Word: polarizes
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...reshuffling of the grizzly- and polar-bear populations is nigh, it's not clear where the new lines will be drawn, says Robert Rockwell, a biologist with the American Museum of Natural History in New York City and co-author of a new paper documenting a spate of recent grizzly sightings in the journal The Canadian Field-Naturalist. Before 1996, there had been no evidence of grizzlies in the national park, but between 1996 and 2009, Rockwell says, there were nine confirmed sightings, plus three more...
Some experts have suggested that the grizzlies might not stick around long enough to face off with the polar bears, says Rockwell, but he isn't buying that. The 4,000-plus-sq.-mi. park where hunting is banned is what Rockwell calls a "food mecca" for grizzlies. Wapusk is home to some 7,000 caribou, an equal number of moose and untold numbers of rabbits, fish, geese and other creatures. When Rockwell and his team ask the real experts - the Cree elders whose ancestors have lived there for generations - they say, "Why would a bear that's found...
Paradoxically, the intrusion of another top predator could in some ways make life easier for the white bears, says Rockwell. "Polar bears will eat anything they can get their grubby little mouths around," he says. "They'll take flightless geese, seals silly enough to get caught on shore when the tide goes out and caribou and moose calves. But they can't run fast enough to bring down adult moose or caribou." Grizzlies can and do - but the catch is, as soon as a grizzly knocks one down, the polar bears will smell it. "An adult male grizzly might weigh...
...more likely scenario is that the grizzlies will snatch polar-bear cubs as they emerge from their winter dens or vice versa, says Rockwell. Most intriguing of all is the possibility that the two species might interbreed. "These guys only split off evolutionarily about 150,000 years ago, so hybrids are viable," he says. That's no speculation: DNA analysis has proven that a bear shot in 2006 in Canada's Northwest Territories was part-grizzly, part-polar bear; the names "grolar bear" and "pizzly" have been floated in reference to it. (The hunter who killed the animal was spared...
...reason for the potential habitat overlap is twofold: grizzlies seem to be expanding their range east and south from the Rockies, mostly as a result of their growing population, says Rockwell. Polar bears, meanwhile, are spending more time on land, as global warming causes ice to break up earlier and refreeze later in the year. And that means that while encounters between these huge bears might be rare today, they could become increasingly common...