There are three distinct regions of Gray wolf habitat in the US. Starting in the west, there are populations in Pacific Northwest states of Washington, Oregon, and California, and in the Northern Rocky Mountain region that includes Idaho, Montana, and Wyoming. Further south, a non-essential experimental population of subspecies Canis lupus baileyiexists along the New Mexico/Arizona border. In the Western Great Lakes region, > 4400 individuals (US Fish and Wildlife Service, 2010) are distributed across Minnesota, Wisconsin and Michigan (Map: U.S. Gray Wolf Distribution and Habitat, n.d.).
Gray wolves require great swathes of land, with pack territories ranging from 50 square miles to 1,000 square miles, and can travel as much as 30 miles in a single day to hunt (USFWS: Gray Wolf Biologue, n.d.). They are extremely adaptable, and can therefor inhabit a wide range of habitats including: temperate forests, mountains, tundra, and grasslands (Species Profile for Gray Wolf(Canis Lupus), n.d.). A great deal of wolf habitat is found on public land where conservation is a priority and protection plans have been adopted to preserve growing wolf populations(US Fish and Wildlife Service, 2010). The only limitations to habitability are insufficient prey density and human harassment (US Fish and Wildlife Service, 2010).
One method researchers are using to determining the suitability of a habitat for supporting a growing wolf population relies on road density, which serves as a proxy for human-caused wolf mortality. Habitat with road densities < 0.7 mi per mi2 are estimated to have >50% probability pack colonization and persistent presence, and are considered prime habitat. Habitats where road density is greater than 1 mi per mi2 only have <10% probability of colonization (Mladenoff et al., 1999). In addition to road density, the following three factors are also being used to predict habitat suitability: human density, density of agricultural lands, and prey density (US Fish and Wildlife Service, 2010).
