Critically endangered Mexican gray wolves can help the bring back the balance in the American Southwest.

.

Beyond being beautiful, wolves are critical keystone species. By regulating prey populations, wolves enable many other species of plants and animals to flourish. Without predators, such as wolves, an ecosystem fails to support a natural level of biodiversity and may cease to exist altogether.

The recovery of the gray wolf after its eradication from Yellowstone National Park, nearly a century ago, serves as a demonstration of how critical keystone species are to the long-term sustainability of the ecosystems they inhabit. In the 70-year absence of wolves in the Park, elk had become accustomed to grazing tender, native willows along stream banks without much predation risk. The consequences of an elk population without a top predator included a decline of the deciduous trees elk eat, a decline of beavers due to the decline of willow and aspen, and a decline in songbirds. These consequences indicate that changes in the wolf population have trickle-down effects on other populations, a phenomenon known as a “trophic cascade.”

With the support of the American public two decades ago, the federal government gave the green light to return wolves to portions of their native range in the West in 1995 and 1996 – including Yellowstone. The wildlife conservation event opened a new chapter in Yellowstone’s history, with a homecoming that changed the Park.

After wolf reintroduction, scientists documented the return of willows and other vegetation. And where the willow returned, the researchers noted more diverse wildlife. Beaver dams and dried up wetlands returned, and wetland birds, waterfowl and other wildlife thrived again where they had been suppressed for decades. Over-grazed grasses flourished anew on upland prairies.

As Mother Nature’s wildlife managers, wolves initiate trickle-down effects that improve ecosystem function and resilience.