The eastern wolf (Canis lycaon or Canis lupus lycaon), also known as the eastern timber wolf, Algonquin wolf or deer wolf, is a canid native to the northeastern side of North America's Great Lakes region. It is a medium-sized canid which, like the red wolf, is intermediate in size between the coyote and Northwestern wolf. It primarily preys on white-tailed deer, but may occasionally attack moose and beaver.
The eastern wolf's taxonomic classification has been under review beginning c. 2000, with various suggestions having been presented as to its derivation, including its being a subspecies of gray wolf, its being conspecific with the red wolf, gray wolf–coyote hybridization, and classification as a separate species within Canis. The eastern wolf is still recognized as a gray wolf subspecies by Mammal Species of the World (as of 2005), but in 2013, following a comprehensive review of several genetic studies, it has been classed as a distinct species by United States Fish and Wildlife Service.
The eastern wolf is currently listed as a threatened species under COSEWIC and with the Committee on the Status of Species at Risk in Ontario (COSSARO), because "new genetic analyses indicate that the eastern wolf is not a subspecies of grey wolf" versus earlier theories that it was a result of hybridization with both gray wolves and coyotes. The eastern wolf is particularly susceptible to hybridization, due to its close relationship to the coyote and its ability to bridge gene flow between both coyotes and gray wolves. Furthermore, human persecution over a period of 400 years caused a population decline which reduced the number of suitable mates, thus facilitating coyote gene swamping into the eastern wolf population. Aside from posing a threat to a unique species, the resulting eastern wolf–coyote hybrids are too small in size to substitute pure eastern wolves as apex predators of moose and deer. The main nucleus of pure eastern wolves is currently concentrated within Algonquin Provincial Park, south central Ontario and south central Quebec.