# Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Yellow-Billed Loon as Threatened or Endangered

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URL: https://www.frixlaw.com/law-library/documents/fr%3AE9-6012

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** March 25, 2009
- **Citation:** 74 FR 12932

## Text

DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FWS-R7-ES-2009-0133; MO9221050083-B2]
Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Yellow-Billed Loon as Threatened or Endangered

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Notice of 12-month petition finding.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), announce a 12-month finding on a petition to list the yellow-billed loon (
Gavia adamsii
) as threatened or endangered, with critical habitat, under the Endangered Species Act of 1973, as amended (Act). The petitioners provided two listing options for consideration by the Service: (1) Listing the yellow-billed loon throughout its range, or (2) listing the United States population of the yellow-billed loon as a Distinct Population Segment (DPS). After a review of the best available scientific and commercial information, we have determined that listing the yellow-billed loon rangewide under the Act is warranted but precluded by other higher priority listing actions.

DATES:

This finding was made on March 25, 2009.

ADDRESSES:

This finding is available on the Internet at
http://www.regulations.gov.
Data, information, comments, or questions regarding this notice should be submitted to the Field Supervisor, Endangered Species Branch, Fairbanks Fish and Wildlife Field Office, U.S. Fish and Wildlife Service, 101-12th Ave., Room 110, Fairbanks, AK 99701. The complete administrative file for this finding is available for public inspection, by appointment, during normal business hours at the above address.

FOR FURTHER INFORMATION CONTACT:

Mr. Ted Swem, Fairbanks Fish and Wildlife Field Office (see
ADDRESSES
) (telephone 907-456-0441; facsimile 907-456-0208). If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Background

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

Previous Federal Actions

On April 5, 2004, we received a petition from the Center for Biological Diversity (CBD) (Sitka, AK), Natural Resources Defense Council (Washington, DC), Pacific Environment (San Francisco, CA), Trustees for Alaska (Anchorage, AK), Kaira Club (Chukotka, Anadyr, Russia), Kronotsky Nature Preserve (Kamchatka Region, Russia), Taiga Rangers (Khabarovsk Region, Russia), Yuzhno-Sakhalinsk Local Public Fund (Sakhalin Region, Russia), Interregional Public Charitable Organization of Far Eastern Resource Centers (Vladivostok, Russia), Kamchatka Branch of Pacific Institute of Geography (Petropavlovsk-Kamchatsky, Russia), and Kamchatka League of Independent Experts (Petropavlovsk-Kamchatsky, Russia) to list the yellow-billed loon as endangered or threatened throughout its range, or as a Distinct Population Segment in the United States, and to designate critical habitat once listed. The petition summarizes threats to the species based on CBD's review of Fair's (2002) report, prepared for the Natural Resources Defense Council and Trustees for Alaska, on the status and significance of the species in Alaska, as well as CBD's review of the scientific literature. In September 2006, the Service completed a “Conservation Agreement for the Yellow-billed Loon (
Gavia adamsii
)” with Federal, State, and local partners. In response to the petition, we published a 90-day finding on the yellow-billed loon in the
Federal Register
on June 6, 2007 (72 FR 31256). In the 90-day finding we determined that the petition presented substantial scientific or commercial information to indicate that a listing may be warranted and announced that a status review would be promptly commenced. In that notice we announced the opening of a 60-day information collection period and invited the public to submit to us any pertinent information concerning the status of or threats to this species. Approximately 28,000 comments were received during the information collection period. We also consulted with recognized yellow-billed loon experts and other Federal and State agencies. We sent letters to national wildlife or natural resource agencies in Canada, China, Japan, North Korea, Norway, Republic of Korea (South Korea), and the Russian Federation, asking for information about ongoing management measures and any conservation and management strategies being developed to protect the species. We received a formal response from the government of Canada, and an informal response from a government biologist in the Russian Federation.

On June 11, 2007, we received a 60-day notice of intent to sue from the Center for Biological Diversity alleging a violation of section 4 of the ESA for failure to complete a 12-month finding on the petition. We informed the plaintiffs by letter dated July 9, 2007, that further action on the petition was precluded by higher priority listing actions but that, pending the fiscal year 2008 allocation of funds, we hoped to complete the 12-month finding within that fiscal year.

On December 19, 2007, the Center for Biological Diversity (CBD) filed a complaint alleging that the Service had failed to make a timely 12-month finding on the petition, as required under section 4 of the ESA. Consistent with a settlement agreement reached between the Service and CBD, the Court ordered the Service to submit this 12-month finding for publication to the
Federal Register
by February 15, 2009. Because the Service later received substantial new information to be evaluated and considered in the 12-month finding, we subsequently sought and were granted a one month extension with a new deadline of March 16, 2009.

This notice constitutes a 12-month finding for the petition to list the yellow-billed loon as threatened or endangered. The petitioners provided two listing options for consideration by the Service: (1) Listing the yellow-billed loon throughout its range, or (2) listing the United States population of the yellow-billed loon as a Distinct Population Segment (DPS). Because we find that listing the yellow-billed loon rangewide is warranted at this time,

there is no need to conduct further analysis of whether listing the United States population of the yellow-billed loon as a DPS, which is a smaller geographic entity than the entire range, is warranted, as this consideration is subsumed by the rangewide warranted but precluded finding.

Outline of This Notice

In this notice, we first provide background information on the biology of the yellow-billed loon. Next, we address each of the categories of factors listed in section 4(a)(1) of the Act. For each factor, we first determine whether any stressors, or risk factors, appear to be negatively affecting yellow-billed loons anywhere within the species' range. If we determine they are, then we evaluate whether each of these risk factors is resulting in population-level effects that are significant to the determination of the conservation status of the species. If so, we describe it as a “threat.” The fact that we find a stressor to be a threat to the species does not necessarily mean that the species meets the definition of threatened or endangered. Rather, in the subsequent finding section, we then consider each of the stressors and identified threats, individually and cumulatively, and make a determination with respect to whether the species is endangered or threatened according to the statutory standard.

The term “threatened species” means any species (or subspecies or, for vertebrates, distinct population segments) that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The Act does not define the term “foreseeable future.” However, in a January 16, 2009, memorandum addressed to the Acting Director of the U.S. Fish and Wildlife Service, the Office of the Solicitor, Department of the Interior, concluded, “* * * as used in the ESA, Congress intended the term ‘foreseeable future' to describe the extent to which the Secretary can reasonably rely on predictions about the future in making determinations about the future conservation status of the species.” In a footnote, the memorandum states, “In this memorandum, references to ‘reliable predictions’ are not meant to refer to reliability in a statistical sense. Rather, I use the words “rely” and “reliable” according to their common, non-technical meanings in ordinary usage. Thus, for the purposes of this memorandum, a prediction is reliable if it is reasonable to depend upon it in making decisions” (M-37021, January 16, 2009).

Species Biology

The yellow-billed loon is a migratory bird. Solitary pairs breed on lakes in the arctic tundra of the United States, Russia, and Canada from June to September. During the remainder of the year the species winters in more southern coastal waters of the Pacific Ocean and the Norway and North Seas. Non-breeding birds remain in marine waters throughout the year, either in wintering areas or offshore from breeding grounds.

The following information regarding the description and natural history of the yellow-billed loon (American Ornithologists' Union 1998, p. 5) has been condensed from the status assessments conducted by North (1994) and Earnst (2004), and updated with information that has become available since then.

Taxonomy and Description

The yellow-billed loon (Order Gaviiformes, Family Gaviidae) is one of the largest of the five loon species and similar in appearance to the common loon (
Gavia immer
). There are no recognized subspecies or geographic variations (American Ornithologists' Union 1998, p. 5). A field characteristic that distinguishes yellow-billed loons from common loons is their larger yellow or ivory-colored bill. Adults weigh 4,000 to 6,000 grams (8.8 to 13.2 pounds) and are 774 to 920 millimeters (30 to 37 inches) in length. Breeding (alternate) plumage of adults of both sexes is black on top with white spots on the wings and underside, and white stripes on the neck. Non-breeding (basic) plumage is gray-brown with fewer and less distinct white spots than breeding plumage, with paler undersides and head, and a blue-gray bill. Hatchlings have dark brown and gray down, and juveniles are gray with a paler head (North 1994, p. 2). Yellow-billed loons are specialized for aquatic foraging with a streamlined shape and legs near the rear of the body, and are unable to take flight from land.

Feeding Habits

Yellow-billed loons forage underwater for fish and aquatic invertebrates. Limited information exists on specific prey species consumed. Marine prey species collected from loons wintering in southeast Alaska and Canada include fish such as sculpins (
Leptocottus armatus, Myoxocephalus
sp.), Pacific tomcod (
Microgadus proximus
), and rock cod (
Sebastodes
sp.), and invertebrates such as amphipods (
Orchomonella
sp.,
Anonyx nirgax
), isopods (
Idothea
sp.), shrimps (
Pandalus danae
,
Spirontocaris ochotensis
), hermit crabs (
Pagarus
sp.), and marine worms (
Nereis
sp.) (Bailey 1922, p. 205; Cottam and Knappen 1939, p. 139; North 1994, pp. 6-7; Earnst 2004, pp. 9-10). Pacific sand dabs (
Citharichthys sordidus
) were found in a yellow-billed loon collected extralimitally (
i.e.
, outside the limits of the species' range) in Baja California (Jehl 1970, p. 376) and sculpin (
Myoxocephalus scorpius
) in a specimen collected in Norway (Collett 1894, p. 280). Prey species taken in other wintering grounds, such as in the Yellow Sea (which supports 276 fish species and 54 crustacean species; UNDP 2002, p. 8) are unknown.

During the breeding season, foraging habitats include lakes, rivers, and the nearshore marine environment. Successfully breeding adults feed their young almost entirely from the brood-rearing lake (North 1994, p. 14). Ninespine sticklebacks (
Pungitius pungitius
) and least cisco (
Coregonus sardinella
) are thought to be the main foods of chicks in Alaska (Earnst 2004, p. 9). Other freshwater prey available in Alaska that are likely utilized include Alaska blackfish (
Dallia pectoralis
), fourhorn sculpins (
M. quadricornus
), amphipods, and isopods (Earnst 2004, p. 9), as well as aquatic plant material (Sjölander and Ågren 1976, p. 460). In arctic Russia, limited stomach content analysis indicates sticklebacks, salmon, crustaceans, beetles, and plant vegetation are consumed during the breeding season (Uspenskii 1969, p. 130).

Breeding Habitat and Territories

Yellow-billed loons nest exclusively on margins of lakes in coastal and inland low-lying tundra from 62° to 74° North (N) latitude. Lakes that support breeding loons have abundant fish populations. Studies of yellow-billed loon habitat have identified several characteristics that predict loon presence. These may be indirect measures or correlates of the actual characteristics necessary or preferred by loons, such as fish availability. Predictors of yellow-billed loon presence on a lake include water depths greater than 2 meters (m) or 6.5 feet (ft) allowing for unfrozen water under the ice during winter; large lake areas (at least 13.4 hectares (ha) or 33 acres (ac)); connections to streams that may supply fish; highly convoluted, vegetated, and low-lying shorelines; clear water; and dependable water levels (Earnst
et al.
2006, pp. 230-233; Stehn
et al.
2005, pp. 9-10; North 1994, p. 6). Probability of yellow-billed loon presence on a lake increases with the absence of Pacific

loons (
Gavia pacifica
) (Earnst
et al.
2006, p. 233; Stehn
et al.
2005, p. 9). Breeding lakes may be near major rivers, but are usually not connected to them, possibly because greater fluctuations associated with river connections may flood nests or cause turbidity that compromises foraging success (North & Ryan 1989, p. 303). Falling water levels may also expose loon nests to increased risk of predation (Kertell 1996, p. 356).

Breeding territories (areas defended against other yellow-billed loons and other loon species, particularly Pacific loons) may include one or more lakes or parts of lakes. Territory size, likely dependent upon lake size and quality, ranged from 13.8 to greater than 100 ha (34 to greater than 247 ac) on the Colville River Delta, Alaska (North 1986, as cited in North 1994, p. 10). It is thought that individual loons occupy the same breeding territory throughout their reproductive life. Some breeding lakes are “known to be reoccupied over long time spans” (North 1994, p. 10), most likely by the same monogamous pair (North 1994, p. 10), similar to common loons (Evers 2004, p. 13).

Nesting Sites and Behavior

Nest sites are usually located on islands, hummocks, or peninsulas, along low shorelines, within 1 m (3 ft) of water. The nest location, which may be used in multiple years, usually provides a better view of the surrounding land and water than other available lakeshore locations. Nests are constructed of mud or peat, and are often lined with vegetation. One or two large, smooth, mottled brown eggs are laid in mid-to late June (North 1994, pp. 11-12). Egg replacement after nest predation occurs rarely; unless failure occurs very early in the season, the short arctic summer probably precludes the production or success of replacement clutches (Earnst 2004, p. 8). Hatching occurs after 27 to 28 days of incubation by both sexes. Although the age at which young are capable of flight is unknown, it is probably similar to common loons (8-9, possibly up to 11, weeks). The young leave the nest soon after hatching, and the family may move between natal and brood-rearing lakes. Both males and females participate in feeding and caring for young (North 1994, p. 13).

