How Do Polar Bears Cope With Summer Conditions Altered by Climate Change?

EPA Grant Number: FP917373
Title: How Do Polar Bears Cope With Summer Conditions Altered by Climate Change?
Investigators: Whiteman, John P
Institution: University of Wyoming
EPA Project Officer: Just, Theodore J.
Project Period: August 1, 2011 through July 31, 2014
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2011) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Global Change


Approximately 40 percent of polar bears globally exist in areas where the sea ice retreats from shore during summer, and individuals may choose to move to shore or follow the ice north. Climate change is reducing the extent of Arctic sea ice and lengthening the summer melt period and as a result, bears that follow the ice north in summer are located over areas of deeper water, and bears that move to shore must remain there for longer time periods; both locations may contain few seals for prey. This research seeks to understand the physiological and behavioral capabilities of polar bears to withstand food deprivation on ice over deep water and on shore, and the results will inform models of future population trends.


Polar bears are captured in early summer and sampled and fitted with GPS collars. They are then recaptured in late summer on sea ice over deep water and on shore. Sampling is repeated and the collar is retrieved. Changes over the summer are quantified for body condition and nutritional state, use of stored energy, protein conservation and reductions in activity and metabolic rate. These changes reflect whether bears are forced to fast and how they cope with fasting, given their location on ice or on shore.

Expected Results:

In this project, it is hypothesized that polar bears on shore during summer employ two strategies: they may fast and reduce activity and metabolic rate, allowing them to minimize loss of body condition; or, they may consume alternative food items available only on shore and maintain normal activity and metabolism. In addition, it is hypothesized that bears on sea ice attempt to continue hunting and maintain high activity rates because prior to recent ice declines, this was a successful summer strategy; however, due to low seal density in deep water they are forced to enter a fast and reduce their metabolic rate to save energy. The results of this project can be used to generate parameters for population models that will forecast probabilities of population increase or decrease in the future, given changes in sea ice conditions.

Potential to Further Environmental/ Human Health Protection

Testing the hypotheses in this project will yield an understanding of how polar bears respond to sea ice loss during summer months. Understanding the behavioral and physiological consequences of this decision under altered summer conditions caused by climate change will provide insights on the long-term persistence of polar bears and assist in making informed management decisions for this symbol of the Arctic.

Supplemental Keywords:

Alaska, Arctic, climate change, polar bear, sea ice, Ursus maritimus