10/10/2012 3:17:09 PM
Studying Southern Polar Bears
The polar bears of James Bay live farther south than any other bears in the world, at the southern end of Hudson Bay. How are they are faring in a warming Arctic? A new study will provide baseline data and help answer this question.
By Dr. Martyn Obbard
We had a successful field season with the Southern Hudson Bay polar bear population this fall. From September 16th to 22nd, we deployed GPS tracking collars on 10 adult female polar bears and collected important biological data and samples from a total of 36 bears. These data and samples will be used to examine the foraging ecology and habitat use of polar bears at the southern limit of the species' range.
The bears we handled were all in the James Bay region, either on the shores of Akimiski Island, Nunavut, or along the Ontario coast. They ranged in age from cubs born the previous winter to adults approaching the end of their expected lifespan.
The physical condition of the bears also varied: one adult female, who was likely pregnant, was in excellent shape, with abundant stored fat on her body. That stored energy will be crucial when she enters a den, gives birth, and nurses up to three cubs before returning to the sea ice next spring. Another adult female, this one with two cubs of the year, was very thin. She faces the significant challenge of waiting up to three more months before the Bay freezes and she can resume hunting seals on the sea ice.
Despite the ice-free conditions, it was remarkable to see that some bears had managed to prey on seals along the coast of Ontario. We observed a group of four large male bears that had recently consumed an entire juvenile bearded seal, leaving only a few bones and pieces of hide uneaten! On that same day, a few kilometers to the south, we observed another adult male that had killed another juvenile bearded seal. In this case, the bear was content to keep possession of the seal, without eating any of it, for the better part of a day. How these bears managed to hunt seals from shore and why one of them elected not to consume its prey is unknown. But there's a lot we don't know about polar bears at the southern limit of their range.
Our fall fieldwork, which was supported by Polar Bears International, and the data we will continue to receive from collared bears, will provide important insights into the ecology of polar bears in the Southern Hudson Bay region and the conservation outlook for the species in a rapidly changing environment.