Trends in body condition in polar bears ( Ursus maritimus ) from the Southern Hudson Bay subpopulation in relation to changes in sea ice

What is it about?

In this paper we show that there has been a long term decline in body condition of polar bears from the Southern Hudson Bay subpopulation that spends the winter on the sea ice in the east half of Hudson Bay. We also show that there has been a long term decline in the length of the ice-covered season for these bears. The results suggest that the bears now have about a month less time to hunt seals than they did in the early 1980s, which would explain their poorer body condition.

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Why is it important?

Sea ice is the most important habitat to polar bears but the duration and distribution of sea ice is changing rapidly across the Arctic. It appears that sea ice is changing more quickly in regions such as Hudson Bay and that these changes have had an effect on the polar bears. Changes in individual-level traits such as body condition can be expected to precede population-level traits such as declines in survival rates and ultimately in the number of bears in a population. The results of our study are another warning sign that major changes are occurring in the marine system of Hudson Bay.