[Federal Register Volume 77, Number 158 (Wednesday, August 15, 2012)]
[Proposed Rules]
[Pages 48934-48947]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-19970]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R5-ES-2012-0056; 4500030113]


Endangered and Threatened Wildlife and Plants; 90-Day Finding on 
a Petition To List the Bicknell's Thrush (Catharus bicknelli) as 
Endangered or Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of petition finding and initiation of status review.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
90-day finding on a petition to list the Bicknell's thrush (Catharus 
bicknelli) as endangered or threatened under the Endangered Species Act 
of 1973, as amended (Act), and to designate critical habitat. Based on 
our review, we find that the petition presents substantial scientific 
or commercial information indicating that listing this species may be 
warranted. Therefore, with the publication of this notice, we will be 
initiating a review of the status of the species to determine if 
listing the Bicknell's thrush is warranted. To ensure that our status 
review is comprehensive, we are requesting scientific and commercial 
data and other information regarding this species. Based on the results 
of our status review, we will issue a 12-month finding on the petition, 
which will address whether the petitioned action is warranted, as 
provided in section 4(b)(3)(B) of the Act.

DATES: We request that we receive information on or before October 15, 
2012. The deadline for submitting an electronic comment using the 
Federal eRulemaking Portal (see ADDRESSES section below) is 11:59 p.m. 
Eastern Time on this date. After October 15, 2012, you must submit 
information directly to the Division of Policy and Directives 
Management (see ADDRESSES section below). Please note that we might not 
be able to address or incorporate information that we receive after the 
above requested date.

ADDRESSES: You may submit information by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. In the Search field, enter FWS-R5-ES-2012-0056, 
which is the docket number for this action. Then click on the Search 
button. You may submit a comment by clicking on ``Comment Now!.'' If 
your submission will fit in the provided comment box, please use this 
feature of http://www.regulations.gov, as it is most compatible with 
our information collection procedures. If you attach your submission as 
a separate document, our preferred file format is Microsoft Word. If 
you attach multiple documents (such as form letters), our preferred 
format is a spreadsheet in Microsoft Excel.
    (2) By hard copy: Submit by U.S. mail or hand-delivery to: Public 
Comments Processing, Attn: FWS-R5-ES-2012-0056; Division of Policy and 
Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax 
Drive, MS 2042-PDM; Arlington, VA 22203.
    This finding is available on the Internet at http://www.regulations.gov at Docket Number FWS-R5-ES-2012-0056. Supporting 
documentation we used in preparing this finding is

[[Page 48935]]

available for public inspection, by appointment, during normal business 
hours at the U.S. Fish and Wildlife Service, New England Field Office, 
70 Commercial Street, Suite 300, Concord, New Hampshire 03301.
    We will post all information we receive on http://www.regulations.gov. This generally means that we will post any 
personal information you provide us (see the Request for Information 
section below for more details).

FOR FURTHER INFORMATION CONTACT: Thomas R. Chapman, Supervisor, U.S. 
Fish and Wildlife Service, New England Field Office, 70 Commercial 
Street, Suite 300, Concord, New Hampshire 03301; by telephone at 603-
223-2541. If you use a telecommunications device for the deaf (TDD), 
please call the Federal Information Relay Service (FIRS) at 800-877-
8339.

SUPPLEMENTARY INFORMATION: 

Request for Information

    When we make a finding that a petition presents substantial 
information indicating that listing a species may be warranted, we are 
required to promptly initiate review of the status of the species 
(status review). For the status review to be complete, and based on the 
best available scientific and commercial information, we request 
information on the Bicknell's thrush from governmental agencies, Native 
American tribes, the scientific community, industry, and any other 
interested parties. We seek information on:
    (1) The species' biology, range, and population trends, including:
    (a) Habitat requirements for feeding, breeding, and sheltering;
    (b) Genetics and taxonomy;
    (c) Historical and current range, including distribution patterns;
    (d) Historical and current population levels, and current and 
projected trends; and
    (e) Past and ongoing conservation measures for the species, its 
habitat, or both.
    (2) The factors that are the basis for making a listing 
determination for a species under section 4(a) of the Act (16 U.S.C. 
1531 et seq.), which are:
    (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.
    (3) Information regarding the potential impacts to the species 
resulting from climate change, such as data, analyses, and predictions 
related to:
    (a) The loss of spruce-fir forested habitat where the species 
breeds, including the projected impacts to the Canadian portion of the 
species' breeding range;
    (b) Impacts to forest habitats in the Caribbean that provide 
important wintering habitat for the species; and
    (c) Alterations to the cycling and productivity in balsam fir cone 
production that may alter population dynamics in red squirrels, a major 
predator of nestling Bicknell's thrush.
    (4) Information regarding the ongoing and projected impacts of 
ground-level ozone emissions on spruce and fir in the northeastern 
United States and Maritime Provinces of Canada.
    (5) Behavioral, survival, and reproductive consequences of various 
mercury accumulation levels in insectivorous songbirds.
    (6) Impacts to the species resulting from the construction and 
operation of commercial wind turbines and transmission lines in 
breeding habitat, including habitat loss, mortality, productivity, and 
avoidance of turbines as a result of blade movements or noise.
    (7) Existing regulatory mechanisms that may be protective of the 
Bicknell's thrush and its habitat, particularly on its wintering 
grounds in the Greater Antilles.
    If, after the status review, we determine that listing the 
Bicknell's thrush is warranted, we will propose critical habitat (see 
definition in section 3(5)(A) of the Act) under section 4 of the Act, 
to the maximum extent prudent and determinable at the time we propose 
to list the species. Therefore, we also request data and information 
on:
    (1) What may constitute ``physical or biological features essential 
to the conservation of the species,'' within the geographical range 
currently occupied by the species;
    (2) Where these features are currently found;
    (3) Whether any of these features may require special management 
considerations or protection;
    (4) Specific areas outside the geographical area currently occupied 
by the species that are ``essential for the conservation of the 
species''; and
    (5) What, if any, critical habitat you think we should propose for 
designation if the species is proposed for listing, and why such 
habitat meets the requirements of section 4 of the Act.
    Please include sufficient information with your submission (such as 
scientific journal articles or other publications) to allow us to 
verify any scientific or commercial information you include.
    Submissions merely stating support for or opposition to the action 
under consideration without providing supporting information, although 
noted, will not be considered in making a determination. Section 
4(b)(1)(A) of the Act directs that determinations as to whether any 
species is an endangered or threatened species must be made ``solely on 
the basis of the best scientific and commercial data available.''
    You may submit your information concerning this status review by 
one of the methods listed in the ADDRESSES section. If you submit 
information via http://www.regulations.gov, your entire submission--
including any personal identifying information--will be posted on the 
Web site. If your submission is made via a hardcopy that includes 
personal identifying information, you may request at the top of your 
document that we withhold this personal identifying information from 
public review. However, we cannot guarantee that we will be able to do 
so. We will post all hardcopy submissions on http://www.regulations.gov.
    Information and supporting documentation that we received and used 
in preparing this finding is available for you to review at http://www.regulations.gov, or by appointment, during normal business hours, 
at the U.S. Fish and Wildlife Service, New England Field Office (see 
FOR FURTHER INFORMATION CONTACT).

Background

    Section 4(b)(3)(A) of the Act requires that we make a finding on 
whether a petition to list, delist, or reclassify a species presents 
substantial scientific or commercial information indicating that the 
petitioned action may be warranted. We are to base this finding on 
information provided in the petition, supporting information submitted 
with the petition, and information otherwise available in our files. To 
the maximum extent practicable, we are to make this finding within 90 
days of our receipt of the petition and publish our notice of the 
finding promptly in the Federal Register.
    Our standard for substantial scientific or commercial information 
within the Code of Federal Regulations (CFR) with regard to a 90-day 
petition finding is ``that amount of information that would lead a 
reasonable person to believe that the measure proposed in the petition 
may be warranted'' (50 CFR 424.14(b)). If we find that substantial 
scientific or commercial information was presented, we are required to 
promptly initiate a

[[Page 48936]]

species status review. The status review and 12-month petition finding 
are combined in a single Federal Register notice.

Petition History

    On August 26, 2010, we received a petition, dated August 24, 2010, 
from Mollie Matteson, Center for Biological Diversity (CBD or 
petitioner), Northeast Field Office, requesting that the Bicknell's 
thrush be listed as threatened or endangered and that critical habitat 
be designated under the Act. The petition clearly identified itself as 
such and included the requisite identification information for the 
petitioner, required at 50 CFR 424.14(a). In a September 9, 2010, 
letter to the petitioner, we responded that we would review the 
information presented in the petition and determine if listing of the 
Bicknell's thrush was warranted. This finding addresses the petition.

Previous Federal Actions

    In 1994, the Bicknell's thrush was determined to be a category 2 
species of concern and we announced that finding in the Animal 
Candidate Review for Listing as Endangered or Threatened Species (59 FR 
58982). Category 2 was defined as including taxa for which the Service 
had information indicating that proposing to list as endangered or 
threatened is possibly appropriate, but for which persuasive data on 
biological vulnerability and threat are not currently available to 
support proposed rules. In 1996, the Service discontinued the list of 
category 2 candidate species, resulting in the removal of the 
Bicknell's thrush from candidate status (61 FR 64481).
    Although the Bicknell's thrush was removed from the list of 
candidate species in 1996, the species was identified by the North 
American Bird Conservation Initiative as one of the Highest Priority 
Landbirds in the Atlantic Northern Forest (Dettmers 2006, p. 21), and 
the Service's New England Field Office has continued to amass 
information related to the species and to support conservation of the 
species.
    On September 9, 2011, the U.S. District Court for the District of 
Columbia approved two settlement agreements: one agreement between the 
Service and CBD and a second agreement between the Service and 
WildEarth Guardians (WEG). The agreements enable the Service to 
systematically, over a period of 6 years, review and address the needs 
of more than 250 species listed on the 2010 Candidate Notice of Review 
(75 FR 69222). The agreements also include additional scheduling 
commitments for a small subset of the actions in the 6-year work plan 
that are consistent with the Service's objectives and biological 
priorities. For the Bicknell's thrush, the settlement agreement with 
WEG specifies that we will complete a 90-day petition finding by the 
end of fiscal year 2012.

