The bighorn sheep (Ovis canadensis) is a species of sheep native to North America. The species is named for its large horns. A pair of horns might weigh up to 14 kg (30 lb); the sheep weigh up to 140 kg (300 lb). Recent genetic testing indicates three distinct subspecies of Ovis canadensis, one of which is endangered: O. c. sierrae. Sheep originally crossed to North America over the Bering land bridge from Siberia; the population in North America peaked in the millions, and the bighorn sheep entered into the mythology of Native Americans. By 1900, the population had crashed to several thousand, due to diseases introduced through European livestock and overhunting.
|Male (ram), Wheeler Peak, New Mexico|
|Female (ewe), Greater Vancouver Zoo|
|Bighorn sheep range|
O. cervina Desmarest
Ovis canadensis is one of three species of mountain sheep in North America and Siberia; the other two species being O. dalli, which includes Dall sheep and Stone's sheep, and the Siberian snow sheep, O. nivicola. Wild sheep crossed the Bering land bridge from Siberia into Alaska during the Pleistocene (about 750,000 years ago) and subsequently spread through western North America as far south as Baja California and northwestern mainland Mexico. Divergence from their closest Asian ancestor (snow sheep) occurred about 600,000 years ago. In North America, wild sheep diverged into two extant species—Dall sheep, which occupy Alaska and northwestern Canada, and bighorn sheep, which range from southwestern Canada to Mexico. However, the status of these species is questionable given that hybridization has occurred between them in their recent evolutionary history.
Starting in 1993, Ramey and colleagues, using DNA testing, have shown this division into seven subspecies is largely illusory. Most scientists currently recognize three subspecies of bighorn. This taxonomy is supported by the most extensive genetics (microsatellite and mitochondrial DNA) study to date (2016) which found high divergence between Rocky Mountain and Sierra Nevada bighorn sheep, and that these two subspecies both diverged from desert bighorn prior to or during the Illinoian glaciation (about 315–94 thousand years ago). Thus, the three subspecies of O. canadensis are:
In addition, two populations are currently considered endangered by the United States government:
Bighorn sheep are named for the large, curved horns borne by the rams (males). Ewes (females) also have horns, but they are shorter with less curvature. They range in color from light brown to grayish or dark, chocolate brown, with a white rump and lining on the backs of all four legs. Males typically weigh 58–143 kg (128–315 lb), are 90–105 cm (35–41 in) tall at the shoulder, and 1.6–1.85 m (63–73 in) long from the nose to the tail. Females are typically 34–91 kg (75–201 lb), 75–90 cm (30–35 in) tall, and 1.28–1.58 m (50–62 in) long. Male bighorn sheep have large horn cores, enlarged cornual and frontal sinuses, and internal bony septa. These adaptations serve to protect the brain by absorbing the impact of clashes. Bighorn sheep have preorbital glands on the anterior corner of each eye, inguinal glands in the groin, and pedal glands on each foot. Secretions from these glands may support dominance behaviors.
Bighorns from the Rocky Mountains are relatively large, with males that occasionally exceed 230 kg (500 lb) and females that exceed 90 kg (200 lb). In contrast, Sierra Nevada bighorn males weigh up to only 90 kg (200 lb) and females to 60 kg (140 lb). Males' horns can weigh up to 14 kg (30 lb), as much as the rest of the bones in the male's body.
The Rocky Mountains and Sierra Nevada bighorn sheep occupy the cooler mountainous regions of Canada and the United States. In contrast, the desert bighorn sheep subspecies are indigenous to the hot desert ecosystems of the Southwestern United States and Mexico. Bighorn sheep generally inhabit alpine meadows, grassy mountain slopes, and foothill country near rugged, rocky cliffs and bluffs. Since bighorn sheep cannot move through deep snow, they prefer drier slopes, where the annual snowfall is less than about 150 cm (60 in) per year. A bighorn's winter range usually lies at lower elevations than its summer range.
Bighorn sheep are highly susceptible to certain diseases carried by domestic sheep, such as scabies and pneumonia; additional mortality occurs as a result of accidents involving rock falls or falling off cliffs (a hazard of living in steep, rugged terrain). Bighorns are well adapted to climbing steep terrain, where they seek cover from predators. Predation primarily occurs with lambs, which are hunted by coyotes, bobcats, lynxes, and golden eagles.
