The results reveal the timing of polar bears' migration can be predicted by how fast the sea ice melts and freezes, and by when specific sea ice concentrations occur within a given area of Hudson Bay.
According to Dr Cherry: "The data suggest that in recent years, polar bears are arriving on shore earlier in the summer and leaving later in the autumn. These are precisely the kind of changes one would expect to see as a result of a warming climate and may help explain some other studies that are showing declines in body condition and cub production."
Recent estimates put the western Hudson Bay polar bear population at around 900 individuals. The population has declined since the 1990s, as has the bears' body condition and the number of cubs surviving to adulthood.
Because polar bears' main food source is seals, and these are hunted almost exclusively on sea ice, the longer bears spend on land, the longer they must go without energy-rich seals. "Climate-induced changes that cause sea ice to melt earlier, form later, or both, likely affect the overall health of polar bears in the area. Ultimately, for polar bears, it's survival of the fattest," says Dr Cherry.
He hopes the results will enable other scientists and wildlife managers to predict how potential climate-induced changes to sea ice freeze-thaw cycles will affect the ecology, particularly the migration patterns, of this iconic species.
|Contact: Becky Allen|