Moose

The moose is the largest and tallest deer that has ever lived, a solitary giant of the northern forests built for deep snow, cold water, and a diet of woody twigs. A big bull, antlers and all, stands taller than a person and outweighs a horse.

Overview

Moose live in the circumboreal forest — the belt of taiga and mixed woodland that circles the Northern Hemisphere through Canada, the northern United States, Scandinavia, and Russia. They favour young forest with plenty of shrubby regrowth to browse, close to lakes, rivers, and marshes. Unlike almost every other deer, moose are solitary, coming together only to breed.

Physical characteristics

The moose silhouette is unmistakable: very long legs, a humped shoulder, a heavy overhanging muzzle, and a dangling flap of skin and hair under the throat called the bell. The long legs are an adaptation for wading through deep snow and water and for reaching high browse.

Only bulls grow antlers, and they are the largest of any living animal — broad palmate blades up to two metres across, regrown from scratch every summer and dropped every winter. Bulls use them to spar for mates and, it is thought, as a sound-reflector that funnels a cow’s calls toward the ears during the rut.

Moose have poor eyesight but an excellent sense of smell and hearing, and they can swivel their ears independently.

Diet

A moose eats around 30 kg of plant matter a day. In summer it strips leaves and shoots and wades into ponds for water lilies, pondweed, and other aquatic plants that supply the sodium its inland diet lacks. In winter it switches to the twigs, buds, and bark of willow, birch, aspen, and fir, using its flexible upper lip to grip and tear.

Reproduction and life cycle

In the autumn rut, bulls stop feeding, thrash vegetation, dig scent pits, and call — a deep moaning grunt from the bull, a wailing bawl from the cow — and fight antler-to-antler for access to females. A cow gives birth in spring to one calf, or twins in good years, weighing 11–16 kg. Calves can outrun a person within days and stay with the mother until she drives them off just before her next calf is born.

Threats and conservation

Globally the moose is Least Concern, with a large and mostly stable population. But at the southern edge of its range — the northern United States, southern Canada, parts of Scandinavia — populations have declined sharply, and climate is central to why:

• Winter ticks. Warmer, later winters let winter tick numbers explode. A single moose can carry tens of thousands, which drain its blood and drive it to rub off its coat, producing pale, weakened “ghost moose” that die of anaemia and cold, especially calves.
• Heat stress. Moose are built for cold and struggle above about 14 °C in winter or 20 °C in summer, spending energy to cool down instead of feed.
• Brainworm, a parasite carried harmlessly by white-tailed deer that is fatal to moose, spreading north as deer expand.
• Predation on calves by wolves and bears, and vehicle collisions on forest roads.