Bighorn sheep of all ages are threatened by bears, wolves, and especially cougars, which are perhaps best equipped with the agility to prey on them in uneven, rocky habitats. They are considered good indicators of land health because the species is sensitive to many human-induced environmental problems. In addition to their aesthetic value, bighorn sheep are considered desirable game animals by hunters.
Bighorn sheep graze on grasses and browse shrubs, particularly in fall and winter, and seek minerals at natural salt licks. Females tend to forage and walk, possibly to avoid predators and protect lambs, while males tend to eat and then rest and ruminate, which lends to more effective digestion and greater increase in body size.
Bighorn sheep live in large herds, and do not typically follow a single leader ram, unlike the mouflon, the ancestor of the domestic sheep, which has a strict dominance hierarchy. Prior to the mating season or "rut", the rams attempt to establish a dominance hierarchy to determine access to ewes for mating. During the prerut period, most of the characteristic horn clashing occurs between rams, although this behavior may occur to a limited extent throughout the year. Bighorn sheep exhibit agonistic behavior: two competitors walk away from each other and then turn to face each other before jumping and lunging into headbutts. Rams' horns can frequently exhibit damage from repeated clashes. Females exhibit a stable, nonlinear hierarchy that correlates with age. Females may fight for high social status when they are integrated into the hierarchy at one to two years of age.
Rocky Mountain bighorn rams employ at least three different courting strategies. The most common and successful is the tending strategy, in which a ram follows and defends an estrous ewe. Tending takes considerable strength and dominance, so ewes are more receptive to tending males, feeling they are the most fit. Another tactic is coursing, which is when rams fight for an already tended ewe. Ewes typically avoid coursing males, so the strategy is not effective. Rams also employ a blocking strategy. They prevent a ewe from accessing tending areas before she even goes into estrus.
Bighorn ewes have a six-month gestation. In temperate climates, the peak of the rut occurs in November with one, or rarely two, lambs being born in May. Most births occur in the first two weeks of the lambing period. Pregnant ewes of the Rocky Mountains migrate to alpine areas in spring, presumably to give birth in areas safer from predation, but are away from areas with good quality forage. Lambs born earlier in the season are more likely to survive than lambs born later. Lambs born late may not have access to sufficient milk, as their mothers are lactating at a time when food quality is lower. Newborn lambs weigh from 3.6 to 4.5 kg (8 to 10 lb) and can walk within hours. The lambs are then weaned when they reach four to six months old. The lifespan of rams is typically 9–12 years, and 10–14 years for ewes.
Many bighorn sheep populations in the United States experience regular outbreaks of infectious pneumonia, which likely result from the introduction of bacterial pathogens (in particular, Mycoplasma ovipneumoniae, and some strains of Mannheimia haemolytica) carried asymptomatically in domestic sheep. Once introduced, pathogens can transmit rapidly through a bighorn population, resulting in all-age die-offs that sometimes kill up to 90% of the population. In the years following pathogen introduction, bighorn populations frequently experience multiple years of lamb pneumonia outbreaks. These outbreaks can severely limit recruitment and likely play a powerful role in slowing population growth.
Two hundred years ago, bighorn sheep were widespread throughout the western United States, Canada, and northern Mexico. Some estimates placed their population at over 2 million. By around 1900, hunting, competition from ranching, and diseases had decreased the population to several thousand. A program of reintroductions, natural parks, and reduced hunting, together with a decrease in domesticated sheep near the end of World War II, allowed the bighorn sheep to make a comeback. In 2009, the California Department of Fish and Game issued 21 permits for the hunting of bighorn sheep, and 19 permits for the 2010–2011 hunting season.
