Wolves ranged widely throughout North America in pre-Columbian times. Worldwide, all wolves, except the red wolf (Canis rufus) of the southeastern United States, are the same species (Canis lupus).

Wolves are highly social animals and live in packs. In Yellowstone, packs contain from 8 to 14 individuals, with some occasionally having twice that number. Pack size varies based on the size of its main prey. The pack is a complex social family, with leaders (the alpha male and alpha female) and subordinates, each having individual personality traits and roles in the pack.

Wolves consume a wide variety of prey, large and small. They efficiently hunt large prey that other predators cannot usually kill. They also compete with coyotes for smaller prey. In Yellowstone, 90% of their winter prey is elk; 25 % of their summer prey is deer. They also can kill adult bison. Many other animals benefit from wolf kill including, ravens, coyotes, and bears.

The gray wolf (Canis lupus) was present in Yellowstone when the park was established in 1872. Predator control was practiced here in the late 1800s and early 1900s. Between 1914 and 1926, at least 136 wolves were killed in the park. In 1995-1996, 31 wolves from Canada were relocated to Yellowstone National Park.

At the end of 2009, at least 96-98 wolves in 14 packs (6 breeding pairs), 1 non-pack grouping, and 2 loners occupied Yellowstone National Park. This represents a 23% decline from 124 wolves in 2008. Despite the decline the number of breeding pairs did not change (6 in both 2008 & 2009). Intraspecific strife, food stress, and mange were likely cause for the decline.

The wolves' future is secure, but needs to be monitored. Approximately 1600 wolves live in the three-state area (Wyoming, Idaho, and Montana). Yellowstone National Park's wolf population declined in 2008 and 2009, but Yellowstone's wolf population is not in danger.

Information provided by the National Park Service and from Yellowstone Resources and Issues, 2010.