Life History

There is no reliable scientific information on lifespan and survivorship, but as large-bodied birds with low clutch size, yellow-billed loons are probably K-selected (long-lived and dependent upon high annual adult survival to maintain populations). On average, individuals reach sexual maturity at 3 years of age, but may not acquire breeding territories until at least 4 years of age (North 1994, p. 15). The average age at first breeding for common loons is 6 years (Evers 2004, p. 18).

Territory occupancy and nesting success of yellow-billed loons were studied on the Colville River Delta during 18 years between 1983 and 2007. Ground-based surveys in 1983 and 1984 found 76 and 79 percent of the territorial pairs nesting, respectively (Field
et al.
1993, p. 329). The same territories studied in 1983 and 1984 were visited in 1989 and 1990, and 42 percent and 67-71 percent, respectively, of the territorial pairs were found nesting (Field
et al.
1993, p. 329; North 1993, p. 46). Low nest occupancy recorded in 1989 may have been a result of surveys being conducted late in incubation (July 9-16, 1989) after nests of some pairs had already failed; weekly monitoring surveys of nesting yellow-billed loons on the Colville River Delta in 2005-2007 found that 19-36 percent of the nests had failed by July 10-12 of those years (Johnson
et al.
2006, Table 5; Johnson
et al.
2007, Table 5; Johnson
et al.
2008, Table 4). However, low nest occupancy occurred in some years during two long-term studies of yellow-billed loons on the Colville Delta. The percentage of territorial pairs nesting ranged from 39 percent to 89 percent during a 6-year ground-based study (1995-2000; Earnst 2004, p. 9) and from 43 percent to 76 percent (average of 58 percent) during 13-years of aerial surveys (1993-2007; ABR, Inc. 2007, Table 1; ABR, Inc., unpublished data).

Reproductive success, like nest occupancy by territorial pairs, varied on the Colville River Delta. Low reproductive success has been attributed to late ice melt or extreme flooding (Earnst 2004, p. 9). Based on Mayfield survival rates (a technique for measuring nesting success in which the number of days from discovery of the nest to fledging or failure (exposure days) is used to compute a daily nest-survival rate) calculated for yellow-billed loons nesting on the Colville River Delta in 1995-2000, 4 percent to 60 percent of eggs/chicks survived from laying to age 6 weeks (Earnst 2004, p. 9). Apparent nesting success [(broods/nests) × 100] based on broods counted on aerial surveys conducted 8 weeks apart during nesting and brood-rearing ranged from 19 percent to 64 percent annually in 13 years between 1993 and 2007 (ABR, Inc. 2007, Table 1; ABR, Inc., unpublished data). During the last three years (2005-2007) of this study, weekly monitoring surveys were conducted after nests were found. Apparent nesting success calculated from these weekly surveys was 1-10 percent higher than calculations based on nesting and brood-rearing surveys conducted 8 weeks apart, because the more frequent surveys identified nests with chicks that did not survive to 5-6 weeks of age (Johnson
et al.
2006, p. 17; Johnson
et al.
2007, p. 16; Johnson
et al.
2008, p. 15). The highest recorded apparent nesting success on the Colville River Delta was 71 percent in 2007 based on weekly monitoring surveys (Johnson
et al.
2008, p. 15).

Breeding Distribution

Yellow-billed loons nest near freshwater lakes in arctic tundra of Alaska on the Arctic Coastal Plain (ACP), northwestern Alaska, and St. Lawrence Island; in Canada east of the Mackenzie Delta and west of Hudson Bay; and in Russia on a relatively narrow strip of coastal tundra from the Chukotka Peninsula in the east and on the western Taymyr Peninsula in the west, with a break in distribution between these two areas (Earnst 2004, p. 3; North 1993, p. 42; Red Data Book of the Russian Federation 2001, p. 366; Ryabitsev 2001, p. 22; Il'ichev and Flint 1982, p. 277; Pearce
et al.
1998, p. 369). Loons are sparsely distributed across their range, although, perhaps because of non-uniform quality of habitat, at a large scale breeding birds are somewhat clumped in distribution.

Breeding Bird Densities

Most of the breeding range of the yellow-billed loon has not been adequately surveyed, and only in Alaska have surveys been conducted specifically for breeding yellow-billed loons. Unless otherwise noted, the following discussion includes data from waterfowl surveys for which loons were not focal species. In these surveys, density estimates were not corrected for visibility bias and so are minimal estimates (
see
discussion in Groves
et al.
1996, pp. 193-194). Surveys enumerate all yellow-billed loons seen on breeding grounds, including an unknown proportion of which are non-breeders (Earnst
et al.
2005, p. 300).

Alaska

Based on fixed-wing aerial survey data (1992 to 2003 ACP and North Slope Eider (NSE) surveys conducted by the Service), Earnst
et al.
(2005, p. 300) calculated that most of the population on the ACP of Alaska occurred within concentration areas with more than 0.11 individuals per square kilometer (km
2
). Such areas comprised only 12 percent of the surveyed area yet contained 53 percent of yellow-billed loon sightings.

The largest concentration area was between the Meade and Ikpikpuk Rivers; it covered only 8 percent of the survey area, but had 38 percent of yellow-billed loon sightings (Earnst
et al.
2005, p. 300). Other notable concentrations were on the Colville River Delta and west, southwest, and east of Teshekpuk Lake (Earnst
et al.
2005, p. 300). In aerial lake-circling surveys designed for yellow-billed loons (fixed-wing aircraft were used 1992-2000; helicopters were used 2001-2007), the average density on the Colville River Delta (363 km
2
(140 mi
2
) survey area) was 0.13 individuals per km
2
during 10 years from 1993 to 2004 (Johnson
et al.
2005, p. 65), and 0.15 to 0.17 individuals per km
2
from 2005 to 2007 (Johnson
et al.
2006, p. 15; Johnson
et al.
2007, p. 16; Johnson
et al.
2008, p. 15). Similar surveys for yellow-billed loons in a larger area (878 km
2
) (339 mi
2
) in the Northeast Planning Area (NE) of the National Petroleum Reserve-Alaska (NPR-A) in 2001-2004 indicated densities there were lower (0.07 individuals/km
2
; Johnson
et al.
2005, p. 68), except that the density in an area adjacent to Fish and Judy Creeks was similar to that of the Colville River Delta (Johnson
et al.
2005, p. 68; Johnson
et al.
2006, p. 15; Johnson
et al.
2007, p. 16). In western Alaska, where fixed-wing aerial surveys were also designed specifically for loons, density on the northern Seward Peninsula averaged 0.058 (standard error (SE)=0.011; standard error is a measure of the variability in the data) individuals/km
2
over 2 years (Bollinger
et al.
2008, p. 5).

Canada

In Canada, concentrations are found on parts of Victoria and Banks Islands, on the mainland, the Kent Peninsula, east of Bathhurst Inlet and west of Ellice River, the west side of Boothia Peninsula, and the lake district between Great Slave Lake and Baker Lake, including the Thelon Game Sanctuary (North 1993, p. 42). Densities obtained in 2005 and 2007 from fixed-winged aerial waterfowl surveys on southern Victoria Island and the Kent Peninsula ranged from 0.017 to 0.16 birds/km
2
(Conant
et al.
2006, pp. 2, 7; Groves in litt. 2008); lower densities (0.004-0.027 birds/km
2
) were found in surveys on the Queen Maud Gulf Migratory Bird Sanctuary, King William Island, Rasmussen Lowlands, and Kugluktuk (Conant
et al.
2007, pp. 10, 12; Groves in litt. 2008). On western Victoria Island, Raven and Dickson (2006, p. 24) estimated densities from 0.004 to 0.08 birds/km
2
from helicopter-based waterfowl surveys. Hines (in litt. 2008) estimated 0.01 yellow-billed loons/km
2
on Banks Island from helicopter-based waterfowl surveys in 1992 and 1993.

Russia

In Russia, breeding concentrations have been identified on the Chukotka (Chukotskiy) Peninsula (Il'ichev and Flint 1982, p. 280; Solovyov 1992, p. 21), Kyttyk Peninsula and Ayon Island in western Chukotka (Solovyova 2007, p. 6), and the western Taymyr Peninsula (Krechmar 1966, p. 200; Il'ichev and Flint 1982, p. 277). Hodges and Eldridge (2001, pp. 141-142), using fixed-winged aircraft in the only aerial waterfowl survey of the eastern Siberian coast, found concentrations of approximately 0.01 birds/km
2
on the Cape Schmidt coast of the Chukotka Peninsula, between the Indigirka and Yana River Deltas, and between the Indigirka and Kolyma Deltas. Post-breeding density on Kyttyk Peninsula in western Chukotka was approximately 0.52 birds/km
2
(including young birds) during late July-August 2003-2007 (calculated from ground surveys, Solovyova 2007, p. 6). No density estimates are available for the Taymyr Peninsula.

Nest Densities

Nest density on 363 km
2
(140 mi
2
) of the Colville River Delta, Alaska, ranged from 0.03 to 0.08 nests/km
2
during 13 years of aerial surveys for yellow-billed loons during 1993-2007 (Johnson
et al.
1999, p. 44; Burgess
et al.
2003, p. 36; Johnson
et al.
2003, p. 43; Johnson
et al.
2004, p. 74; Johnson
et al.
2005, p. 64; Johnson
et al.
2006, p. 15; Johnson
et al.
2007, p. 16; Johnson
et al.
2008, p. 15). Nest density in an 878 km
2
(339 mi
2
) survey area of NE NPR-A was 0.03 nests/km
2
in each year during 2002-2004. Higher densities within this area were found along Fish and Judy Creeks (helicopter-based surveys; Johnson
et al.
2005, p. 68). In Russia, Solovyov (1992) reported 0.18 nests/km
2
on a 27.6 km
2
(10.6 mi
2
) plot searched from the ground on Belyaka Spit near Kolyuchin Bay on the Chukotka Peninsula. On the Kyttyk Peninsula in western Chukotka, yellow-billed loons nest on approximately 25 percent of lakes larger than 4 ha (9.9 acres) (Solovyova 2007, p. 6).

Foraging Distribution During Breeding Season

Yellow-billed loons use nearshore and offshore marine waters adjacent to their breeding areas for foraging in summer. Such habitats are likely used by both breeding adults and younger or non-territorial birds (Earnst 2004, p. 7). Earnst (2004, pp. 6-7) reviewed yellow-billed loon distribution information from fixed-wing aerial waterfowl surveys that Fischer
et al.
(2002) conducted in 1999 and 2000 off the coasts of Canada's arctic islands and the ACP of Alaska between Cape Halkett and Brownlow Point. Similar surveys conducted between Barrow and Demarcation Point in 2001 also included yellow-billed loon observations in Elson Lagoon (Fischer 2001, p. 4; Fischer and Larned 2004, p. 146). During fixed-wing aerial surveys for common eiders in late June of 1999 through 2007, between 23 and 99 yellow-billed loons were observed in nearshore waters and along barrier islands of the Beaufort and Chukchi Seas (Dau and Larned 2007, p. 18). Yellow-billed loons used lagoons and nearshore waters along the coast of St. Lawrence Island in summer in the 1950s (Fay and Cade 1959, pp. 92, 100). In Russia, Solovyova (coastal boat surveys; 2007, p. 6) reported densities of 0.24 birds/km
2
using coastal waters near the Kyttyk Peninsula and Ayon Island at the northern end of Chaun Bay in western Chukotka, and 0.04 birds/km
2
at the southern end of Chaun Bay near the Chaun River Delta in 2006. Vronskiy (1987, p. 30) observed individual yellow-billed loons and pairs in bays 100-150 m (328-492 ft) offshore of northwestern Taymyr during summer. Yellow-billed loons occurred in summer along the coast of Wrangel Island, although there were no indications of nesting on the island (Stishov
et al.
1991, p. 20). In boat-based surveys in the Kara and Barents Seas, arctic (
Gavia arctica
) and red-throated (
G. stellata
) loons were abundant in the nearshore marine waters of the western Kara Sea and in the Ob' and Yenisey estuaries, especially in Baidaratskaya Bay, and occurred in smaller numbers in the Pechora Bay in the Barents Sea in August and September 1995, but no yellow-billed loons were observed (Decker
et al.
1998, pp. 9, 11). In subsequent boat surveys between 1998 and 2003, only one yellow-billed loon was observed in mid-August 1998 in coastal waters northeast of Dolgy Island (west of Vaigach Island) in the Pechora Sea (M. Gavrilo, in litt. 2008).

