Reindeer (Caribou)

In their native range, the caribou diet consists of lichens, grasses, shrubs, and other vegetation. Depending on the season, they look for young flowering buds and new leaves to get the best nutrients. In the winter, they mainly eat lichen, which is high in carbohydrates but low in protein.

At the zoo, our reindeer receive grain, alfalfa, hay, and browse as their regular diet. They sometimes will receive beet pulp or other novel foods when training.

Caribou are found in many northern areas of North America and Eurasia. Although historically more widespread, in North America the reindeer can now be found in Alaska and Canada. In Europe and Asia, populations occur in Norway, Finland, Russia, Greenland, Iceland, and Mongolia.

Caribou inhabit several different habitats from coastal plains, mountain ranges, sub-Arctic tundra, and boreal coniferous forests.

Depending on the location and habitats gray wolves, wolverines, lynx, and dholes predate on caribou. Brown bears, ravens, and eagles may prey on calves.

Although caribou are not globally endangered, some populations are decreasing due to overhunting and poaching. Human activities like oil exploration, industrial development, logging, and recreation are also invading their habitats. In North America, changes to the environment have allowed white-tailed deer to spread into caribou areas, bringing harmful parasites. In Finland, there's a risk that caribou could mix with semi-domesticated reindeer.

Climate change is another big challenge for caribou. It could lead to more rain, which can freeze over food, making it hard for caribou to find enough to eat and risking starvation. Warmer temperatures might also affect their migration patterns by changing sea ice and could lead to more parasites for reindeer.

Reindeer are different from their wild relatives, known as caribou, because they have been selectively bred to be smaller and sturdier. Wild caribou are generally larger and have longer legs. Their fur can be many colors, from dark brown to nearly white, and it changes with season, subspecies, and location. Reindeer are completely covered in fur that provides insulation against the cold. They have long hairs under their necks, around their hooves, and near their tails that are almost white. Their fur has two layers: a soft undercoat and a top layer made of long, hollow guard hairs. These guard hairs trap air, keeping them warm in windy and cold weather. They also help them float when swimming. Even their nostrils are lined with fur to warm cold air before it enters their lungs, reducing heat loss when they breathe out.

Reindeer have a great sense of smell, which helps them locate food buried under the snow and detect danger. Their hooves are designed for grip on slippery surfaces, like ice and snow, and they have spongy pads under their hooves to help them walk in muddy areas. In winter, their hooves harden, allowing them to dig through ice and snow for food. Their broad hooves can also push water aside while swimming and scrape snow to find food. Each leg has a long dewclaw that gives extra support when they climb rough terrain. When they walk, their leg tendons produce a clicking sound, which may help a herd stay together in a blizzard.

Caribou have the largest antlers relative to their body size of all deer species. Male antlers can grow up to 51 inches long, while females can reach about 20 inches. Antlers grow from the frontal bones of the skull and have a structure similar to a tree, with a main trunk and branches. Unlike horns, which are permanent, antlers fall off and grow back each year. When antlers first grow, they are covered in soft skin called velvet. Once this velvet dries, caribou rub it off against trees or rocks, revealing solid bone underneath. Interestingly, both male and female caribou grow antlers. Males start growing theirs in February and shed them in November, while females begin growing in May and keep them until they give birth in May.

Caribou can see ultraviolet (UV) light, which helps them find food and stay safe in the Arctic. This ability allows them to avoid the painful snow blindness that humans experience from UV light.

During the breeding season, male caribou enter a period called the "rut," where they compete fiercely for the chance to mate. To prepare, they scrape off the velvet from their antlers and gain weight. Their necks become thicker, and the fur around their throats grows longer. This time is tough for the males, as they can lose up to 25% of their body weight. The strongest males, or winners, will gather a group of 5 to 15 females, known as a "harem," to mate with.

In the spring, pregnant females leave the herd and travel to a specific calving ground. They usually give birth within 10 days of each other, mostly in May and June. Typically, females have one calf, although twins can happen sometimes. Unlike other deer, the calves are not spotted. They're able to stand just an hour after they're born and can follow their mother at five to seven hours old. Remarkably, they can even outrun a human by the time they are just one day old! A caribou calf drinks its mother's rich milk and starts eating solid food about a week after birth. By two weeks, the calf's weight has doubled, and it is weaned about six months later. Antlers begin to appear as small hairy buds when a caribou is in its second year.

Vocalizations include snorts, grunts, and hoarse calls, especially during the breeding season or rut. Calves bleat to call to their mother.

Caribou are animals that travel and eat together in groups called herds. These herds can be small, with about 10 caribou, or really large, with hundreds of them. In spring, they can form super herds of 50,000 to 500,000 caribou. They move around a lot, usually searching for food, and can travel south for as much as 1,000 miles when it gets hard to find food in the winter.

Being in a big herd helps keep caribou safe from predators, since there are more eyes to spot danger. Healthy adult caribou are typically safe, but young calves are the most at risk. Older, weaker, sick, or injured caribou also have a higher chance of being prey. After mating season, many male caribou can be tired or hurt, making them more vulnerable as well.