Although caribou and reindeer belong to the same species of Rangifer tarandus, there are numerous differences between them. Caribous are bigger, elk-like, and are dominantly habitats of northern North America and Greenland. Caribous thrive in the wild and have never been kept as domestic animals. Reindeer, on the other hand, are comparatively smaller in body size and thrive both as wild and domestic animals. Records show that they have been domesticated for over 2,000 years in the northern Eurasia region. Reindeer are kept in homes of Arctic people in Asia and Europe where they depend on the animal for economic sustainability. However, the animals share common characteristics and behaviors as discussed below.
The unique physical feature of the animals is the antlers. The horn-like elongations grow on the upper head and can be as long as 53 inches in beam length in males with a width of 39 inches. Antlers vary in length, circumference, and shape depending on habitat and subspecies. Antlers grow annually through a process of antlerogenesis after the existing antlers are lost during autumn. The skin color varies between subspecies, habitat, and season. Those in the north are comparatively whiter with a smaller body structure compared to those on the south which are larger and covered with darker fur. Due to the cold ecosystem, their skin has two layers of the coat which act as an insulator. The undercoat is dense and wooly while the outer coat is made of long, hallow, air-filled fur. To minimize heat loss, the animals have a mechanism known as Countercurrent heat exchange (CCHE) whereby blood pumped to the legs is cooled by blood on veins returning to the heart. Heat is therefore recycled rather than being dissipated. Their hooves are large and concave with adaptations to walk on snow with the aid of their crescent-shaped toes which further assist when digging and foraging for food under the snow. Harsh effects of winter are mitigated by the long strand of hair that covers the pads. Most subspecies produce a clicking sound as they walk which originates from the tendons of their knees.
Biology and Behavior
The gestation period is between 228 and 234 days after the mating season which begins in September and ends in November. The calves are usually born around May or June and within 45 days they are able to eat grass though they become independent in the following autumn. Calves reach sexual maturity when they are between one and three years. The lifespan of a female is almost 17 years while males live a shorter time by about 4 years. The main diet is lichens during winter although they occasionally eat the fallen antlers as well as rodents, mushrooms, and bird eggs. They are ruminants as evidenced by the 4-chambered stomach which enhances digestion. To survive in both hot and cold seasons, the animals have adaptations to regulate heat through optimal metabolic reaction. The body mass differs with breeding females having a higher body mass than those not breeding.
Reindeer are of great economic importance to the people in the polar region including the Chukchi, Evenks, Nenets, Saami, and the Eurasian Koryaks. The animal provides meat, fur, and blood while in the Asian countries, the reindeer’s antlers are sold as an aphrodisiac as well as medicinal and nutritional supplements. Such interaction with human coupled with the fact that they are also predated upon by grey wolf, bears, ravens, foxes, hawks and blood sucking insects has led to their decline.