MMS ENVIRONMENTAL STUDIES PROGRAM: ONGOING STUDIES
MMS OCS Region: Alaska
Title: Demography and Behavior of Polar Bears Feeding on Stranded Marine Mammal Carcasses
Total Cost: Period of Performance: FY 2002 - 2003
Conducting Organization: USGS, Biological Resource Division, or Competitive
MMS Contact:

Chief, Alaska Environmental Studies Section
Description:
Background  In the Beaufort Sea, polar bears make extensive movements between the United States and Canada. Alaskan polar bears spend most of the year on the drifting pack ice, but in late summer and fall, polar bears travel along the coast and barrier islands of Alaska and have been observed feeding on stranded marine mammal carcasses. In recent years large numbers of polar bears congregate at whale harvest sites near Kaktovik, Barrow, Cross Island, and barrier island complexes along the Beaufort Sea. In addition, an increase in polar bear numbers and an earlier more protracted use of the Beaufort Sea coastline and barrier islands in Alaska have been noted in recent years.

Certain sex-age classes of polar bears may use beached marine mammal carcasses more frequently than other sex-age classes. Studies by Canadian scientists indicate that on sea ice, independent yearlings, subadults, and family groups may be displaced from their kills by larger, more dominant bears (Stirling 1974). Stranded marine mammal carcasses may provide an important alternative food source to animals unable to compete with dominant male polar bears for their primary food source, ringed seals. Marine mammal carcasses may also be important during periods of a polar bear's life cycle when energetic demands are increased. Examples are females with increased energetic costs associated with milk production for cubs and younger bears with increased metabolic needs associated with growth. Bears in these situations are more likely to become nutritionally stressed (Lunn and Stirling 1985).

No systematic observations have been conducted to quantify the level of use or potential importance of marine mammal carcasses to certain age and sex classes of polar bears. Beginning in 2000, however, industry will be conducting aerial polar bear surveys of coastal habitat over a series of years during the open water season until freeze-up in the Beaufort Sea. These surveys are required by stipulations set forth in the Northstar Environmental Impact Statement. The objective of these surveys is to provide general information regarding seasonal trends in the distribution and relative abundance of polar bears in terrestrial habitat.

Objectives  The purposes of this pilot study are to identify the magnitude of interchange of bears to and from feeding sites, the sex/age composition, utilization patterns, and behaviors of polar bears using beach cast marine mammal carcasses along the Beaufort Sea coastline in Alaska. These objectives will complement information obtained from aerial surveys.
Methods  Polar bears feeding on the remains of a hunter-harvested bowhead whale carcasses at Kaktovik and other locations along the Beaufort Sea coastline will be monitored. Observations will be conducted with binoculars and spotting scopes during daylight hours for up to 30 days to determine the exchange rates, sex/age composition, activity budgets, and behavior of bears at the feeding site. A report summarizing the findings will be prepared.
Importance to MMS Oil and gas operations on the Coastal Plain of the Beaufort Sea are ongoing and expanding to offshore areas. Recent Environmental Impact Statements (e.g., Northstar) have highlighted the need for additional information on polar bear use of coastal habitats. Estimating the number, sex, and age class of polar bears using marine mammal carcasses will help managers document and evaluate the ecological significance of coastal areas to polar bears. Results from this study can also be used to implement measures that decrease impacts of human activities on polar bear feeding habitat and minimize human interactions with polar bears.
Current Status:
Final Report Due:
Publications:
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Revised date: March 2002
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