In 1936, the Arizona Boy Scouts mounted a statewide campaign to save the bighorn sheep. The scouts first became interested in the sheep through the efforts of Major Frederick Russell Burnham, the noted conservationist who has been called the "Father of Scouting". Burnham observed that fewer than 150 of these sheep still lived in the Arizona mountains. He called George F. Miller, then scout executive of the Boy Scout council headquartered in Phoenix, with a plan to save the sheep. Burnham put it this way, "I want you to save this majestic animal, not only because it is in danger of extinction, but of more importance, some day it might provide domestic sheep with a strain to save them from disaster at the hands of a yet unknown virus."
Several other prominent Arizonans joined the movement, and a "save the bighorns" poster contest was started in schools throughout the state. Burnham provided prizes and appeared in store windows across Arizona. The contest-winning bighorn emblem was made into neckerchief slides for the 10,000 Boy Scouts, and talks and dramatizations were given at school assemblies and on radio. The National Wildlife Federation, the Izaak Walton League, and the National Audubon Society also joined the effort.
These efforts led to the establishment of two bighorn game ranges in Arizona: Kofa National Wildlife Refuge and Cabeza Prieta National Wildlife Refuge. On January 18, 1939, over 600,000 hectares (1,500,000 acres) of land were set aside and a civilian conservation corps side camp was set up to develop high-mountain waterholes for the sheep. The desert bighorn sheep is now the official mascot for the Arizona Boy Scouts.
Bighorn sheep were among the most admired animals of the Apsaalooka (Crow) people, and what is today called the Bighorn Mountain Range was central to the Apsaalooka tribal lands. In the Bighorn Canyon National Recreation Area book, storyteller Old Coyote describes a legend related to the bighorn sheep. A man possessed by evil spirits attempts to kill his heir by pushing the young man over a cliff, but the victim is saved by getting caught in trees. Rescued by bighorn sheep, the man takes the name of their leader, Big Metal. The other sheep grant him power, wisdom, sharp eyes, sure-footedness, keen ears, great strength, and a strong heart. Big Metal returns to his people with the message that the Apsaalooka people will survive only so long as the river winding out of the mountains is known as the Bighorn River.
Bighorn sheep are hunted for their meat and horns, which are used in ceremonies, as food, and as hunting trophies. They also serve as a source of ecotourism, as tourists come to see the bighorn sheep in their native habitat.
Bighorn sheep were once known by the scientific identification "argali" or "argalia" due to assumption that they were the same animal as the Asiatic argali (Ovis ammon). Lewis and Clark recorded numerous sightings of O. canadensis in the journals of their exploration—sometimes using the name argalia. In addition, they recorded the use of bighorn sheep horns by the Shoshone in making composite bows. William Clark's Track Map produced after the expedition in 1814 indicated a tributary of the Yellowstone River named Argalia Creek and a tributary of the Missouri River named Argalia River, both in what is today Montana. Neither of these tributaries retained these names, however. The Bighorn River, another tributary of the Yellowstone, and its tributary stream, the Little Bighorn River were both indicated on Clark's map and did retain their names, the latter being the namesake of the Battle of the Little Bighorn.
The Badlands bighorn, Ovis canadensis auduboni, also commonly known as Audubon's bighorn sheep, is an extinct subspecies of bighorn sheep of the northern Great Plains in North America. Its existence as a separate subspecies is disputed.Buffalo Peaks Wilderness
The Buffalo Peaks Wilderness is a U.S. Wilderness Area located in San Isabel and Pike National Forests in central Colorado. The 43,410-acre (175.7 km2) wilderness was named after two highly eroded volcanic mountains, East Buffalo Peak and West Buffalo Peak, in the Mosquito Range and was established in 1993. The wilderness contains Colorado's largest herd of bighorn sheep.Coso Rock Art District