Species Information

    The Bicknell's thrush (Catharus bicknelli) is the smallest of North 
American Catharus thrushes in the family Turdidae, which includes all 
birds related to the robins (Rimmer et al. 2001, p. 2). Rimmer et al. 
(2001, pp. 1-28) provides a comprehensive overview of the species' 
biology. Field identification of the Bicknell's thrush is difficult, 
because of close similarities in appearance with the gray-cheeked (C. 
minimus) and the Swainson's (C. ustulatus) thrushes (Wallace 1939, p. 
217; Rimmer et al. 2001, p. 2). The total population of Bicknell's 
thrush is estimated to be 95,000 to 126,000 birds (International 
Bicknell's Thrush Conservation Group (IBTCG) 2010, p. 6).
    The Bicknell's thrush was considered a subspecies of the gray-
cheeked thrush until 1993. Ornithologists carefully evaluated the 
species' morphology, range, song, behavior, habitat, and genetic 
divergences and detected significant differences between the taxa. This 
evaluation subsequently led to the recommendation that the Bicknell's 
thrush be elevated to a full species (Ouellet 1993, p. 568). The 
American Ornithologist Union (1995, p. 824) recognizes the Bicknell's 
thrush as a species, and the Service concurs with that taxonomic 
change.
    The Bicknell's thrush is a migratory species, meaning it travels 
between different geographical areas to fulfill life-history functions 
like breeding and raising its young. The species feeds predominantly on 
insects, but during migration and on its wintering grounds, the species 
can shift its diet almost entirely to the consumption of several 
varieties of small fruits (Beal 1915 in Wallace 1939, p. 295; Rimmer et 
al. 2001, pp. 9-10; Townsend et al. 2010, p. 517). Bicknell's thrush 
forages for food among trees, feeding among the branches or hawking 
(pursuit in flight); however, most foraging activity takes place on or 
near the ground through litter pecking or gleaning (Wallace 1939, p. 
295; Sabo 1980, p. 251; Rimmer et al. 2001, pp. 9-10).
    The Bicknell's thrush breeds in portions of the northeastern United 
States and eastern and southern Canada and winters in the Greater 
Antilles. On its way between the breeding and wintering grounds, the 
Bicknell's thrush flies along the Atlantic coast and may stop in 
certain areas for resting and feeding. The breeding range of the 
species extends from the northern Saint Lawrence area of Quebec and the 
Maritime Canadian Provinces south through New England and New York to 
that State's Catskill Mountains (Wallace 1939, pp. 258-259; Ouellet 
1993, pp. 563-564; Rimmer et al. 2001, p. 1). Breeding habitat for the 
Bicknell's thrush is described as dense tangles of both living and dead 
``stunted'' trees that are predominately balsam fir (Abies balsamea) 
with lesser amounts of red spruce (Picea rubens) and white birch 
(Betula papyrifera var. cordifolia) (Wallace 1939, p. 285; Rimmer et 
al. 2001, p. 7; Ouellet 1993, p. 561). Depending upon location, white 
spruce (P. glauca) or an occasional black spruce (P. mariana) can also 
provide breeding habitat, as can pin cherry (Prunus pennsylvanica), 
mountain ash (Sorbus americanus), shadbush (Amelanchier spp.), and 
other deciduous species (Wallace 1939, pp. 285-286; Sabo 1980, p. 242; 
Ouellet 1993, p. 561; Rimmer et al. 2001, p. 7). Except in the case of 
the Maritime Provinces, where the species can be found at lower 
elevations using regenerating industrial forests, the species breeds 
mostly in stunted high elevation, or montane spruce-fir forests located 
close to, but below, timberline, which usually occurs at elevations in 
excess of 900 meters (m) (3,000 feet (ft)) elevation (Wallace 1939, pp. 
248 and 286; Ouellet 1993, pp. 560, 561; Atwood et al. 1996, p. 652; 
Rimmer et al. 2001, p. 7).
    The montane spruce-fir forests that this species prefers for 
breeding are typical of chronically disturbed areas associated with 
altered growing conditions resulting from human activities (e.g., ski 
trails) and natural processes. Natural disturbances include `terrific' 
winds, which can exceed 45 meters per second (mps) (100 miles per hour 
(mph)), and heavy rime ice accumulation that occurs when supercooled 
water droplets undergo rapid freezing upon contact with a cold surface 
(Wallace 1939, p. 282; Rimmer et al. 2001, p. 7). As a result of these 
conditions, trees are stunted and the mean canopy height in areas where 
the Bicknell's thrush is found in the White Mountains of New Hampshire 
is 4.8 m (15.7 ft) (Sabo 1980, p. 250). Habitats of this type provide 
approximately 100,000 to 150,000 hectares (ha) (247,105 to 370,658 
acres (ac)) of Bicknell's thrush nesting habitat for the United States' 
breeding population, which is estimated to be between 57,000 and 77,000 
birds

[[Page 48937]]

and represents approximately 60 percent of the global population 
(Atwood et al. 1996, p. 654; IBTCG 2010, p. 6).
    The remaining global population of the Bicknell's thrush, or 37,000 
to 49,000 birds, breeds in Canada (IBTCG 2010, p. 6). While Bicknell's 
thrush can be found in Canadian habitats associated with industrial 
forests at elevations as low as 175 m (574 ft), most are found in 
montane spruce-fir forests at elevations exceeding 600 m (1968 ft) 
(Ouellet 1993, pp. 560-563; Nixon et al. 2001, p. 38). Bird densities 
in lower elevation habitats range from 16 to 40 pairs per 100 ha (247 
ac), which is much lower than the 90 to 100 pairs per 100 ha (247 ac) 
densities measured during a 4-year study in montane habitat on 
Vermont's Mount Mansfield (Nixon et al. 2001, p. 38; Rimmer et al. 
1996, p. 641).
    Although the Bicknell's thrush exhibits some flexibility in the 
elevation of breeding habitats used, the species demonstrates a strong 
preference for a specific vegetation structure. Breeding habitats in 
montane habitats or in lower elevation areas are characterized by dense 
vegetation (Rimmer et al. 2001, pp. 7-8).
    Breeding occurs in June, with males singing to attract a mate 
(Wallace 1939, p. 311; Rimmer et al. 2001, p. 12). Both males and 
females will mate with multiple partners, resulting in multiple 
paternity within the same nest (Rimmer et al. 2001, p. 13). Nest 
building and egg incubation is the sole responsibility of the female, 
but both males and females feed the chicks (Wallace 1939, pp. 323-325; 
Rimmer et al. 2001, pp. 15-17). Fledging occurs at 9 to 14 days, at 
which time the young either stay in the vicinity of the nest or depart 
to other areas, including down-slope, hardwood-dominated habitats 
(Rimmer et al. 2001, p. 18). The sex ratio of Bicknell's thrush 
nestlings can vary from 1 male:1.5 females to 2 males:1 female (Rimmer 
et al. 2001, p. 13; Townsend et al. 2009, pp. 92-93).
    By the end of September, the Bicknell's thrush departs its breeding 
grounds (Wallace 1939, p. 259). Migration patterns are poorly known 
(Ouellet 1993, p. 564; Rimmer et al. 2001, pp. 6-7); however, fall 
migration progresses at a ``leisurely'' pace with most birds usually 
remaining at some stop-over locations for a day or two and some 
documented to stay for as long as 7 days (Wallace 1939, p. 259; Rimmer 
et al. 2001, p. 7). Fall migration follows a coastal route, south to 
the mid-Atlantic coast where it is thought that most birds depart land 
and fly across the ocean, finally arriving in the Greater Antilles by 
early November (Ouellet 1993, p. 564; Rimmer et al. 2001, pp. 6-7).
    Wintering occurs exclusively in the Greater Antilles, with the 
majority of birds on the island of Hispaniola, in Haiti and the 
Dominican Republic. The species can also be found on the islands of 
Cuba, Jamaica, and Puerto Rico (Rimmer et al. 2001, pp. 3-4), although 
it is considered an uncommon migrant in Hispaniola; a rare migrant to 
the Bahamas, Cuba, and Jamaica; and a vagrant on Puerto Rico and the 
Virgin Islands (Raffaele et al. 1998, p. 376). In the Dominican 
Republic, the Bicknell's thrush can be found from sea level to 2,200 m 
(7,200 ft), although most occur in mesic to wet broadleaf montane 
forests in excess of 1,000 m (3,300 ft) elevation (Rimmer et al. 2001, 
p. 8). The Bicknell's thrush can also be found in dry, pine-dominated 
forests (Rimmer et al. 2001, p. 6). The species prefers dense thicket 
vegetation similar to habitats selected during the breeding season 
(Townsend et al. 2010, p. 520), and individuals (both males and 
females) defend and maintain exclusive territories where conspecifics 
(members of the same species) are excluded (Townsend et al. 2010, p. 
517).
    In spring, the birds leave the Greater Antilles, probably by late 
April (Rimmer et al. 2001, p. 5). They first appear in Florida, and by 
the end of May they can be found back in the mountains of New England 
and Canada (Wallace 1939, p. 259; Rimmer et al. 2001, p. 5). Males 
typically arrive sooner than the females (Rimmer et al. 2001, p. 5).

Population Trends

    Conducting comprehensive surveys for the Bicknell's thrush is 
difficult because of the species' patchy distribution. As a result, 
Bicknell's thrush is under-represented in the United States' historical 
Breeding Bird Survey data, making detection of long-term trends 
difficult (Bystrak 1981, p. 38). However, several local extirpations 
from former breeding habitat have been detected (Rimmer et al. 2001, p. 
4). For example, in Massachusetts, the Bicknell's thrush breeding 
population on Mount Greylock gradually declined from 10 pairs in 1950 
to 0 pairs in 1973, and visits to Saddle Ball Mountain during the 
period 1992 to 1995 failed to detect the species (Atwood et al. 1996, 
p. 657). This same survey also failed to detect the Bicknell's thrush 
where it had historically occurred in Vermont on Glebe and Molly Stark 
Mountains, as well as Mounts Aeolus and Ascutney. In New Hampshire, 
Bicknell's thrush was not found on Mounts Pemigewasset, Monadnock, and 
Sunapee, as well as North Moat Mountain, where the species had been 
previously located.
    In Canada, the species has disappeared from Seal and Mud Islands in 
Nova Scotia (Committee on the Status of Endangered Wildlife in Canada 
(COSEWIC) 2009, p. 9), despite being relatively common at the time of 
Wallace's writing (1939, p. 331), when at least a dozen nests were 
found on Seal Island. Bicknell's thrush has also been absent from 
formerly occupied habitats on Cape Breton Island and Cape Forchu, Nova 
Scotia (COSEWIC 2009, p. 9; Rimmer et al. 2001, p. 4). In Quebec, the 
Bicknell's thrush has not been observed in the last 10 years in the 
following previously occupied locations: Montagne Noire; Monts Sir-
Wilfrid, des [Eacute]boulements, Comi, and St-Pierre; at some 
previously occupied sites in the zec des Martres; M[eacute]tis-sur-Mer; 
and on Bonaventure and Magdalen Islands (COSEWIC 2009, p. 9). In New 
Brunswick since the 1980s, the species has apparently become absent as 
a breeder from the southern half of the province, including from Grand 
Manan Island and the Rapidy Brook area (COSEWIC 2009, p. 9).
    To obtain better information on the population status of all birds 
occupying high-elevation spruce-fir habitat in New Hampshire's White 
Mountains, a comprehensive survey was conducted during the period of 
1993 to 2003 (King et al. 2008). This survey effort involved annual 
bird counts at 768 points on 42 transects located along hiking trails. 
The results revealed that in a 10-year period (1993 to 2003), the 
Bicknell's thrush population had declined by 7 percent (Lambert et al. 
2008, p. 607) in the survey area. However, results from this study may 
not be indicative of Bicknell's thrush populations rangewide, 
especially when considering that the combined trend data from across 
the United States' breeding range have been stable for the period 2001 
to 2009, with local abundance increasing in the Adirondack Mountains 
(New York), while remaining the same in the Catskills (New York), the 
Green Mountains (Vermont), and the White Mountains (New Hampshire) 
(IBTCG 2010, p. 7). Conversely, survey data from Canada demonstrate a 
17 percent annual decline in New Brunswick and a 15 percent annual 
decline in Nova Scotia (IBTCG 2010, p. 7). On Mont Gosford, there were 
60 percent fewer individuals detected in 2007 than in 2001 (IBTCG 2010, 
p. 7). Long-term Canadian Breeding Bird Survey data for the period of 
1966 to 2008 show a 9 percent decline (IBTCG 2010, p. 7).
    In summary, the readily available current population trend 
information

[[Page 48938]]

seems to indicate a static or slightly declining Bicknell's thrush 
breeding population from historical population levels. However, there 
is no information readily available to the Service about the species' 
wintering population. Further information about the species' overall 
population numbers and trends will be gathered during the status 
review.

