A female polar bear swam 426 miles (687 kilometers) straight, the length from Boston to Washington DC and the longest swim for a polar bear ever recorded. Sadly, the reason for her 9-day swim in the icy waters of the Beaufort Sea is global warming, which has led to the sea ice shrinking. The bear had to swim such a huge distance in order to find land.
Says National Geographic:
Until 1995, summer sea ice usually remained over along the continental shelf of the Beaufort Sea, a critical habitat for polar bears due to its rich seal population. Now the sea ice in the Beaufort and Chukchi Seas is retreating from the coast by hundreds of kilometers, [George] Durner [a U.S. Geological Survey research zoologist in Anchorage, Alaska], said.
In 2010, Arctic sea ice extent was the third lowest on record, part of a long-term trend of ice loss that will continue for decades to come, according to the National Snow and Ice Data Center in Boulder, Colorado.
The polar bear’s epic swim came at a harsh price, the loss of her cub, who died at some point after the swim started. The bear also lost 22 percent of her body weight swimming in near-freezing waters.
The bear was one of 68 female bears collared between 2004 and 2009, with the intent of studying their movements. Biologists noted gaps in the data on the bears and linked these to when they were at sea; they correlated the female polar bears’ long-distance swimming (defined as swims longer than 30 miles (50 kilometers) ) to the survival of their cubs. Five out of eleven mothers who had cubs prior to the long swims no longer had them when they were again on land, scientists found.
As Steve Amstrup, a former scientist at the USGS and now chief scientist at Polar Bears International and a co-author of a study on the bears, said in MSNBC:
“Young bears don’t have very much fat and therefore they aren’t very well insulated and cannot cope with being in cold water for very long.”
Because they are leaner than their parents, Amstrup said, “they probably aren’t as buoyant (as adult polar bears) so in rough water they’ll have more difficulty keeping their heads above water.
According to MSNBC, in June, the arctic sea ice extent — the area covered by sea ice — was the second lowest since 1979, according to the National Snow and Ice Data Center.
Polar bears are listed as a threatened species in the US; in Canada, they are listed as a species at risk. But if female polar bears are forced to make such long-distance swims, it doesn’t bode well for their cubs’ survival; for the polar bears’ survival.
Photo by USFWS Headquarters