Newborn calves weigh an average of 13 pounds 6 kg and grow very quickly. They may double their weight in days. Weights of adult bulls average pounds kg.
However, weights of pounds kg have been recorded. Mature females average pounds kg. Caribou in northern and southwestern Alaska are generally smaller than caribou in the Interior and in southern parts of the state. In Europe, caribou are called reindeer, but in Alaska and Canada only the semi-domesticated form is called reindeer. All caribou and reindeer throughout the world are considered to be the same species, but there are 7 subspecies: barrenground Rangifer tarandus granti , Svalbard R.
Alaska has predominantly the barren-ground subspecies and one small herd of woodland caribou, the Chisana herd, which moves into Canada in the Wrangell-St.
Elias area of Southcentral Alaska. Canada has three subspecies, the Peary, woodland and barren-ground.
Caribou in Alaska are distributed in 32 herds or populations. A herd uses a distinct calving area that is separate from the calving area of other herds, but different herds may mix on winter ranges. Like most herd animals, the caribou must keep moving to find adequate food.
Smaller herds may not migrate at all. In summer May-September , caribou eat the leaves of willows, sedges, flowering tundra plants, and mushrooms. They switch to lichens reindeer moss , dried sedges grasslike plants , and small shrubs like blueberry in September. Regarding the audio sample under the "Listen" tab: The 'huffs' are a cow; in the background you can hear a calf calling as well.
Cows and calves are most vocal during calving and early summer because it's a primary means of maintaining contact. The only time bulls vocalize is during rut — bulls are less guttural and more 'airy' than cows. Life history events for caribou occur in different seasons, but identifying those seasons varies between herds and caribou biologists.
Calving occurs in mid-late May in Interior Alaska and in early June in northern and southwestern Alaska. If females are in very good condition they can breed when they are 16 months old, but in most herds they do not breed until they are 28 months old. Most adult cows are pregnant every year and give birth to one calf — twins are very rare. In some areas, wolves, grizzly bears, and golden eagles kill large numbers of newborn calves. Predators and scavengers are also quick to target stillborn or unhealthy calves.
These large groups of caribou stay together in the high mountains and along seacoasts where wind and cool temperatures protect them from summer heat and insects. During post-calving, at least for this herd, bulls and nonmaternal caribou are still segregated from cows with neonates newborn calves.
Due to different census techniques and schedules, as well as annual fluctuations in populations, it is not possible to say for certain which of these three herds is currently the largest. Several caribou herds in northern and northeastern Canada that used to be quite large have recently declined to very low numbers, causing concern about the future of these herds. Adult caribou range in size from 3 to 4 feet tall. Their size and weight varies by sex and region.
For example, caribou are fairly small in northern Alaska. Males average about to pounds, females about pounds. In southern Alaska, caribou are considerably larger -- males average to pounds and females average to pounds.
Caribou are the only deer in which both sexes have antlers. Males shed their antlers in late fall, just after the breeding season young males retain their antlers longer that mature males. Pregnant females keep their antlers all winter and shed them soon after the calves are born in the spring.
Non-pregnant females shed their antlers during the winter. Caribou do not store much of their fat in muscle tissue, so their meat is leaner than beef which often is "marbled" with fat. Caribou meat is considered more healthy than beef, and is quite tasty. Caribou commonly gather in large herds about three weeks after the calves are born.
At this time the great herds increase their rate of movement, and caribou tend to be less wary when they are in very large groups. Caribou will generally not let you approach them, but if you sit quietly in the path of a group that is moving in your direction, you might be fortunate enough to see them up close as they pass by. Caribou populations are rarely stable for very long. Under natural conditions, the size of a particular herd will tend to increase slowly for years, then decline, sometimes rapidly, before again beginning to increase.
Many things can influence whether a herd is increasing or declining. When factors having negative effects on caribou births and deaths occur more frequently more bad years than good years , populations decline. Caribou populations increase when the opposite occurs. Usually a combination of factors cause caribou numbers to change. Harsh weather can reduce plant growth, which causes poor caribou nutrition, and reduced survival. Some years, insect harassment interferes with caribou foraging, which also decreases survival.
If it rains during the winter, ice can prevent caribou from getting their food. They may starve when this happens. Wolf populations in caribou winter ranges can increase in response to higher levels of other prey such as moose. When caribou return to the winter range they are preyed on more heavily by the increased number of wolves. On the other hand, when arctic foxes reach a high in their population cycle, they sometimes spread rabies to neighboring wolves.
This results in reduced wolf predation on caribou. Most male caribou live about seven to eight years. Females often live longer, to years. These are very general numbers. Every animal faces its own set of situations that lead to a shorter or longer life. If a caribou lives in a herd that is declining, it probably will have a shorter life than a caribou in a healthy or expanding herd.
Also, many caribou die within the first year after they are born, so never reach adult age. Orphan caribou calves are not adopted by other caribou mothers. If the mother dies, or the calf becomes permanently separated from its mother before the end of its first summer of life, the calf will probably not survive.
Several species are known to prey on caribou. Wolves prey on caribou throughout the year, but most frequently in the winter. Bears prey on caribou during spring, summer and fall.
