Hunting Patterns of Wolves Change Yellowstone Ecology

October 21, 2005 -- The reintroduction of wolves to Yellowstone National Park 10 years ago has greatly changed the park’s ecosystem. Over the last decade, the wolf population has grown from 31 gray wolves, to about 130 wolves that roam the park in 13 packs.

Wolves have reduced the size of the elk population, as well as altered the movement of herds, forcing the animals to continuously seek safer regions of the park to graze. With the redistribution and lower population of elk, vegetation has begun to flourish in certain areas, which in turn allows other wildlife populations to swell. Willow and cottonwoods stabilize streams, increasing the amount of trout. Beavers that feed on willow and aspen are thriving; there are now 10 dams where there was only one in 1996. Grizzlies, coyotes, magpies, and ravens feast on the elk carcasses left by wolves.

The National Research Council report, Ecological Dynamics on Yellowstone’s Northern Range, examines how populations of ungulates -- elk, bison, deer, and other species -- affect the vegetation and landscape of Yellowstone's Northern Range, and how natural regulation would influence those interactions. The report discusses, among other factors, how wolves, recently re-introduced, might cause additional ecological changes there.

• Ecological Dynamics on Yellowstone’s Northern Range (2002)

• Wolves at Yellowstone National Park
• “Wolves and the Ecology of Fear” BioScience August 2004 Vol. 54 No. 8 (1.27 MB, requires free Adobe Acrobat