Evaluation of Information for This Finding

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations at 50 CFR 424 set forth the procedures for adding a species 
to, or removing a species from, the Federal Lists of Endangered and 
Threatened Wildlife and Plants. A species may be determined to be an 
endangered or threatened species due to one or more of the five factors 
described in section 4(a)(1) of the Act:
    (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range;
    (B) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (C) Disease or predation;
    (D) The inadequacy of existing regulatory mechanisms; or
    (E) Other natural or manmade factors affecting its continued 
existence.
    In considering what factors might constitute threats, we must look 
beyond the mere exposure of the species to the factor to determine 
whether the species responds to the factor in a way that causes actual 
impacts to the species. If there is exposure to a factor, but no 
response, or only a positive response, that factor is not a threat. If 
there is exposure and the species responds negatively, the factor may 
be a threat, and we then attempt to determine how significant a threat 
it is. If the threat is significant, it may drive or contribute to the 
risk of extinction of the species such that the species may warrant 
listing as threatened or endangered as those terms are defined by the 
Act. This does not necessarily require empirical proof of a threat. The 
combination of exposure and some corroborating evidence of how the 
species is likely impacted could suffice. The mere identification of 
factors that could impact a species negatively may not be sufficient to 
compel a finding that listing may be warranted. The information shall 
contain evidence sufficient to suggest that these factors may be 
operative threats that act on the species to the point that the species 
may meet the definition of threatened or endangered under the Act.
    In making this 90-day finding, we evaluated whether information 
regarding threats to the Bicknell's thrush, as presented in the 
petition and other information available in our files, is substantial, 
thereby indicating that the petitioned action may be warranted. Our 
evaluation of this information is presented below.

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

Information Provided in the Petition
    The petitioner asserts that the ``primary threat to the long-term 
persistence of the Bicknell's thrush is habitat loss'' (Center for 
Biological Diversity 2010 petition (Petition), p. 24). The petitioner 
concludes that ``montane ecosystems that host populations of the 
Bicknell's thrush are small and fragmented, heightening their 
vulnerability to a number of complex, interrelated threats'' (Petition, 
p. 24). ``Foremost among these threats is global climate change,'' the 
petitioner asserts, that will result in disappearance of montane 
forests from the species' current breeding range (Petition, p. 24). In 
addition to direct and indirect impacts of climate change, the petition 
also describes other factors that contribute to the loss of important 
breeding and wintering Bicknell's thrush habitat, including: (1) Acid 
rain deposition; (2) ground-level ozone and nitrogen atmospheric 
deposition; (3) recreational, telecommunication, and wind energy 
development activities; and (4) timber extraction that results in the 
conversion of breeding habitat to other land uses (Petition, pp. 6, 
24).
Evaluation of Information Provided in the Petition and Available in 
Service Files
Climate Change--Impacts to Breeding and Wintering Habitat
    The petitioner states that ``Climate change represents the gravest 
threat to the long-term survival of the Bicknell's thrush'' (Petition, 
p. 24). The petition provides an overview of global climate change 
research, including past, present, and predicted future climate change 
conditions (Petition, pp. 24-28). Following this overview of the 
scientific basis of global climate change, the petitioner discusses 
observed and predicted impacts to Bicknell's thrush habitat. The 
petitioner asserts that the predicted global climate change will result 
in increased July temperatures that could lead to a reduction in the 
amount of spruce-fir habitat for the Bicknell's thrush by over 95 
percent (Petition, p. 29), as well as increase the frequency of erratic 
and severe weather events. The petition also cites references that 
indicate that climate change will result in drying trends for the 
Caribbean Basin that may reduce the suitability of important wintering 
habitats, as well as an increase in the frequency of tropical storms 
that may destroy habitat (Petition, pp. 31, 33).
    Regarding climate change-induced increased summer temperatures in 
the Northeast, several studies provide relevant information. For 
example, the petitioner asserts that the Fourth Assessment Report: 
Climate Change 2007 (hereafter referred to as AR4), prepared by the 
Intergovernmental Panel on Climate Change (IPCC) presents the best 
available science on global climate change. We concur that the 
information on global climate change contained within AR4 is reliable. 
The IPCC concludes that warming of the climate system is unequivocal, 
as is now evident from observations of increase in global average air 
and ocean temperatures, widespread melting of snow and ice, and rising 
global average sea level (IPCC 2007, p. 2). Further, they attribute the 
warming to a 70 percent increase in greenhouse gas (mostly 
CO2) emissions from human activities during the period 1970 
to 2004, and those emissions result in a marked increase in global 
concentration of contributing gases, as evidenced by ice core samples 
(IPCC 2007, p. 5). In conclusion, the IPCC expresses a ``very high 
confidence'' that the net effect of recent human activities has been 
one of warming (IPCC, p. 5).
    This warming trend is expected to continue as a result of a 
projected increase of global greenhouse gas emissions by 25 to 90 
percent between 2000 and 2030, which would be greater than the change 
observed during the 20th century (IPCC, p. 7). Although there is some 
uncertainty regarding the mechanics of climate change and how much 
temperatures will change, the projected global average surface 
temperature increase is estimated to range from 1.1 [deg]C to 6.4 
[deg]C (2.0 [deg]F and 11.5 [deg]F) in 2090 to 2099, over the 
temperatures observed during the 19-year period of 1980 to 1999 (IPCC 
2007, p. 8). Consistent with this increase in global average 
temperatures, at a regional scale, average annual temperatures in the 
northeastern United States are also projected to rise by 2.9 [deg]C to 
5.3 [deg]C (5.0 [deg]F to 10.0 [deg]F) by 2070 to 2099, in comparison 
to the period of 1961 to 1990 (Hayhoe et al. 2007, p. 388).
    The petition presents research, supported by readily available 
information in our files, which demonstrates that climate change-
induced habitat loss has occurred

[[Page 48939]]

within the range of the Bicknell's thrush. The spruce-fir/deciduous 
ecotone is correlated with elevation areas that have a mean July 
temperature of approximately 17 [deg]C (63 [deg]F); consequently, 
montane spruce-fir forests are restricted to upper elevations (Cogbill 
and White 1991, pp. 169 and 171). During the period of 1964 to 2004, 
analysis of forest plots in Vermont's Green Mountains indicates a 19 
percent increase in the dominance of northern hardwood species in the 
northern hardwood-boreal forest ecotone, at the expense of red spruce, 
balsam fir, and montane paper birch (Beckage et al. 2008, p. 4197). 
This tree species shift is corroborated by remotely sensed data from 
1962 to 2005 that indicates a 92-m (302-ft) and 119-m (390-ft) upslope 
movement in the northern hardwood to boreal ecotone on two mountains: 
Mount Abraham, which supports a breeding population of the Bicknell's 
thrush (Rimmer et al. 2005a, p. 27) and Camels Hump. This change 
coincides with an increase of 1.1 [deg]C (2 [deg]F) in annual 
temperature during the same period, and the authors propose that this 
climate change promotes the growth and recruitment of northern 
hardwoods at higher elevations (Beckage et al. 2008, p. 4201). The 
authors then suggest that the increase in northern hardwood species is 
made possible by vacancies left by boreal forest species that have, 
possibly, succumbed to the effects of acid rain depositions, to which 
red spruce mortality has been attributed (Beckage et al. 2008, p. 
4201). In conclusion, the authors suggest ``that high-elevation forests 
may be jeopardized by climate change * * *'' (Beckage et al. 2008, p. 
4197). Similar information also exists from other Vermont sites 
(Friedland 1989, pp. 240-241) and from New York (Cook 1985 and Johnston 
et al. 1988 in Friedland 1989, p. 242).
    The montane spruce-fir forests of New York and northern New England 
provide breeding habitat for approximately 60 percent of the world's 
estimated Bicknell's thrush population (IBTCG 2010, p. 6). Rodenhouse 
et al. (2008, p. 525) suggest that because the occurrence of this 
habitat type is primarily controlled by climate, projected warming has 
the potential to alter the distribution and abundance of the Bicknell's 
thrush. To evaluate the consequences of climate change to Bicknell's 
thrush habitat, Rodenhouse et al. (2008, p. 525) evaluate the potential 
impacts of a warming climate on modeled Bicknell's thrush habitat. The 
authors argue a warming climate will enable northern hardwoods to 
encroach on red spruce and balsam fir, causing the montane spruce fir 
forest to shift out of Bicknell's thrush habitat suitability 
(Rodenhouse et al. 2008, p. 525). Based on their results, regional 
warming of 1 [deg]C (1.8 [deg]F) will reduce Bicknell's thrush habitat 
by more than one-half, while an increase of 2 [deg]C (3.6 [deg]F) may 
result in the elimination of all breeding sites from the Catskill 
Mountains and most of Vermont. Furthermore, with an increase of 3 
[deg]C (5.4 [deg]F), most Bicknell's thrush will be eliminated from the 
northeastern United States. With an increase of 5 [deg]C (9 [deg]F), 
nearly all the habitat will be eliminated, but some small habitat 
patches may persist (Rodenhouse et al. 2008, p. 526). This information 
is relevant, because the average annual temperatures in the 
northeastern United States are projected to rise by 2.9 [deg]C to 5.3 
[deg]C (5.0 [deg]F to 10.0 [deg]F) by 2070 to 2099, above those of the 
period 1961 to 1990 (Hayhoe et al. 2007, p. 388).
    The petitioner indicates that she is unaware of any climate 
modeling for Canadian highland forests used by Bicknell's thrush 
(Petition, p. 31). This will be further investigated during our 12-
month status review.
    In regard to increasing frequency of storms, the petitioner also 
indicates that climate change will cause ``more erratic and severe 
weather events'' but acknowledges that how or to what extent the bird's 
breeding habitat will be impacted is unknown (Petition, p. 33). There 
is no information readily available to the Service specific to the 
expected frequency or intensity of storms that may impact montane 
spruce-fir breeding habitat, but this will be further investigated 
during our 12-month status review.
    In addition to climate change impacts to breeding habitat, the 
petitioner asserts that the quality of wintering habitat for the 
Bicknell's thrush in the Greater Antilles will be reduced by climate 
change-induced drought (Petition, p. 31) and more intense and frequent 
El Ni[ntilde]o Southern Oscillation events (Petition, p. 33). By 2050, 
the observed significant drying trends in the Caribbean are expected to 
reduce water resources (Neelin et al. 2006, p. 6110; IPCC 2007, p. 52). 
The impacts of these drought conditions or flooding that may result 
from El Ni[ntilde]o events on the Bicknell's thrush and its habitat are 
unclear. There is no information readily available to the Service on 
climate change in this area, but this will be further investigated 
during our 12-month status review.
Climate Change--Changing Dynamic of Forest Pests and Disease
    The petition suggests that climate change may alter the disturbance 
dynamics of native forest insects and diseases, as well as facilitate 
the establishment and spread of nonindigenous species (Hunt et al. 
2006, pp. 6-7). In addition to the direct degradation of breeding 
habitat, these pests may facilitate invasion of montane spruce-fir 
forests by northern hardwoods (Beckage et al. 2008, p. 4201), as 
discussed below.
    The spruce budworm (Choristoneura fumiferana) is the most important 
native pest of spruce and fir in the Northeast and is capable of 
substantially modifying large areas of boreal forest (Fleming and 
Candau 1998, p. 236). The spruce budworm is a naturally outbreaking 
insect that can be extremely abundant for periods of 5 to 15 years, 
with populations reaching 10\8\ fourth instar larvae per ha (> 40 
million per ac). This level of abundance can kill most trees in dense, 
mature balsam fir stands (Fleming and Candau 1998, pp. 236, 237; Gitay 
et al. 2001, p. 291). These periods of abundance can be followed by 
periods of up to 60 years when the budworm is relatively rare. Budworm 
outbreaks frequently follow droughts or hot, dry summers. This event 
sequencing may lead to increased egg production and disruptions in the 
timing of budworm and several of its parasitoid predators, thereby 
increasing population growth potential in the budworm (Gitay et al. 
2001, p. 291). Therefore, the environmental changes resulting from 
climate change could affect spruce budworm populations by altering any 
of the relationships among host tree species, the budworm, and its 
natural enemies (Fleming and Candau 1998, p. 236).
    Local extinction of balsam fir is one potential outcome of climate 
change-induced intensification of spruce budworm outbreaks (Fleming and 
Candau 1998, p. 246). However, a potential benefit of this change is 
that the Bicknell's thrush is known to use regenerating forests 
disturbed by spruce budworm infestations (COSEWIC 2009, p. 10; Bredin 
and Whittam 2009, p. 13). As we describe above in the Species 
Information section, Bicknell's thrush feed on many insects, including 
species of lepidopteran larvae (Wallace 1939, p. 295), which may 
include the spruce budworm.
    The balsam woolly adelgid (Adelges piceae) is another insect that 
the petitioner discusses as a threat to Bicknell's thrush habitat. The 
balsam woolly adelgid is an exotic pest of fir

