Without Wolves

1926-1995

The wolves of Yellowstone National Park were eliminated by 1926, influencing a cascade of changes that altered the park’s entire ecosystem.

ELK,  no longer pressured by predatory wolves, were killed and relocated in large numbers by park rangers to control their burgeoning population. Having lost the fear of being hunted, elk gathered near streams, overbrowsing willows, cottonwoods, and shrubs that grow on banks and prevent erosion. Birds lost nesting space. Habitat for fish, amphibians, and reptiles declined as waters became broader, shallower, and, without shade from streamside vegetation, warmer.

ASPEN  trees seldom reached full height in Yellowstone’s northern valleys, where elk winter. Browsed by elk, the new sprouts were eaten, and existing trees were stunted.

COYOTES,  no longer having to share the land with wolves, became much more abundant. Though they often kill elk calves, coyotes prey mainly on ground squirrels, voles, and other small mammals. They also specialize in killing the fawns of pronghorn antelope. The lack of carcasses left behind by wolves reduced the food traditionally available for coyotes, foxes, badgers, raptors, and other scavengers.

With Wolves

1995-Present

ELK numbers have decreased. Their behavior changed as wolves returned. No longer lingering along streams, elk retreat to higher ground with better vistas for spotting predators, allowing riparian areas to recover. Additionally, drought, severe winters, and other large predators, including grizzly bears, have all contributed to the recent decline in elk within the park.

ASPEN, willows, cottonwood, and other vegetation have resumed their natural growth with reduced pressure from elk, stabilizing trampled stream banks and restoring the natural water flow. Overhanging branches shade the streams, providing cooler water and benefiting trout and other aquatic life. Songbirds nest in willows. Streamside trees provide food for beavers and materials for building dams that hold back ponds and create a thriving aquatic habitat.

COYOTE numbers dropped as they once again shared the land with wolves. Many coyotes were killed or driven away by wolves, helping to bring about a resurgence in pronghorn.

WOLVES, now returned to their original habitat, play a vital role in keeping the world of predator and prey in balance. Once they’ve eaten their fill, the leftovers from their kills provide food for scavengers, including bald and golden eagles, coyotes, ravens, and bears.

Since 1995, when wolves were reintroduced to the American West, they have restored stability to the ecosystems they live in. This has increased populations of countless species from birds of prey, to pronghorn antelope, and even trout.

In the short time since wolves were reintroduced to the American West in 1995, scientific research has revealed that they have restored stability ecosystems.  Because of this role, wolves are designated a “keystone species” and often referred to as “ecosystem managers.”