Polar bears and other Arctic animals are shifting their distributions toward icier regions, according to new research suggesting that at least some species are attempting to adapt to climate-related changes in their habitat, such as dramatic losses of sea ice.
Individual animals are not marching northward en masse, according to Elizabeth Peacock, a U.S. Geological Society researcher who recently studied polar bears. Rather, the population distribution shifts appear to be gradual and subtle.
The bears, as well as certain other animals, literally are trying to go with the flow.
"In general, polar bears move with their habitat," explained Peacock, whose study is published in the latest issue of PLOS ONE.
"Sea ice is like a moving sidewalk and they travel with it," she continued. "Bears likely move towards places with better access to prey and mates."
Sea ice is important to polar bears, she said, because they use it as a platform for access to prey (seals), for migration, mating and denning. Without much ice, they have to swim greater distances in expanses of open water. Additionally, the bears may go into a "walking hibernation" on land and stop eating.
"The longer the ice-free period," she said, "the longer the time without feeding."
As a result, it appears that polar bears over the past 15 to 45 years have shifted their distribution more toward the Canadian Archipelago, which is north of the Canadian mainland in the Arctic.
Peacock and her team identified four genetically similar clusters of polar bears identified by their primary location: Eastern Polar Basin, Western Polar Basin, Southern Canada and the Canadian Archipelago. DNA analysis found that there is directional gene flow toward the latter.
Polar bears aren't the only animals exhibiting such changes.
"There are a number of other Arctic species that have shifted distributions with loss of sea ice," Kristin Laidre at the University of Washington's Polar Science Center told Discovery News.