[[Page 48940]]

trees, introduced from central Europe, and is impacting large stands of 
fir in the southern Appalachians (Iverson et al. 1999, p. 176; 
Ragenovich and Mitchell 2006). Weather is an important factor in the 
survival of this insect, because in cold winters, only those adelgids 
below the snowline will survive temperatures below -1 [deg]C (30 
[deg]F) (Ragenovich and Mitchell 2006, p. 9). Furthermore, only the 
first instar can survive the winter. In montane spruce-fir habitats, 
the season may be too short for this insect to complete a second 
generation, which affords some protection to high elevation Bicknell's 
thrush breeding habitat (Ragenovich and Mitchell 2006, p. 9). There is 
the potential, however, for the balsam woolly adelgid to have 
deleterious effects on the Bicknell's thrush breeding habitat quality 
(Lambert et al. 2005, p. 7; IBTCG 2010, p. 14) if overall temperatures 
rise as modeled by the IPCC.
    Summary of Climate Change--Results of the empirical studies we 
discuss above suggest that breeding habitat within the United States, 
and possibly in Canada, may decrease with a warming climate. Although 
the impacts of a warming climate on the species' wintering range have 
not been quantified, habitat modeling indicates that continued warming 
may lead to the complete loss of the species' breeding habitat within 
the United States by the end of the 21st century. In addition, the 
predicted warming trends may result in more favorable conditions for 
forest pests such as the spruce budworm and balsam woolly adelgid. 
Therefore, information presented in the petition and readily available 
in our files indicates that environmental impacts associated with 
climate change may be a threat to the Bicknell's thrush.
Atmospheric Acid and Nitrogen Deposition and Ground-Level Ozone
    The petition asserts that deposition of acid and nitrogen poses a 
serious threat to Bicknell's thrush habitat throughout its high-
elevation habitat (Petition 2010, pp. 33-36). Acid deposition, commonly 
referred to as acid rain, is mostly derived from the burning of fossil 
fuels, such as coal and gas, that results in the production of sulfur 
dioxide and nitrogen oxides that in turn react with atmospheric water, 
oxygen, and other chemicals to form various acidic compounds (U.S. 
Environmental Protection Agency (EPA) 2012, http://www.epa.gov/acidrain/). The deposition of these acidic compounds in high-elevation 
montane habitats occurs in either rain or cloud water. The pH values 
for these waters have been measured at 2.1, which is extremely acidic 
(DeHayes et al. 1999, p. 789). Air pollution also results in the 
deposition and accumulation of sulfur and nitrogen (nitrates or ammonia 
or both) in forest soils, which can impact soil health (Driscoll et al. 
2001, p. 12; Driscoll et al. 2003, p. 357, ITBCG 2010, p. 13). 
Regulations have been passed to reduce acid deposition, and while the 
Acid Rain Program, established under Title IV of the 1990 Clean Air Act 
Amendments, has reduced sulfur dioxide and nitrogen oxide emissions and 
average ambient concentrations, high levels of acid deposition continue 
in the northeastern United States (EPA 2009, p. 1; Driscoll et al. 
2001, p. 6).
    Information in our files suggests that deposition of acid may have 
several implications for the Bicknell's thrush and its habitat. First, 
deposition of acidic ions is known to reduce soil calcium, which likely 
leads to calcium deficiencies that render red spruce needles vulnerable 
to freezing damage. This damage reduces a tree's tolerance to low 
temperatures and increases the occurrence of winter injury and 
subsequent mortality (DeHayes et al. 1999, p. 798). Second, acidic 
deposition may also increase soil aluminum availability, which may 
limit the ability of red spruce trees to take up water and nutrients 
through their roots (Cumming and Brown 1994, p. 597).
    Information in our files also suggests that deposition of nitrogen, 
a major plant nutrient, may also affect Bicknell's thrush habitat when 
the nitrogen deposition acts in concert with increased spruce-fir 
mortality resulting from deposition of acid; deposition of nitrogen, a 
major plant nutrient, may also affect Bicknell's thrush habitat. In 
high elevation spruce-fir forests, nutrient cycling is naturally low 
due to slower decomposition and low biological nitrogen demand; 
however, high-elevation areas receive greater amounts of atmospheric 
nitrogen than do low-elevation areas (McNulty et al. 1991, p. 16). 
Several research studies document a shift in species vegetation that 
favors hardwood tree species when montane spruce-fir stands were 
exposed to naturally occurring and artificially manipulated levels of 
atmospheric nitrogen (McNulty et al. 2005, p. 290; McNulty et al. 1996, 
p. 109; Beckage et al. 2008, p. 4201). The resulting vegetation shift 
towards more hardwoods may decrease the quality of foraging or nesting 
areas for the Bicknell's thrush (IBTCG 2010, p. 13).
    The petition goes on to suggest, without providing any supporting 
references, high spruce mortality, as a result of acid and nitrogen 
deposition, provides a more open canopy and may expose adult Bicknell's 
thrush to greater risk of predation. The petitioner states the increase 
in exposure requires resident thrushes to spend more time being 
vigilant for predators instead of spending more time and energy on 
other vital life functions (Petition, p. 33). There is no evidence 
presented with the petition to support this concern. In fact, 
information in our files indicates that Bicknell's thrush frequently 
sing from exposed perches atop dead snags (Rimmer et al. 2001, p. 12). 
Furthermore, Rimmer et al. (2004, pp. 27, 30) found no significant 
differences in adult survivorship or breeding productivity of 
Bicknell's thrush between ski areas, which provide greater openings 
than would a solitary red spruce snag, and more natural areas. This 
study suggests that there is little risk of increased predation of 
Bicknell's thrush in the presence of red spruce snags, as a result of 
increased spruce mortality, and a more open canopy (Rimmer et al. 2004. 
pp. 22-27).
    The petition suggests that ground-level ozone is another air 
pollutant that is putting Bicknell's thrush habitat at risk of long-
term and potentially irreversible decline (Petition, p. 35). Ozone is 
the product of a reaction of sunlight on nitrogen oxide and 
hydrocarbons, which can cause foliage damage and lead to reduced growth 
in plants (Lovett and Tear 2008, pp. 4-5). To support this position, 
the petition provides information regarding the impacts that ground-
level ozone has had on western conifers (Petition, p. 35). However, the 
petition acknowledges that ozone impacts to montane red spruce and 
balsam fir are not described. Likewise, we are also unaware of any 
information suggesting that ground-level ozone is impacting Bicknell's 
thrush habitat.
    Summary of Atmospheric Deposition and Ground-Level Ozone--The 
results of the studies we discuss above suggest that Bicknell's thrush 
breeding habitat within the United States may decrease as a result of 
atmospheric acid and nitrogen deposition. Researchers have suggested 
that this deposition contributes to declines in red spruce and balsam 
fir in montane habitats, and may facilitate the establishment of 
hardwood species. Also, atmospheric deposition of acid and nitrogen is 
occurring throughout the species' breeding range. Therefore, 
information presented in the petition and readily available in our 
files indicates that the present or threatened destruction, 
modification, or curtailment of its range by impacts caused by 
atmospheric deposition of acid and nitrogen may be

