During poor food years, grizzly bears turn to wolf kills

During poor food years, grizzly bears turn to wolf kills
In bear-wolf confrontations, the larger carnivore almost always wins

Grizzly bears in the Yellowstone ecosystem appear to be benefiting from the wolves' presence in the region. How? Thanks to the wolves, there are more carcasses on which to feed.

According to Doug Smith, leader of the Yellowstone Wolf Project, grizzly bears will often take over carcasses that are a result of a wolf kill. This happens more frequently during poor food years, when one of the grizzly's main food sources, whitebark pine nut, is not plentiful. This has been documented and proven true during poor nut years, says Smith.

In a grizzly bear-wolf interaction, most of the time it's no contest. The bear wins. In fact, Smith says, the larger of the carnivores wins about 80 percent of the time.

Smith says it's not that spectacular when a bear takes over a wolf-killed ungulate. Bears have great noses and they follow their nose to the bounty.

"The bear just walks in," explains Smith. "He walks up to the carcass and the wolves just kind of fall away. It's not a huge battle. Occasionally a wolf bites a bear in the ass, but they tend not to be huge battles. In such confrontations, wolves are more of an annoyance to the bear than a threat," he says.

Smith has observed bears taking over carcasses on a few occasions. One observation occurred when wolves took down a bull elk, whose carcass ended up in Pelican Creek. A grizzly sow and her cub took it over.

"The wolves always try to play a game," explains Smith. "They're not as strong, but they're quicker, they're faster and they have greater numbers. So their game is to harass, harass, harass."

Smith describes the scene of the sow and her cub taking over the wolves' carcass in Pelican Creek:

"You can see the bear getting noticeably agitated, plus she's got a cub. So she's lunging at the wolves. She's splashing through the water at a wolf trying to get in at the food. The wolf knows if it's caught, it will be dead, so the wolves take the bear's approach very seriously…The wolves were not uptight, though. They were in a playful mood trying to get at their meat but the grizzly was deadly serious. It was as if she were saying 'I'm protecting my young and I'm protecting my food and if you mess with me, I'm going to kill you.'"

Smith says the scene showcased a real contrast in styles.

"The wolves just kind of swirled around trying to keep her off," he explains. "Typically what happens is the bears camp out as long as they want to, sometimes hours, and the wolves have to wait, even though it's their kill."

Smith says on a couple of such occasions, the grizzly actually lays down over the carcass.

"They get tired of chasing all of these wolves off so they just lay down on top of the carcass," he says.