Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water

Canadian Journal of Zoology
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Abstract

Polar bears (Ursus maritimus Phipps, 1774) depend on sea ice for catching marine mammal prey. Recent sea-ice declines have been linked to reductions in body condition, survival, and population size. Reduced foraging opportunity is hypothesized to be the primary cause of sea-ice-linked declines, but the costs of travel through a deteriorated sea-ice environment also may be a factor. We used movement data from 52 adult female polar bears wearing Global Positioning System (GPS) collars, including some with dependent young, to document long-distance swimming (>50 km) by polar bears in the southern Beaufort and Chukchi seas. During 6 years (2004-2009), we identified 50 long-distance swims by 20 bears. Swim duration and distance ranged from 0.7 to 9.7 days (mean = 3.4 days) and 53.7 to 687.1 km (mean = 154.2 km), respectively. Frequency of swimming appeared to increase over the course of the study. We show that adult female polar bears and their cubs are capable of swimming long distances during periods when extensive areas of open water are present. However, long-distance swimming appears to have higher energetic demands than moving over sea ice. Our observations suggest long-distance swimming is a behavioral response to declining summer sea-ice conditions.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water
Series title Canadian Journal of Zoology
DOI 10.1139/Z2012-033
Volume 90
Issue 5
Year Published 2012
Language English
Publisher National Research Council of Canada
Publisher location Ottawa, Canada
Contributing office(s) Alaska Science Center Biology MFEB
Description 14 p.
First page 663
Last page 676
Online Only (Y/N) N
Additional Online Files (Y/N) N
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