Melting Sea Ice Forcing Polar Bears to Swim Longer Distances, Putting Cubs at Risk


Source: Marketwire

Study Represents the First Empirical Research to Find a Significant, Increasing Trend in Polar Bear Long-Distance Swimming

OTTAWA, ONTARIO -- (Marketwire) -- 07/20/11 -- Sea ice loss from climate change is causing polar bears to swim longer distances to find stable ice or to reach land, resulting in greater risk to their cubs, according to a new paper co-authored by a WWF expert.

'Climate change is pulling the sea ice out from under polar bears' feet, forcing some to swim longer distances to find food and habitat,' said Geoff York, WWF Polar Bear Expert who is an author of the study.

'This research is the first analysis to identify a significant multi-year trend of increased long-distance swimming by polar bears. Prior research had only reported on single incidents,' said York.

U.S. Geological Survey biologist and lead author Anthony Pagano presented the study ('Long-distance swimming events by adult female polar bears in the southern Beaufort and Chukchi Seas') on July 19 at the International Bear Association (IBA) Conference held in Ottawa, Canada.

Between 2004 and 2009 researchers collected data from 68 GPS collars deployed on adult female polar bears, in combination with satellite imagery of sea ice, to identify incidences of bears swimming more than 30 miles at a time. Researchers identified 50 long-distance swimming events during the six year period involving 20 polar bears. Swimming events ranged in distance up to 426 miles and in duration up to 12.7 days.

Eleven of the polar bears that swam long distances had young cubs at the time of collar deployment; five of those bears lost their cubs during swimming - a 45% morality rate. In contrast, only 18% of cubs died that were not compelled to swim long distances with their mother.

Key Facts

--  Arctic sea ice extent has dropped to record low levels in July 2011; sea
    ice volume is now 47% lower than 1979 levels when satellite records
    began (Source: University of Washington Polar Science Center).
--  The annual Arctic sea ice minimum will be reached in mid-September.
    September 2010 saw the third lowest sea ice extent on record. The lowest
    and second-lowest extents occurred in 2007 and 2008 (Source: National
    Snow and Data Center).
--  Long-distance swimming puts polar bears at risk of drowning due to
    fatigue or rough seas and requires large amounts of energy that the
    bears need to survive in the Arctic.
--  Adult male polar bears were not studied because they cannot retain GPS
    collars because their muscular necks are larger than their heads.

High-resolution photos and video available upon request

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