Elk

The elk, or wapiti, is one of the largest species within the deer family, Cervidae, in the world, and one of the largest land mammals in North America and Eastern Asia. This animal should not be confused with the still larger moose (Alces alces) to which the name "elk" applies in British English and in reference to populations in Eurasia. Apart from the moose, the only other member of the deer family to rival the elk in size is the south Asian sambar (Rusa unicolor).

Elk range in forest and forest-edge habitat, feeding on grasses, plants, leaves, and bark. Male elk have large antlers which are shed each year. Males also engage in ritualized mating behaviors during the rut, including posturing, antler wrestling (sparring), and bugling, a loud series of vocalizations that establishes dominance over other males and attracts females.

Although they are native to North America and eastern Asia, they have adapted well to countries in which they have been introduced, including Argentina and New Zealand. Their great adaptability may threaten endemic species and ecosystems into which they have been introduced.

Elk are susceptible to a number of infectious diseases, some of which can be transmitted to livestock. Efforts to eliminate infectious diseases from elk populations, largely by vaccination, have had mixed success.

Some cultures revere the elk as a spiritual force. In parts of Asia, antlers and their velvet are used in traditional medicines. Elk are hunted as a game species. The meat is leaner and higher in protein than beef or chicken.

It was long believed to be a subspecies of the European red deer (Cervus elaphus), but evidence from a number of mitochondrial DNA genetic studies beginning in 1998 show that the two are distinct species. Key morphological differences that distinguish C. canadensis from C. elaphus are the former's wider rump patch and paler-hued antlers. The elk is a large animal of the ungulate order Artiodactyla, possessing an even number of toes on each foot, similar to those of camels, goats and cattle. It is a ruminant species, with a four-chambered stomach, and feeds on grasses, plants, leaves and bark. During the summer, elk eat almost constantly, consuming between 4 and 7 kilograms (8.8 and 15.4 lb) of vegetation daily. In North America, males are called bulls, and females are called cows. In Asia, stag and hind, respectively, are sometimes used instead.

Elk are more than twice as heavy as mule deer and have a more reddish hue to their hair coloring, as well as large, buff colored rump patches and smaller tails. Moose are larger and darker than elk; bulls have distinctively different antlers. Elk gather in herds, while moose are solitary. Elk cows average 225 to 241 kg (496 to 531 lb), stand 1.3 m (4.3 ft) at the shoulder, and are 2.1 m (6.9 ft) from nose to tail. Bulls are some 40% larger than cows at maturity, weighing an average of 320 to 331 kg (705 to 730 lb), standing 1.5 m (4.9 ft) at the shoulder and averaging 2.45 m (8.0 ft) in length. The largest of the subspecies is the Roosevelt elk (C. c. roosevelti), found west of the Cascade Range in the U.S. states of California, Oregon and Washington, and in the Canadian province of British Columbia. Roosevelt elk have been reintroduced into Alaska, where the largest males are estimated to weigh up to 600 kg (1,300 lb). More typically, male Roosevelt elks weigh around 300 to 544 kg (661 to 1,199 lb), while females weigh 260 to 285 kg (573 to 628 lb). The smallest-bodied race is the tule elk (C. c. nannodes), which weighs from 170 to 250 kg (370 to 550 lb) in both sexes.

Only the males have antlers, which start growing in the spring and are shed each winter. The largest antlers may be 1.2 metres (3.9 ft) long and weigh 18 kilograms (40 lb). Antlers are made of bone which can grow at a rate of 2.5 centimetres (0.98 in) per day. While actively growing, the antlers are covered with and protected by a soft layer of highly vascularised skin known as velvet. The velvet is shed in the summer when the antlers have fully developed. Bull elk may have eight or more tines on each antler; however, the number of tines has little to do with the age or maturity of a particular animal. The Siberian and North American elk carry the largest antlers while the Altai wapiti have the smallest. The formation and retention of antlers is testosterone-driven. After the breeding season in late fall, the level of pheromones released during estrus declines in the environment and the testosterone levels of males drop as a consequence. This drop in testosterone leads to the shedding of antlers, usually in the early winter.

During the fall, elk grow a thicker coat of hair, which helps to insulate them during the winter. Males, females and calves of Siberian and North American elk all grow thin neck manes; female and young Manchurian and Alaskan wapitis do not. By early summer, the heavy winter coat has been shed, and elk are known to rub against trees and other objects to help remove hair from their bodies. All elk have small and clearly defined rump patches with short tails. They have different coloration based on the seasons and types of habitats, with gray or lighter coloration prevalent in the winter and a more reddish, darker coat in the summer. Subspecies living in arid climates tend to have lighter colored coats than do those living in forests. Most have lighter yellow-brown to orange-brown coats in contrast to dark brown hair on the head, neck, and legs during the summer. Forest-adapted Manchurian and Alaskan wapitis have darker reddish-brown coats with less contrast between the body coat and the rest of the body during the summer months. Calves are born spotted, as is common with many deer species, and they lose their spots by the end of summer. Adult Manchurian wapiti may retain a few orange spots on the back of their summer coats until they are older. This characteristic has also been observed in the forest-adapted European red deer. Elk are ruminants and therefore have four-chambered stomachs. Unlike white-tailed deer and moose which are primarily browsers, elk have a similarity to cattle as they are primarily grazers, but like other deer, they also browse. Elk have a tendency to do most of their feeding in the mornings and evenings, seeking sheltered areas in between feedings to digest. Their diets vary somewhat depending on the season, with native grasses being a year-round supplement, tree bark being consumed in winter and forbs and tree sprouts during the summer. Elk consume an average of 9.1 kilograms (20 lb) of various vegetation daily. Particularly fond of aspen sprouts which rise in the spring, elk have had some impact on aspen groves which have been declining in some regions where elk exist. Modern subspecies are descended from elk that once inhabited Beringia, a steppe region between Asia and North America that connected the two continents during the Pleistocene. Beringia provided a migratory route for numerous mammal species, including brown bear, camel, horse, caribou, and moose, as well as humans. As the Pleistocene came to an end, ocean levels began to rise; elk migrated southwards into Asia and North America. In North America they adapted to almost all ecosystems except for tundra, true deserts, and the gulf coast of the U.S. The elk of southern Siberia and central Asia were once more widespread but today are restricted to the mountain ranges west of Lake Baikal including the Sayan and Altai Mountains of Mongolia and the Tianshan region that borders Kyrgyzstan, Kazakhstan, and China's Xinjiang Province. The habitat of Siberian elk in Asia is similar to that of the Rocky Mountain subspecies in North America.