[[Page 48941]]

a threat to the Bicknell's thrush. Conversely, information provided by 
the petitioner and readily available information in our files does not 
indicate that the present or threatened destruction, modification, or 
curtailment of its range by ground-level ozone may be a threat to 
Bicknell's thrush. However, the potential for ground-level ozone to 
threaten habitat for the Bicknell's thrush will be further investigated 
during our 12-month status review.
Recreational, Telecommunication, and Wind Energy Development
    The petitioner asserts that development for recreation (i.e., ski 
areas), especially the cumulative effect of multiple ski areas, 
directly results in the loss and fragmentation of Bicknell's thrush 
breeding habitat (Petition, pp. 35-36). Information in our files 
demonstrates that this concern is shared by others; however, the 
cumulative effects of these threats across the range of the Bicknell's 
thrush are poorly known (Rimmer et al. 2001, p. 21; Bredin and Whittam 
2009, pp. 12, 13; COSEWIC 2009, p. 32), and the assessment of this 
threat is typically based on localized studies.
    In Vermont, 13 mountains that are greater than 915 m (3,000 ft) 
elevation are developed for recreational skiing, and many of these ski 
areas offer mountain bike activities during the Bicknell's thrush 
breeding season (Rimmer et al. 2001, p. 21). Similar pressures may 
occur in New Hampshire and Maine, but less so in the Catskills and 
Adirondacks in New York (Rimmer et al. 2001, p. 21) and in Canada 
(COSEWIC 2009, p. 32). In the short term, construction of these 
recreational developments resulted in the loss of some amounts of 
Bicknell's thrush habitat (Rimmer et al. 2001, p. 21). For example, the 
proposed expansion of the Whiteface Mountain trail system in New York's 
Adirondack Mountains was expected to remove up to 4.8 ha (11.8 ac) of 
the Bicknell's thrush breeding habitat and isolate an additional 1.8 ha 
(4.4 ac) (Rimmer et al. 2004, p. 8). This loss constitutes up to 0.26 
percent of the suitable habitat in the Adirondack Park's Whiteface 
Mountain Habitat Unit that includes high-elevation songbird habitat on 
Whiteface Mountain, Little Whiteface Mountain, Esther Mountain, Lookout 
Mountain, and Baldwin Hill, and less than 0.001 percent of the total 
breeding habitat available in the northeastern United States (Rimmer et 
al. 2004, p. 10).
    Information in our files provides variable data on these 
developments' long-term impacts on local populations of the Bicknell's 
thrush. For example, research at the Stowe Mountain Resort on Mount 
Mansfield and the Stratton Mountain Resort in Vermont demonstrates that 
there are few differences in various Bicknell's thrush population and 
reproductive parameters (including nest predation, nest success, 
parental care, movement patterns, survivorship, or productivity) 
between habitat patches at the ski areas and natural forests on each of 
the respective resorts' mountains (Rimmer et al. 2004, p. 2). Radio 
telemetry data reveals that adult thrushes avoid trail crossings wider 
than 50 m (164 ft), while trails 35 to 40 m (115 ft to 131 ft) in width 
exhibit some restrictions on the movement of Bicknell's thrush (Rimmer 
et al. 2004, p. 2). Yet, in a different study, Glennon and Karasin's 
(2004, p. 1) investigations of existing ski trails and glades on 
Whiteface Mountain in New York show no statistical differences in 
abundance of Bicknell's thrush. We interpret Glennon and Karasin's 
(2004) study to mean that, although the species may not cross some 
wider ski trails, Bicknell's thrush still successfully reproduces in 
the surrounding habitat. Therefore, these results suggest that while 
the construction of ski areas produces an immediate loss of Bicknell's 
thrush habitat, the birds may be able to adapt by shifting to reproduce 
in adjacent habitat if the ski trails do not completely fragment 
habitat to a degree that adult Bicknell's thrush movements are 
inhibited.
    In addition to ski area development, the petitioner asserts that 
infrastructure development for telecommunication and wind energy 
projects poses a threat to Bicknell's thrush habitat (Petition, p. 37). 
Wind and telecommunications structures are often placed on exposed 
high-elevation areas (Petition, p. 37), which may include areas of 
suitable Bicknell's thrush breeding habitat. Information in our files 
indicates that construction of wind and telecommunication facilities 
potentially impacts the species through habitat removal.
    Limited information is available from existing or proposed wind 
turbine sites (MacFarland et al. 2008, p. 5). In some instances, 
construction of these facilities, including their associated 
infrastructure (e.g., roads), can directly impact Bicknell's thrush 
habitat (Rimmer et al. 2001, p. 21; MacFarland et al. 2008, p. 1; 
COSEWIC 2009, p. 32). For example, Noble Environmental Power (2008, in. 
litt) calculates that their Granite Reliable wind power project, 
located on Owlhead Mountain and Mount Kelsey in New Hampshire, will 
result in the removal of approximately 23.5 ha (58 ac) of high-
elevation spruce and spruce-fir forest, some of which is known to be 
occupied by Bicknell's thrush. In addition, several wind power projects 
are located within Bicknell's thrush habitat in Quebec and New 
Brunswick (COSEWIC 2009, p. 32). Although these projects result in the 
direct loss of habitat due to removal, secondary impacts may also be 
caused by these projects, including habitat fragmentation and possibly 
behavioral impacts, such as avoidance of turbine sites due to noise 
(COSEWIC 2009, p. 32).
    There are few examples of completed wind turbine construction 
projects in Bicknell's thrush habitat, but MacFarland et al. (2008, p. 
8) assess the relationship of Bicknell's thrush breeding habitat to 
available wind resources. The authors determine that nearly 94 percent 
of the potential Bicknell's thrush habitat found in the Northeastern 
Highlands region of Vermont overlaps areas of Class 4 (> 7 mps (15.7 
mph)) or higher wind power, which are considered good resources for 
generating wind power with large turbines. However, the area of overlap 
between Bicknell's thrush habitat and Class 4 or higher wind areas 
represents only 7 percent of the total available high-value wind 
resource area. The MacFarland et al. (2008, p. 8) analysis suggests 
that a large portion (93 percent) of the potentially suitable wind 
power terrain could be developed without directly impacting Bicknell's 
thrush habitat. A visual comparison of modeled Bicknell's thrush 
habitat with wind resource data from throughout the Bicknell's range 
yields a similar assessment as MacFarland et al.'s (2008) regional 
study (A. Tur, pers. comm. 2012). Loss of Bicknell's thrush habitat 
from wind power development may be a threat to the species if the 
development sites do not occur outside the area of overlap discussed 
above.
    Summary of Recreational, Telecommunication, and Wind Energy 
Development--Development of recreational areas (including ski areas), 
wind turbines, and telecommunication facilities and their associated 
infrastructure (i.e., roads) has resulted in the loss and fragmentation 
of Bicknell's thrush habitat (IBTCG 2010, p. 12). The Bicknell's thrush 
may show some ability to adapt and persist in the vicinity of ski 
resorts (Rimmer et al. 2004, p. 1). The species may adapt similarly to 
the construction of wind turbines. Information presented in the 
petition and readily available in our files indicates that the present 
or threatened destruction, modification, or

[[Page 48942]]

curtailment of its range by impacts attributed to recreational, 
telecommunication, and wind energy development may be a threat to the 
Bicknell's thrush.
Logging and Forest Fragmentation
    The petition asserts that logging in Canada and northern Maine is 
``a prime threat'' to Bicknell's thrush breeding habitat (Petition, pp. 
37-39). Specifically, the petitioner suggests that dramatic drops in 
Bicknell's thrush presence at Canadian monitoring sites over the last 1 
to 2 decades provide a clear indication that logging damages habitat 
and threatens the long-term survival of the species. However, 
information in our files suggests that the Bicknell's thrush is often 
found in managed forests, and it is unclear how forestry practices 
alter the amount and suitability of breeding habitat in Canada and 
northern Maine (IBTCG 2010, p. 11).
    Throughout the industrial highlands of Canada and northern Maine, 
the practice of clearcutting may impact Bicknell's thrush by 
temporarily removing forest habitat. But, the petitioner acknowledges, 
and information in our files suggests, that regeneration of balsam fir 
and spruce in these areas is known to result in the creation of 
breeding habitat (Ouellet 1993, p. 566; Chisholm and Leonard 2008, p. 
218; COSEWIC 2009, p. 31; IBTCG 2010, p. 11; Petition 2010, p. 38). 
Following clearcutting, dense regeneration of spruce and fir often 
follows, resulting in the creation of suitable Bicknell's thrush 
breeding habitat (Nixon et al. 2001, p. 34; Chisholm and Leonard 2009, 
p. 218; IBTCG 2010, p. 11). Although Bicknell's thrush occupy 25- to 
40-year-old second growth stands, optimal conditions for Bicknell's 
thrush occur in 5- to 12-year-old clear cuts that have high densities 
of the 5- to 10-cm-diameter (2 to 4 inches (in.)) stem class (Nixon et 
al. 2001, p. 39; Connolly et al. 2002, p. 338; Chisholm and Leonard 
2008, p. 222). Despite the species' presence in managed forests, it is 
difficult to assess the immediate impacts of clearcutting on Bicknell's 
thrush because little work has been done to determine the extent to 
which the species makes use of mature forest habitat prior to the 
implementation of forestry practices (COSEWIC 2009, p. 31).
    Information in our files suggests other forestry practices may also 
impact Bicknell's thrush habitat. Specifically, precommercial thinning 
that reduces stem densities to maximize growth in remaining trees 
results in the reduced abundance of Bicknell's thrush (Chisholm and 
Leonard 2008, p. 222). Precommercial thinning could also directly 
destroy Bicknell's thrush nests because thinning is often conducted 
during the bird's nesting season (Makepeace and Aubry, unpubl. data in 
COSEWIC 2009, p. 31).
    In addition to the petitioner's discussion of the impacts of 
forestry practices on breeding range habitat, information in our files 
indicates an ongoing loss and degradation of important forested 
wintering habitat through logging, subsistence farming, and human-
caused fires (Rimmer et al. 2001, p. 4; Rimmer et al. 2005b, p. 228; 
Townsend and Rimmer 2006, p. 454; COSEWIC 2009, p. 32). As discussed 
above in the Species Information section, the Bicknell's thrush winters 
exclusively in the Greater Antilles. The overall loss of winter forest 
habitat, including the Bicknell's thrush preferred montane forests, has 
been severe (Rimmer et al. 2001, p. 4), and this loss may impact the 
species despite its flexibility in selection of wintering habitat types 
and elevation. For example, there is some evidence in the Dominican 
Republic that Bicknell's thrush exhibits sexual segregation based on 
geography and the segregation may be the result of birds moving from 
areas of disturbed habitat (Rimmer et al. 2001, p. 9). Indeed, less 
than 1.5 percent of original montane forest habitat remains in Haiti, 
and about 10 percent remains in the Dominican Republic (Rimmer et al. 
2001, p. 4). Jamaica has lost 75 percent of its original forest, and 
Cuba has lost 80 to 85 percent (Rimmer et al. 2001, p. 4). While the 
Dominican Government has established a number of areas to protect 
important forest habitat (Latta et al. 2003, p. 180), habitat loss due 
to illegal logging and slash-and-burn agriculture continues both there 
and in Haiti (Rimmer et al. 2005b, p. 1; Rimmer et al. 2005d, 
unnumbered page; Townsend and Rimmer 2006, p. 452; IBTCG 2010, p. 12). 
Furthermore, subsistence farming, involving free-ranging cattle and the 
presence of feral pigs, severely damages forest understory growth at 
some wintering sites in Hispaniola and degrades Bicknell's thrush 
wintering habitat quality (IBTCG 2010, p. 12).
    Summary of Logging and Forest Fragmentation--Forestry practices may 
result in the loss and fragmentation of important Bicknell's thrush 
breeding habitat, particularly in the Canadian portion of the species 
range. Clearcutting may be beneficial by creating additional breeding 
habitat for the species, but this is difficult to assess because of a 
lack of information regarding habitat use of these forests prior to 
timber management (IBTCG 2010, p. 12). There is evidence that 
precommercial thinning occurring in occupied breeding habitat renders 
the area immediately unsuitable for nesting, thereby contributing to 
the loss of habitat. On the wintering grounds, habitat loss may be a 
serious concern, due to the species' restricted wintering habitat, as 
well as the historical and continuing loss of habitat to logging, 
subsistence farming, and fire (IBTCG 2010, p. 12). Therefore, 
information presented in the petition and readily available in our 
files indicates that the present or threatened destruction, 
modification, or curtailment of its range by logging and forest 
fragmentation may be a threat to the Bicknell's thrush.
    Summary of Factor A--Information presented in the petition and 
readily available in our files indicates that the present or threatened 
destruction, modification, or curtailment of the Bicknell's thrush 
range caused by: (1) Climate change; (2) atmospheric deposition of acid 
and nitrogen; (3) recreational (ski areas), telecommunication, and wind 
energy development; and (4) logging and forest fragmentation may be a 
threat to the Bicknell's thrush. Information presented in the petition 
and readily available in our files does not indicate that the present 
or threatened destruction, modification, or curtailment of the species' 
range as a result of ground-level ozone may be a threat to the 
Bicknell's thrush. However, the potential for ground-level ozone to 
threaten habitat for the Bicknell's thrush will be further investigated 
during our 12-month status review.

