Summer declines in activity and body temperature offer polar bears limited energy savings

Science
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Abstract

Polar bears (Ursus maritimus) summer on the sea ice or, where it melts, on shore. Although the physiology of “ice” bears in summer is unknown, “shore” bears purportedly minimize energy losses by entering a hibernation-like state when deprived of food. Such a strategy could partially compensate for the loss of on-ice foraging opportunities caused by climate change. However, here we report gradual, moderate declines in activity and body temperature of both shore and ice bears in summer, resembling energy expenditures typical of fasting, nonhibernating mammals. Also, we found that to avoid unsustainable heat loss while swimming, bears employed unusual heterothermy of the body core. Thus, although well adapted to seasonal ice melt, polar bears appear susceptible to deleterious declines in body condition during the lengthening period of summer food deprivation.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Summer declines in activity and body temperature offer polar bears limited energy savings
Series title Science
DOI 10.1126/science.aaa8623
Volume 349
Issue 6245
Year Published 2015
Language English
Publisher American Association for the Advancement of Science
Publisher location New York, NY
Contributing office(s) Alaska Science Center Biology MFEB
Description 4 p.
First page 295
Last page 298
Online Only (Y/N) N
Additional Online Files (Y/N) N