Throughout their range, they live in forest and in forest edge habitat, similar to other deer species. In mountainous regions, they often dwell at higher elevations in summer, migrating down slope for winter. The highly adaptable elk also inhabit semi-deserts in North America, such as the Great Basin. Manchurian and Alashan wapiti are primarily forest dwellers and their smaller antler size is a likely adaptation to a forest environment.

Range and wildlife managers conduct surveys of elk pellet groups to monitor populations and resource use. Adult elk usually stay in single-sex groups for most of the year. During the mating period known as the rut, mature bulls compete for the attentions of the cow elk and will try to defend females in their harem. Rival bulls challenge opponents by bellowing and by paralleling each other, walking back and forth. This allows potential combatants to assess the other's antlers, body size and fighting prowess. If neither bull backs down, they engage in antler wrestling, and bulls sometimes sustain serious injuries. Bulls also dig holes in the ground, in which they urinate and roll their body. A male elk's urethra points upward so that urine is sprayed almost at a right angle to the penis. The urine soaks into their hair and gives them a distinct smell which attracts cows.

Dominant bulls follow groups of cows during the rut, from August into early winter. A bull will defend his harem of 20 cows or more from competing bulls and predators. Only mature bulls have large harems and breeding success peaks at about eight years of age. Bulls between two and four years and over 11 years of age rarely have harems, and spend most of the rut on the periphery of larger harems. Young and old bulls that do acquire a harem hold it later in the breeding season than do bulls in their prime. A bull with a harem rarely feeds and he may lose up to 20 percent of his body weight. Bulls that enter the rut in poor condition are less likely to make it through to the peak conception period or have the strength to survive the rigors of the oncoming winter.

Bulls have a loud vocalization consisting of screams known as bugling, which can be heard for miles. Bugling is often associated with an adaptation to open environments such as parklands, meadows, and savannas, where sound can travel great distances. Females are attracted to the males that bugle more often and have the loudest call. Bugling is most common early and late in the day and is one of the most distinctive sounds in nature, akin to the howl of the gray wolf. Female elk have a short estrus cycle of only a day or two, and matings usually involve a dozen or more attempts. By the autumn of their second year, females can produce one and, very rarely, two offspring, although reproduction is most common when cows weigh at least 200 kilograms (440 lb). The gestation period is 240 to 262 days and the offspring weigh between 15 and 16 kilograms (33 and 35 lb). When the females are near to giving birth, they tend to isolate themselves from the main herd, and will remain isolated until the calf is large enough to escape predators. Calves are born spotted, as is common with many deer species, and they lose their spots by the end of summer. Manchurian wapiti may retain a few orange spots on the back of their summer coats until they are older. After two weeks, calves are able to join the herd, and are fully weaned at two months of age. Elk calves are as large as an adult white-tailed deer by the time they are six months old. The offspring will remain with their mothers for almost a year, leaving about the time that the next season's offspring are produced. The gestation period is the same for all subspecies.

Elk live 20 years or more in captivity but average 10 to 13 years in the wild. In some subspecies that suffer less predation, they may live an average of 15 years in the wild. Wolf and coyote packs and the solitary cougar are the most likely predators, although brown and black bears also prey on elk. Coyote packs mostly prey on elk calves, though they can sometimes take a winter-weakened adult. In the Greater Yellowstone Ecosystem which includes Yellowstone National Park, bears are the most significant predators of calves. Major predators in Asia include the wolf, dhole, brown bear, Siberian tiger, Amur leopard, and snow leopard. Eurasian lynx and wild boar sometimes prey on Asian elk calves. Historically, tigers in the Lake Baikal region fed on Manchurian wapiti, and continue to do so in the Amur region.

Male elk retain their antlers for more than half the year and are less likely to group with other males when they have antlers. Antlers provide a means of defense, as does a strong front-leg kick, which is performed by either sex if provoked. Once the antlers have been shed, bulls tend to form bachelor groups which allow them to work cooperatively at fending off predators. Herds tend to employ one or more scouts while the remaining members eat and rest.

After the rut, females form large herds of up to 50 individuals. Newborn calves are kept close by a series of vocalizations; larger nurseries have an ongoing and constant chatter during the daytime hours. When approached by predators, the largest and most robust females may make a stand, using their front legs to kick at their attackers. Guttural grunts and posturing effectively deter all but the most determined predators.