Female polar bears prowling springtime sea ice have extreme weight swings, some losing more than 10 percent of their body mass in just over a week.
And the beginnings of bear video blogging help explain why.An ambitious study of polar bears (Ursus maritimus) in Alaska has found that their overall metabolic rate is 1.6 times greater than thought, says wildlife biologist Anthony Pagano of the U.S. Geological Survey in Anchorage. With bodies that burn energy fast, polar bears need to eat a blubbery adult ringed seal (or 19 newborn seals) every 10 to 12 days just to maintain weight, Pagano and his colleagues report in the Feb. 2 Science. Camera-collar vlogs, a bear’s-eye view of the carnivores’ diet and lifestyle secrets, show just how well individual bears are doing.
The study puts the firmest numbers yet on basic needs of polar bears, whose lives are tied to the annual spread and shrinkage of Arctic sea ice, Pagano says. As the climate has warmed, the annual ice minimum has grown skimpier by some 14 percent per decade (SN Online: 9/19/16), raising worries about polar bear populations. These bears hunt the fat-rich seals that feed and breed around ice, and as seal habitat shrinks, so do the bears’ prospects.
Weight changes varied a lot for the nine female polar bears studied for 8 to 11 days. Fat seals were the richest prey, but hungry bears also picked muscle tissue out of seal carcasses and took advantage of a whale that human hunters had caught.
Pagano and colleagues used helicopters to search for polar bears on ice about off the Alaska coast in…
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