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

Information Provided in the Petition
    The petitioner did not present information suggesting that 
overutilization is affecting Bicknell's thrush populations.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    One reference in our files indicates that 3 of 108 Vermont nests 
monitored during the period of 1992 to 2000 were abandoned and that 
abandonment may be caused by researcher disturbance (Rimmer et al. 
2001, p. 21). This appears to be an isolated circumstance, and we are 
unaware of any other instances of overutilization for commercial, 
recreational, scientific, or educational purposes.

[[Page 48943]]

    Summary of Factor B--Information presented in the petition and 
readily available in our files does not indicate that overutilization 
for commercial, recreational, scientific, or educational purposes may 
be a threat to the Bicknell's thrush. However, whether this factor is a 
threat to the species will be further investigated during our 12-month 
status review.

C. Disease or Predation

Information Provided in the Petition
Disease
    The petitioner asserts that disease (e.g., avian malaria) could 
have a substantial effect on the population viability of the Bicknell's 
thrush (Petition, p. 40).
Predation
    The petitioner states that climate change may increase predation of 
the Bicknell's thrush by altering environmental conditions currently 
limiting the distribution of predators, and allowing ``novel 
predators'' to access the bird's habitat (Petition, pp. 39-40). The 
petitioner also states that the red squirrel (Tamiasciurus hudsonicus), 
a known Bicknell's thrush nest predator, may become more abundant as a 
result of climate change, which the petitioner suggests will bring 
about increased production of balsam fir cones (Petition, p. 40). The 
petitioner asserts that red squirrel populations are closely tied to 
balsam fir cone crop production. As climate change progresses cyclical 
production of heavy cone crops is expected to increase in frequency. 
This may result in increasing numbers of squirrels and, with it, 
increasing depredation of the Bicknell's thrush eggs and nestlings 
(Petition, p. 40).
Evaluation of Information Provided in the Petition and Available in 
Service Files
Disease
    The petitioner asserts that disease (e.g., avian malaria) could 
have a substantial effect on the population viability of the Bicknell's 
thrush (Petition, p. 40). While the petitioner provides information 
regarding the presence of avian malaria in New England and some bird 
species, the petitioner acknowledges that ``bird populations have 
largely adapted to malarial parasites'' and provides no information 
indicating that avian malaria or other diseases may be a threat to the 
Bicknell's thrush. In addition, we are unaware of any information that 
may substantiate this speculation. Therefore, the information presented 
in the petition and readily available in our files does not indicate 
that disease may be a threat to the Bicknell's thrush. However, disease 
impacts to the Bicknell's thrush will be further investigated as part 
of our 12-month status review.
Predation
    Documented predation of adult Bicknell's thrush is limited to only 
a few predators. Of 8 depredation events on radio-tagged breeding 
adults, 7 were attributed to the sharp-shinned hawk (Accipiter 
striatus) and 1 to the long-tailed weasel (Mustela frenata) (Rimmer et 
al. 2001, pp. 13-14). On the wintering grounds, of 53 radio-tagged 
individuals, 5 were depredated by introduced Norway (Rattus norvegicus) 
and black (Rattus rattus) rats, presumably while the birds were 
sedentary on their nocturnal roosts (Townsend et al. 2009a, p. 565). 
The available information suggests that predation of adult Bicknell's 
thrush is not a threat to the species on a population level, although 
it may influence winter roost site selection (Townsend et al. 2009a, p. 
568).
    The sharp-shinned hawk, American marten (Martes americana), long-
tailed weasel, deer mouse (Peromyscus maniculatus), and blue jay 
(Cyanocitta cristata) are known to be predators of bird eggs and 
nestlings. The red squirrel is the only predator known to have a major 
impact on the demographic characteristics of the Bicknell's thrush 
(Wallace 1949, p. 216; COSEWIC 2009, p. 19; IBTCG 2010, p. 6). Wallace 
(1949, p. 215) suggests that high mortality and low breeding rate 
contribute to the restricted distribution of the Bicknell's thrush. He 
notes that 9 of 13 observed nests on Vermont's Mount Mansfield failed, 
while only 2 of the remaining nests were fully successful. While 
acknowledging the limitations of his small, 1-year sample size, Wallace 
(1949, p. 215) at the time concludes that the Bicknell's thrush 
population is either no more than stable or more likely declining 
because the production of 0.85 young fledged per pair constitutes a 
rate at which adults are unable to replace themselves during two 
seasons.
    Since Wallace's observations, additional evidence demonstrates a 
somewhat loose 2-year (biennial) cycle in nest survival rates on 
Stratton Mountain and Mount Mansfield, Vermont (Rimmer et al. 2001, p. 
19). This Bicknell's thrush biennial pattern is attributed to the 
biennial pattern of balsam fir cone crop production and red squirrel 
abundance. A fall season with abundant cone production is followed by a 
spring and summer with high numbers of red squirrels, and results in 
high nest predation rates and low productivity in Bicknell's thrush. In 
some years, no Bicknell's thrush young are produced (COSEWIC 2009, p. 
17). The second part of the biennial cycle is explained when years of 
abundant cone production are followed by years when few cones are 
produced; accordingly, red squirrel numbers drop, along with nest 
predation rates, and Bicknell's thrush nesting success can reach as 
high as 90 percent (Rimmer et al. 2001, p. 19).
    The petitioner asserts, with no supporting information, climate 
change may alter this biennial cycle of balsam fir cone production and 
red squirrel abundance (Petition, p. 40). Information in our files 
suggests balsam fir cone production has been linked to climatic 
variables (Messaoud et al. 2007). For example, two variables that may 
be associated with increased balsam fir reproduction potential are the 
number of growing degree days greater than 5 [deg]C (41 [deg]F) and the 
maximum temperature of the warmest month in the year prior to cone 
production (Messaoud et al. 2007, p. 753). As a consequence, it may be 
reasonable to assume that increased temperatures attributed to climate 
change may lead to increased cone production. However, we have no 
information to suggest that taking that assumption further, to link the 
increase in balsam fir cone production to an increase in squirrel 
densities and a resulting decrease in Bicknell's thrush productivity 
throughout the bird's breeding range, is reasonable, because it is 
unclear if or when this climate change-induced alteration of the 
biennial cycle may occur.
    In addition to biennial cycle disruptions, the petition also 
asserts that climate change will allow ``novel'' predators (i.e., 
previously unknown), such as the raccoon (Procyon lotor), to move into 
previously unoccupied habitat as vegetation types shift (Petition, p. 
40). Information in our files indicates that the red fox (Vulpes 
vulpes), coyote (Canis latrans), bobcat (Lynx rufus), and raccoon have 
all been observed in Bicknell's thrush breeding habitat, and no 
predation by these species is mentioned (Wallace 1949, p. 215; Rimmer 
et al. 2001, p. 14). These observations do not suggest that climate 
change may increase exposure of Bicknell's thrush to novel predators.
    Summary of predation--We have no information to suggest that adult 
Bicknell's thrush predation or predation by novel predators may be a 
threat to the species. In addition, there is no information to suggest 
existing nest

[[Page 48944]]

predation by red squirrels may increase to a level impacting the 
species throughout its breeding range if climate change-induced warmer 
temperatures result in an increase in balsam fir cone production and 
subsequent red squirrel numbers. However, we will fully investigate 
predation in our 12-month status review.
    Summary of Factor C--Information presented in the petition and 
readily available in our files does not indicate that disease or 
predation may be a threat to the Bicknell's thrush.