Wintering Habitat and Distribution

Wintering habitats include sheltered marine waters less than 30 m (98.4 ft) deep, such as fiords and areas between islands on the inner coast in Norway (Strann and Østnes 2007, p. 2). Schmutz (2008, p. 1) found that throughout migrating and wintering seasons, yellow-billed loons marked with satellite transmitters occurred from 1 to 20 miles offshore. The wintering range includes coastal waters of southern Alaska and British Columbia from the Aleutian Islands to Puget Sound; the

Pacific coast of Asia from the Sea of Okhotsk south to the Yellow Sea; the Barents Sea and the coast of the Kola Peninsula; coastal waters of Norway; and possibly Great Britain (Earnst 2004, pp. 13-14; North 1993, pp. 42-43; Ryabitsev 2001, p. 22; Schmutz in litt. 2008, p. 1; Strann and Østnes 2007, p. 2; Burn and Mather 1974, p. 278; Gibson and Byrd 2007, p. 68). A small proportion of yellow-billed loons may winter in interior lakes or reservoirs in North America (North 1994, p. 3).

Winter population distribution and numbers of yellow-billed loons are not well documented, but some information is available from marine bird surveys. Earnst (2004, p. 14) summarized loon observations in boat-based marine bird population surveys in Lower Cook Inlet, Prince William Sound, and Kodiak Island. In these surveys, estimates of yellow-billed loons were in tens to low hundreds, with wide confidence limits. In many cases, loons were not identified to species. Strann and Østnes (2007, p. 3) counted 1,160-1,605 yellow-billed loons on surveys conducted off the coast of Norway from 1986 to 1994, confirming Norway as the most important known wintering area for the species in Europe. No surveys have been conducted in Asian wintering areas. In some regularly used wintering areas such as the Yellow Sea, the Aleutian Islands, and Great Britain, the yellow-billed loon's small population and scattered marine distribution may have contributed to the impression that yellow-billed loons are vagrants or rare visitors (Lepage 2008, p. 1; Gibson and Byrd 2007, p. 68; Dudley
et al.
2006, p. 533; Scott and Shaw 2008, pp. 241-248).

Immature loons and possibly some non-breeding adults stay in wintering areas throughout the year (North 1994, p. 4). Earnst (2004, pp. 11-12) summarized yellow-billed loon observations in summer marine boat-based surveys conducted in lower Cook Inlet and Prince William Sound in southcentral Alaska, and in southeast Alaska. Estimates from all these surveys totaled only 339 yellow-billed loons, but many loons were not identified to species (Earnst 2004, p. 11). In boat-based surveys of murrelets conducted in July of 2002-2004 from Icy Bay to LeConte Bay in southeast Alaska, Kissling
et al.
(2007, Appendices 7, 8) counted 20 yellow-billed loons. Yellow-billed loons have been observed throughout summer months in the Aleutians (Gibson and Byrd 2007, p. 68). According to the Red Data Book of Kamchatka (2006, p. 92), non-breeding birds occur off the coast of Kamchatka in summer.

Migration

Yellow-billed loon migration routes are thought to be primarily marine. Schmutz (in litt. 2008, p. 1) found that yellow-billed loons marked with satellite transmitters generally remained between 1 and 20 miles from land during migration and winter. Yellow-billed loons migrate singly or in pairs, but gather in polynyas (areas of open water at predictable, recurrent locations in sea-ice covered regions), ice leads (more ephemeral breaks in sea ice, often along coastlines), and early-melting areas off river deltas near breeding grounds in spring along the Beaufort Sea coast of Alaska and Canada (Barry
et al.
1981, pp. 29-30; Barry and Barry 1982, p. 25; Woodby and Divoky 1982, p. 406; Johnson and Herter, 1989, p. 9; Barr 1997, pp. 12-13; Alexander
et al.
1997, pp. 15, 17; Mallory and Fontaine 2004, pp. 52-53).

These observations of yellow-billed loons in the Beaufort Sea during migration establish that at least some yellow-billed loons breeding in Canada's Arctic Islands and along the adjacent Canadian coast use this migration route. North (1993, pp. 45-46) examined evidence of alternative migration routes for yellow-billed loons wintering in southeast Alaska and British Columbia, suggesting that they could migrate overland to mainland breeding areas in Canada, particularly around Great Slave Lake. Yellow-billed loons have been observed on inland lakes in Canada and Alaska (North 1993, pp. 43, 46). The existence of this route is still hypothetical, and the number of yellow-billed loons in interior mainland Canada is highly uncertain (discussed below under Population Size).

Yellow-billed loons breeding in Alaska have been studied to determine migration routes. Nineteen yellow-billed loons captured on the ACP between 2002 and 2008 were outfitted with satellite transmitters (Schmutz in litt. 2008, p. 1). All of them migrated to Asia, predominantly south along the Russian coastline from the Chukotka Peninsula (either through the Bering Strait or across the mountains from the north side of the Chukotka Peninsula to the Gulf of Anadyr), and along the Kamchatka coast. They wintered in the Yellow Sea and Sea of Japan off China, North Korea, Russia, and Japan (near Hokkaido). All 10 yellow-billed loons fitted with transmitters on the Seward Peninsula, Alaska, in 2007 and 2008 also used the Bering Strait region after leaving breeding grounds. Five of these migrated to Asian grounds as described above for ACP breeding birds; the other 5 wintered throughout the Aleutian Islands from Shemya Island in the west to the Semidi Islands off the coast of the Alaska Peninsula (Schmutz in litt. 2008, p. 1). Most of these yellow-billed loons departed breeding areas in late September, arrived in wintering locations in mid-November, started spring migration in April, and arrived on breeding grounds in the first half of June; these dates are consistent with breeding ground arrival dates reported by North (1994, p. 5). Non-breeders or failed nesters may start fall migration in July.

The migration routes of yellow-billed loons breeding in Russia have not been studied. Because of the proximity of the Chukotka Peninsula to the ACP in Alaska, and the fact that ACP breeding yellow-billed loons use the Chukotka Peninsula during migration (Schmutz in litt. 2008, p. 1), it is likely that some or all yellow-billed loons from eastern Russia migrate through the Bering Strait to Asian wintering areas.

Population Size

ACP, Alaska

Yellow-billed loon population indices on the ACP of Alaska were determined by two independent fixed-wing aerial transect surveys conducted each year by the Service's Migratory Bird Management program. Surveys were flown in early June each year from 1992 through 2008 (NSE survey, 1992-2008, an average of 1,304 km
2
(503.5 mi
2
) transect area that sampled a total area of 30,465 km
2
(11,763 mi
2
), for 4.3 percent coverage) and late June each year from 1986 through 2006 (ACP survey, 1986-2006, average of 1,256 km
2
(485 mi
2
) transect area which sampled a total area 61,645 km
2
(23,801 mi
2
), for 2.0 percent coverage of a larger area than that covered by the NSE survey). The average population index from the NSE survey is 1,119 yellow-billed loons (95 percent confidence interval (CI) = 1,012 to 1,226, Larned
et al.
2009, p. 24). (Note: In order to estimate the reliability of a sample statistic, such as an average, it is common to set confidence limits to it (Sokal and Rohlf 1995, p. 139). The limits will show the maximum and minimum numbers the statistic (e.g., average) is likely to be, along with a measure of that likelihood (e.g., 95 percent). So, when an average number of birds, for example, is reported, followed by a confidence interval, the confidence interval shows the statistical range of values that provides cutoff points for the likely values for the average.) The long-term mean from the ACP survey is 2,611 loons (95 percent CI = 2,218 to 3,005; Mallek
et al.
2007, p. 10; USFWS unpublished data). The

confidence intervals around these 16- and 21-year means incorporate the variation due to within-year sampling error, the spatial variability among transects and within strata, and variation among years related either to detection rate (observer ability, habitat change, weather conditions) or the availability of birds to be seen (arrival or departure of population components, behavior associated with nesting chronology). One study integrated results from both the early and late surveys, incorporating covariates adjusting for detection rates (Earnst
et al.
2005). The 12-year mean (1992 through 2003) resulted in an estimate of 2,221 individuals (95 percent CI = 1,209-3,233) in early June and 3,369 individuals (95 percent CI = 1,910-4,828) in late June (Earnst
et al.
2005, p. 295). Another estimate of population size was determined by lake-circling aerial searches of greater than 7-ha (17.3-acre) lakes on 7 × 7-km (4.35 × 4.35-mi) plots as part of a 2003-2004 study of yellow-billed loon habitat preferences (Stehn
et al.
2005, pp. 1-37). This survey was flown from June 15 through 22 each year. Based on average density observed, the estimated total population index was 2,544 (95 percent CI = 1,780-3,308) yellow-billed loons (Stehn in litt. 2008, p. 1).

Western Alaska

Seward Peninsula and Cape Krusenstern fixed-wing aerial lake-circling surveys, on 12 × 12-km (7.46 × 7.46-mi) sample plots, were flown in June of 2005 and 2007, and resulted in an estimate of 431 (95 percent CI = 280-582) yellow-billed loons on these western Alaska breeding grounds (Bollinger
et al.
2008, p. 1). Additional aerial transects sampling an area of 15,234 km
2
(5,882 mi
2
) were flown on Selawik National Wildlife Refuge and adjacent wetlands in June in the years 1996 and 1997 (Platte 1999, p. 3), but only three yellow-billed loons were sighted, resulting in an estimated mean population index of 44 birds (95 percent CI = 0-95) (USFWS unpublished data). Yellow-billed loons were documented nesting on St. Lawrence Island in the 1950s (Fay and Cade 1959, pp. 84, 100), but there is no more recent information. Adding western Alaska population figures to those from the ACP results in an estimated total of 3,000 to 4,000 yellow-billed loons on breeding grounds in Alaska.

Canada

Although overall breeding population estimates for yellow-billed loons in Canada do not exist (
http://www.bsc-eoc.org/clls-bw1.html
, accessed May 19, 2008), and yellow-billed loons are not summarized in the Waterfowl Population Status annual reports compiled by the U.S. and Canadian governments for North American Waterfowl (USFWS 2007, pp. 1-62), several recent fixed-wing aerial waterfowl surveys included loon observations in parts of Nunavut and Northwest Territories. Loons were not the focus of the surveys, so it is possible that observer effort or identification ability varied, and no visibility correction factors or seasonal timing factors were applied. Helicopter surveys yielded estimates ranging from 659 (SE 359) to 1,784 (SE 502) on northwest Victoria Island, and from 98 (SE 70) to 258 (SE 146) birds in the southwest part of the island (Raven and Dickson 2006). A fixed-winged survey included Kent Peninsula and southeastern Victoria Island in 2005, and Queen Maud Gulf, King William Island, Rasmussen Lowlands, and near Kugluktuk in 2006; all areas from both years were repeated in 2007 but with fewer transects sampled per unit area. The combined estimate for both areas from 2005-2006 fixed-winged surveys and the 2007 estimate were similar, at 2,500-3,000 birds (Conant
et al.
2006, p. 7; Conant
et al.
2007, p. 12; Groves in litt. 2008). Hines (in litt. 2008) estimated there were 500-1,000 yellow-billed loons on Banks Island, based on helicopter aerial surveys conducted in 1992 and 1993. The range of these point estimates suggests that between 3,750-6,000 birds occur on breeding grounds in the surveyed areas.

The rest of the yellow-billed loon's range on the Canadian mainland has not been surveyed. Based on the vast number of large, fish-bearing lakes north of treeline (an area of 500,000-750,000 km
2
) (193,051-289,577 mi
2
) minus the surveyed areas on the mainland (46,000 km
2
), (17,761 mi
2
) and using opportunistic observations of yellow-billed loons by Northwest Territory and Nunavut checklist survey cooperators over the last decade, Poter (in litt. 2008, p. 2, adjusted from Hines in litt. 2008, p. 1) calculated that a density of 0.01-0.02 birds/km
2
would yield an estimate of 4,500-14,000 birds in mainland breeding areas in Canada, not including surveyed areas in the arctic described in the previous paragraph. This estimate is based on a very large land area bounded at the southern end by an area of documented yellow-billed loon breeding between Great Slave Lake and Baker Lake, particularly in or near the Thelon Game Sanctuary (North 1993, p. 42). Between this area and the arctic coast is a large area where breeding has not been documented (North 1993, Figure 2). Fair (2002, p. 30) estimated the yellow-billed loon population on interior Canadian breeding grounds to be 4,800, using a density of 0.02 loons in a 100,000 km
2
area around the Sanctuary, and a lower density of 0.007 for the wider area of 400,000 km
2
. Fair's estimate of 4,800 is close to the lower end of Poter's (2008, p. 1) estimate of 4,500. We believe Fair's analysis more accurately reflects likely yellow-billed loon distribution in Canada, because it reflects a lower average density for the large area where breeding has not been documented. Combining the 4,500 to 14,000 breeding birds estimated for interior Canada, and 3,750 to 6,000 breeding birds estimated for the arctic (and rounding to thousands), we conclude that the Canadian breeding population size is 8,000 to 20,000, but that it is most likely at the lower end of this range.

