STUDY TITLE: Winter distribution and abundance of Steller’s eiders (Polysticta 

stelleri) in Cook Inlet, Alaska, 2004-2005 

REPORT TITLE: Same as above 

CONTRACT NUMBER: Intra-agency Agreement number 0104RU34160 

SPONSORING OCS REGION: Alaska 

FISCAL YEARS OF PROJECT FUNDING: 2004, 2005 

COMPLETION DATE OF REPORT: January 2007 

COSTS: FY2004: $50,322 FY2005: $57,962 TOTAL PROJECT COST: $108,284 

PROJECT MANAGER: William W. Larned 

AFFILIATION: U.S. Fish and Wildlife Service, Migratory Bird Management 

ADDRESS: 1011 E. Tudor Rd., Anchorage, AK 99503 

PRINCIPAL INVESTIGATOR: William W. Larned 

KEY WORDS: Aerial survey, Alaska, Cook Inlet, distribution, Polysticta stelleri, sea 

duck, sea ice, Steller’s eider 

BACKGROUND: The Minerals Management Service (MMS) has offered oil and gas 

leases in offshore waters of Cook Inlet, and has plans to continue doing so in the future. 

Historic and recent studies have indicated a significant presence of Steller's eiders 

(Polysticta stelleri), a species listed as "threatened" under the Endangered Species Act 

(ESA), wintering in lower Cook Inlet near the offshore MMS lease sale area. This study 

was designed by the U.S. Fish and Wildlife Service (FWS) to address MMS's obligation 

to evaluate potential effects of their action upon Steller's eiders, as required in the 

implementing regulations for Section 7(a)(2) of the ESA (50 CFR 402.14(i)(3)). 

Furthermore, this study partially fulfills MMS's obligations under section 7(a)(1) of the 

ESA, and provides preliminary information useful for long-term monitoring. 

 

OBJECTIVES: The following objectives of this study were determined by MMS: 

1. Identify habitats important to Steller’s eiders wintering in Lower CI, as evidenced by 

persistent use within and among years. 

2. Describe temporal variation in Steller’s eider winter use of the waters in Lower CI 

during two winters. 

3. Estimate total numbers of Steller’s eiders wintering in the eastern and western 

portions of Lower CI. 
DESCRIPTION: Visual observations of Steller's eiders were collected along fixed aerial 

transects, perpendicular to shorelines, extending from the shoreline to the nearest 20m 

depth contour with a 2km lateral spacing. Steller's eiders in flocks containing <20 birds 

were recorded within strips 600m in width. Densities were extrapolated from surveys to 

the entire sampled survey area. Steller's eiders in flocks of ≥20 birds within the sampled 

area inside and outside the 600m strips were also recorded. Observations were assigned 

geographic coordinates via laptop computers equipped with a GPS-linked voice recording 

program. Surveys were conducted monthly, with complete survey area coverage in 

March, April, and December, 2004, and from January – April, 2005. Partial coverage 

was completed in January and February 2004. 

STUDY RESULTS: Steller's eiders were detected and recorded in eastern and western 

CI in all completed surveys. Largest monthly estimates were 1,247 and 4,200, in eastern 

and western survey areas, respectively, in January 2005. December 2004 estimates 

accounted for <50% of these monthly peaks, and by April numbers had dwindled, 

suggesting departure for Arctic breeding grounds. The pattern of habitat sites occupied 

was relatively consistent among months and years, while numbers of birds at each 

occupied site varied considerably within and among years. Temporary major departure 

from the observed distribution pattern during mid-winter 2005 appeared related primarily 

to displacement of birds by sea ice. The typical distribution of Steller's eiders observed 

during our survey is illustrated by the March 2005 location data (Fig. 1). Most eiders in 

Western CI were in the Kamishak Bay area, between Cape Douglas and Iniskin Bay, 

while most in eastern CI were from 20km north of Ninilchik to the Homer Spit (Fig. 1). 

A maximum estimate of 2,500 Steller's molting eiders were recorded in the Douglas 

River Shoals area (Fig. 1) during aerial surveys conducted in August and September 

subsequent to this study by the Primary Investigator of this study and the AK Department 

of Fish and Game. 

