Moose are the largest members of the deer family, rivaling an adult horse in size. They are dark brownish to black on their back and sides with fairly large, humped shoulders. Their long, dark hair in the winter provides them great insulation against winter cold. Both sexes have a pendulous muzzle with a large over-hanging upper lip and a dewlap or “bell” which is a large tuft of hair hanging from their throat. Males in the northern Rockies may weigh up to a 1000 pounds (450 kg), females up to 920 pounds (430 kg), but further north in Alaska, they may weigh 80 to 300 pounds more. The males have antlers unique in the deer family; they are large and palmate with tines extending off the palm part, rather than consisting of a main beam with tines or points. They may have antlers up to 80 inches across in Alaska, but less than that in Idaho. Females do not have antlers. Their large body size and long legs allow them to forage in deep snows of winter, and deep water of ponds in summer.
Moose range through most of Canada, south to Maine and west through the northern Lake States, in the west down through the Rocky Mountains through Idaho to northeastern Utah and northwest Colorado. They are circumpolar in distribution, ranging across northern Eurasia, but are called elk in Europe and Asia. They are found in some of the coldest parts of the continent during the winter.
Moose prefer a mosaic of second-growth forests, openings, lakes, and wetlands, but basically are inhabitants of the northern boreal forest. In Idaho, they prefer shrubby, mixed coniferous and deciduous forests with nearby lakes, marshes and bogs. They range over wide areas, and dispersing young may be found in drier parts of southeastern Idaho, which hardly resembles northern boreal forests. They seem to require water bodies for foraging and beaver ponds provide this, and hardwood or conifer forests for winter cover. They avoid hot summer conditions by utilizing dense shade or bodies of water. During hot summer days, they are known to completely submerse themselves in shallow water and mud of beaver ponds, with the exception of their nose. A northern Idaho study found old-growth grand fir and Pacific yew stands were critical components of their winter habitat. In some areas of the northern Rockies, moose are known to migrate to higher elevations during the winter, seemingly to seek out wind-blown ridges where snow depth is less and browse more attainable. Moose tend to use even-aged pole timber and open areas in summer. In southeast Idaho, they occasionally wander into towns and cities such as Pocatello and Idaho Falls. Moose are excellent swimmers and have been observed swimming across large lakes at up to 6 miles per hour.
Moose are primarily browsers, and rely on browse much more than elk. In summer they browse on new growth of trees and shrubs, and on vegetation associated with water; they seem attracted to the high-sodium content of aquatic plants. In winter they feed on conifer and hardwood twigs. An Idaho study found menziesia , yew, alder, maple and willow were their most important diet items. Willow, aspen and fir are known to be important food for moose in most locales. Adult moose are known to consume 40 to 50 pounds of browse per day.
Moose can be active day or night, but they are mainly crepuscular . Depending on the habitat, their home range may reach several thousand ha. An Idaho study reported a cow's summer home range was 15.5 to 25.9 km2, a bull's was 31-51.8 km2; their winter home range was reduced to 5.2 to 15.5 km2. Population density has been reported at up to 11.6 per 10 km2, but 18 to 20 per 10 km2 was reported in un-hunted areas in eastern Quebec. Moose tend to be solitary, although cows typically have their young with them through most of the winter. Cows typically chase away their young before giving birth, but appear to occasionally accept a yearling back after the birth of their calf. They may herd in winter along river and creek bottoms where there is an abundance of willow. Snow characteristics, such as depth, density, hardness and the length of persistence of these factors, may affect populations more than predator density. Their main predators in the north are wolves, and grizzlies take calves in the spring. Human hunting and road kills can be major mortality factors in some regions. Moose do seem to adapt to humans in some areas, especially in towns and cities of Alaska. Favorable winter conditions may produce a large annual increase (20-25%) in population size. Large populations may degrade habitat, resulting in population declines, as will severe snow conditions in extremely cold winters.
Moose breed in September to late October. During the rut , or breeding season, bulls can be dangerous and unpredictable. Some have been known to charge vehicles and there is an account of one charging a train. The outcome of that charge should be obvious. Cows with calves are also protective and dangerous. Gestation lasts 240 to 246 days. One calf, less commonly two, is born late May-early June. In years when winter weather is mild, and nutritional health of the female is high, there is a higher occurrence of twin calves. Calves are a lighter, almost chocolate brown to reddish in color and are not spotted. Young forage for vegetation in two weeks after birth and can move about with its mother hours after birth. Sexual maturity occurs in 1.5 years, although most males breed at 5 to 6 years due to intrasexual competition ; females reach peak productivity at 4 years.
Important State References:
Pierce, J.D. and J.M. Peck. 1984. Moose habitat use and selection patterns in north-central Idaho. J. Wildl. Manage. 48:1335-1343.