Russia

Information on the breeding-ground population size of yellow-billed loons for Russia is limited. Hodges and Eldridge (2001, Appendix 2) estimated 674 yellow-billed loons (coefficient of variation (C.V., a measure of dispersion in a probability distribution) 0.55) in a 157,611-km
2
(60,854-mi
2
) fixed-wing aerial survey area of the eastern Siberia arctic coast from Kolyuchin Bay to the Lena River Delta. We know of no other loon surveys within the breeding range of the yellow-billed loon in Russia. Red Data Books for the Russian Federation (2001, pp. 366-367), Yakutia (1987, p. 33), and the Northern Far East of Russia (1998, pp. 97-98) do not offer population estimates. Kondratiev (1989, p. 37) estimated that 2,000 birds nested in Chukotka, but did not give a basis or sources for his estimate. Fair (2002, p. 31) projected, based on this estimate of 2,000 birds in Chukotka (Kondratiev 1989, p. 37), that another 2,000 nested on the Taymyr Peninsula, and that perhaps another 1,000 were scattered across the arctic coast, giving 5,000 birds on Russian breeding areas. Syroechkovsky (in litt. 2008) suggested (based on field observations but not scientific surveys) that the number of birds on breeding grounds (including non-breeding birds) is around 3,000 for Chukotka, 500 for Yakutia, and about 1,200 for Taymyr, for a total of around 4,700 birds. However, Solovyova (in. litt. 2008, p. 1; calculated from Solovyova 2007, p. 6) recently estimated the post-breeding population of the Kyttyk Peninsula on Chaun Bay in western Chukotka at 1,000, and the post-breeding population of nearby Ayon Island at 900 birds. Given

Solovyova's (in. litt. 2008, p. 1) estimates for her study area in Chukotka, she estimated that the total breeding ground population in Chukotka might be as high as 5,000 birds. If the Chukotka population is 5,000, the total for Russia could be as high as 8,000 based on habitat availability. Thus, our best information suggests the Russian breeding population is between 5,000 and 8,000 birds.

In summary, the global breeding ground population size for yellow-billed loons is unknown, but probably at the lower end of the range of 16,000 to 32,000. The Alaska population estimate of 3,000 to 4,000 is derived from surveys. Less certain estimates based on the amount of available habitat (plus limited survey data) are the lower end of the range of 8,000 to 20,000 birds in Canada, and 5,000 to 8,000 in Russia.

Population Trend

Alaska

The only population trends available for yellow-billed loons breeding in Alaska are on the ACP, where the ACP and NSE waterfowl surveys are conducted. We note that because we count only the breeding component of the population, the total population could decline without being detected for a number of years. This could occur because increased mortality of breeding birds could be masked by movements of birds without territories (either sub-adult birds or adults which have not found territories) into vacated territories. With this caution, we believe the time series of at least 17 years for the surveys described below gives us a reasonably reliable data set for observing population trends, and these data represent the best information available at this time.

A population growth rate, or lambda, less than 1.00 would indicate population decline (negative “growth”), while a lambda greater than 1.00 would indicate population growth. For the ACP survey 1986-2006, the average growth rate was 0.9886 (95 percent CI = 0.9625-1.0154) (Mallek
et al.
2007, p. 21), and for the NSE survey 1992-2008 (a smaller area than that covered by the ACP survey, and surveyed earlier in June), the average growth rate was 1.016 (95 percent CI = 0.995-1.036) (calculated from Larned
et al.
2009, Figure 1). Thus, these surveys provide slightly conflicting perspectives, with one suggesting a stable or slightly declining population (with a point estimate of a decline of 1.1 percent/yr.) and the other suggesting a stable or slight increasing population (with a point estimate of an increase of 1.6 percent/yr.) on the ACP.

Earnst
et al.
(2005, pp. 289-304) sought to improve the estimates above by using a statistical model that takes into account possible confounding factors of survey type, spring timing, and observer experience. They used this model to analyze ACP and NSE survey data through 2003. Controlling for these confounding factors, they (p. 298) estimated average population growth rate to be 0.991 (95 percent CI = 0.964-1.018), also indicating a stable or slightly declining population.

We also examined a subset of the NSE data through 2008 that included only the observations of the most consistent and experienced pilot-observer, who has flown all 16 early-June NSE surveys during 1992-2008. Each survey includes observations of two observers: the pilot-observer in the left-side seat of the aircraft, and a second observer in the right-side seat. There have been numerous “right-side observers” over the course of the NSE survey. Each of these observers has a different ability to see and identify birds, and this ability often increases over successive surveys as the observer gains experience. Our analysis of the left-side pilot-observer eliminated the necessity to estimate the variable magnitudes of influence of right-side observer experience. In addition, the increased interest in yellow-billed loons in 2002 may have influenced new right-side observers to search more intensively for yellow-billed loons than earlier observers, who focused on waterfowl. Our analysis of the pilot-observer data from the NSE survey also eliminated the need to reconcile the later timing and different survey extent of the ACP survey. The average growth rate using this subset of data was slightly lower and more precisely estimated at 0.986 (95 percent CI = 0.967-1.006) (USFWS unpublished data) than the estimate of 0.991 from Earnst
et al.
's (2005, p. 298) model, and the results also indicate a relatively stable or slightly declining population.

In summary, the information available from the ACP does not allow us to precisely determine current population trends. Two surveys and multiple analytical approaches used to control for confounding factors provide estimates indicating trends ranging from slightly increasing to slightly decreasing, and all estimates have 95 percent CIs that include a lambda of 1.0, indicating that possible trends cannot be distinguished from population stability with reasonable certainty. Although the population trend on the ACP is uncertain, we conclude that the number of breeding yellow-billed loons on the ACP breeding grounds is either stable or declining slightly, with point estimates from models controlling for confounding factors estimating decline on the order of ~1 percent per year. We will continue to look for ways to improve our ability to detect trends. Surveys in western Alaska have not been conducted for a long enough period (2005 and 2007) to detect trends.

Russia

In Russia, recent data are fragmentary, making it difficult to determine trends. In the west, the Red Data Book of the Russian Federation (2001, p. 366) stated that the species no longer nests in European Russia where it was formerly found, such as the Kola Peninsula, the archipelago of Novaya Zemlya, and Vaigach and Ainovy Islands in the Kara Sea, although it is unclear how abundant or widespread the species was in these areas historically. (However, Kalyakin (2001, p. 10) reports finding it nesting on Novaya Zemlya, although it is “extremely rare.”) Similarly, according to the Red Data Book of the Yamal-Nenets Autonomous District (1997) near the western end of the Russian breeding range, in the previous 20 years only a few non-breeding yellow-billed loons were recorded in the District. Strann (in litt. 2008) speculated that since the early 1990s there may have been a decline in the number of yellow-billed loons in the main Norway wintering area, which would be consistent with a western Russian breeding ground range contraction if birds nesting in western Russia migrate to Norway for winter (which seems logical). We were unable to find either the source of the Red Data Book statements or supporting evidence for this potential range contraction. In eastern Russia, yellow-billed loons apparently no longer nest along the northern coast of the Sea of Okhotsk where they occurred 30-50 years ago, nor on the Anadyr River delta (Red Data Book of the Russian Federation 2001, p. 366; Red Data Book of the Northern Far East of Russia 1998, p. 97). However, Solovyova (in litt. 2008) reported that the number of breeding yellow-billed loons may be increasing in some locations in eastern Siberia, specifically near Chaun Bay in western Chukotka, and at Belyaka Spit near Kolyuchin Bay in northeastern Chukotka.

In summary, we found unsubstantiated reports that the species may no longer be found in parts of its historical range in Russia, but there is somewhat contradictory information for some areas and a lack of survey data for all areas. Yellow-billed loons may also be increasing in some areas in Russia.

We conclude that we do not have reliable trend information for the Russian breeding grounds.

Canada

As described above for Population Size, survey data for Canadian breeding grounds cover a small portion of the range, and have not been conducted for enough years to analyze trends. We conclude that we do not have reliable trend information for Canadian breeding grounds.

To summarize rangewide population trend information, we have reliable data indicating that the ACP breeding population is stable or slightly declining. We do not have reliable evidence from other breeding areas that breeding populations are increasing or decreasing. There have been no surveys of yellow-billed loons on wintering areas, so we have no trend information from those areas.

Population Resiliency

Certain intrinsic aspects of yellow-billed loon ecology and demography, including low and variable productivity, adult survival, and low population numbers, are relevant to the species' status. Stable populations of K-selected species, such as the yellow-billed loon, are characterized by low annual productivity rates balanced with high annual survival rates, meaning that individuals must live many years to replace themselves with offspring that survive to recruit into the breeding population. Low productivity means that depleted K-selected species have lower recovery potential and slower recovery rates following population declines than r-selected species, which are characterized by high annual productivity. Factors that reduce productivity, including loss of productive breeding habitats, reduction in prey populations, and increases in nest predators, may further constrain K-selected species' recovery potential. Further, most arctic species are characterized by variable annual productivity, given the vagaries and severity of arctic weather, fluctuations in predator-prey relationships, and other aspects of arctic ecology. The population impact of threats that reduce productivity could be magnified if coincident with an infrequent year of otherwise high productivity.

Although factors that compromise productivity can cause populations to decline, adult survival is likely the more important determinant of K-selected species' population size and persistence (Smith and Smith 2001, p. 235). If enough adults are removed from the population prior to replacing themselves (i.e., adult survival is decreased), the population will decline. Perhaps most pertinent to a discussion of extinction, rare species—those with low numbers—are intrinsically closer to a threshold below which recovery is not possible (i.e., minimum viable population) (Hunter 1996, p. 137).

These intrinsic aspects of yellow-billed loon ecology and demography signal the continuing need to monitor yellow-billed loon populations, despite the fact that the species continues to be widely distributed across both its arctic breeding range, which is nearly holarctic, and in its wintering range.

Factors Affecting the Yellow-Billed Loon

Section 4(a)(1) of the Act (16 U.S.C. 1533(a)(1)) and regulations promulgated to implement the listing provisions of the Act (50 CFR part 424) set forth the procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants. A species may be determined to be an endangered or threatened species due to one or more of the five factors described in section 4(a)(1) of the Act. Below, we provide a summary of our analysis of threats to the yellow-billed loon.

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

We considered whether yellow-billed loon habitats are threatened by oil and gas development (including disturbance, changes in freshwater chemistry and pollutant loads, and changes in freshwater hydrology), by degradation of the marine environment from pollution or overfishing, or by climate change. Potential threats from oil and gas development are addressed by the petitioners under Factor E, but are discussed here under Factor A because they are potential mechanisms for rendering breeding habitats unsuitable. Potential direct impacts on loon mortality associated with development, such as increased predation and oil spills, are discussed under Factors C and E, respectively.

Terrestrial Oil and Gas Development

Terrestrial and marine oil and gas development occurs in the range of the yellow-billed loon. Here we discuss terrestrial development in Alaskan and Russian breeding grounds. We are not aware of any terrestrial oil or gas development within the breeding range of the yellow-billed loon in Canada; planned terrestrial development on the Mackenzie River Delta is outside the breeding range, although activity there could affect loons migrating through adjacent marine waters. Marine activities related to oil and gas development are discussed under Factor E.

Much of the yellow-billed loon's breeding habitat in Alaska is within areas available for oil and gas leasing and development. Approximately three-quarters of the yellow-billed loons that nest in Alaska, and over 90 percent of those that nest on Alaska's ACP, occur within the 9.5-million-ha (23.5-million-ac) NPR-A (Earnst
et al.
2005, p. 300), in areas that are leased or available for leasing for oil and gas exploration and development. Approximately 29 percent of yellow-billed loons breeding on the ACP nest in NPR-A tracts that have been leased (Stehn and Platte, U.S. Fish and Wildlife Service, in litt. 2008, p. 1), and 25 exploration wells were drilled during the period 2000-2007 (
http://www.blm.gov/ak/st/en/prog/energy/oil_gas/npra.html
, accessed 3 June 2008). The Northwest Planning Area (NW) NPR-A Integrated Activity Plan/Environmental Impact Statement Record of Decision (ROD) (USDOI-BLM 2004a, p. 5) has made 100 percent of the NW NPR-A available for leasing. The Final NE NPR-A Supplemental Integrated Activity Plan/Environmental Impact Statement ROD (USDOI-BLM 2008b, p. 1) allows leasing of 86 percent (1.6 million ha, or 3.94 million ac) of the NE NPR-A immediately, and an additional 9 percent beginning in 2018. Virtually all yellow-billed loon breeding habitat in the NE NPR-A is within areas currently available for leasing (USDOI-BLM 2008a, Volume 6, Maps 2-4 and 3-10).

If offshore development occurs in the Chukchi Sea, it is anticipated that a 500-km (300-mi) oil pipeline will be built across the NPR-A from the coast between Icy Cape and Point Belcher to the Trans-Alaska Pipeline (USMMS 2008, p. IV-10). The State of Alaska also leases rights to oil and gas development on its land, including the Colville River Delta (ADNR 2008, p. 1), where development has already occurred within the range and habitats of the yellow-billed loon (ADNR 2008, p.1). Thus, as a result of past and possible future oil and gas lease sales, and ongoing exploratory efforts, a significant portion of the yellow-billed loon's breeding habitat in NPR-A is subject to potential oil and gas development. Additionally, resource development in adjacent offshore areas may result in the construction of pipelines across breeding habitat in NPR-A.