Coso Rock Art District, containing the Big and Little Petroglyph Canyons, is a rock art site containing over 100,000 Paleo-Indian and/or Native American Petroglyphs. The Coso Range is between the Sierra Nevada and the Argus Range. Indian Wells Valley lies to the south of this location. This north-south trending range of about 400 square miles (1,000 km2) consists of rhyolitic domes and outcrops of volcanic rock. Also known as Little Petroglyph Canyon and Sand Tanks, Renegade Canyon is but one of several major canyons in the Coso Range, each hosting thousands of petroglyphs (other locations include Haiwee Springs, Dead End Canyon, and Sheep Canyon). The majority of the Coso Range images fall into one of six categories: bighorn sheep, entopic images, anthropomorphic or human-like figures (including animal-human figures known as pattern-bodied anthopomorphs), other animals, weapons & tools, and "medicine bag" images. Most of the Coso Range is on the Naval Air Weapons Station China Lake, where visitation is restricted, vandalism is low, and preservation is most likely. China Lake is located near the towns of China Lake and Ridgecrest, California. There are several other distinct canyons in the Coso Rock Art District besides the Big and Little Petroglyph Canyons. The most popular subjects are bighorn sheep, deer, and antelope. Big and Little Petroglyph Canyons were declared a National Historic Landmark in 1964. In 2001, they were incorporated into a larger National Historic Landmark District, called Coso Rock Art District.A November 2007 Los Angeles Times' Travel feature article includes it within a top 15 list of California places to visit. The area was also mentioned in Groupon's "10 Most Unique Autumn Festivals in the Country" as a part of the Ridgecrest Petroglyph Festival.Desert bighorn sheep
Desert bighorn sheep (Ovis canadensis nelsoni) is a subspecies of bighorn sheep (Ovis canadensis) that is native to the deserts of the USA's intermountain west and southwestern regions, as well as northwestern Mexico.
The trinomial of this species commemorates the American naturalist Edward William Nelson (1855–1934). The characteristics and behavior of desert bighorn sheep generally follow those of other bighorn sheep, except for adaptation to the lack of water in the desert. They can go for extended periods of time without drinking water.
The desert bighorn sheep is also the mascot of the Universidad Autónoma de Baja California.Fossil Ridge Wilderness
The Fossil Ridge Wilderness is a U.S. Wilderness Area located approximately 16 miles (26 km) north of Gunnison, Colorado in the Gunnison National Forest. The 13,992-acre (56.62 km2) wilderness includes Fossil Ridge, a high, exposed ridge of Paleozoic carbonates that contain epeiric sea fossils. Elevations in the wilderness range from 8,880 feet (2,710 m) at Summerville Creek to 13,254 feet (4,040 m) at the summit of Henry Mountain. Elk, deer, mountain goats, and bighorn sheep can be found in the wilderness.Hart Mountain National Antelope Refuge
Hart Mountain National Antelope Refuge is a National Wildlife Refuge on Hart Mountain in southeastern Oregon, which protects more than 422 square miles (1,090 km2) and more than 300 species of wildlife, including pronghorn, bighorn sheep, mule deer, sage grouse, and Great Basin redband trout. The refuge, created in 1936 as a range for remnant herds of pronghorn, spans habitats ranging from high desert to shallow playa lakes, and is among the largest wildlife habitats containing no domestic livestock.Havasu National Wildlife Refuge
Havasu National Wildlife Refuge is a U.S. National Wildlife Refuge on the lower Colorado River in Arizona and California. It preserves habitat for desert bighorn sheep to the endangered southwestern willow flycatcher, birds and other animals. The refuge protects 30 river miles - 300 miles (480 km) of shoreline - from Needles, California, to Lake Havasu City, Arizona. One of the last remaining natural stretches of the lower Colorado River flows through the 20-mile-long (32 km) Topock Gorge.
Animal species that inhabit this refuge include peregrine falcon, coyote, fox, desert bighorn sheep, greater roadrunner, bobcat, and cougar. Thousands of bats emerge from historic mines and razorback suckers swim in the back of Beal Lake.
A large river in a dry, hot land attracts wildlife and people like a powerful magnet. Many thousands of visitors annually flock to the refuge to boat through the Topock Gorge, watch waterbirds in Topock Marsh, or hike to the Havasu Wilderness Area.
