ACCESS NUMBER: 85166

STUDY TITLE: Polar Bear Feeding and Monitoring 

REPORT TITLE: Demographics and Behavior of Polar Bears Feeding on Bowhead 

Whale Carcasses at Barter and Cross Islands, Alaska, 2002-2004 

CONTRACT NUMBER: IA 0103RU85166 

MMS STUDY NUMBER: 2006-014 

SPONSORING OCS REGION: Alaska 

APPLICABLE PLANNING AREA: Beaufort Sea 

FISCAL YEARS OF PROJECT FUNDING: 2002-2006 

COMPLETION DATE OF REPORT: April 2006 

COSTS: BY FISCAL YEAR: 2002 $ 64,279 

 2003 $ 48,577 

 2004 $ 35,115 

 2005 $ 30,476 

 2006 $ 38,320 

CUMULATIVE PROJECT COST: $216,767 

PROJECT MANAGERS: Scott Schliebe, Polar Bear Project Leader 

AFFILIATION OF PROJECT MANAGER: U.S. Fish and Wildlife Service, Marine 

Mammals Management 

ADDRESS: 1011 E. Tudor Road, Anchorage, Alaska 99503 

PRINCIPAL INVESTIGATORS: Susanne Miller, Scott Schliebe, and Kelly Proffitt 

KEY WORKDS: Polar bears, feeding ecology, Beaufort Sea, Alaska, demographics, 

behavior 

BACKGROUND: In 2001, Minerals Management Service funded this study to 

increase understanding of foraging patterns of polar bears along the Beaufort Sea coast 

of Alaska. During the fall open-water period, polar bears have been observed in 

increasing numbers in the near shore environment, particularly in areas where hunterharvested bowhead whale remains occur. The near shore environment is subject to oil 

and gas development and other human activities that have the potential to impact polar 

bears and their foraging habits and activity patterns. 
ACCESS NUMBER: 85166

OJBECTIVES: The objectives of this study are to: 1) determine the number, age/sex 

composition, behavior, and habitat use of polar bears using bowhead whale carcasses 

at Barter and Cross Islands during fall months; and 2) determine the magnitude of 

interchange of polar bears between Barter Island and Cross Island during fall months. 

DESCRIPTION: Data was collected by direct observation of polar bears during 3-hour 

sessions systematically selected during day, dawn/dusk, and night. Whole island 

counts were conducted to obtain daily estimates of polar bears in the area. Scan 

sampling (at 15 minute intervals) was used to determine the number, age and sex of 

bears present at study sites; focal animal sampling of randomly selected individuals was 

used to record behavior (during 20-minute intervals) and frequency of marine habitat 

use. 

SIGNIFICANT CONCLUSIONS: Results from this study confirm that polar bears tend 

to aggregate on Barter and Cross islands during the fall open water period, with greater 

numbers observed at Barter Island than at Cross Island. Bowhead whale remains likely 

play a role in concentrating polar bears that are using coastal areas during fall months. 

Polar bears did not remain exclusively on land; rather, at Barter Island they used marine 

habitat regularly to access and depart from the feeding site. One factor that may affect 

numbers of polar bears using whale carcasses is time of day; bear density was 

generally higher during dark. Local factors such as the social dynamics among polar 

bears, brown bears, and humans, may also influence bear use of the feeding sites. For 

example, in 2003 and 2004 the presence of 8-12 grizzly bears resulted in frequent 

displacement of polar bears from the carcass remains. To our knowledge, these are the 

first recorded observations of polar and brown bears simultaneously using and 

interacting at a carcass feeding site in Alaska. Overall, polar bears exhibited a high 

degree of tolerance of each other at the feeding sites; all age/sex classes of polar bears 

were often observed feeding simultaneously, including large adult males feeding right 

next to females with dependent cubs with little time spent in aggressive interactions. 

Aggressive interactions among all polar bears tended to be short in duration and 

initiated by mothers or curious cubs. 

Results from this study are being used to monitor long-term trends of polar bear use of 

the Beaufort Sea coastline and for planning human activities, such as oil and gas lease 

sales. The study has also increased awareness to a growing concern over large 

numbers of bears concentrating near human developments, and the subsequent 

potential for increased bear-human conflicts. 

STUDY RESULTS: A total of 1,231 hours of observations were conducted during the 

course of the study, including 4,733 scans and 925 focal samples. An average of 33 

(range 0-65) and 6 (range 0-13) polar bears used Barter and Cross islands, 

respectively. The highest number of bears we saw feeding at one time was 37; use was 

highest at night. Bear numbers at both islands increased over the 3-year study period. 

Individual polar bears were not observed using both Barter and Cross islands during our 

study periods; however, telemetry data indicates that some interchange between the 

two islands can occur later in the season. At Barter Island, polar bears frequently swam 
ACCESS NUMBER: 85166

from Bernard Spit (an off shore barrier island) to the carcass site, and also frequently 

entered water between feeding bouts. Family groups spent more time in the water than 

other cohorts. 

All age-sex classes of polar bears were observed at both Barter and Cross islands; the 

highest proportion of animals observed at the Barter Island feeding site were bears in 

family groups, whereas the highest proportion of animals on Cross Island were single 

adult bears. Generally, polar bears tended to be least active (laying, sitting) during day 

and more active (walking, feeding, swimming, interacting) during dark. Overall, polar 

bears spent little time interacting and appeared to be quite tolerant of each other in 

relatively high densities. Interactions tended to be short in duration and most frequently 

initiated by mothers or curious cubs. When brown bears were present, they tended to 

be dominant over polar bears and sometimes displaced polar bears from the feeding 

site. 

STUDY PRODUCTS: MMS Report; results are also being prepared for publication in a 

scientific journal. 
ACCESS NUMBER: 85166

Figure 1. General study area of polar bear study, 2002-2004.