Although lease sales and exploratory efforts set the stage for possible future development in yellow-billed loon breeding habitat in northern Alaska,

determining the likelihood and timing of eventual development is difficult. In northeast NPR-A, several satellite production pads associated with existing infrastructure and facilities outside NPR-A at the Alpine field on the Colville River delta are in various stages of planning, permitting, and construction. It is very likely that within the next 10 to 20 years at least 5 to 7 satellite production pads feeding the existing central processing facility will be in operation, with some pads on State lands on the delta and some on adjacent Federal lands in NPR-A. Elsewhere in NPR-A the likelihood and timing of possible future development are more difficult to predict. BLM estimates that exploratory activities take roughly 10 years before construction begins (USDOI-BLM 2008c, p. 13), with roughly 70 years from the initiation of exploration until final field abandonment. Initial exploratory activities have commenced in some areas in NPR-A; exploration has yet to begin on some existing leased tracts elsewhere; and other lands have not yet been leased or offered for lease. Thus, yellow-billed loon habitat in the Colville River delta and adjacent NPR-A varies in its potential for future oil and gas development, and the timing of development, where it occurs, will be staggered starting with imminent development on and near the Colville River delta, followed by exploration, construction, and production over a period of several decades elsewhere, persisting for at least 70 years and possibly longer in various areas.

Terrestrial oil development is ongoing, and likely to increase, at the western edge of Russian yellow-billed loon breeding range. These areas have never been systematically surveyed for loons, so the historical occurrence and degree to which development areas overlaps areas used by loons is unknown. On the Yamal Peninsula, the largest gas field is the Bovanenkovskeo field, which is projected, beginning in 2011, to produce approximately 115 billion cubic meters (4 trillion cubic ft) of gas, which will be transported by new railways and a 2,451-km (1,523-mi) long pipeline currently under construction (Barents Observer 2008, p. 1). A liquefied-natural-gas plant is planned on the Kara Sea coast of the peninsula. The Yuzhnoe-Khykchuyu oil field in the Timan-Pechora province near the port of Varandey on the Pechora Sea is among the largest in Russia, and is planned as an anchor field for further development (ConocoPhillips 2008, p. 1). Major western Siberian oil fields in the Pechora River basin of the Komi Republic have operated for decades upstream of yellow-billed loon breeding range, and a large mining industry operates out of Norilsk on the Taymyr Peninsula. Gazprom, Russia's largest oil and gas company, is developing new discoveries in Chukotka near Anadyr (Gazprom Neft 2004, p. 1). In addition to these activities at the western edge of the Russian breeding area, reserves exist but are not currently planned for development in the Laptev formation on the arctic coast east of the Lena River (USGS 2007, pp. 1-2).

We are not aware of any yellow-billed loon surveys in the Taymyr, Timan-Pechora, and Yamal districts described above; so we do not know whether or to what extent yellow-billed loon breeding habitat overlaps with zones of industrial activity in this area. It is possible that the reported potential contraction at the western edge of the yellow-billed loon's range in Russia (Red Data Book of the Russian Federation 2001, p. 366) could have resulted from the effects of resource extraction in the region, but we have no evidence for or against this possibility. No data are available on potential effects of disturbance on yellow-billed loons, and we know of no special protection to prevent disturbance of yellow-billed loons or other nesting birds in Russian oil fields (Syroechkovskiy 2008, p. 1). Likewise, we have no information on the possible impacts of oil spills, facility development, and lake-water withdrawals on yellow-billed loons in Russia. Therefore, the remainder of this section will focus on available information regarding potential impacts associated with oil and gas exploration and development in Alaska.

The potential negative effects of industrial development in yellow-billed loon nesting areas includes disturbance caused by aircraft, vehicular traffic, heavy-equipment use, maintenance activities, and pedestrian traffic. Disturbance to nesting birds from oil infrastructure has been widely discussed but poorly documented (NRC 2003, p. 49; USDOI-BLM 2008a, pp. 4-890, 4-891). Loons as a genus are susceptible to disturbance, although they sometimes habituate to predictable disturbance (discussed in Vogel 1995, pp. 15-18; Barr 1997, pp. 22-23; Evers 2004, pp. 35-37; Earnst 2004, pp. 19, 31; Mills and Andres 2004, pp. 212-213; North 1994, p. 16). Human disturbance can cause yellow-billed loons to abandon reproductive efforts or leave eggs or chicks unattended and exposed to predators or bad weather (Earnst 2004, p. 19). Observations by Earnst (2004, p. 31) indicated that adults left nests when an approaching human is as much as 1.6 km (1 mi) away, or as close as a few meters (yards). These behaviors varied by individual and circumstance, and have not been subject to formal study (Earnst 2004, p. 31); more importantly, the impacts to fitness and the potential for habituation have not been studied. Preliminary observations have been made on the Colville River Delta, Alaska, where oil field development has occurred in yellow-billed loon nesting habitat. Yellow-billed loons were surveyed during nesting and brood-rearing before (1993, 1995-1997) and during (1998-2001) the oil-facility-development phase; surveys are continuing in the oil production phase that began in 2000 (ABR Inc. 2007, pp. 1-2; Johnson
et al.
2008, p. i). Between 16 and 30 nests were identified each year. No statistical comparisons among phases are available, but the proportion of territories with nests and nest success appeared roughly comparable before and during construction and during production. Too few pairs (3) have been within 1.6 km (1 mi) of facilities to allow meaningful comparisons of potential disturbance among phases (ABR 2007, pp. 3-4).

Potential disturbance and other habitat degradation on NPR-A oil fields will likely be mitigated by stipulations and required operating procedures (ROPs) described in the RODs for the Northwest and Northeast Planning Areas and included in oil and gas leases for those areas (USDOI-BLM 1998, Appendix B, pp. 29-43; USDOI-BLM 2004a, Appendix B, pp. B-1-B-18; USDOI-BLM 2008b, Appendix A, pp. 33-74). Most of the area leased is subject to the performance-based stipulations and ROPs described here; for tracts leased in 1999 and 2002 under the 1998 ROD, prescriptive stipulations and ROPs apply (USDOI-BLM 1998, Appendix B, pp. 29-43). When lessees propose specific development plans for those tracts, there will be opportunities for the BLM to apply conservation measures for yellow-billed loons, as appropriate. For tracts leased under more recent RODs (USDOI-BLM 2004a, Appendix B, pp. B-1-B-18; USDOI-BLM 2008b, Appendix A, pp. 33-74), ROP E-11 requires facility setbacks from lakes known to harbor nesting yellow-billed loons, and E-2 and K-2 require smaller setbacks for other water bodies. The current ROP E-11 states that if yellow-billed loons are found during required aerial surveys, design and location of facilities must minimize disturbance; default mitigation is a 1-mile buffer around nest sites and a 500-meter buffer around the remainder of

the lake shoreline (USDOI-BLM 2004a, Appendix B, p. B-9; USDOI-BLM 2008b, Appendix A, pp. 51-53). The size of these buffers was determined in consultation with the Service and loon experts. Deviations to ROPs and stipulations can be authorized if it is demonstrated that the conservation objective of the stipulation or ROP can be met, or if it is determined that no other options are available (USDOI-BLM 2008b, Appendix A, pp. 52-53). Such deviations are sometimes exercised (e.g., USDOI-BLM 2004b, p. 1033), but BLM has committed in writing to close collaboration with the Service in its evaluation of a deviation request that may affect yellow-billed loons (V. Galterio, in litt. 2008, p. 1). Specifically, BLM has stated in writing that any exception or deviation would be required to meet the management objective of minimizing disturbance to the species and would, at a minimum, need to provide the same level of protection that the default buffers provide (V. Galterio, in litt. 2008, p. 2). This and other ROPs and stipulations are also discussed under Factor D.

Varner (2008a, pp. 1-4) analyzed the likelihood that oil-field facilities placed randomly (i.e., without regard to loon distribution) on the landscape would occur proximal to loon nesting or brood-rearing areas. Using data from Stehn
et al.
(2005, pp. 1-38) that identified lakes within NPR-A leased tracts that have a less than 30 percent likelihood of yellow-billed loon presence (moderate-high potential yellow-billed loon lakes) and BLM's projected development scenarios for NW and NE NPR-A, Varner (2008a, p. 4) estimated that 52 percent of 12 projected facilities would occur within the 1.6 km (1 mi) buffer of a moderate-high potential yellow-billed loon lake, and 38 percent would occur within a 500-m (1,640 ft) buffer. In other words, approximately half of projected developments would require additional consideration during site layout and design to avoid yellow-billed loon buffers. We note that this development projection is uncertain, and it is possible that either a smaller or greater number of facilities could actually be built.

In summary, based on our understanding of factors affecting nest success in other species and our knowledge of loon behavior, we have identified potential impacts of disturbance to loons in NPR-A. However, the only data on the effect of oil development disturbance on yellow-billed loons are from the Colville River Delta, where small sample size and lack of controls or replicates make inference difficult. As suggested by Earnst (2004, p. 31), a well-designed study is needed to determine the most appropriate buffer distance between loon nesting lakes and oil facilities. However, we believe that current buffer distances are conservative and will protect loons from disturbance. We do not know how much development will occur in NPR-A, nor do we know the timeline over which development will occur. In NPR-A, where 90 percent of yellow-billed loons breeding on the ACP occur, we expect that adherence to current BLM regulations will ameliorate impacts by requiring that planners build facilities outside buffers or find other ways to comparably minimize disturbance.

Terrestrial oil or fuel spills occur during oil and gas extraction activities from multiple sources, including well blowouts, pipeline leaks, failure of fuel storage tanks, and accidents transporting fuel. Spills of saline water produced with oil or derived from seawater used in oil recovery also occur frequently (NRC 2003, pp. 47, 230). Marine oil spills may damage prey populations, and air and boat traffic associated with oil and gas extraction offshore could affect yellow-billed loon habitat by disturbing loons so that they decrease foraging success or avoid disturbed areas. Both non-nesting and breeding yellow-billed loons on Alaska's ACP use marine areas of the Beaufort and Chukchi Seas to forage during the nesting season. In addition, in spring yellow-billed loons gather in polynyas, ice leads, and open shorelines near river deltas offshore of breeding areas in Alaska and Canada prior to dispersing to nesting grounds. Here we discuss effects of spills on loon habitat; direct effects of oil spills on loon mortality are discussed under Factor E.

Negative effects are expected to result for bird habitats contacted by oil spills (USDOI-BLM 2008a, pp. 4-760, 4-916). Changes in freshwater chemistry or pollutant loads due to oil spills associated with oil and gas development could render breeding habitats unsuitable (NRC 2003, pp. 6-7, 73-74). Oil or saline water spills could have long-term effects on tundra waters by killing prey and shoreline vegetation (NRC 2003, pp. 95, 119, 124-125, 230-231; USDOI-BLM 2008a, pp. 4-914, 4-915), thereby reducing food availability and cover.

On Alaska's North Slope oil fields, one of the most closely regulated oil production areas in the world, there were 3,696 spills from oil production, pipeline, and oil exploration facilities between July 1995 and June 2005 totaling more than 6.8 million liters (L) (1.8 million gal) of sea water, produced water, crude and diesel oil, and drilling muds (ADEC 2007, p. 49). Most spills have been relatively small and caused minimal impacts to surrounding habitats or wildlife, although three major spills have occurred from the North Slope segment of the Trans-Alaska Pipeline (NRC 2003, p. 47), and a transit pipeline accident spilled 6,357 barrels (bbl) of crude oil in 2006 (ADEC 2008, p. 1). It is difficult to predict the likelihood of future spills, in part because technology continues to improve. Based on previous spill rates, BLM estimates that development in NE NPR-A could result in more than 2,000 small oil spills (less than 500 bbl), and approximately 3 large spills (greater than 500 bbl) (USDOI-BLM 2008a, pp. 4-60-4-62); in the next 100 years, there is a 4.2 percent chance of a very large (238,000 bbl, or 10-million-gal) blowout oil spill in NPR-A (USDOI-BLM 2008a, p. 4-910). If, as expected, development is concentrated in specific areas that overlap with high-density loon breeding habitat, the potential for oil spills affecting some loon nesting lakes exists. However, as discussed above and under Factor D, measures are in place in NPR-A to lessen this potential. For example, ROP E-11 requires minimizing disturbance to loons using setbacks of permanent infrastructure around nesting lakes that would make spills less likely to affect these lakes; other stipulations and ROPs require minimizing the potential for pipeline leaks and protecting fish-bearing water bodies (USDOI-BLM 2008b, Appendix A, pp. 33-74).

