Bighorn sheep

Ovis canadensis

The bighorn sheep is a species of sheep in North America named for its large horns. These horns can weigh up to 30 lb , while the sheep themselves weigh up to 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. Conservation efforts have restored the population.
Portrait of a Bighorn Ram While watching some bighorn rams in Yellowstone National Park, this ram approached the area I was crouched in to a distance that made even myself uncomfortable. Likely, this mature ram would not show any aggression towards me, but he is wild and unpredictable. I was waiting by the Yellowstone River for the rams to come down for a drink or eat grass by along the river bank when he walked up and starting browsing at a distance of only 4 or 5 meters! He was even kind enough to pose for me. Bighorn sheep,Geotagged,Mammals,Ovis canadensis,United States,Winter,Wyoming,Yellowstone National Park

Appearance

Bighorn sheep are named for the large, curved horns borne by the rams . Ewes 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 127–316 lb , are 36–41 in tall at the shoulder, and 69–79 in long from the nose to the tail. Females are typically 75–188 lb , 30–36 in tall and 54–67 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 500 lb and females that exceed 200 lb . In contrast, Sierra Nevada bighorn males weigh up to only 200 lb and females to 140 lb . Males' horns can weigh up to 30 lb , as much as the rest of the bones in the male's body.
Bighorn Ewes Butting Heads Bighorn rams are known to butt heads in an annual ritual that places the sheep in a social hierarchy that decides who is top ram and who gets the best breeding rights. But apparently ewes, or female sheep, also tend to disagree on matters occasionally, as this photo shows. Captured in Badlands National Park, South Dakota. Badlands National Park,Bighorn sheep,Geotagged,Ovis canadensis,South Dakota,Summer,United States,mammals

Naming

In 1940, Cowan split the species into seven subspecies:
⤷  Rocky Mountain bighorn sheep, ''O. c. canadensis'', are found from British Columbia to Arizona.
⤷  California bighorn sheep, ''O. c. californiana'', are found from British Columbia south to California and east to North Dakota. The definition of this subspecies has been updated .
⤷  Nelson's bighorn sheep, ''O. c. nelsoni'', the most common desert bighorn sheep, ranges from California through Arizona.
⤷  Mexican bighorn sheep, ''O. c. mexicana'', range from Arizona and New Mexico south to Sonora and Chihuahua.
⤷  Peninsular bighorn sheep ''O. c. cremnobates'', occur in the Peninsular Ranges of California and Baja California.
⤷  Weems' bighorn sheep, ''O. c. weemsi'', also are found in Baja California.
⤷  Audubon's bighorn sheep, ''O. c. auduboni'', occurred in North Dakota, South Dakota, Montana, Wyoming, and Nebraska. This subspecies has been extinct since 1925.

However, starting in 1993, Ramey and colleagues, using DNA testing, have shown this division into seven subspecies is largely illusory. The taxonomy of ''Ovis canadensis'' continues to be refined as new genetic and morphologic data become available, but most scientists currently recognize these subspecies of bighorn:...hieroglyph snipped...
⤷  Rocky Mountain bighorn sheep , occupying the U.S. and Canadian Rocky Mountains and the northwestern U.S.
⤷  Sierra Nevada bighorn sheep , formerly California bighorn sheep, a genetically distinct subspecies that only occurs in the Sierra Nevada
⤷  Desert bighorn sheep , occurring throughout the southwestern desert regions of U.S. and Mexico.

In addition, two populations are currently considered endangered by the United States government:
⤷  Sierra Nevada bighorn sheep ,
⤷  Peninsular bighorn sheep, a distinct population segment of desert bighorn sheep .
Boys Like Girls ll - Bighorn Sheep - Stagleap Provincial Park, BC A bighorn ram sniffs an ewe while she feeds. Even though this is the post-rut season and the sheep are done breeding, the males can be pushy. This must be a universal behavior seen across many species...Captured in Stagleap Provincial Park, British Columbia, Canada. Bighorn sheep,British Columbia,Canada,Geotagged,Mammals,Ovis canadensis,Stagleap Provincial Park,snow,winter

Behavior

Bighorn sheep live in large flocks, 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. 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 will also employ a blocking strategy. They will 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 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.
Bighorn ram climbing rock face in Yellowstone National Park A bighorn ram scrambles up the side of a near-vertical rock face near the confluence of Soda Butte and Lamar Rivers in Yellowstone National Park's northern reaches.  Bighorn Sheep,Bighorn sheep,Geotagged,Mammals,Ovis canadensis,United States,Winter,Wyoming,Yellowostone,Yellowstone National Park,sheep

Habitat

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. Bighorn sheep generally inhabit alpine meadows, grassy mountain slopes, and foothill country near rugged, rocky cliffs and bluffs. Since bighorn sheep cannot move though deep snow, they prefer drier slopes, where the annual snowfall is less than about 60 inches a year. A bighorn's winter range usually lies at 2,500–5,000 feet in elevation, while its summer range is tends to be at 6,000–8,500 feet . 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 . 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....hieroglyph snipped... 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.
Descendants A young and old ram stand side by side watching me take pictures of them. They were grazing on the mountainside just above the Yellowstone River, YNP.  Bighorn sheep,Geotagged,Ovis canadensis,United States,Winter

Reproduction

Bighorn sheep live in large flocks, 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. 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 will also employ a blocking strategy. They will 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 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.
Bighorn Lamb - Too Innocent This bighorn lamb was just hanging out by the side of the road a little ways away from the rest of the herd. It looks a little too innocent in my opinion...Captured in Badlands National Park, South Dakota. Badlands National Park,Bighorn sheep,Geotagged,Ovis canadensis,South Dakota,United States,fall,mammals

Cultural

Bighorn sheep were among the most-admired animals of the Apsaalooka 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.

The Rocky Mountain bighorn sheep is the provincial mammal of Alberta and the state animal of Colorado and as such is incorporated into the symbol for the Colorado Division of Parks and Wildlife....hieroglyph snipped...

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 . Lewis and Clark recorded numerous sightings of ''Ovis canadensis'' in the journals of their exploration—sometimes using the name argalia. In addition, they recorded the use of bighorn sheep by the Shoshone in making 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.

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Taxonomy
KingdomAnimalia
DivisionChordata
ClassMammalia
OrderArtiodactyla
FamilyBovidae
GenusOvis
SpeciesO. canadensis