As More Arctic Ice Melts, Polar Bears Get Creative to Feed Themselves

As warming temperatures change the landscape of the Arctic, polar bears there are showing remarkable resiliency in surviving by changing their diet to accommodate, according to recent research.

Historically, polar bears' prey of choice are ringed seal pups. But as a warming climate causes Arctic sea ice to melt quicker each year, it limits hunting opportunities for polar bears, who venture out on the ice in search of prey.

A group of researchers from the American Museum of Natural History observed polar bears living along the western Hudson Bay, noting a variety of adaptive foraging strategies to find food on land, including prey-switching and eating a mixed diet of plants and animals.

"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, a research associate in the Museum's Department of Ornithology. "But we're finding that they might be more resilient than is commonly thought."

A trio of research papers by Museum scientists have documented these dietary adaptations in polar bears.

The first, published lat year, documented the first time polar bears were witnessed hunting lesser snow geese. A second paper highlighted the polar bear diet through an analysis of its excrement, noting how the animal's diet had shifted in the past four decades. Today's polar bears are preying more upon snow geese and caribou than in the past, the researchers found.

The third paper in the series, which was published by Rockwell and Linda Gormezano, a postdoctoral researcher in the Museum's Division of Vertebrate Zoology, in the December 2013 edition of the journal BMC Ecology, explores how the polar bears are compensating for energy deficits that result from being able to eat fewer seals.

To make up the deficit, the researchers found that polar bears, with few exceptions, are now consuming a mixed diet of plants and animals.

"The predominance of local vegetation in collected scat suggests little movement among habitat types between feeding sessions, indicating that the polar bears are keeping energy expenditure down," the Museum wrote in a press release Tuesday, adding that the during this period of less Arctic ice the polar bears are exhibiting a "flexible-foraging" strategy.

"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 Gormezano. "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. Our results suggest that some polar bears may possess this flexibility and thus may be able to cope with rapidly changing access to their historic food supply."