Construction of roads, gravel pads, and facilities on the North Slope of Alaska has affected freshwater flow and drainage as a result of permafrost decay consequent to infrastructure placement, vegetation damage, or fluid extraction and injection (NRC 2003, pp. 3, 10, 64-72, 126-127). North (1994, p. 16) and North and Ryan (1989, p. 303) suggested that permafrost decay consequent to infrastructure placement and disturbance of vegetation could cause breaching of rivers into yellow-billed loon breeding lakes, rendering them unsuitable due to fluctuating water levels (causing drowned nests) or increased turbidity (negatively affecting foraging success). The requirement in ROP E-11 of a 1.6 km (1 mi) buffer around nest sites and a 500-meter (1600-ft) buffer around the remainder of the lake shoreline or an equally protective alternative where no permanent infrastructure would occur (USDOI-BLM 2004a, Appendix B, p. B-9; USDOI-BLM 2008b, Appendix A, pp. 51-53) will likely lessen the chances of such damage. It is possible that ice

roads on breeding lakes could compact lake ice and delay melting (USDOI-BLM 1998, p. IV-3-b-1-b), thus delaying or discouraging yellow-billed loon breeding, since loons require lakes to be largely clear of ice before they commence nesting. There are currently no regulations which would prevent ice roads on breeding lakes.

It is possible that lake-water depletion or drawdown could affect connectedness, depth, or melt date of yellow-billed loon nesting or brood-rearing lakes and could render such areas unsuitable as breeding habitats. Fluctuations in lake water levels during nesting could cause nests to flood, or alternately could leave nests stranded away from the water during incubation, making them more vulnerable to depredation or abandonment (e.g., Kertell 1996, pp. 356-366 for Pacific loons; Fair 1979, pp. 57-63 for common loons; see also discussion in Earnst 2004, p. 19). Earnst (2004, p. 19) proposed that yellow-billed loons might be less adapted to fluctuating water levels than other loons, in part because the short arctic summer does not allow the opportunity to re-nest or delay nest initiation. Water withdrawals could have additional impacts on habitat suitability by affecting fish populations that breeding yellow-billed loons depend upon for food.

Usually taken by pumping in winter, water from lakes is used in arctic oil fields for exploratory drilling, as well as winter road and pad construction and facility use. From 1999 through 2006, approximately 2 billion L (513 million gal) of water from 126 lakes were used to drill 20 wells and construct 23 ice drill pads and roads in the NW NPR-A (USDOI-BLM 2008a, p. 3-26). During development, water is needed for drilling and facility use. According to BLM, “Drilling water demand is estimated to be 21,000 to 63,000 gal per day, or 850,000 gal per well. Water demand is estimated to be 100 gallons per day per person. Potable water demand would drop after 2 to 4 drilling seasons, when the major construction phase would be finished. Approximately 160 persons would be on site during the production and development phases for each CPF (central processing facility) and 4 to 6 satellite fields (S. Rothwell, ConocoPhillips, pers. comm.). Drilling-water demand over the 20-year production life of the field (largely for workover operations and infill drilling) would likely be less than the 21,000 gal per day estimated above” (USDOI-BLM 2008a, p. 4-30).

During production, waterflooding (injecting water into the reservoir) is sometimes used, but it is more cost-effective to use treated sea water rather than freshwater from lakes (Varner in litt. 2008b, p. 1). BLM has included potential use of lakes for waterflooding in their consideration of environmental effects of oil and gas development in NPR-A (USDOI-BLM 2008a, pp. 4-31-4-32), but at present such use is considered unlikely, particularly considering present stipulations and ROPs protecting lake fish and wildlife habitat (Varner in litt. 2008b, p. 1). Injection water demands can be met by produced formation water (i.e., water within the pores of rock) once production begins (Varner in litt. 2008b, p. 1; USDOI-BLM 2008a, pp. 4-31-4-32).

The actual amount of water withdrawn from lakes is highly variable and dependent upon the type of water use. To build ice roads, the amount taken from a given lake may be lower than allowed limits because it is not efficient to transport water a long distance; in contrast, lakes used for facility use or drilling are pumped more frequently and throughout the year (Hinzman
et al.
2006, pp. 14, 56; Baker Inc. 2007, p. 4; Moulton 2007, p. 11).

Most pumped lakes monitored by oil companies on the ACP have recharged completely in spring from snowmelt or river flooding; however, most removals were much less than the 30-percent volume permitted at the time by State of Alaska regulations (Hinzman
et al.
2006, p. 143; URS 2001, p. 4-1; Baker 2007, pp. 77-79; Baker 2008, pp. 7, 38). Two adjacent lakes monitored at Alpine Development showed different patterns in 2007: One recharged adequately from estimated snowmelt runoff given the allowable withdrawal volume of 30 percent; the other lake did not do so, and would likely be below required levels if river flooding did not occur (Baker 2008, p. 38).

We examined whether current regulations will likely be adequate to protect loon nesting lakes from excessive water withdrawal. Ninety percent of yellow-billed loon nesting range on the ACP is under BLM management in NPR-A. Outside NPR-A, the Alpine development on the Colville River Delta is the only set of oil facilities in ACP yellow-billed loon nesting range under sole State of Alaska management. At this facility, the State increased the 15-percent limit on water withdrawal from one lake with nesting yellow-billed loons to 30 percent because “the previous criterion imposed a severe constraint on the project” (Moulton 2007, p. 4). However, since that decision, the State of Alaska has participated in the “Conservation Agreement for the Yellow-billed Loon (
Gavia adamsii
),” making a commitment to protect yellow-billed loons (Conservation Agreement 2006, p. 11) and, therefore, making it less likely that the State would allow such activities to occur if they might negatively affect loons.

In NPR-A, water-withdrawal stipulations and ROPs are specifically designed to protect and monitor fish-bearing lakes. The current Federal (BLM) requirements for NE NPR-A, based on State of Alaska permit regulations, allow up to 15 percent of lake volume below ice cover to be removed from lakes deeper than 2.1 m (7 ft) with “sensitive” fish species (i.e., fish other than ninespine stickleback and Alaska blackfish) and up to 30 percent of lake volume from lakes deeper than 1.5 m (5 ft) with non-sensitive fish species; up to 35 percent may be removed from lakes without fish (USDOI-BLM 2008b, Appendix A, pp. 44-45). Permits are based on a site-specific analysis. At present, there are no requirements to prevent pumping of known loon-nesting lakes, and no requirements for direct measurements of effects on lake biota, including fish. However, in a letter to the Service emphasizing the BLM's commitment to supporting conservation of the yellow-billed loon, the BLM State Director for Alaska expressly clarified the ROPs and stipulations in NPR-A leases concerning water withdrawal. Underscoring the importance of continued collaboration with the Service (V. Galterio, in litt. 2008, pp. 1-3), the State Director explained that it will require a water-quality monitoring plan to be developed that will outline specific physical and biological water-quality parameters to be collected in lakes harboring yellow-billed loons (V. Galterio, in litt. 2008, pp. 1-3). We believe these requirements will protect yellow-billed loon lakes from deleterious effects of water withdrawals. See discussion under Factor D, Inadequacy of Existing Regulatory Mechanisms.

In conclusion, we have identified several mechanisms by which development could affect yellow-billed loons, including disturbance, oil spills, facility development, and lake-water withdrawals. Although we believe onshore oil and gas activity is likely to increase in Alaskan and Russian breeding grounds in the foreseeable future, we do not believe these activities will result in significant population-level impacts. Although a large proportion of high-density yellow-billed loon nesting habitat on Alaska's ACP coincides with areas of high potential

for oil and gas development in NPR-A, the BLM, through stipulations and ROPs required to be included in oil and gas leases, has established a number of mechanisms to protect yellow-billed loons from the effects of oil and gas activities in NPR-A, if development ultimately does overlap with yellow-billed loon breeding habitat. We believe that disturbance and spills will likely be minimized through requirements that facilities be built at least 1.6 km (1 mi) from nests, and 500 m (1,640 ft) from lake shorelines, or an equally protective alternative. The BLM and the State of Alaska have committed to work with the Service to minimize impacts through water quality monitoring. With current projections of approximately 12 facilities in NPR-A, we believe the current regulations and close consultation with the Service are sufficient to protect yellow-billed loons from population-level effects of oil and gas development on the ACP. Based on the best available information we find that oil and gas development in the ACP is not a threat to the yellow-billed loon now or in the foreseeable future.

On western Russian breeding grounds, we do not have information on whether yellow-billed loon distribution overlaps with zones of industrial activity. Due to lack of study, regulation, and available information, the environmental impacts of industrial development in the Russian yellow-billed loon breeding range are not well understood. Because the bulk of the Russian breeding population appears to occur in eastern Siberia (Yakutia and Chukotka), where little industrial development is occurring or planned, most potential impacts of industrial development in Russia are limited to the western edge of the range. Based on the best available information, we find that oil and gas development is not a threat to the yellow-billed loon in its Russian breeding range now or in the foreseeable future.

We expect large spatial and temporal variation in the level of oil and gas development activities on yellow-billed loon breeding habitat, but most such habitat will remain undeveloped in the foreseeable future. We do not expect terrestrial oil and gas development to occur in the Canadian breeding range, and Russian oil and gas development is likely to be confined to the western edge of the breeding range there. In Alaska's NPR-A, some areas are likely to be developed, particularly at the eastern edge of NE NPR-A near the Alpine development. In Alaska, we believe that existing required protective measures will protect the yellow-billed loon from impacts of development. We find that degradation of breeding grounds throughout its range from oil and gas development is not a threat to the yellow-billed loon now or in the foreseeable future.

Temperate Marine Habitat: Degradation of Marine Habitats in Migration and on Wintering Grounds

The marine environment is clearly important for yellow-billed loons, as that is where they spend their first 3 years, and subsequently at least 8 months per year. Wintering areas along the coast of Alaska and British Columbia, Canada, are relatively pristine. Two important wintering areas for yellow-billed loons, the western Pacific Ocean coastal waters of the Yellow Sea and Sea of Japan, and the North and Norwegian Seas, have recently been identified among the ocean ecosystems with the greatest human impacts, and therefore degradation, of any in the world (Halpern
et al.
2008, p. 949). Possible effects of human activities on yellow-billed loon marine migrating and wintering habitats include depletion of the prey base through a variety of mechanisms, including pollution-induced hypoxia and destructive fishing practices, as discussed below. Potential effects on loons from depletion of the winter prey base include reduced body condition, which could result in mortality or reduced breeding propensity.

Effects of marine oil spills, other effects of marine oil and gas development, and potential direct effects of contaminants on yellow-billed loons are discussed under Factor E.

Asian seas, where 24 out of 29 Alaska-breeding yellow-billed loons with satellite transmitters wintered (Schmutz in litt. 2008, p. 11), are undergoing environmental stress. The United Nations Global International Waters Assessment (GIWA) Regional Assessment of the Yellow Sea described Yellow Sea fisheries as threatened by “pollution and loss of biomass, biodiversity and habitat, resulting from extensive economic development in the coastal zone” (Teng
et al.
2005, p. 33), caused by a tenth of the world's humans (approximately 600 million) living in surrounding watersheds. For example, the East China Sea (adjacent to the Yellow Sea) is undergoing “severe environmental degradation” from inputs of inorganic nitrogen, phosphate, oil hydrocarbons, organic matter, and heavy metals (Li and Daler 2004, p. 107). A significant effect of pollution inputs in aquatic systems are zones of eutrophication-induced hypoxia (“dead zones”), which are among the most deleterious anthropogenic influences on marine environments, leading to mass mortality of fish and invertebrates, and major changes in community structure (Diaz and Rosenberg 2008, p. 926). Large ecosystem effects of eutrophication and hypoxia have been documented in coastal waters of Japan (
e.g.
, Ueda
et al.
2000, pp. 906-913; Suzuki 2001, pp. 291-302; Kodama
et al.
2002, pp. 303-313), Korea (Lim
et al.
2006, p. 1525), and the East China Sea (Chen
et al.
2007, p. 399). However, these effects are seasonal, occurring more often in summer, when adult breeding yellow-billed loons would have migrated from the area. These effects also vary geographically, with most severe dead zones occurring at mouths of watersheds with large population centers or that deliver large quantities of nutrients.

Unsustainable fishing practices, including overfishing, indiscriminate trawling, and use of pesticides for fishing (Teng
et al.
2005, pp. 34-35), have resulted in significant changes in the fisheries of the intensively exploited Yellow Sea and other Asian fisheries. These changes include significant declines in fish populations and changes in community structure, with larger (and commercially important) species replaced by smaller (and less valuable) fish (Teng
et al.
2005, p. 33). Unsustainable exploitation of marine natural resources is expected to continue over the next 20 years, causing fisheries production to decrease by 30-50 percent (Teng
et al.
2005, p. 35).