A non-profit membership organization supports and advocates for the refuge. It assists refuge staff with several of the refuge annual events, help to obtain grants to support refuge projects, conducts fund-raising activities to support environmental education programs, and helps the United States Fish and Wildlife Service operate and maintain the refuge facilities and programs by providing volunteer labor.Kofa National Wildlife Refuge
The Kofa National Wildlife Refuge is located in Arizona in the southwestern United States, northeast of Yuma and southeast of Quartzsite. The refuge, established in 1939 to protect desert bighorn sheep, encompasses over 665,400 acres (2,693 km2) of the Yuma Desert region of the Sonoran Desert. Broad, gently sloping foothills as well as the sharp, needlepoint peaks of the Kofa Mountains are found in the rugged refuge. The small, widely scattered waterholes attract a surprising number of water birds for a desert area. A wide variety of plant life is also found throughout the refuge.Mueller State Park
Mueller State Park is a Colorado state park encompassing 5,112 acres (20.69 km2) of land outside Divide, Colorado, southwest of Colorado Springs, Colorado. The park offers many outdoor activities. There are 55 miles (89 km) of trails, biking, camping year-round, hunting, hiking, horseback riding. It is open in the winter and snowshoeing, sledding and snowtubing is allowed as well. Mueller is a diverse home to a variety of animals including elk, black bear, eagles, hawks and bighorn sheep.Pikeview, Colorado
Pikeview (Pike View, Pike's View) is a neighborhood of Colorado Springs, annexed to the city as the "Pike View Addition" on August 1, 1962. In 1896 there was a Denver and Rio Grande Western Railroad station in Pikeview, and miners had begun digging a shaft for the Pikeview Coal Mine. Pikeview also had a quarry beginning 1905 for the mining of limestone for concrete. Coal mining ended in 1957, but the Pikeview Quarry continues to operate. Quarry operations, though, have created a gash or scar in the landscape and efforts have been made since the late 1980s to reclaim the hillside landscape. The Greg Francis Bighorn Sheep Habitat in what had been Queens Canyon Quarry was founded in 2003 in recognition of the individuals and organizations that have worked to create a nature hillside habitat.San Andres Mountains
The San Andres Mountains are a mountain range in the southwestern U.S. state of New Mexico, in the counties of Socorro, Sierra, and Doña Ana. The range extends about 75 miles (120 km) north to south, but are only about 12 miles (19 km) wide at their widest. The highest peak in the San Andres Mountains is Salinas Peak, at 8,965 feet (2,733 m).San Andres National Wildlife Refuge
The San Andres National Wildlife Refuge is located in the southern San Andres Mountains of southcentral New Mexico, USA. The refuge, which lies within the northernmost extension of the Chihuahuan Desert, has elevations ranging from 4,200 feet (1,300 m) to 8,239 feet (2,511 m) feet. Refuge habitats vary from creosote and Chihuahuan desert grasslands in the bajadas to pinyon-juniper woodlands at higher elevations. A few springs, seeps, and seasonal streams provide water for wildlife and riparian habitats in the refuge.
San Andres NWR is completely surrounded by the White Sands Missile Range and is closed to the public for security reasons.Sheep River Provincial Park
Sheep River Provincial Park is a provincial park located in Alberta, Canada, 23 km west of Turner Valley on highway 546. It is part of the Kananaskis Country park system.
