Smaller grizzly bears show larger polar bears who's the boss at a bone pile, confirming what a recent study said about grizzlies being socially dominant.
It was a social behavior that scientists discovered by accident. U.S. Fish and Wildlife Service biologist Susanne Miller was studying polar bear behavior several years ago, when she and her team were spending their evenings watching and recording the bears at an onshore bone site.
When they noticed, according to Miller, that "brown bears just showed up and polar bears left" the team decided to change the focus of their study from strictly polar bear behavior to instead targeting interspecies behavior.
They have since published a study that confirms that smaller grizzly bears exhibit dominance over their larger polar cousins.
The video shows polar bears feeding at the bone pile, until evening when a smaller grizzly makes an appearance and drives off the polar bears.
They chronicled 137 encounters between the two species and in most cases the polar bears were submissive to the grizzlies, even though, according to Miller, "the grizzlies did not exhibit overtly aggressive behavior".
Once when approximately 15 polar bears were eating from the bone pile, they suddenly left. A grizzly bear had walked in to the pile. "He just wandered in from behind the bone pile and all but one of the big polar bears ran away," said study coauther Ryan Wilson.
The grizzlies, says Miller, "look like they're half the size of the polar bears." Yet there is something about them that spooks the polar bears. Scent and an aggressive nature likely have something to do with it. In one incident the carcass of a grizzly that was dumped onto the bone pile was enough to keep the polar bears at bay.
"I think it's attitude," said Alaska Department of Fish and Game biologist Richard Shideler of the grizzlies. "They're more aggressive in terms of bear-bear interaction."
The study suggests that grizzlies tend to be more aggressive in competing for food as they build fat stores for hibernation, than are polar bears, which do not hibernate.