Reintroduction of Wolves to Yellowstone
Decision to Reintroduce
In 1970, Nathaniel Reed, an official from the Dept. of the Interior organized an official meeting to discuss the reintroduction of the gray wolf to Yellowstone. The participants of the meeting decided that a study should be conducted. In 1978, a biologist by the name John Weaver wrote to the U.S. Department of the Interior after he had studied the gray wolf’s place in the Yellowstone ecosystem, saying that the ecological niche of the wolf in Yellowstone was empty and they should be reintroduced. It wasn't until 1994 that a plan to reintroduce the gray wolf to Yellowstone was officially endorsed, with wolves restored to the park in 1995.
Reintroduction Method
The idea was to release around 15 wolves a year into the Greater Yellowstone Area for 3-5 years. Wolves would be brought down from Canada and spend around 2 and a half months or 10 weeks in acclimatization pens. After this, they would be released into the park and the surrounding area.
Early Results
Initially, fears and hesitation revolved around the many livestock in the area and the fear of what effect a wolf population would have on the livestock populations. These fears were largely unfounded in the first several years. The wolves attacked far fewer livestock than expected, primarily preying on the large elk herds in the Greater Yellowstone Area. Individuals and packs of wolves were sometimes penned for a period of time before release for their own safety as well as the safety of livestock.
Ecosystem Changes
By the end of 1996, 40 wolves were free-ranging in the park and surrounding area, many were expected to produce pups within their packs. Preliminary results of the release showed that wolves were having an effect on the movement of elk herds as they preyed on elk and their calves, as well as some smaller predators like coyotes in their territories. This pressure especially on the elk herds has been associated with a trophic cascade in the Yellowstone area.
Trophic Cascade
The gray wolf retaking its place on the food chain in the Greater Yellowstone Area has seen a beneficial effect on the health of the environment and biodiversity in the area. The pressure on elk herds to keep moving causes them to graze less heavily on vulnerable areas like willow stands. This allows the willows to survive and grow to a size where they make a viable food and building source for beavers. This results in a higher beaver population, and the resulting dams create rich ecosystems for a plethora of life. The wolves also act as a food delivery service, as instead of winter being the only cause of elk deaths, wolf-killed elk occurs at all times of the year. This means more food for carrion eaters like eagles, coyotes, ravens, and bears. This increase in food stability increases the population of these animals as well. This behavior shows the reason behind native stories talking about ravens following wolves: food.