Alces alces shirasi, one of four subspecies of moose in North America, is found in forested areas and willow flats from southeastern British Columbia to northern Colorado. They are better adapted to survival in deep snow than other ungulates in Greater Yellowstone. Although some moose in Grand Teton and Yellowstone migrate to lower elevations in winter, others move to higher elevations where they can browse beneath a mature forest canopy that reduces snow accumulation. Except during the rut, moose are usually found alone or in small family groups. This behavior, and their use of habitat where they are often well concealed, impedes accurate estimates of population size and distribution.