Caribou (Rangifer tarandus) are the only deer in which male and females both have antlers-though only some females have them. Caribou have large hooves that support the animal on snow and soft tundra and help them paddle efficiently through the water. The hoof's underside is hollowed out like a scoop and used for digging through the snow in search of food. In the winter, they eat lichens and dried sedges, while the summer offers a more varied diet including willows, grasses, and flowering plants.
The shedding of velvet (the fur covering on antlers) in late August and early September by large bulls marks the approach of the rutting season when bulls will fight with one another for access to breeding cows. Cows have one calf each year, born in May. Newborn calves weigh an average of 13 pounds and grow very quickly, often able to stand only a few minutes after birth and ready to travel with its mother by the next day.
Caribou, along with moose, are the only members of the deer family in the Lake Clark area. The Mulchatna Caribou Herd range through the foothill lakes and tundra plains of the western preserve. Surveys indicate that the herd size is down from an estimated 200,000 animals in 1999 and is now closer to 30,000 animals.