Description
The elk is a large animal, 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 kg (10 to 15 lb) 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 and moose do not herd. Elk cows average 225 kg (500 lb), stand 1.3 m (4½ ft) at the shoulder, and are 2 m (6½ ft) from nose to tail. Bulls are some 25% larger than cows at maturity, weighing an average of 320 kg (700 lb), standing 1.5 m (5 ft) at the shoulder and averaging 2.5 m (8 ft) in length. The largest of the subspecies is the Roosevelt elk, found west of the Cascade Range in the California, Oregon and Washington, and in British Columbia. Roosevelt elk have been reintroduced into Alaska, where males have been recorded as weighing up to 600 kg (1,300 lb).
Only the males have antlers, which start growing in the spring and are shed each winter. The largest antlers may be 1.2 m (4 ft) long and weigh 18 kg (40 lb). Antlers are made of bone which can grow at a rate of 2.5 cm (1 inch) 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 six 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 thick neck manes; female and young Manchurian and Alashan 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 large 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 Alashan 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.
Behavior
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 cows 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 others 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. 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 to 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.
Reproduction and lifecycle
Female elk have a short estrus cycle of only a day or two and matings usually involve a dozen or more attempts. By the fall of their second year, females can produce one and, very rarely, two offspring, though reproduction is most common when cows weigh at least 200 kg (450 lb). The gestation period is 240 to 262 days and the offspring weigh between 15 and 16 kg (33 to 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 weigh as much 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.
Migration
The Greater Yellowstone Ecosystem elk herd numbers over 200,000 individuals and during the spring and fall, they take part in the longest elk migration in the continental U.S. Elk in the southern regions of Yellowstone National Park and in the surrounding National Forests migrate south towards the town of Jackson, Wyoming where they winter for up to six months on the National Elk Refuge. Conservationists there ensure the herd is well fed during the harsh winters. Many of the elk that reside in the northern sections of the Greater Yellowstone Ecosystem migrate to lower altitudes in Montana, mainly to the north and west.
As is true for many species of deer, especially those in mountainous regions, elk migrate into areas of higher altitude in the spring, following the retreating snows, and the opposite direction in the fall. Hunting pressure also impacts migration and movements. During the winter, they favor wooded areas and sheltered valleys for protection from the wind and availability of tree bark to eat. Roosevelt elk are generally non-migratory due to less seasonal variability of food sources.
Health issues
Brainworm is a parasitic nematode that has been known to affect the spinal cord and brain tissue of elk, leading to death. The nematode has a carrier in the white-tailed deer in which it normally has no ill effects. It is also carried by snails which can be inadvertently consumed by elk during grazing.
Chronic Wasting Disease affects the brain tissue in elk, and has been detected throughout their range in North America. First documented in the late 1960s in mule deer, the disease has affected elk on game farms and in the wild in a number of regions. Elk that have contracted the disease begin to show weight loss, increased watering needs, disorientation and listlessness, and at an advanced stage the disease leads to death. The disease is similar to but not the same as Mad Cow Disease, and no dangers to humans have been documented, nor has the disease been demonstrated to pose a threat to domesticated cattle.
Brucellosis occasionally affect elk in the Greater Yellowstone Ecosystem, the only place in the U.S. where the disease is still known to exist. In domesticated cattle, brucellosis causes infertility, abortions and reduced milk production. It is transmitted to humans as undulant fever, producing flu-like symptoms which may last for years. Though bison are more likely to transmit the disease to other animals, elk inadvertently transmitted brucellosis to horses in Wyoming and cattle in Idaho. Researchers are attempting to eradicate the disease through vaccinations and herd management measures, which are expected to be successful.
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