Grizzly bears have entered polar bear territory, setting the stage for deadly bear versus bear encounters to come, suggests a study recently published in the journal Canadian Field Naturalist.
Should the bears meet, the grizzlies could do some serious damage.
"This is worrying for the polar bears because grizzly bears would likely hibernate in polar bear maternity denning habitat," explained Linda Gormezano, a co-author of the paper. "They would come out of hibernation at the same time and can kill polar cubs."
(Go to this page to see a video of a polar bear cub nursing.)
Gormezano and her colleagues documented sightings of the bears in Canada's Wapusk National Park. The bears are moving into the Canadian province of Manitoba in regions traditionally thought of as polar bear habitat.
"Grizzly bears are a new guy on the scene, competition and a potential predator for the polar bears that live in this area," said Robert Rockwell, who also worked on the study. He is a research associate at the American Museum of Natural History and a professor of biology at the City College of the City University of New York.
He shared that "the first time we saw a grizzly we were flying over the middle of Wapusk, counting fox dens" when Gormezano "shouted, 'Over there, over there—a grizzly bear.' And it wasn't a dirty polar bear or a moose—we saw the hump."
Before 1996, there was no evidence that grizzly bears encroached on polar bear territory. From that year on, however, there have been at least 12 sightings, negating the prior theory that the barren landscape north of the Hudson Bay was impassable, in terms of resources, for migrating grizzly bears. But the flexible bears, which can eat everything from meat to berries, have crossed the gap and likely won't look back much, since the polar bear region is known for its abundant caribou, moose, fish and berries.
"Although we don't yet know if they are wandering or staying—the proof will come from an observed den or cubs—these animals will eventually be residents of this national park," said Rockwell. "The Cree elders we talked to feel that now that grizzly bears have found this food source they will be staying."
Gormezano continued, "A big question is how to deal with these new residents. In Canada, both the polar and grizzly bear are federally listed as species of special concern. In Manitoba, the polar bear is provincially listed as threatened while the prairie population of the grizzly bear is listed as extirpated."