Study: Wolves Sustain Wildlife by Sharing Prey

ByABC News
October 15, 2003, 10:09 AM

Oct. 16 -- Here's a bit of irony. The much-maligned wolf, one of the fiercest predators on the planet, has become an important provider of food for other animals in the few years since it was returned to Yellowstone National Park.

It's not that the wolf is all that magnanimous. It's just that the 14 wolf packs that now call Yellowstone home have found themselves in a land of plenty.

The National Park Service began reintroducing Northern Rocky Mountain wolves, a subspecies of the gray wolf (Canis lupus), to Yellowstone in 1995, much to the consternation of nearby ranchers who feared the predators would feed on their cattle, and the concerns of citizens who worried about the impact on other wildlife in the park.

These carnivores have indeed become major players in the park's ecological system, but it turns out that there are lots of other critters in the park that depend on the scraps left over from a wolf feast for their own survival.

Easy Come, Easy Go

The wolves don't really care all that much about the other animals, says animal ecologist Christopher C. Wilmers of the University of California, Berkeley. It's just that even a pack of wolves has trouble eating an entire elk, so after a kill, there's plenty of food left over.

Everything from coyotes to magpies invite themselves in for lunch, and the wolves "are sort of drunk on food," Wilmers says. "They move off rather than drunkenly fend off other scavenger species."

That's especially true during the hard months of winter, when food is scarce for most animals but plentiful for wolves. They know it's not going to be hard to get their next meal.

"In winter, the Yellowstone elk condition is highly correlated with snow depths," says Wilmers, whose research is part of the Yellowstone Wolf Project, an ambitious park service program aimed at determining the true impact of the return of the wolves. "As snow depths increase, the elks have a harder time moving around, and they have a harder time gaining access to the grass underneath. So they become increasingly vulnerable to predation by wolves."