are detected 
equaling or exceeding these thresholds, the Service, in combination 
with other PDM participants, will investigate causes of these declines. 
The investigation will be to determine if the Kirtland's warbler 
warrants expanded monitoring, additional research, additional habitat 
protection or brood

[[Page 54463]]

parasite management, or resumption of Federal protection under the ESA. 
For example, monitoring Kirtland's warbler singing males, annual 
habitat management acres, and brown-headed cowbird abundance or 
parasitism rates will inform partners on the Kirtland's warbler's 
status. If the population falls below 1,300 pairs, this would trigger 
the partners to (1) schedule a meeting, (2) discuss what is causing the 
decline, (3) decide how to respond, and (4) implement the recommended 
changes. The PDM requires census or selectively sampling the Kirtland's 
warbler breeding population every other year for a period of 12 years. 
The final PDM plan is available at https://www.fws.gov/midwest/Endangered/birds/Kirtland.

Required Determinations

National Environmental Policy Act

    We determined that we do not need to prepare an environmental 
assessment or an environmental impact statement, as defined under the 
authority of the National Environmental Policy Act of 1969 (42 U.S.C. 
4321 et seq.), in connection with regulations adopted pursuant to 
section 4(a) of the ESA. We published a notice outlining our reasons 
for this determination in the Federal Register on October 25, 1983 (48 
FR 49244).

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994, 
``Government-to-Government Relations with Native American Tribal 
Governments'' (59 FR 22951), Executive Order 13175, Secretarial Order 
3206, the Department of the Interior's manual at 512 DM 2, and the 
Native American Policy of the Service, January 20, 2016, we readily 
acknowledge our responsibility to communicate meaningfully with 
recognized Federal Tribes on a government-to-government basis. We 
contacted the tribes in the Midwest within the range of the Kirtland's 
warbler and requested their input and comments on the proposed 
delisting rule.

References Cited

    A complete list of all references cited in this rule is available 
at http://www.regulations.gov under Docket No. FWS-R3-ES-2018-0005 or 
upon request from the Field Supervisor, Michigan Ecological Services 


    The primary authors of this rule are staff members of the Michigan 
Ecological Services Field Office in East Lansing, Michigan, in 
coordination with the Midwest Regional Office in Bloomington, 

List of Subjects in 50 CFR Part 17

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

Regulation Promulgation

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


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

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

Sec.  [thinsp]17.11  [Amended]

2. Amend Sec.  [thinsp]17.11 in the table in paragraph (h) by removing 
the entry for ``Warbler (wood), Kirtland's'' under ``BIRDS'' from the 
List of Endangered and Threatened Wildlife.

    Dated: August 29 2019.
Stephen Guertin,
Principal Deputy Director, U.S. Fish and Wildlife Service, Exercising 
the Authority of the Director, U.S. Fish and Wildlife Service.
[FR Doc. 2019-22096 Filed 10-8-19; 8:45 am]