Caribou Ecology

In Alberta, there are two ecotypes of woodland caribou: ‘mountain caribou’ which are found in the foothills of the Rocky Mountains, and ‘boreal caribou,’ which are found in northern and northeastern Alberta. The ACC remains focused on conservation aspects of the boreal caribou herds.

Appearance

Boreal woodland caribou are larger than their barren-ground cousins, and mature bulls typically measure 1.2 m tall at the shoulder, and average 180 kg in weight. Cows are smaller, averaging 115 kg. Both males and females grow antlers, but cow’s antlers are shorter and have fewer points. Caribou are well adapted to travel in snow, and have large, wide hooves that support their weight.

Ecology

Caribou mate in early to mid-October, and calves are born from late May to early June of the following year. Cows typically do not breed until they are two years old and usually have only one calf per year. On average, caribou tend to live about 6 years. Most boreal caribou are found in small groups of less than 10, but are more solitary during calving.

Boreal caribou are non-migratory, and range over very large areas (>500 km² per year). They tend to remain in poorly drained muskegs – also known as peatlands, or bogs and fens – as well as mature pine and black spruce forests. Caribou rely on slow-growing lichens for food in winter, often ‘cratering’ through snow to reach patches of lichens. Caribou may in fact be able to smell lichen patches through several feet of snow! In summer, caribou eat a variety of forbs, shrubs, and other green vegetation.

Predators such as wolves and bears result in most mortality for adults. Smaller predators like coyotes, wolverines, or lynx are also able to kill calves. Disease, vehicle collisions, drowning, and human harvest (either poaching or legal hunting by the aboriginal hunters) are other mortality factors for caribou. Caribou tend to avoid predators through a ‘spatial separation’ strategy, whereby their use of muskeg and peatland habitats reduces their overlap with moose and deer, which are found in well-drained uplands. This reduces the likelihood of encountering wolves that prey on moose or deer.

Caribou populations in Alberta appear to be declining in most regions. Predation is the proximate cause of most caribou deaths, but a variety of factors can influence the rate of predation on caribou, or combine to limit the growth of caribou populations. For example, resource development can increase access for human hunters, or increase the hunting efficiency of wolves and other natural predators. Greater road density in caribou range may also increase vehicle collisions. Alteration of habitats by wildfire or development activities may increase moose and deer densities, leading to greater numbers of wolves that may prey on caribou.

Importance

Woodland caribou are an important part of the natural biotic systems in boreal forests. They are a part of predator-prey interactions and in lichen-herbivore dynamics. Aboriginal peoples have used caribou for subsistence hunting, and First Nation cultures and traditions of are often bonded with caribou ecology. Because caribou are found in low densities and are slow to reproduce, they are sensitive to habitat degradation, and can be seen as indicators of human impacts on natural ecosystems.

More Information

Please visit our section on caribou research or the BCRP website for more information on caribou ecology.