Receding sea ice poses threat to polar bears
anchorage (Alaska) — Some polar bears in the Arctic are shedding pounds during the time they should be beefing up, a new study shows. It’s the climate change diet and scientists say it’s not good.
They blame global warming for the dwindling ice cover on the Arctic Ocean that bears need for hunting seals each spring.
For their research, the scientists spied on the polar bears by equipping nine female white giants with tracking collars that had video cameras and the bear equivalent of a Fitbit during three recent springs. The bears also had their blood monitored and were weighed.
What the scientists found is that five of the bears lost weight and four of them lost 2.9 to 5.5 pounds (1.3 to 2.5 kilograms) per day. The average polar bear studied weighed about 386 pounds (175 kilograms). One bear lost 51 pounds (23kg) in just nine days.
“You’re talking a pretty amazing amount of mass to lose,” said US Geological Survey wildlife biologist Anthony Pagano, lead author of a new study in Thursday’s journal Science .
Researchers studied the bears for 10 days in April, when they are supposed to begin putting on weight so they can later have cubs, feed the cubs and survive through the harsh winter.
But because the ice is shrinking, the bears are having a harder time catching seal pups even during prime hunting time, Pagano said. The United States Fish and Wildlife Service lists polar bears as a threatened species. Polar bears hunt from the ice. They often wait for seals to pop out of holes to get air and at other times they swim after seals. If there is less sea ice and it is broken apart, bears have to travel more — often swimming — and that has serious consequences, such as more energy use, hypothermia and risk of death, said University of Alberta biology professor Andrew Derocher, who wasn’t part of the study. The study found that on the ice, the polar bears burn up 60 per cent more energy than previously thought, based on these first real-life measurements done on the ice. —