New research from the University of Alberta reveals that an increasing number of polar bears have been undertaking long-distance swims, which can be dangerous.
The researchers defined long-distance as swims exceeding 50 kilometres. Between 2004 and 2012, the number of polar bears that undertook long-distance swims more than doubled in some years. The increase is a result of a loss of sea ice due to climate change.
“Recent studies indicate that swimming may be energetically costly to polar bears,” lead author Nicholas Pilfold explained in a news release. “Given the continued trend of sea ice loss, we recognize that an increased frequency in the need to engage in this behaviour may have serious implications for populations of polar bears living around the Arctic Basin.”
The researchers found that in 2012, when sea ice was at a record low, 69% of adult females in the Beaufort Sea swam more than 50 kilometers at least once. In years where less ice melted completely, less than 30% of the bears swam long distances. Bears in the Hudson Sea, where sea ice melt hasn’t changed, were less likely to undertake long-distance swims.
“While polar bears as a species are eminently suited to swimming, not all bears are equally able to swim long distances,” said study co-author Andrew Derocher. “The youngest, oldest and skinniest bears are much more vulnerable to drowning. With more open water, we can expect increased mortality associated with more long-distance swimming.”
To learn more:
- Read the news release: Sink or swim: polar bears swimming more as sea ice retreats
- Read the study abstract: Migratory response of polar bears to sea ice loss: to swim or not to swim
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