SIGNIFICANT CONCLUSIONS: Our data, in conjunction with other survey and 

telemetry data reviewed in this report, provide the basis for the following preliminary 

conceptual model of seasonal distribution that should enable industry and regulatory 

agencies to make management decisions that provide a large measure of protection for 

Steller's eiders wintering in CI: 

 Following nesting in high Arctic Russia and Alaska, most Steller's eiders migrate to 

southwest Alaska, including lower CI, most arriving by late August. Eider numbers 

continue to build in CI habitats through early winter, peak in January and February, then 

decline as they depart on spring migration to nesting grounds from early March through 

mid to late April. The chronology described likely varies somewhat among and within 

years depending on weather and sea ice dynamics, and perhaps also as a function of 

physiological condition of the birds. 

The highest wintering population estimates from this study were 1,247 and 4,284 

eiders in eastern and western CI, respectively, in January 2005. We believe most of the 

estimates made during this study are biased slightly low because data were not corrected 

for eiders not detected during surveys. Also, variation among years is evidenced by an 

estimate (2,370 eiders) from a portion of eastern CI that was recorded during an aerial 
survey in early March, 2001 (W. Larned, U.S. Fish and Wildlife Service, unpubl. data), a 

number much higher than any observed during this study in that area. 

Areas frequented by substantial numbers of Steller's eiders in winter during these 

surveys (with maximum estimates recorded) included, in eastern CI, the nearshore area 

from Anchor Point to 25km north of Ninilchik (1,141 in January 2005, Table 3, Fig. 16, 

and 2,370 in March 2001, W. Larned, U.S. Fish and Wildlife Service, unpubl. data), and 

the nearshore area from Homer Spit to Anchor Point (338 in February 2004, Table 2, Fig. 

12). Important areas included in western CI were southern Kamishak Bay from Douglas 

River to Bruin Bay, including the shoreline between Bruin Bay and Ursus Cove, a shoal 

12km southeast of Bruin Bay (3,921 in January 2005, Table 3, Fig. 16), and the mouth of 

Iniskin Bay (363 in January 2005, Table 3, Fig. 16). Observations of eiders molting in 

the Douglas River shoals in August and September, as noted in RESULTS above suggest 

that portions of Kamishak Bay may be occupied nearly year-round. 

During the winter, limited satellite telemetry data (D. Rosenberg, Alaska Department 

of Fish and Game, unpubl. data) indicated that birds in at least one location (southern 

Kamishak Bay) may have moved to Kodiak and other portions of the species winter 

range outside the study area, apparently in response to displacement from favored feeding 

areas by sea ice and possibly inclement weather. 

STUDY PRODUCTS: 1. Final Report: Larned, William W. 2006. Winter distribution 

and abundance of Steller’s eiders (Polysticta stelleri) in Cook Inlet, Alaska, 2004-2005. 

U.S. Fish and Wildlife Service, Waterfowl Management Branch, Anchorage, Alaska. 

OCS Study, MMS 2006-066. 37 pp. (20 bound hard copies, one camera ready master 

copy, and computer files of report in MS WORD and ADOBE .pdf format) 

2. Excel files containing all aerial data collected during this study for Steller's eiders, 

other incidental waterbird and marine mammal observations, with date, time, observer, 

location coordinates, and ancillary environmental data for each observation 

3. 23 digital photographic images made during the study, with written description of 

each image, all on CD. 

4. Appendix to Final Report containing brief accounts of other marine birds and marine 

mammals recorded during the survey. 
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ÊÚ

ÊÚ

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ÊÚ

Nin ilc hik

An ch or

Po int

Ho me r

Ninilchik

Anchor

Point

Homer

1E

2E

3E

4E

Kenai

COOK

INLET

Kachemak Bay

1W

2W

3W

4W

5W

Kamishak Bay

Tuxedni Bay

Chinitna

 Bay

Iniskin

Bay

Illiamna

 Bay

Ursus

Cove

Bruin

Bay

McNeil

 Cove

Akumwarvik

 Bay

Douglas

R. Shoals

Cape

 Douglas

10m isobath

20m isobath

Transects flown

STEI Flocks Observed # 1 - 19

# 20 - 90

# 91 - 170

# 171 - 300

# 301 - 520

N

20 0 20 40 Kilometers

Figure 1. Transects flown and locations of Steller's eider groups recorded during an 

aerial survey, Cook Inlet, Alaska, 2-4 March 2005. Flock symbols are proportional to 

ranges of numbers of eiders as noted in the legend.