Polar bears are listed as threatened under the Endangered Species Act and ‘vulnerable’ on the IUCN Red List. They face an increasing number of threats that have shifted over the last 40 years from hunting to climate change.
Scientists at the American Museum of Natural History (AMNH) recently published the final paper in a three-part series about the status of polar bears in a changing environment. The study suggests that as the Arctic warms, polar bears are coping by switching to alternative food sources.
Arctic sea ice is melting earlier and freezing later every year, which limits the amount of time that polar bears have to hunt their preferred prey (ringed seal pups) and increases the amount of time they must spend on land. The polar bears’ problem with a shorter season on ice is that they gain most of their annual fat reserves in the spring by consuming seal pups before coming ashore for the summer. Now, they must find ways to compensate for their limited seal-hunting time.
The study indicates that at least some polar bears in the Western Hudson population are using “flexible foraging strategies” while on land, which include hunting alternative prey and eating a mixed diet of plants and animals.
Here are the highlights of the three-part series:
- Part one, published in spring 2013, reveals that polar bears are hunting adult and juvenile lesser snow geese during mid-to-late summer.
- Part two, published in summer 2013, reveals that the diet of some polar bears has shifted to include more caribou and snow geese since climate change began affecting the Hudson Bay lowlands 40 years ago.
- Part three, published in December 2013, reveals that most polar bears consuming a mixed diet of plants and animals.
- The researchers suggest that their flexibility in diet comes from their shared genetic heritage with brown bears. Polar bears became distinct from brown bears about 600,000 years ago.
The results show that while polar bears are still threatened by climate change, at least some may be able to cope with the longer ice-free seasons and limited access to their typical food supply.
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