Degradation of temperate marine wintering and migrating yellow-billed loon habitats could deplete the yellow-billed loon prey base, which could cause reduced body condition, mortality, fewer birds migrating, and reduced breeding propensity. Although information exists regarding pollution occurrence and effects on fisheries in temperate marine waters in Asian wintering areas, we do not know which species yellow-billed loons eat there. We therefore do not know whether yellow-billed loon prey species have been affected. Indeed, documented changes in community structure from large finfish to smaller forage fish could benefit yellow-billed loons, as their diet items are relatively small. Further, although pollution and declines in fisheries are documented in Asian Pacific wintering areas, the information is inadequate to assess what proportion of the habitat or wintering loons is affected. We also have no data on yellow-billed loon mortality due to habitat degradation in wintering areas or migration routes, or on body condition at any season.

In summary, yellow-billed loon mortality from marine pollution has not been documented. The only other source of information we have to evaluate this factor is population trend information from the ACP. Yellow-billed loons breeding on the ACP migrate to Asian wintering grounds (Schmutz in litt. 2008, p. 1). If deterioration of these wintering areas were resulting in population-level effects on yellow-billed loons, we would expect to see evidence of a large population decline on the Alaska breeding grounds. Instead, survey trends indicate a slightly declining or stable population. We do not have information indicating that the current effects to the species from the degradation of temperate marine waters will change in the future. Therefore, we find that degradation of temperate marine waters is not a threat to yellow-billed loons now or in the foreseeable future.

Climate Change

While climate change impacts to some environmental features (e.g., sea ice) can be reliably assessed to some degree into the future, assessment of climate-induced changes to yellow-billed loon habitat in arctic terrestrial and freshwater systems and arctic and temperate marine systems is complex, with highly variable predictions of effects. Current models suggest that global temperatures are likely to continue to rise for up to 50 years, even if greenhouse gas emissions were curbed today (Meehl
et al.
2007, p. 749). Below, we evaluate the available information on possible climate-change effects in these systems that could affect yellow-billed loons.

I. Arctic Habitats

There is strong evidence of ongoing impacts of climate change in the arctic, all of which are predicted to continue or accelerate in the next century (Anisimov
et al.
2007, pp. 662-663; Christensen
et al.
2007, pp. 902-903), although with varying degrees of uncertainty and regional variation (Reist
et al.
2006b, p. 381) in effects on different biotic communities, hydrology, and geomorphology. Impacts include rising air temperatures (Anisimov
et al.
2001, summarized in Anisimov
et al.
2007, p. 656) at approximately twice the global rate (McBean
et al.
2005, p. 39), declining summer sea ice (Richter-Menge
et al.
2008, p. 1), increasing coastal erosion (Mars and Houseknecht 2007, p. 585; Rachold
et al.
2002, cited in Walsh
et al.
2005, p. 233), rising sea levels (Walsh
et al.
2005, pp. 232-234), a small increasing trend in precipitation (McBean
et al.
2005, p. 39), warming and thawing permafrost, and decreasing extent of land underlain by permafrost (Clow and Urban 2008, p. 3; Walsh
et al.
2005, p. 210; Jorgenson
et al.
2006, p. 1; Jorgenson
et al.
2008, p. 1). All of these could interact via feedback loops, as described below.

With respect to the yellow-billed loon, we are most concerned about effects of potential climate-induced changes on morphology of breeding lakes and prey fish communities. In northern areas, such as along the arctic coast in most of the yellow-billed loon's breeding habitat (Siberia, Alaska's ACP, and most of the Canadian breeding range), permafrost is continuous, and could be hundreds of meters (ft) deep. However, some habitat extends south of this region to areas of discontinuous permafrost, which is more susceptible to the effects of climate change (Seward Peninsula, southern part of the Canadian range). Yellow-billed loon breeding habitat on the arctic coast depends on a unique hydrological system, which is in turn dependent upon cold temperatures resulting in continuous and stable permafrost underlying perched (i.e., isolated above the groundwater) lakes (Rovansek
et al.
1996, p. 316) and relatively consistent weather patterns, such as most precipitation deposited in winter as snow, and spring ice-jams and floods contributing to lake recharge (Prowse
et al.
2006, pp. 330-331). A community of fish species has adapted to this system, overwintering in deeper lakes, but also entering or leaving some lakes during spring river floods.

Morphology of Breeding Lakes

Permafrost thawing could reduce the size, number, or suitability of lakes that yellow-billed loons use for nesting and brood-rearing, especially near the southern boundary of continuous and discontinuous permafrost. When near-surface permafrost thaws, unfrozen channels develop between and below water bodies, allowing subsurface drainage to occur. In addition, permafrost degradation around edges of lakes near river channels can cause lakes to be breached and drained (Mars and Houseknecht 2007, p. 586). Permafrost degradation has already affected lakes in some areas at the southern boundary of continuous permafrost. In Siberia, L.C. Smith
et al.
(2005, p.1) documented a decline in lake abundance and area in zones of discontinuous permafrost. Yoshikawa and Hinzman (2003, p. 151) documented numerous shrinking ponds on Alaska's Seward Peninsula, at the southern boundary of the yellow-billed loon's range, due to an increase in internal drainage following permafrost degradation between 1950 and 2000. Because a limited number of loon surveys have been conducted on the Seward Peninsula, we do not know whether these changes are affecting yellow-billed loons there. Riordan
et al.
(2006, p. 1) observed ponds shrinking throughout subarctic Alaska, and attributed this drying to permafrost warming, as well as increased evaporation during a warmer and longer growing season. The arctic zone of continuous permafrost has relatively cold air temperatures and is considered relatively stable. However, Clow and Urban (2008, p. 3) measured increases for a total average warming of 3.5 K (kelvin) (3.5 degrees C, 6.3 degrees F) during 1989-2007, and Jorgenson
et al.
(2006, p. 1) observed a recent, abrupt increase in the extent and rate of ice wedge degradation on Alaska's ACP. Ice wedges are 2-4 m deep polygons of ice, more than 3,000 years old, occurring just below the vegetation layer in ice-rich regions of the arctic. Both effects were coincident with record warm air temperatures in the late 1990s.

Permafrost warming and thawing is predicted to continue as the arctic climate warms (Meehl
et al.
2007, p. 772). Zhang
et al.
(2007, p. 443) simulated changes in Canada's permafrost distribution using a model driven by six general circulation models. They predicted that active layer (the top layer of soil that thaws in summer) thickness would increase, the boundary between continuous and discontinuous permafrost would move north, and there would be significant impacts on surface and ground hydrology. Stendel
et al.
(2007, pp. 203, 211) used a high-resolution regional climate model to predict changes to permafrost in eastern Siberia over the next century, and concluded that under the various modeling scenarios reviewed by the Intergovernmental Panel on Climate Change (IPCC), the active layer depth would increase up to 1 m (3.1 ft) along the arctic coast. These predictions suggest that some breeding lakes, particularly in the southern part of the yellow-billed loon's range, could be altered, but overall effects will depend on the magnitude and direction of other changes (e.g., precipitation).

Arctic sea-ice loss accelerates air temperature warming, which, in turn, increases permafrost warming. Recently, Lawrence
et al.
(2008, p. 1) evaluated how periods of abrupt rapid sea-ice loss affect terrestrial arctic climate and ground thermal state in the Community Climate System Model. They found that arctic land warming trends would be 3.5 times greater during periods of rapid

sea-ice loss than otherwise predicted for the 21st century. They predicted that such a warming period would increase ground heat accumulation substantially, increasing the vulnerability of permafrost to degradation (Lawrence
et al.
2008, p. 1). The 2007 arctic summer sea-ice extent was a new record minimum since satellite measurements began in 1979, with a large reduction in area compared to the previous record set in 2005 (Richter-Menge
et al.
2008, p. 1), and the 2008 extent was similar (National Snow and Ice Data Center,
http://nsidc.org/data/seaice_index/index.html
).

Aside from causing increased land warming trends, loss of sea ice could affect freshwater breeding lakes adjacent to marine shorelines through breaching and increased salinity, because shorelines would no longer be protected from storms by summer and fall shorefast ice (Mars and Houseknecht 2007, p. 586). Coastal erosion rates are increasing, with land loss rates in some of Alaska doubling in the last half century (Mars and Houseknecht 2007, p. 585), and parts of the Laptev Sea coast in arctic Russia are retreating at an average rate of 2.5 m (8.2 ft) per year (Rachold
et al.
2002, cited in Walsh
et al.
2005, p. 233), but it is not known whether yellow-billed loon breeding lakes in this region are close enough to the coast to be affected. These effects are exacerbated by rising global sea levels. The greatest sea-level increases over the next century are projected for the arctic, although with much uncertainty (Christensen
et al.
2007, p. 914; Walsh
et al.
2005, pp. 232-234).

The amount and timing of precipitation also influences the permafrost active layer, and is predicted to increase in the arctic (Christensen
et al.
2007, pp. 902-906), with a greater percentage increase in winter and less in summer. Increased snow cover in winter is likely to contribute to permafrost warming, as snow limits heat exchange between the atmosphere and the ground; significant snow cover keeps the ground warmer than the air (Stieglitz
et al.
2003, p. 1). Predicted increased frequency of rain-on-snow events in Alaska and eastern Siberia (Rennert
et al.
2008, p. 4) would exacerbate the warming effect on permafrost, as latent heat release from a single large rain-on-snow event can constrain the soil temperature to 0 degrees C (32 degrees F) for months (Putkonen and Roe 2002, p. 1,188).

There could also be direct effects of changes in precipitation on lakes used by yellow-billed loons. Increased winter precipitation could provide more spring floodwater to recharge lake basins (Walsh
et al.
2005, p. 188; Prowse 2006, pp. 330-331). In contrast, increased summer rainfall will likely be lost to stream flow, increased subsurface storage, and increased evaporation in warmer air temperatures (Rovansek
et al.
1996, p. 311; Bowling
et al.
2003, p. 2-1). Earlier snow melt from increasing air temperatures and the predicted increase in winter rain events could decrease large breakup events in the spring, perhaps reducing lake replenishment from ice-jam flooding.

Overall, it is possible that lakes at the southern boundary of continuous permafrost could be affected, that this boundary will move north, and that eventually even northern areas of continuous permafrost could experience changes that will negatively affect lakes. For the yellow-billed loons, these effects could mean reduced habitat in the southern part of its range in the near-term (an uncertain period, but perhaps the next several decades), and eventually, in the northern parts of its range. At present, however, models have not been developed to make reliable predictions about the timing or extent of such habitat reductions and associated impacts on the species. Although permafrost degradation has already occurred in southern parts of the breeding range, such as the Seward Peninsula, there have been no observed effects on loon breeding lakes, and we do not have trend information for that population (which could provide some indication of the population impacts of permafrost degradation). Therefore, based on currently available information we find that climate-induced changes to the morphology of the yellow-billed loon's breeding lake habitats are not a threat to the species now, and we cannot reasonably predict that they will become a threat to the species in the future.

Prey Fish Communities

Climate change could alter yellow-billed loon prey fish communities in breeding lakes; species potentially affected include ninespine sticklebacks, Alaska blackfish, and least cisco (considered among the most vulnerable to extirpation through changes in species composition) (Wrona
et al.
2006, p. 413). We are uncertain, however, about the form or timing that potential effects on fish communities might have on yellow-billed loons due to the interaction of factors influencing community composition. Fish species vary with lake depth and resulting ice thickness. Shallow (less than 2 m) (less than 6.6 ft) lakes that freeze to the bottom cannot harbor overwintering fish, and even somewhat deeper lakes may have low dissolved oxygen levels, allowing only species adapted to these low levels, such as sticklebacks and Alaska blackfish, to survive. Shallow lakes that freeze to the bottom sometimes maintain fish populations via replenishment from spring river floods. If ice thickness declines in a warmer climate, deep lakes could have increased oxygen, allowing less tolerant species to overwinter, and shallower lakes would be able to harbor overwintering fish. Conversely, shallow lakes might lose replenishment with decreased spring flooding (Hershey
et al.
2005, pp. 39, 52). Fish habitat is also dependent on basin shape, since shallow littoral zones are needed to provide food for fish; lower water levels might alter or diminish littoral habitats. Fish habitat characteristics are reflected in yellow-billed loon habitat preferences modeled by Earnst
et al.
(2006). Loons were found more often on medium or deep lakes than on shallow (less than 2 m) (less than 6.6 ft) lakes that freeze to the bottom, and for shallow lakes, loons were more likely to be present if the lake was connected to streams or other lakes. Proportion of shoreline with vegetation, indicating littoral habitat, was a positive indicator of yellow-billed loon presence. Loons preferred both 2 to 4 m (6.6 to 13.1 ft) deep lakes and greater than 4 m (greater than 13.1 ft) deep lakes, but because the latter are rare on the North Slope, 64 percent of yellow-billed loon sightings were on lakes 2 to 4 m (6.6 to 13.1 ft) deep (Earnst
et al.
2006, p. 235). In summary, although climate change could have negative effects on prey communities, there could be positive effects. Not only is there considerable uncertainty as to the possible effects to prey communities from climate change, there is also substantial uncertainty about the timing over which changes will occur. Scientists have not yet developed the specific predictive models and empirical research to improve our understanding of these changes and enable us to predict the timing with which they might occur.