Located on the eastern slopes of the Rocky Mountains, the park includes the Sheep River Wildlife Sanctuary, which provides permanent habitat for bighorn sheep, while the eastern part of the reserve extends to the Foothills Natural Region, offering summer range for elk and deer.Sierra Nevada bighorn sheep
Sierra Nevada bighorn sheep (Ovis canadensis sierrae) is subspecies of bighorn sheep unique to the Sierra Nevada mountains of California. A 2016 genetics study confirmed significant divergence between the three subspecies of North America's bighorn sheep: Sierra Nevada bighorn sheep, Rocky Mountain bighorn sheep and desert bighorn sheep. Sierra Nevada bighorn sheep were listed as a federally endangered subspecies in 2000. As of 2016, over 600 Sierra bighorn remain in the wild.Siffleur Wilderness Area
The Siffleur Wilderness Area is a provincially designated wilderness area in the Canadian Rockies of Alberta. It was established in 1961 and it, as one of the three wilderness areas of Alberta, has the strictest form of government protection available in Canada. All development is forbidden and only travel by foot is permitted. Hunting and fishing are not allowed. The other two wilderness areas are White Goat Wilderness Area and Ghost River Wilderness Area and together the three areas total 249,548.80 acres (100,988.82 ha).Siffleur is located near the west end and south side of Canadian Highway 11 and slightly south of the White Goat Wilderness area. It is near the north end of Banff National Park and the south end of Jasper National Park. Mountains rise to 3,300 metres (10,800 ft). The area has rugged mountains, glacier-carved valleys, mountain lakes, and alpine meadows. There are two distinct vegetation zones. Above 2,100 metres (6,900 ft), the tree line, are grasses, sedges and wildflowers. Below that are subalpine forests of spruce, fir, and lodgepole pine. At even lower elevations there are aspen and balsam poplar. Animals in the lower regions include woodland caribou, moose, elk, white-tailed deer, mule deer, grizzly bear, black bear, cougar, coyote, timber wolf, and wolverine. Animals in the upper regions include golden-mantled ground squirrels, bighorn sheep, mountain goat, hoary marmot, pika, white-tailed ptarmigan, grey-crowned rosy finch, water pipit and horned lark. Eagles are seen in both the lower and upper regions.Like Siffleur Mountain and Siffleur River, the French siffleur name was applied by James Hector in 1858 for the shrill whistles of the marmot which inhabit the area.Snow sheep
The snow sheep (Ovis nivicola), or Siberian bighorn sheep, is a species of sheep from the mountainous areas in the northeast of Siberia. One subspecies, the Putorana snow sheep (Ovis nivicola borealis), lives isolated from the other forms in the Putoran Mountains.State Forest State Park
State Forest State Park is a Colorado State Park located in Jackson and Larimer counties east of Walden, Colorado, United States. The 70,838-acre (286.67 km2) park was established in 1970 in the Medicine Bow Range of the Rocky Mountains. Facilities include a visitors' center, 187 campsites (including RV and tent sites), over 60 dispersed camping sites, 15 cabins and yurts, picnic sites, boat ramps and 94 miles (151 km) of hiking trails.About 52,000 acres (210 km2) of the park are forested in lodgepole pine, Douglas fir, Colorado blue spruce, aspen and other species. An unprecedented epidemic of Mountain pine beetle is currently reshaping the park's flora landscape. Wildlife in the park includes moose ("Moose is our claim to fame"), bighorn sheep, black bear, mule deer and elk.Whiskey Mountain
Whiskey Mountain (11,157 ft (3,401 m)) is located in the northern Wind River Range in the U.S. state of Wyoming. Located 5 mi (8.0 km) south of Dubois, Wyoming, Whiskey Mountain is within the Whiskey Mountain Wilderness Study Area, which has the largest wintering concentration of Rocky Mountain Bighorn sheep in the coterminous United States.White Goat Wilderness Area
The White Goat Wilderness Area is a provincially designated wilderness area in the Canadian Rockies of Alberta. It was established in 1961 and it, as one of the three wilderness areas of Alberta, has the strictest form of government protection available in Canada. All development is forbidden and only travel by foot is permitted. Hunting and fishing are not allowed. The other two wilderness areas are Ghost River Wilderness Area and Siffleur Wilderness Area and together the three areas total 249,548.80 acres (100,988.82 ha).White Goat is located near the west end and north side of Canadian Highway 11 and slightly north of the Siffleur Wilderness area. It is near the north end of Banff National Park, the south end of Jasper National Park, and east of the Columbia Icefield. Mountains rise to over 3,300 metres (10,800 ft). The area has rugged mountains, glacier-carved valleys, mountain lakes, waterfalls, and alpine meadows. There are two distinct vegetation zones. Above 2,100 metres (6,900 ft), the tree line, are grasses, sedges and wildflowers. Below that are spruce, fir, and lodgepole pine. Animals in the lower regions include woodland caribou, moose, elk, white-tailed deer, mule deer, grizzly bear, black bear, cougar, coyote, timber wolf, and wolverine. Animals in the upper regions include golden-mantled ground squirrels, bighorn sheep, mountain goat, hoary marmot, pika, white-tailed ptarmigan, grey-crowned rosy finch, water pipit and horned lark. Eagles are seen in both the lower and upper regions.
Extant Artiodactyla species
Game animals and shooting in North America