Caribou cow, Denali National Park and Preserve, 2015.

Caribou (Rangifer tarandus) have large, concave hooves that help support them in the deep snows of winter and on the soft surface of tundra. They are also the only member of the deer family in which both the male and female grow antlers; though antlers of the bulls are massive while cows grow much shorter, slender, irregular antlers. Like most herd animals, caribou must keep moving to find adequate food. Large herds may migrate large distances up to 400 miles (640 km) between their summer and winter ranges. Caribou in Alaska are distributed in 32 populations/herds. Each herd uses a distinct calving area separate from other herds; however, herds may mix in their winter ranges. Big hooves for paddles and hollow hair for bouyancy make caribou good swimmers. That's important because they have to swim across the Kobuk River twice a year as they migrate. In fact, thousands of caribou like this one traditionally cross the Kobuk River near Onion Portage in the fall. People have also been harvesting caribou near this spot for about 9,000 years.