Jodi Peterson

Associate Editor

Elk like to graze along streams and in meadows, chomping on tender cottonwood, willow and aspen seedlings. When enough elk browse them, most of those seedlings don’t ever mature into trees, and in turn there go beaver, songbirds, and a host of other species in what scientists call a “trophic cascade” (see our story “Tinkering with Nature“). However, in areas where wolves have been reintroduced, the predators find elk out in the open to be easy pickings, so the ungulates learn to stay in safer, heavily wooded areas. That gives the willow and aspen a chance to regrow, and then the other creatures return as well.

But that compelling narrative, often cited to show how wolves affect entire ecosystems, may be challenged by a new study just completed in Yellowstone. The Casper Star-Tribune reports:

A University of Wyoming professor has concluded that wolves don’t cause elk to vary their behavior enough to allow aspen stands to recover, contradicting in some ways earlier studies indicating an “ecology of fear” had taken root in the big game animals.

Researcher Matt Kauffman concluded that the dramatic recovery of Yellowstone’s willow groves after the reintroduction of wolves was caused simply by a drop in elk numbers, not by changes in elk behavior. And elk numbers have been reduced by several factors beyond just wolf predation, including drought.

The final verdict on just how wolves affect elk and ecosystems is far from in, of course. In the meantime, it’s good news for Rocky Mountain National Park, which has been considering ways to thin its overgrown elk herd (see our story “An ecosystem wanting for wolves“). The park favors the use of sharpshooters over wolf reintroduction, but this study suggests that population cuts alone will help overgrazed willow and aspens to recover, even without wolves to scare elk away from streams and meadows.