D. The Inadequacy of Existing Regulatory Mechanisms

Information Provided in the Petition
    The petition states that existing Federal, state, or international 
regulatory mechanisms protecting the Bicknell's thrush or its habitat 
are inadequate. More specifically, the petition states that existing 
international and U.S. regulatory mechanisms to reduce global 
greenhouse gas emissions are inadequate to safeguard the Bicknell's 
thrush against extinction resulting from climate change (Petition, p. 
40).
Evaluation of Information Provided in the Petition and Available in 
Service Files
Species-Specific Regulatory Mechanisms
    The petitioner cites national and international regulatory 
mechanisms that are generic to migratory birds, as well as some that 
are specific to the Bicknell's thrush (Petition, pp. 41-42, 44). For 
example, the petitioner asserts that existing Federal regulatory 
mechanisms, including the Migratory Bird Treaty Act of 1918, as amended 
(MBTA), do not protect habitat for migratory birds, including the 
Bicknell's thrush. In the United States, under the MBTA, it is unlawful 
to take, capture, kill, or possess migratory birds, their nests, eggs, 
and young. The MBTA was not crafted to specifically protect habitat, 
although it may provide indirect benefits to migratory bird habitat, 
and, therefore, cannot be considered an inadequate existing regulatory 
mechanism for habitat protection. In addition, the petitioner further 
states that the Migratory Bird Conservation Act, the Neotropical 
Migratory Bird Conservation Act, and the identification of birds of 
management concern through the Birds of Conservation Concern apply to 
the Bicknell's thrush. These various actions are intended to foster 
proactive conservation, are nonregulatory (Petition, pp. 41-42; USFWS 
2008, p. 30) and, therefore, cannot be considered inadequate existing 
regulatory mechanisms.
    As for international regulatory mechanisms, the Bicknell's thrush 
is protected in Canada under the Migratory Birds Convention Act of 
1994. In addition, the Committee on the Status of Endangered Wildlife 
in Canada designated the bird as threatened in Quebec, New Brunswick, 
and Nova Scotia (COSEWIC 2009, pp. iii, vi). The COSEWIC is a panel of 
species experts who evaluate the conservation status of Canadian 
species according to a set of criteria and recommend which species 
should be protected under Canada's Species at Risk Act (SARA). While 
COSEWIC has evaluated the Bicknell's thrush as a threatened species, 
the Minister of Environment has not yet added the species to SARA's 
Schedule 1 (threatened and endangered wildlife). Bicknell's thrush is 
considered a SARA Schedule 3 Species of Concern, which means the 
Schedule 1 protection and conservation provisions of SARA do not apply. 
With regard to the Dominican Republic and Haiti, the petitioner asserts 
that current protections are minimal and confined to the designation of 
several national parks that provide limited protection to a small 
portion of the bird's wintering habitat where habitat degradation due 
to human activities continues (Petition, pp. 55-56). Although not 
specifically stated by the petition under Factor D, the petition 
asserts in Factor E that wintering habitat in Cuba is inadequately 
managed (Petition, p. 56). We have no readily available information in 
our files that addresses the regulatory mechanisms that may or may not 
be protective of Bicknell's thrush in Canada or the Greater Antilles. 
We will further investigate Canadian and Greater Antilles regulations 
during our 12-month status review.
    The petitioner provides no information regarding any action taken 
by a state or provincial entity that specifically protects the 
Bicknell's thrush under existing authorities for threatened or 
endangered wildlife, but does provide information on how forested 
habitat, which may be occupied by Bicknell's thrush, is managed in each 
state (Petition, pp. 47-54). Information in our files indicates that 
the Bicknell's thrush has been identified as a species of special 
concern in Maine, New York, Vermont, and New Hampshire (IBTCG 2010, p. 
7). Species afforded this designation receive no legal status under 
existing state endangered species statutes. Similarly, the species is 
considered ``vulnerable'' in Nova Scotia and ``may be at risk'' in New 
Brunswick and Quebec, but these designations provide little to no 
additional protection (IBTCG 2010, p. 7; Petition, p. 44).
    In the Puerto Rican portion of its wintering range, the Bicknell's 
thrush is protected under the MBTA, as described previously. The 
petitioner provides no information, and we are not aware of any 
information, regarding the legal status of Bicknell's thrush in the 
Dominican Republic, Haiti, Jamaica, or Cuba. In addition, we have no 
readily available information, either from the petition or in our 
files, on any existing regulatory mechanisms that would provide 
specific protections for the Bicknell's thrush in the national parks of 
Hispaniola.
    Summary of Species-Specific Regulatory Mechanisms--We will further 
investigate whether inadequate regulatory mechanisms that result in 
habitat loss in its wintering range may be a threat to the Bicknell's 
thrush during our 12-month status review.
Atmospheric Acid, Nitrogen Deposition, Mercury, and Ground-Level Ozone 
Regulatory Mechanisms
    The petitioner asserts that amendments to the Clean Air Act in 1990 
have strengthened regulations to control the emission of airborne 
pollutants, but it has not been effective in alleviating the harmful 
effects of mercury, acid deposition, ground-level ozone, or nitrogen 
nutrification in Bicknell's thrush habitat (Petition, p. 42). 
Specifically, the petitioner asserts that EPA has delayed regulating 
mercury emissions as a result of legal actions against the agency, 
while regulations to control acid deposition have not been ambitious 
enough to address the problem (Petition, p. 43). Furthermore, the 
petitioner asserts that, while the 1990 Clean Air Act amendments have 
helped reduce nitrogen dioxide emissions that lead to ozone pollution, 
greater reductions are needed to prevent ongoing ozone pollution that 
the petitioner states is damaging the habitat of Bicknell's thrush 
(Petition, p. 43). The petitioner also states that an international 
agreement to regulate mercury pollution is being developed, but has not 
yet been implemented (Petition, p. 44).
    As discussed above in Factor A, information presented in the 
petition and readily available in our files does not indicate that 
ground-level ozone may be threat to the Bicknell's thrush. Therefore, 
ground-level ozone may be adequately regulated.
    Summary of Atmospheric Acid, Nitrogen Deposition, Mercury, and 
Ground-Level Ozone Regulatory Mechanisms--As discussed in Factor A, 
deposition of acid precipitation and

[[Page 48945]]

nitrogen nutrification may be threats to the species' habitat. As 
discussed in Factor E, deposition of mercury may also be a threat to 
the species. While the Clean Air Act amendments have reduced the 
overall levels of mercury, acid deposition, and ground-level ozone, the 
Clean Air Act amendments have not alleviated the harmful effects of 
those pollutants on the Bicknell's thrush and its habitat (see Factors 
A and E). Therefore, the information presented in the petition and 
readily available in our files indicates that inadequate regulatory 
mechanisms for atmospheric acid, nitrogen deposition, and mercury 
impacts to the Bicknell's thrush habitat may be a threat to the bird. 
However, information presented in the petition and readily available in 
our files does not indicate that inadequate regulatory mechanisms for 
ground-level ozone may be a threat to the Bicknell's thrush.
Climate Change Regulatory Mechanisms
    Finally, the petitioner states that the effect of climate change on 
the montane habitat of the Bicknell's thrush is the most serious threat 
to its continued existence, and that existing international and U. S. 
regulatory mechanisms to reduce global greenhouse gas emissions are 
clearly inadequate (Petition, pp. 40, 44). The petitioner argues that 
national and international reductions in emissions are urgently needed 
to safeguard the Bicknell's thrush against extinction resulting from 
climate change.
    The Clean Air Act of 1970 (42 U.S.C. 7401 et seq.), as amended, 
requires the EPA to develop and enforce regulations to protect the 
general public from exposure to airborne contaminants that are known to 
be hazardous to human health. In 2007, the Supreme Court ruled that 
gases that cause global warming are pollutants under the Clean Air Act, 
and that the EPA has the authority to regulate carbon dioxide and other 
heat trapping gases (Massachusetts et al. v. EPA 2007 [Case No. 05-
1120]). The EPA published a regulation to require reporting of 
greenhouse gas emissions from fossil fuel suppliers and industrial gas 
suppliers, direct greenhouse gas emitters, and manufacturers of heavy 
duty and off-road vehicles and engines (74 FR 56260; October 30, 2009). 
The rule, effective December 29, 2009, does not require control of 
greenhouse gases; rather it requires only that sources above certain 
threshold levels monitor and report emissions (74 FR 56260; October 30, 
2009). On December 7, 2009, the EPA found under section 202(a) of the 
Clean Air Act that the current and projected concentrations of six 
greenhouse gases in the atmosphere threaten public health and welfare. 
The finding itself does not impose requirements on any industry or 
other entities but is a prerequisite for any future regulations 
developed by the EPA.
    As of August 24, 2010, the time of the petition's receipt, it was 
not known what regulatory mechanisms would be developed in the future 
as an outgrowth of EPA's finding that the Clean Air Act is insufficient 
to regulate greenhouse gases or how effective they would be in 
addressing climate change. Climate change regulations, and to what 
extent they adequately address threats to Bicknell's thrush and its 
habitat, will be investigated in our 12-month status review.
    Summary of Factor D--The inadequacy of existing regulatory 
mechanisms for (1) Factor A--the present or threatened destruction, 
modification, or curtailment of the species' habitat caused by climate 
change; atmospheric deposition of acid and nitrogen; and recreational 
(ski areas), telecommunication, and wind energy development; and (2) 
Factor E (see discussion below)--other natural or manmade factors 
affecting its continued existence resulting from: Atmospheric mercury 
deposition; decreased dietary calcium; increased interspecific 
competition facilitated by climate change; and collision with 
stationary and moving structures may be a threat to Bicknell's thrush.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

Information Provided in the Petition
    The petitioner asserts that mercury exposure and accumulation, 
decreased dietary calcium due to acid deposition, direct mortality 
caused by climate change, increased interspecific competition caused by 
climate change, and disturbance by recreationists are all threats to 
the Bicknell's thrush.
Evaluation of Information Provided in the Petition and Available in 
Service Files
Mercury
    The petitioner discusses information regarding the atmospheric 
deposition of mercury, a potent neurotoxin, and the process by which it 
accumulates in the Bicknell's thrush (Petition, pp. 56-58). According 
to the petition, mercury originating mostly from coal-fired power 
plants accumulates in wildlife and is influencing some wildlife 
populations. The petitioner recognizes documentation of methylmercury 
burdens, the toxic form of mercury, in terrestrial montane songbirds is 
a recent discovery (Petition, p. 57). Among four evaluated songbirds, 
the Bicknell's thrush had the highest blood mercury concentrations, 
with birds in the southern portion of the species' range having higher 
loads than in northern areas. In addition, atmospheric deposition of 
mercury is two to five times higher in montane areas than in adjacent 
low-elevation areas (Petition, p. 57).
    Elevated levels of toxic mercury have been found in Bicknell's 
thrush tissue and may be cause for concern (IBTCG 2010, p. 13). Mercury 
in the northeastern United States and eastern Canada is derived from 
local, regional, and global emissions; however, most estimates show 
that approximately 60 percent of mercury in this area is derived from 
sources located within the United States (Evers 2005, p. 5). Mercury 
toxicity is largely dependent upon whether it is converted to the 
bioavailable toxic form known as methylmercury, as well as an 
organism's trophic position (e.g., its level in the food chain). 
Trophic position influences mercury exposure due to the processes of 
bioaccumulation (increase in the body over time) and biomagnification 
(increase in concentration from one trophic level to another) (Evers 
2005, p. 6). Generally, a species that is higher in the food chain has 
a greater exposure to mercury if its prey has mercury in its body when 
consumed as food.
    Mercury deposition is highest on high mountain summits in 
comparison to other landscape positions primarily as a result of the 
summits' greater exposure to cloud-based mercury sources (Miller et al. 
2005, p. 63). Compounding this problem, evergreen foliage generally 
exhibits higher mercury concentrations than deciduous foliage at the 
same site. These higher concentrations are due to the longer retention 
time of mercury in needles as compared to leaves, which are typically 
shed annually (Miller et al. 2005, p. 62). Consequently, the high-
elevation montane insectivores, such as songbirds, that consume insects 
feeding on this vegetation contain relatively high levels of mercury 
when compared with other songbirds from low-elevation habitats. Of 
those montane insectivores, the Bicknell's thrush has the highest 
concentrations of mercury, ranging from 0.08 to 0.38 micrograms/gram 
across 21 distinct breeding sites (Rimmer et al. 2005c, pp. 227, 232). 
Although no clear pattern in mercury levels was observed, mercury 
concentrations in the blood and feathers of Bicknell's thrush from 
southern portions of the species' breeding range were highest, which 
implies greater atmospheric deposition

