The largest living member of the deer family, the moose is found in northern North America from Alaska to Newfoundland and Labrador and Maine, and in northern Europe and Asia. An adult bull averages about 450 kg (990 lb.) in weight, while a larger subspecies from Alaska and Yukon attains weights in excess of 600 kg (1,320 lb.). Bulls are about 30% heavier than cows.

The moose is a strong swimmer and has been known to dive to depths of 5.5 m (18 ft.) and remain submerged for 30 seconds in search of underwater roots.

An adult bull is a dangerous adversary and is often able to repel attacks by small packs of wolves. They are particularly truculent during the mating season. They have keen senses of smell and hearing, which means the only chance to successfully approach them is from upwind.