In addition to breeding lakes, yellow-billed loons in summer use shallow nearshore marine waters (less than 10 m (33 ft), roughly within 20 km (12.4 mi) of shore) adjacent to mainland habitats and near barrier islands (Earnst 2004, p. 7). Little is known about the prey species that yellow-billed loons use in these habitats, although they are known to eat a variety of species in winter marine habitats (see Feeding Habits, above; also reviewed in North 1994, p. 7 and Earnst 2004, pp. 9-10). Changes in arctic marine ecosystems, including

increased primary production, introduction of new species, and population shifts in existing species could occur as the climate warms (Perry
et al.
2005, p. 1,912; Behrenfeld
et al.
2006, p. 752; Reist
et al.
2006a, pp. 370-380). These changes to summer marine prey communities would be complex, and the form of potential new species assemblages cannot be reliably predicted at this time.

Increased ocean acidification as a result of increasing levels of atmospheric carbon dioxide could affect marine food webs, but the form, magnitude, and timing of such effects are unknown. Due to limited research and understanding of the processes involved (Zeebe
et al.
2008, p. 52), it is not possible to predict effects on loon prey species from ocean acidification at this time.

Therefore, as discussed above, due to a paucity of information and models available to reliably predict effects of climate-induced changes to yellow-billed loon prey species assemblages in breeding lake and marine habitats, we find that climate-induced changes to yellow-billed loon prey species is not a threat to this species now or in the foreseeable future.

Polynyas and Ice Leads

We also considered whether polynyas and ice leads, both of which provide feeding and staging areas for yellow-billed loons in spring before the breeding season, were likely to disappear as the arctic climate changes. Arctic sea ice is projected to decline most, and surface air temperatures increase most, in summer and fall (Walsh 2008, p. S19). In 2007, there was a record sea-ice minimum in the arctic in September, and the Chukchi Sea did not freeze until early December, but an advancing ice field covered most of the eastern Bering Sea shelf by mid-January 2008. A subsequent near record maximum ice extent occurred in March 2008, and the Bering Sea was not ice free until almost July 2008 (Overland and Stabenow 2008, p. 2). Overland and Stabenow (2008, p. 5) predicted that although arctic sea ice will continue to decrease seasonally in late summer and fall, sea ice will still form in winter, extending south to the Bering Sea. If this projection is correct, polynyas and ice leads should continue to provide productive spring habitat for yellow-billed loons, even as the arctic climate continues to warm. Therefore, we find that loss of polynyas and ice lead habitats is not a threat to yellow-billed loons now or in the foreseeable future.

Shipping Traffic

We also evaluated the potential effects of increased disturbance and oil spills to arctic yellow-billed loon habitat from increased shipping traffic, as a result of summer and autumn sea-ice loss, throughout arctic marine waters near loon breeding areas. Because of the sea-ice decline discussed above, in 2008 both the Northwest passage and the so-called Northeast Passage, or Northern Sea Route, along the Russian arctic coast were ice free likely for the first time since the last ice age 125,000 years ago (NSIDC 2008). As the extent of arctic sea ice in the summer has declined and the duration of ice-free periods has increased, interest in shipping within and through arctic waters has increased (Brigham and Ellis 2004, p. 2). This potential increase in shipping could affect yellow-billed loons through habitat degradation, disturbance, or fuel spills. However, we have not found any reliable predictions about the location, type, and amount of shipping that might occur as ice-free periods increase. In addition, the wide distribution and low density of yellow-billed loons in arctic marine areas during the breeding season makes it unlikely that the population would be at increased risk if shipping traffic were to increase. Because we are uncertain about the magnitude of shipping traffic increases and because the low density of loons in the environment makes them less vulnerable to vessel accidents or disturbance, we find that increased arctic shipping is not a threat to yellow-billed loons now or in the foreseeable future.

In summary, our evaluation of climate-change effects on arctic yellow-billed loon habitats included documented and predicted climate-induced changes to various features of the environment, followed by hypothetical but reasonable suppositions about possible alterations to habitats important to yellow-billed loons. There are no data to suggest that climate-induced changes documented to date have resulted in breeding-habitat changes, and based on the stable or slightly declining trend on the ACP, it does not appear that these changes have affected the yellow-billed loon population there. At this time, we are unable to predict potential future changes to yellow-billed loons and their habitats discussed above, because, in addition to uncertainty about the magnitude, direction, and timing of climate-induced changes to the environment, no empirical data exist regarding the effects of those potential changes on yellow-billed loons or their habitats.

In arctic areas, there is strong evidence that coastal erosion is occurring, and some evidence for breaching of freshwater lakes adjacent to coasts, but little or no information on whether these environmental changes have affected yellow-billed loon breeding lakes. While there is strong evidence that climate change is causing permafrost loss, no information is available on how this could affect freshwater lake morphology and the yellow-billed loon prey base in the future. Based on the best available data, we believe that important polynyas and ice-lead spring staging habitat are likely to continue to exist in the foreseeable future. While ocean acidification will likely have long-term effects on marine communities, we do not know how it will affect loons. We believe the effects of increased shipping in arctic seas will be negligible because yellow-billed loons are widely dispersed across breeding and migrating landscapes.

II. Temperate Habitats

Global ocean temperatures increased (0.1 degrees C (0.2 degrees F) from 1961 to 2003, although with some cooling since 2003; Bindoff
et al.
2007, p. 387), and effects on primary productivity and dissolved oxygen varied with latitude. Primary productivity in warm, low-latitude oceans declines as upper-ocean temperature increases, while warmer temperature at high latitudes increases productivity and decreases oxygen levels (Behrenfeld
et al.
2006, p. 752; Bindoff
et al.
2007, p. 400).

For the yellow-billed loon wintering at low latitudes in the Yellow Sea and the Japan (East) Sea, a drop in primary productivity might mean decreased prey availability. However, as already observed in northern environments (e.g., Perry
et al.
2005, pp. 1,912-1,915), marine animals, including yellow-billed loons, might shift north to colder, more productive waters if winter sea ice is not a barrier. As noted for northern marine species (e.g., Perry
et al.
2005, p. 1,914) the movements of species as a result of climate change will likely be complex, so predicting the form of new species assemblages is difficult.

Potential expansion of oxygen-deficient “dead zones” in Asian coastal waters where yellow-billed loons winter depends partly on how climate change affects water-column stratification (Diaz and Rosenberg 2008, p. 929). Warming ocean temperatures could increase stratification, deepening the depletion of oxygen, but increased storminess, such as hurricanes, could increase mixing and thereby lessen stratification.

Changes in rainfall patterns could change freshwater and nutrient inputs. At this time, available data on the effects of climate change on dead zones in winter marine habitats of the yellow-billed loon are uncertain.

In summary, climate change effects on the temperate-latitude wintering habitat of the yellow-billed loon include increases in ocean temperature and decreases in primary productivity and dissolved oxygen levels, which could potentially affect prey fish communities and their distribution. The magnitude and form of these effects are highly uncertain, but would most likely involve a northward shift of prey species, which could be mirrored by their predators, such as wintering yellow-billed loons. Therefore, while we conclude that the effects of climate change will be widespread and will likely have some impact on yellow-billed loons in temperate habitats, we find that climate-induced changes in the temperate marine habitat are not a threat to the yellow-billed loon now or in the foreseeable future.

There are multiple hypothetical mechanisms associated with climate change that could affect loons and their breeding and non-breeding habitats. Unlike documented and predicted declines in sea ice, an obligate habitat for other arctic species such as polar bears (
Ursus maritimus
), we lack predictive models on how climate change will affect yellow-billed loon terrestrial, freshwater, and marine habitats. Manifestations of climate-mediated changes throughout arctic and temperate yellow-billed loon habitats will emerge as models continue to be refined and effects are documented, but at this time the timing, magnitude, and net effect of the impacts are uncertain.

In our analysis of Factor A, we identified and evaluated the risks to the yellow-billed loon's habitats, including: Oil and gas development (i.e., disturbance, changes in freshwater chemistry and pollutant loads, and changes in freshwater hydrology); pollution; overfishing; and climate change. Based on our review of the best available information, we find that the present or threatened destruction, modification, or curtailment of the yellow-billed loon's habitat or range is not a threat to the species now or in the foreseeable future.

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

Subsistence harvest, as well as, bycatch of loons during commercial and subsistence fishing are discussed under Factor E.

Researchers seeking to understand the life history of yellow-billed loons have implanted 29 yellow-billed loons with satellite transmitters to date (19 birds on the ACP and 10 birds on the Seward Peninsula, Alaska; Schmutz in litt. 2008). This research is permitted by the Service under the Migratory Bird Treaty Act (MBTA) and by the Alaska Department of Fish and Game (ADFG) under State law. Although it is reasonably likely that there could be heightened risks of mortality and reduced productivity in individual birds implanted with transmitters, the number of loons in this study is not sufficient to cause population-level effects.

We do not have any evidence of risks to yellow-billed loons from overutilization for commercial, recreational, scientific, or educational purposes, and we have no reason to believe this factor will become a threat to the species in the future. Therefore, we find that overutilization for commercial, recreational, scientific or educational purposes is not a threat to the yellow-billed loon now or in the foreseeable future.

Factor C: Disease or Predation

Loons are susceptible to avian diseases, including avian cholera (from
Pasteurella multocida
), aspergillosis (from
Aspergillus fumigatus
), and avian botulism (from Clostridium botulinum) (Friend and Franson 1999, pp. 79, 130, 274), but we are not aware of any large disease-related die-offs in yellow-billed loons. Loons are susceptible to avian influenza, but in Alaska, none of six loons sampled, including two yellow-billed loons, tested positive for avian influenza viruses in 2006 (USFWS/USGS 2007, pp. 1-93; Y. Gillies in litt. 2008, p. 1), and worldwide the highly pathogenic H5N1 has not been detected in loons (
http://www.who.int/csr/disease/avian_influenza/en/
, accessed 11/24/2008).

Predation on adult yellow-billed loons is thought to be uncommon, but predation on nests on the ACP has been attributed as the primary cause of egg loss and therefore reduced productivity in some years (Earnst 2004, p. 22). Yellow-billed loon nest predators include glaucous gull (
Larus hyperboreus
), parasitic jaeger (
Stercorarius parasiticus
), and arctic fox (
Alopex lagopus
); pomarine jaeger (
Stercorarius pomarinus
), common raven (
Corvus corax
), snowy owl (
Nyctea scandiaca
), red fox (
Vulpes fulva
), and grizzly bear (
Ursus arctos horribilis
) also predate nests (North 1994, p. 11; Earnst 2004, p. 22). Many of these predators are attracted to infrastructure, which is used as nesting platforms or is associated with food sources, and so predation might be expected to increase as development in yellow-billed loon nesting habitat increases (NRC 2003, p. 6; Earnst 2004, p. 19). However, in Alaska, NPR-A ROP A-2 and A-8 require control of waste and other measures to prevent attracting wildlife to infrastructure (USDOI-BLM 2008b, Appendix A, pp. 37, 41-42), reducing the risks associated with future development. We do not know whether similar regulations would be implemented in Canada should development occur there. The extent of infrastructure increase in Russian yellow-billed loon nesting habitats, and accompanying regulation, is unknown.

In conclusion, we note that no large disease-related mortality events have been documented for yellow-billed loons. Indeed, yellow-billed loons might be relatively protected from avian disease mass mortality events that are more common in other water birds because of the loon's dispersed distribution and relatively solitary habits. We have no reason to believe that disease outbreaks will increase or will have more severe effects on yellow-billed loons in the future. Nest predation might affect current productivity, but population-level effects are more likely to results from decreases in adult survival (see Population Resiliency, above). Moreover, due to regulations associated with infrastructure development that also target increasing human safety, we believe that nest predation is unlikely to cause population-level effects in the future, at least in Alaska and Canada; no information is available that would indicate future effects of such development in Russia. Therefore, we find that neither disease nor predation is a threat to the yellow-billed loon now or in the foreseeable future.

Factor D: Inadequacy of Existing Regulatory Mechanisms

To determine if existing regulatory mechanisms protect yellow-billed loons, we evaluated existing international and United States conventions, agreements, and laws for the specific protection of yellow-billed loons or their marine and terrestrial habitats in the countries where yellow-billed loons winter, migrate, or breed. In July 2008, we sent letters to national wildlife or natural resource agencies in Canada, China, Japan, North Korea, Norway, Republic of Korea (South Korea), and the Russian Federation, asking for information about ongoing management measures and any conservation and management strategies being developed to protect the species.

We received a formal response from the government of Canada, and an informal response from a government biologist in the Russian Federation (discussed below).

The yellow-billed loon is included in the 2008 International Union for the Conservation of Nature (IUCN) Red List Category as a “Least concern” species; widespread and abundant taxa are

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3AE9-6012. Public record. Not legal advice.