In Arctic waters, where ice pack is thinning and making it difficult for polar bears to hunt seals, snow goose eggs may help stave off their starvation. New research shows that ice is breaking up earlier in the season because of global warming, forcing polar bears to come ashore when snow geese nest.
鈥淣ow suddenly the thing that is supposed to be causing the bears the problem may be helping them,鈥 says Robert Rockwell, an ornithologist at the American Museum of Natural History and an author of the study.
In his 40 years studying the Arctic, Rockwell has seen six polar bears, the world鈥檚 largest land predators, in the fields of snow goose nests. They push their noses against the eggs until the shells break so the bears can eat the nutritious embryos. Four of the six animals seen were observed after 2000.
With four eggs in a clutch, the bears can consume roughly 800 to 900 calories per nest. And there can be hundreds of nests in a field. In an area with 325 nests, one young polar bear ate the eggs in 206 of them鈥攚hich is equal to about eight seals鈥攊n just 96 hours. Although nobody is sure how many seals a polar bear eats in year, Rockwell estimates that one hunt for eggs could supply a quarter of a bear鈥檚 annual diet. 鈥淓ggs don鈥檛 run, so this is a really cost effective dinner,鈥 he says.
The snow goose population has been exploding by five to six percent every year since 1970, and is now to the point where the environment can no longer support so many birds. The Canadian government as well as environmentalist have been trying all sorts of ways to reduce the environmental damage from the flocks, but haven鈥檛 had very much success. If more polar bears begin eating the eggs, the decrease in the goose population could actually benefit the environment. 鈥淭his is one of the most exciting things that鈥檚 happened since the snow goose boom,鈥 says Rockwell.
Courtesy of the U.S. Fish and Wildlife Service
Now that the polar bear is listed as threatened under the Endangered Species Act, officials are trying to make decisions about how to protect the animals. Rockwell argues that this recent finding shows that the authorities should be making decisions based on how the bears are acting now, not how they鈥檝e acted in the past. They鈥檙e opportunists and some may be able to adapt to the shifting conditions. 鈥淚f you鈥檙e a top end predator, you鈥檙e not going to turn your nose up at anything. As the habitat changes, behavior changes, too,鈥 he says.