Caribou shows variation in antler and body size throughout its wide distribution across the Northern Hemisphere where it inhabits montane, boreal, subarctic and arctic habitats. In B.C., Woodland Caribou is a moderately large deer with long, slender legs and large, semicircular hooves, each with a prominent dew claw just above it. The rather blunt, square nose is covered by short hair, and the ears are short, broad and not pointed. Body colour varies from light brown to almost chocolate-brown in summer, and light grey or brown in winter, sometimes becoming bleached even lighter by the end of winter. The neck is usually lighter coloured than the rest of the body, and females can also show some areas of lighter grey-brown just behind the shoulders. Males sometimes have a light, horizontal flank stripe above a darker belly band. The face is generally dark from the top of head to the nose, although the lower cheeks may be lighter, especially in older males. The white tail is relatively short, and is surrounded by a medium-sized light or white rump patch. There is a noticeable thin band of white hairs (called socks) running above the upper edge of each main hoof. Adult males develop a mane of longer hairs along the underside of the neck as far back as the chest, and during the rut, both the light neck and mane contrast strongly with the darker body.
When walking or running, Caribou make a characteristic clicking sound. This is caused by small tendons stretching over bone protuberances (sesamoid bones) in their feet. Skin glands in Caribou include antorbital, caudal, and on the hind feet, tarsal and interdigital.
Caribou is unique among the world’s deer, because females regularly develop antlers. Although there is variation among the subspecies and among individuals, male Caribou antlers generally consist of a long oval-shaped main beam that rises up and back from the head before curving forward again to form a clear “C” shape when viewed from the side. The brow tine is often palmated and vertically oriented with small points along the edge, with often one brow tine larger than the other. The second tine may be branched into small points, and in some individuals may be palmated. The first two tines point forward. The third, if present, is located in the middle of the main beam and projects backwards; it is short, unpalmated and unbranched. The end of the main beam is usually moderately palmated, with points along the upper edge. Adult female antlers are much smaller and simpler in structure than those of adult males, being about the same size as those of one- and two-year-old males. Female antlers also lack the large, vertically palmated first tine that adult males have. Unlike other deer species in British Columbia, Caribou may grow short spiked antlers, less than 300 mm long, in their first year. The surface of the main beam of Caribou antlers is much smoother than in other deer, and the impressions of major blood vessels can often be traced along its length.
A Caribou has small upper canines, that rarely project beyond the maxilla of the skull or the gum of the live animal. Upper incisors are absent and the lower incisors and canines are small and peglike. The molars have a simplified selenodont enamel pattern. A small extension of the maxilla prevents the premaxilla from meeting the nasal bone, and the anterior nasal opening is large. There is a moderately deep antorbital depression on the lachrymal bone in front of the orbit, and the pedicels are located well back on the skull so that they are partially on the frontal and parietal bones.