January 23, 2014
Polar Bears Change Diet To Adapt To Climate Change
Lee Rannals for redOrbit.com - Your Universe Online
Polar bears are able to switch up their diet in order to help them survive the warming Arctic, according to a new study. Scientists at the American Museum of Natural History performed a three-part study that shows how polar bears switch up plant and animal food sources as they face the changing climate.
Arctic sea ice is beginning to melt earlier and freezing later each year, so polar bears are having a limited amount of time to hunt ringed seal pups, their preferred prey, and are having to spend more time on land. The new studies find that some polar bears are switching their foraging strategies while on land by 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," Robert Rockwell, a research associate in the Museum's Department of Ornithology, said in a statement. "But we're finding that they might be more resilient than is commonly thought."
The United States Endangered Species Act lists polar bears as a threatened species and the International Union for Conservation of Nature and Natural Resources' Red List lists the animals as “vulnerable.” Climate change is shrinking the bears' Arctic habitat, and an alteration in diet means that bears may not get that extra layer of fat reserve they need to survive the harsh conditions.
Researchers gathered video data on polar bears as they pursued, caught and ate adult and juvenile snow geese during the mid-to-late summer. Polar bear scat revealed that some of the polar bear diet has changed from what it was 40 years ago, before climate change was affecting the Hudson Bay lowlands. Scat samples also showed polar bears are consuming a mixed diet of plants and animals.
The team said that the polar bears’ flexible foraging behavior likely stems from a shared genetic heritage with brown bears.
"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, a postdoctoral researcher in the Museum's Division of Vertebrate Zoology.
"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.”
Gormezano said that their findings suggest the flexibility polar bears possess could help them cope with rapidly changing access to their historic food supply. The team published their findings in the journals Polar Ecology, Ecology and Evolution and BMC Ecology.