In 1995, after a seventy-year absence, wolves were reintroduced into Yellowstone National Park. How have they fared? According to a study by William Ripple and Robert Beschta of Oregon State University, not only have the wolves thrived, but their presence has wrought a cascade of favorable changes in the park. Wolf predation has altered both the population and behavior of elk, which in turn has allowed entire habitats to recover.
The Gibbon wolf pack in Yellowstone.
Without wolves, elk had been allowed free reign to browse where they liked. This resulted in the decimation of many types of bushes and trees and caused changes to the entire Yellowstone ecosystem. In particular, critical habitats within and around streams were annihilated by the elimination of adjacent trees. Now that the elk are held in check, the plant life has rebounded. With them has come a resurgence in a great many species, including songbirds, beaver and fish, all of whom rely on healthy streams.
It seems that reintroducing the wolves has been a win-win for almost all the species within Yellowstone. Although the elk might dissent from this view, their numbers are still holding strong as well.
Here’s a description by Ripple (that unfortunately cuts off abruptly at the end):