[[Page 48946]]

rates (Rimmer et al. 2005c, p. 235). In addition, blood mercury 
concentrations in wintering birds were generally 2 to 3 times higher 
than in birds sampled on their breeding sites (Rimmer et al. 2005c, p. 
230). The authors state that this result is unexpected and counter to 
what they would have expected given the lack of local or regional 
industrial sources of mercury in the wintering range (Rimmer et al. 
2005c, p. 235). Further studies of the Bicknell's thrush biochemical 
processes may illuminate the reason behind the higher mercury level in 
the wintering range. Although we do not know the exact cause of the 
elevated blood mercury levels, the information indicates that there may 
be a differing level of exposure between the breeding and wintering 
grounds, and that the source of the exposure mechanism, as well as the 
elevated blood mercury level itself, may pose a threat to the species.
    The specific pathway by which the Bicknell's thrush consumes 
mercury and the effects that the burden has on the birds is unknown 
(Rimmer et al. 2005c, p. 237; Evers 2005, p. 16). Although species-
specific responses to mercury concentrations make direct comparisons 
unreliable, studies of aquatic birds (e.g., mallard ducks and common 
loons) indicate changes in behavior, reproduction, and body chemistry 
are possible (Evers 2005, p. 6; IBTCG 2010, p. 13).
    Summary of Mercury Effects--Information presented in the petition 
and readily available in our files indicates that atmospheric 
deposition of mercury may be a threat to the Bicknell's thrush.
Decreased Dietary Calcium
    The petitioner asserts that acid deposition impacts the habitat of 
the Bicknell's thrush by reducing calcium availability that has been 
shown to influence survival of red spruce. The petitioner also asserts 
that acid deposition can directly alter calcium availability for 
breeding songbirds that may impact eggshell production (DeHayes et al. 
1999, p. 798; Petition, p. 58; IBTCG 2010, p. 13). Acid deposition 
leaches calcium from red spruce forest soils, including soils from many 
Bicknell's thrush breeding sites (DeHayes et al. 1999, p. 798; Driscoll 
et al. 2001, p. 11). This reduction in the availability of calcium has 
been linked to declines in the calcium levels in some invertebrate prey 
items and reduced dietary calcium for songbirds, including the wood 
thrush in the eastern United States, through the bioaccumulation and 
biomagnifications processes mentioned above (Mand et al. 2000, p. 64; 
Hames et al. 2002, pp. 11238-11239). As discussed above in the Species 
Information section, insects are the primary food source for the 
Bicknell's thrush in its breeding range (Beal 1915 in Wallace 1939, p. 
295; Rimmer et al. 2001, pp. 9-10). Although it has not been confirmed, 
calcium depletion and lower availability may affect egg formation and 
productivity in the Bicknell's thrush, as has been suggested for the 
wood thrush, especially in ``highland areas with thin and poorly 
buffered soils'' (King et al. 2008, p. 2697).
    Summary of decreased dietary calcium--Information presented in the 
petition and readily available in our files indicates that decreased 
dietary calcium from soil leaching by acid precipitation may be a 
threat to the Bicknell's thrush.
Direct Mortality Due to Climate Change
    The petitioner asserts that increased storm frequency and intensity 
have the potential to increase mortality in the Bicknell's thrush 
(Petition, p. 58). Information in our files suggest most Bicknell's 
thrush nesting failures are attributed to predation, but climate change 
scenarios predict increases in the frequency of wind and precipitation 
that may result in additional nest failures (Hayhoe et al. 2007, p. 
389; IBTCG 2010, p. 14). In addition, more frequent tropical storms and 
increasing erratic weather caused by climate change (Angeles et al. 
2007, p. 567) may increase mortality of migrating Bicknell's thrush 
(IBTCG 2010, p. 14; Petition, p. 58). The sources of information in the 
petition and our files do not contain an analysis or modeling of storm 
events to determine the extent to which the storm events may be a 
threat to the Bicknell's thrush species as a whole. We do not have 
information regarding whether mortality is occurring, or if it is 
occurring, whether impacts to individual Bicknell's thrushes relates to 
impacts to the species as a whole.
    Summary of direct mortality--Information presented in the petition 
and readily available in our files does not indicate that direct 
mortality resulting from climate change may be a threat to the 
Bicknell's thrush. However, we will fully investigate direct mortality 
resulting from climate change during our 12-month status review.
Increased Interspecific Competition With Climate Change
    The petitioner asserts that climate change will increase 
encroachment of the Bicknell's thrush by competitors that were formerly 
restricted to lower elevations (Petition, p. 58). The petition 
acknowledges that the Swainson's thrush (Catharus ustulatus) is the 
only potential competitor that has been discussed in the scientific 
literature (Petition, p. 58). The Bicknell's and Swainson's thrushes 
generally inhabit mutually exclusive elevation ranges. There are slight 
overlaps in the lower elevation portion of the Bicknell's thrush 
breeding range (Able and Noon 1976, p. 287), as well as in regenerating 
stands following commercial forestry operations in New Brunswick (Nixon 
et al. 2001, p. 34). Swainson's and Bicknell's thrushes may compete for 
nesting territories, and observations of the two species demonstrate 
occasional agonistic encounters on the breeding grounds, including 
chases and displacement from song-posts (Able and Noon 1976, p. 287; 
Rimmer et al. 2001, p. 13).
    The Bicknell's thrush is considered to be better adapted to colder 
environments than is the Swainson's thrush (Holmes and Sawyer 1975 in 
Nixon et al. 2001, p. 38). Lambert et al. (2005, p. 7) suggest that a 
rise in summer temperatures could reduce separation between the two 
species by nullifying Bicknell's thrush's greater tolerance for cold, 
thereby facilitating the establishment of Swainson's thrush at higher 
elevations. Information in our files indicates that temperatures may be 
an important factor in the distribution of these two thrush species 
(Holmes and Sawyer 1975 in Nixon et al. 2001, p. 38), and climate 
change may allow Swainson's thrush to breed at higher elevations.
    Summary of increased interspecific competition--Information 
presented in the petition and readily available in our files indicates 
that increased interspecific competition from Swainson's thrush as a 
result of increasing temperatures associated with climate change may be 
a threat to the Bicknell's thrush.
Disturbance by Recreationists
    The petitioner asserts that recreational use (hiking and biking) in 
Bicknell's thrush habitat poses a threat to the species (Petition, p. 
59; IBTCG 2010, p. 12). The petitioner states that the backcountry 
areas of the White Mountain National Forest in New Hampshire, including 
the high-elevation spruce-fir habitat occupied by the Bicknell's 
thrush, received about 31,400 visitors in 2005 (Petition, p. 59; King 
et al. 2008, p. 2698). Similar visitation is expected in New York's 
Adirondack Park (IBTCG, p. 12). Research suggests that nesting 
Bicknell's thrush are able to tolerate high or moderate levels of

[[Page 48947]]

human activity by becoming habituated to nearby disturbance, while 
females in undisturbed areas demonstrate greater sensitivity to 
disturbance (Rimmer et al. 2001, p. 21). Off-trail excursions by hikers 
into vegetation that may contain a Bicknell's thrush is unlikely, given 
the thick habitat preferred by the species (Wallace 1939, p. 285). As a 
result, most recreational use is confined to the existing trails (A. 
Tur, pers. observation 2012). Hiking trails impact a very small portion 
of the available Bicknell's thrush nesting habitat, and, therefore, it 
seems unlikely that recreational activities in the Bicknell's thrush 
breeding habitat may be a significant threat.
    The petitioner cites Rimmer et al. (2001) as a source of research 
information regarding disturbance of nesting Bicknell's thrush by 
bicyclists. However, Rimmer et al. (2001, p. 21) merely acknowledge 
that mountain biking occurs on ski area trails during the summer 
months. The authors do not provide any analysis of whether mountain 
bike use causes disturbance to the species, and we have no other 
information to suggest that mountain biking may be a threat to the 
Bicknell's thrush.
    Summary of disturbance by recreationists--Information presented in 
the petition and readily available in our files does not indicate that 
recreational disturbance may be a threat to the Bicknell's thrush. 
However, the role of recreational activities as a potential threat to 
the species will be further investigated during our 12-month status 
review.
Collision With and Disturbance by Stationary and Moving Structures
    As previously described above in Factor A and as indicated in the 
petition, construction of telecommunications structures (stationary 
structures) and wind turbines (moving structures) on exposed high-
elevation areas (Petition, p. 37) can directly impact Bicknell's thrush 
habitat (Rimmer et al. 2001, p. 21; MacFarland et al. 2008, p. 1; 
COSEWIC 2009, p. 32). In addition to habitat impacts, information in 
our files suggests that construction and operation of these facilities 
may also impact the species by increasing injury and direct mortality 
of individuals through take of Bicknell's thrush nests if construction 
occurs in occupied breeding habitat, and collisions occur with 
telecommunication towers and, if present, the guy wires used to support 
them (Rimmer et al. 2001, p. 20; MacFarland et al. 2008, p. 3). 
Mortality of birds resulting from collision with wind turbines has also 
been documented (Johnson et al. 2002, p. 879; USFWS 2003, p. 1), 
including thrush species (Erickson et al. 2001, pp. 59, 61; Jain et al. 
2007, pp. 43-44). While we have no information on specific injury or 
mortality to Bicknell's thrush, we find that documented injury and 
mortality of similar species indicates that collision with stationary 
and moving structures may be a threat to the Bicknell's thrush.
    Information in our files suggests that individual Bicknell's thrush 
may be disturbed by wind towers and exhibit avoidance of wind turbine 
areas in response to noise and movement from the spinning blades 
(MacFarland et al. 2008, p. 5). However, the impact of turbine 
construction and operation to Bicknell's thrush in the vicinity of 
these structures has not been assessed by the authors (MacFarland et 
al. 2008, p. 5) as a threat to the species as a whole, only a mention 
that some individuals may avoid turbines. Therefore, information 
presented in the petition and readily available in our files does not 
indicate that disturbance, as discussed above as active avoidance of 
wind turbine areas due to noise, may be a threat to the Bicknell's 
thrush.
    Summary of collision with and disturbance by stationary and moving 
structures--Information presented in the petition and readily available 
in our files indicates that collision with stationary and moving 
structures may be a threat to the Bicknell's thrush, but does not 
indicate that disturbance from wind turbines may be a threat to the 
bird.
    Summary of Factor E--Information presented in the petition and 
readily available in our files indicates that other natural or manmade 
factors affecting the Bicknell's thrush continued existence resulting 
from: atmospheric mercury deposition; decreased dietary calcium; 
increased interspecific competition facilitated by climate change; and 
collision with stationary and moving structures, may be threats to the 
bird. Information presented in the petition and readily available in 
our files does not indicate that other natural or manmade factors 
affecting the Bicknell's thrush continued existence resulting from more 
frequent storms caused by climate change, disturbance by 
recreationists, and disturbance by wind turbines, may be threats to the 
bird.

Finding

    On the basis of our determination under section 4(b)(3)(A) of the 
Act, we determine that the petition presents substantial scientific or 
commercial information indicating that listing the Bicknell's thrush 
throughout its entire range may be warranted. This finding is based on 
information provided under factors A, D, and E. We determine that the 
information provided under factors B and C is not substantial.
    Because the petition presents substantial information indicating 
that listing the Bicknell's thrush may be warranted, we will be 
initiating a status review to determine whether listing the Bicknell's 
thrush under the Act is warranted.
    The ``substantial information'' standard for a 90-day finding 
differs from the Act's ``best scientific and commercial data'' standard 
that applies to a status review to determine whether a petitioned 
action is warranted. A 90-day finding does not constitute a status 
review under the Act. In a 12-month finding, we will determine whether 
a petitioned action is warranted after we have completed a thorough 
status review of the species, which is conducted following a 
substantial 90-day finding. Because the Act's standards for 90-day and 
12-month findings are different, as described above, a substantial 90-
day finding does not mean that the 12-month finding will result in a 
warranted finding.

References Cited

    A complete list of references cited is available on the Internet at 
http://www.regulations.gov and upon request from the New England Field 
Office (NEFO) (see FOR FURTHER INFORMATION CONTACT).

Author

    The primary authors of this notice are the staff members of the 
NEFO.

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

    Dated: July 31, 2012.
Daniel M. Ashe,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2012-19970 Filed 8-14-12; 8:45 am]
BILLING CODE 4310-55-P