Once the most effective combination is determined, the researchers will set up perhaps 500 or more hair traps in the Yellowstone ecosystem.

Yet there are another 6,000 mining claims on land in the Yellowstone ecosystem.

Mr. Frye estimates that the greater Yellowstone ecosystem is now home for about 230 grizzlies.

But as the biologists talked, the role the wolves play in the greater Yellowstone ecosystem became clearer and clearer.

This scene, played out here and at 22 other feeding grounds at the southern end of the Yellowstone ecosystem, may seem benign.

Scientists have been researching and studying the impacts on the Yellowstone ecosystem since re-introduction in 1995.

Complicating the issue further is that the greater Yellowstone ecosystem is an ecological "island" with no link to other grizzly bear populations.

A 2011 study combined several climate models to estimate how fire could change in the Yellowstone ecosystem.

"A good place to start is the Yellowstone ecosystem, because we still have a relatively large number of migrations that still exist," he said.

He has conducted 8 years of a planned 15-year study of the effects of wolves on the Yellowstone ecosystem.