Polar Bear Diet Changes as Climate Warms and Ice Melts

The polar bear is the poster child for climate change. Its habitat is being impacted drastically as sea ice melts and temperatures warm. Now, though, scientists have discovered that polar bear behavior is also changing due to shifting conditions. They've found that these bears are seeking alternate food sources as ice melts, changing their diets in order to survive.

Currently, polar bears are listed as threatened species under the United States Endangered Species Act. Populations of these bears are declining in polar regions as their habitat continues to melt and disappear. Spring time is especially hard for these creatures since that's when they normally consume seal pups in order to store up fat for the winter. Unfortunately, the declining ice means that gaining access to these seal pups is becoming harder and harder. Yet it seems that polar bears are beginning to adapt.

"There is little doubt that polar bears are very susceptible as global climate change continues to drastically alter the landscape of the northern polar regions," said Robert Rockwell, one of the researchers, in a news release. "But we're finding that they might be more resilient than is commonly thought."

The researchers have now found evidence of polar bears pursuing, catching and eating adult and juvenile lesser snow geese during mid-to-late summer when the geese are replacing their primary flight feathers. In addition, bears are preying more on caribou and snow geese eggs.

The findings reveal that polar bears are exhibiting flexible foraging behavior during ice-free periods. In fact, it's likely that this behavior is derived from shared genetic heritage with brown bears, form which polar bears separated about 600,000 years ago.

"For polar bear populations to persist, changes in their foraging will need to keep pace with climate-induced reduction of sea ice from which the bears typically hunt seals," said Linda Gormezano, one of the researchers, in a news release. "Although different evolutionary pathways could enable such persistence, the ability to respond flexibly to environmental change, without requiring selective alterations to underlying genetic architecture, may be the most realistic alternative in light of the fast pace at which environmental changes are occurring."

The findings are published in several articles in Polar Biology, Ecology and Evolution and BMC Ecology.