Rocky Mountain Elk (Cervus canadensis nelsoni) are large mammals in the deer family that live in Colorado’s forests. Revered as a symbol of the American West, they have played an important role in Colorado’s ecology and natural history. Each year, millions of people travel to Rocky Mountain National Park and Colorado’s National Forests to catch a glimpse of these animals. In addition to drawing tourists, the state’s elk populations also attract hunters from around the globe.
Historically, Colorado’s elk populations have oscillated widely. Elk, or wapiti—a Shawnee Indian term for the animals—moved across the Bering Strait from Asia at least 120,000 years ago. Their distribution and abundance in North America ebbed and flowed in relation to periods of glaciation, but they roamed from northern Canada into Mexico. Elk arrived in northern Colorado about 8,000–10,000 years ago and in southern Colorado about 4,000–5,000 years ago. Historical estimates suggest that the elk population might have exceeded 10 million prior to European arrival on the continent in 1492.
The North American elk is a gregarious grazer, feeding mostly on grasses and forbs instead of shrubs. Their current preference for forest cover is thought to be an innovation, as their herding behavior is typical of mammals that live in open country. Winter elk herds are large, ranging from fifty to several hundred individuals of both sexes. Winter herds disband as bulls move first to summer range, following the retreating snowline and the advance of green herbage. Cow and calves follow bulls to summer range, and the great winter herds break up into smaller bands.
The crisp air of late September carries the bugling of bulls, signaling the beginning of the rut, or mating, season. Contrary to popular belief, bugling is neither a challenge nor a threat. It is partly a release of tension built up during the bull’s seasonal changes; the shoulders and neck swell with the rut, and antlers sharpen. Bugling peaks in early October, and the most aggressive bulls assert authority over bands of five to fifteen cows. Another bull may challenge that authority through sparring, an antler-clashing battle for dominance.
Gestation takes about 250 days, and a single calf weighing about thirty-three pounds is born in June. With an odor seemingly detectable only by the mother, the calf remains motionless and is left alone as the mother forages. As typical of ungulates, the calves are mobile within hours of birth. The calf develops quickly and is usually weaned by late summer. At six months it may weigh 265 pounds. Cows are mature by their second autumn and usually begin reproducing after three years. Because of the social structure of the herd, bulls do not generally acquire cows and begin breeding until their fourth or fifth year.
At one time gray wolves preyed on elk, and mountain lions still take a few annually. A pack of coyotes can kill a weakened elk or one immobilized by deep snow. As with deer, moose, and caribou, elk harbor parasites, including flukes, tapeworms and roundworms, lice, botflies, and mites. Chronic wasting disease (CWD)—a contagious neurological disease affecting the brains of deer, moose, and elk—is known in some Colorado elk populations, including those in Rocky Mountain National Park. CWD predominantly affects adult animals and typically results in dramatic behavioral changes. Infected elk are less social and may suffer from tremors, listlessness, nervousness, and excessive salivation, the latter which is thought to contribute to the spread of the disease. CWD’s common denominator is chronic weight loss, which ultimately leads to death.
Where elk appeared in abundance, indigenous peoples hunted them for food, clothing, and tools. In Colorado, Navajo, Ute, Jicarilla Apache, Havasupai, Hopi, Zuni, and other peoples harvested elk in the southern Rocky Mountains and the Four Corners region.
The pre-European period of abundance ended abruptly in the mid-nineteenth century. As white settlement and railroads moved westward, elk, bison, deer, and bighorn sheep were hunted to feed the growing western population and to suppress Native Americans. This reduced the elk population from an estimated 10 million to fewer than 100,000 in 1907 and approximately 90,000 in 1922. About one-third of those elk lived in the Yellowstone area and Canada.
Colorado’s elk had a similar experience. The Colorado Gold Rush of 1858–59 ushered in a period of intense exploitation that did not cease until the early 1900s, when Colorado began enacting strict hunting regulations to conserve its remaining elk. The US Forest Service estimated that Colorado’s 1910 population contained 500 to 1,000 head of elk, with the largest herds in the White and Gunnison watersheds. The diminishing elk herds prompted Colorado to halt elk hunting throughout most of the state from 1903 to 1933. From 1912 to 1928, the Colorado Department of Game and Fish (the predecessor to Colorado Parks and Wildlife) reintroduced 350 elk from Jackson Hole, Wyoming, into fourteen areas, including the Hermosa Creek drainage north of Durango in 1912. During the 1930s, after elk populations had rebounded, the state trapped elk from abundant herds in southwest Colorado and transplanted them to other states to begin new herds.
Return to Abundance
Elk have been successfully restored to Colorado. In fact, with an estimated elk population of 280,000, the state hosts the largest elk population in North America. The relatively docile ungulates may be a reliable tourist draw, but excessively large elk populations can result in overgrazing that threatens ecosystem stability.
With humans having severely reduced the state’s population of mountain lions, wolves, and coyotes, state and federal wildlife officials use artificial strategies such as hunting and culling to manage elk populations. About 250,000 hunters pursue elk each year in Colorado, harvesting nearly 50,000. Culling, meanwhile, involves killing off fertile females when the elk population approaches a predetermined peak population. The need for such lethal management strategies demonstrates that Colorado’s elk population has cycled back to abundance after its severe reduction in the nineteenth and early twentieth centuries.
Adapted from Scott Wait and Mike Japhet, “Wildlife of the San Juans: A Story of Abundance and Exploitation,” in The Eastern San Juan Mountains: Their Geology, Ecology, and Human History, ed. Rob Blair and George Bracksieck (Boulder: University Press of Colorado, 2011) and David M. Armstrong, “Order Artiodactyla: Even-toed Hoofed Mammals,” in Rocky Mountain Mammals: A Handbook of Mammals of Rocky Mountain National Park and Vicinity, 3rd ed. (Boulder: University Press of Colorado, 2008).