The moose (Alces alces) is the largest member of the deer family, characterized by its massive size and impressive palmate antlers. Its distribution across the United States is highly restricted to specific northern and high-altitude habitats. This large mammal is adapted to cold environments, limiting its range to areas where temperatures and vegetation align with its specialized physiological needs. Consequently, its presence is confined to a discontinuous arc of northern forests and mountainous zones.
Moose in the Northeast and Great Lakes States
The Eastern Moose subspecies is found in the spruce-fir and mixed-transitional forests of the Northeast and Upper Midwest. In New England, populations are concentrated in Maine, New Hampshire, Vermont, and the northern parts of Massachusetts and New York. Maine hosts the largest population in the contiguous United States, estimated at around 65,000 animals, and its core habitat remains stable.
Moving west, the distribution continues into the Upper Great Lakes states, including northern Minnesota, Wisconsin, and Michigan’s Upper Peninsula. Habitat in these areas is defined by boreal ecosystems featuring wetlands, thick spruce-fir stands, and abundant woody browse like willow and birch. Despite stability in Maine, populations face challenges, particularly in the southern range. Minnesota’s population has declined significantly, dropping from over 8,000 animals to a current estimate of 3,000–4,000. The primary factor driving this decline is the proliferation of the winter tick, which has caused calf mortality rates as high as 90% in some monitored areas.
Moose in the Western United States
In the Western United States, the distinct Shiras Moose subspecies inhabits the high-elevation zones of the Rocky Mountains. This subspecies is the smallest of the North American moose, occupying a vast range across six states. Key populations are found in Wyoming, particularly within the Yellowstone and Grand Teton National Park ecosystems, and extend through Montana, Idaho, Utah, Colorado, and northeastern Washington.
The Shiras Moose relies on elevation to secure the cold conditions it requires, differentiating its habitat from the boreal forests of the Northeast. These animals primarily seek out riparian areas, such as riverbanks and stream bottoms, where willows provide both cover and forage. They are also found in conifer forests dominated by Engelmann spruce and lodgepole pine, often migrating to higher, cooler elevations during the summer. Utilizing mountainous terrain for thermal relief is central to the persistence of the Shiras Moose in the American West.
Alaska’s Massive Moose Population
Alaska is home to the vast majority of all moose in the United States, supporting an estimated population of 175,000 to 200,000 animals. This northern range is dominated by the Alaska-Yukon Moose, recognized as the largest subspecies of moose in the world. The animals are distributed widely across the state’s interior, populating areas from the Kenai Peninsula to the North Slope.
Due to this abundance, populations are managed differently than those in the lower 48 states, focusing on sustainable harvest and monitoring. Population density is especially high along the riparian corridors of major river systems like the Yukon and Kuskokwim, where willow thickets provide winter browse. Management efforts are often directed toward increasing densities in certain areas through habitat manipulation and predator control to meet specific objectives.
Environmental Limits on US Distribution
The distribution of moose is defined by their sensitivity to heat, which confines them to the coldest regions of the country. Moose begin to show signs of heat stress at relatively low summer temperatures, around 57°F to 68°F (14°C to 20°C). This physiological strain causes them to reduce foraging time and seek out shade or cool water, leading to nutritional deficits and lower body mass.
Warmer conditions also favor the survival of the winter tick, a parasite that attaches to moose in large numbers. Milder, shorter winters allow more ticks to survive, increasing the parasite load on the animals. The combination of heat stress and high parasite load reduces calf survival and cow reproduction, effectively setting the southern boundary for moose distribution.