Golden eagles take young calves during the early summer, and lynx are able to kill calves in the fall when caribou migrate into forested areas. When snow is deep, wolverines are sometimes able to kill caribou. Humans have hunted caribou for many thousands of years. The female doesn't actually pick males with large antlers, but the females do often end up breeding with males that have large antlers.
This is because the mature males those with the largest antlers work hard to keep younger males with smaller antlers away from the females during breeding time. The males with the largest antlers are in the best health, and they have been good at finding food all their lives so their bodies can grow these large antlers.
When these animals do most of the breeding, their genes are passed on to new generations, and this ensures that the herd remains healthy. Both caribou and elk are hoofed mammals of the deer family. Caribou males weigh about pounds are generally smaller than elk males weigh about pounds.
Caribou often occur in large herds which migrate over long distances. Elk generally occur in smaller herds, and migrate over relatively short distances. They usually migrate between summer ranges at higher elevations, and winter ranges in mountain valleys.
Caribou are native to North America, whereas reindeer are found in Scandinavia and northern Asia. Some reindeer have been domesticated by humans for hundreds of years. These are used for food and for pulling sleds. Reindeer are smaller and have shorter legs than caribou. A number of reindeer have been imported to Alaska, primarily to the Seward Peninsula. These herds are owned by Alaska Natives. In the U. There are currently over different wildlife refuges. Refuge lands are legally protected from activities and developments which are harmful to wildlife or their habitat.
Human activities which are compatible with refuge purposes are allowed on wildlife refuges. In Alaska, the Arctic National Wildlife Refuge protects the primary calving grounds and some of the wintering areas of the Porcupine caribou herd, one of the major caribou herds in North America.
Caribou are well equipped to survive in cold, snowy places. In winter, their hair is about three inches long. This winter hair is hollow inside, to trap air and keep warmth near their bodies.
This hollow hair also helps the caribou to cross rivers and lakes after spring thaws, because it acts like a life jacket full of air, and helps them to float. Caribou have four hoofed "toes" on each foot. They usually walk on the two larger ones, like a cow does. When they are in snow, however, these four "toes" spread out wide to act like snow-shoes, which help the caribou walk on deep snow.
Caribou are well adapted to cold, dry conditions that were typical in the Arctic region since the last ice age. When the snow is cold and dry, winter winds will often blow it away, exposing the ground and allowing caribou to walk around and graze more easily. Warmer, wetter winters bring deeper, denser snow and ice that makes it difficult for caribou to dig down to the lichens they eat during winter. Caribou can walk on bumpy ice without slipping, but if they get onto shiny, smooth ice, their hooves slide out from under them and they may fall.
Sometimes they even break their legs this way. Most encounters are brief, but serious battles do occur which can result in injury or death. Most caribou winter in forested areas, where snow conditions are more favorable. Caribou are able to locate forage under snow, apparently by their ability to smell it. To reach the forage they use their front paws to dig craters. Dominant caribou frequently usurp craters dug by subordinate animals.
Caribou communicate among themselves through vocal, visual, chemical, and tactile cues. They have a keen sense of smell, which allows them to find food buried deep under snow. Caribou are primarily grazing herbivores. Their diet is most variable during the summer, when they consume the leaves of willows and birches, mushrooms, cotton grass, sedges and numerous other ground dwelling species of vegetation.
Lichens are an important component of the diet, especially in winter, but are not eaten exclusively. Calves are highly vulnerable to predation by bears, wolves, and other predators during their first week of life. Healthy adult caribou are less susceptible to predation until old age and illness weakens them.
By traveling in herds, caribou increase the number of individuals that can watch for predators. Through their foraging activities, caribou have a dramatic impact on communities of vegetation throughout their range. They are also important prey species for large predators, such as bears and wolves, especially during the calving season. Caribou have been used extensively for their meat, fur and antlers.
Reindeer, the domesticated subspecies of caribou, have been herded throughout their range for thousands of years. Although Alaska, with its more than 30 herds, has nearly double the number of caribou 1,, than people, caribou in the contiguous US are considered endangered.
They are listed as Endangered under the Endangered Species Act in these regions. Loss of habitat, overhunting, and other factors has contributed to the precarious position the woodland caribou now exists in the US. Worldwide, the caribou population is estimated to be around 5 million.
The largest herds now occur in Alaska, Canada, and Russia. Humans have heavily hunted this species. They have been extinct in most parts of Europe since at least the s. Exploration for oil and minerals in Canada may threaten woodland caribou habitat. High Arctic caribou populations are also thought to be vulnerable. Despite their status in the wild, domestic herds of reindeer flourish in the Old World, in Canada, in Alaska, and in the lower 48 states including Michigan.
Caribou, and their domestic counterparts - reindeer, have been very important in the cultures of native peoples througout the arctic. Several Siberian, Scandinavian, and American native cultures are built around herding caribou. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico. In otherwords, Europe and Asia and northern Africa. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.
Synapomorphy of the Bilateria. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a now extinct synapsid ancestor; the fossil record does not distinguish these possibilities.
Convergent in birds. Iteroparous animals must, by definition, survive over multiple seasons or periodic condition changes. For example: antlers, elongated tails, special spurs. Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth.
Some deciduous trees also may be present. A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.
Dalrymple, B. North american big-game animals. Outdoor Life Books, New York.
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