Yellowstone National Park, Wyoming, October 2020
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January 12, 2020, marked the 25th anniversary of the Gray Wolf’s return to Yellowstone. Wolf packs once roamed from the Arctic tundra to Mexico, but loss of habitat and extermination programs led to their demise throughout most of the United States by the early 1900s. In 1973, the U.S. Fish and Wildlife Service (FWS) listed the northern Rocky Mountain wolf (Canis lupus) as an endangered species and designated Greater Yellowstone Ecosystem (GYE) as one of three recovery areas. From 1995 to 1997, 41 wild wolves from Canada and northwest Montana were released in Yellowstone. As expected, wolves from the growing population dispersed to establish territories outside the park, where they are less protected from human-caused mortalities. The park helps ensure the species’ long-term viability in GYE and has provided a place for research on how wolves may affect many aspects of the ecosystem.
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Wolves are highly social animals and live in packs. Worldwide, pack size will depend on the size and abundance of prey. In Yellowstone, average pack size is 10 individuals. Research in Yellowstone since reintroduction has highlighted the adaptive value of social living in wolves – from cooperative care of offspring, group hunting of large prey, defense of territory and prey carcasses, and even survival benefits to infirmed individuals.
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(from https://www.nps.gov/yell/learn/nature/wolves.htm#:~:text=Numbers,and%20108%20wolves%20since%202009.)