Bighorn Sheep - Yellowstone National Park (U.S. National Park Service) (2024)

Bighorn Sheep - Yellowstone National Park (U.S. National Park Service) (1)

Although widely distributed across the Rocky Mountains, bighorn sheep (Ovis canadensis) persist chiefly in small, fragmented populations that are vulnerable to sudden declines as a result of disease, habitat loss, and disruption of their migratory routes due to roads and other human activities. Between 10 and 13 interbreeding bands of bighorn sheep occupy steep terrain in the upper Yellowstone River drainage, including habitat that extends more than 20 miles north of the park. These sheep provide visitor enjoyment as well as revenue to local economies through tourism, guiding, and sport hunting. Mount Everts receives the most concentrated use by bighorn sheep year-round.

Bighorn Sheep - Yellowstone National Park (U.S. National Park Service) (2)


From the 1890s to the mid-1960s, the park’s bighorn sheep population fluctuated between 100 and 400. Given the vagaries of weather and disease, bighorn sheep populations of at least 300 are desirable to increase the probability of long-term persistence with minimal loss of genetic diversity. The count reached a high of 487 in 1981, but a keratoconjunctivitis (pinkeye) epidemic caused by Chlamydia reduced the population by 60% the following winter, and the population has been slow to recover. Although the temporary vision impairment caused by the infection is rarely fatal for domestic sheep that are fenced and fed, it can result in death for a sheep that must find its forage in steep places.

During the 2018 survey, a total of 345 bighorn sheep were observed, including 214 in Montana and 131 inside Yellowstone National Park. This is slightly below the 10-year average of 358 sheep. Additionally, in 2018, lamb-to-ewe ratios of 20:100 were below the 10-year average (28:100), with very low lamb recruitment observed on the Cinnabar, Corwin, and Mt. Everts winter ranges.

During 2005-2015, the population increased steadily. A decline occurred in 2015 related to an all-ages pneumonia event. In spite of the 2015 decline, overall bighorn sheep numbers in the northern Yellowstone remain substantially above the long-term average.

  • Inside Yellowstone - Bighorn Sheep

    Bighorn Sheep can be seen on some of the cliffs in the park. Their remarkable adaptations allow them to escape predators by running down cliffs that the predators cannot handle. Duration: 2 minute 17 seconds

    2 minutes, 16 seconds

Competition with Other Species

Bighorn sheep populations that winter at high elevations are often small, slow-growing, and low in productivity. Competition with elk as a result of dietary and habitat overlaps may have hindered the recovery of this relatively isolated population after the pinkeye epidemic. Rams may be hunted north of the park, but the State of Montana has granted few permits in recent years because of the small population size.

Although wolves occasionally prey on bighorn sheep, the population has increased since wolf reintroduction began in 1995. Longer-term data are needed to show whether sheep abundance may be inversely related to elk abundance on the northern range. The Wyoming Game and Fish Department, Montana Fish, Wildlife & Parks, the Idaho Department of Fish and Game, Montana State University, the US Forest Service, and several nongovernmental organizations are cooperating with the National Park Service to study how competition with nonnative mountain goats, which were introduced in the Absaroka Mountains in the 1950s, could affect bighorn sheep there.

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Barmore, W.J. Jr. 2003. Ecology of ungulates and their winter range in Northern Yellowstone National Park, Research and Synthesis 1962–1970. Yellowstone Center for Resources.

Buechner, H.K. 1960. The bighorn sheep in the United States, its past, present, and future. Wildlife Monographs May 1960(4):174.

Fitzsimmons, N.N., S.W. Buskirk, and M.H. Smith. 1995. Population history, genetic variability, and horn growth in bighorn sheep. Conservation Biology 9(2):314–323.

Geist, V. 1976. Mountain sheep a study in behavior and evolution. Chicago: University of Chicago Press.

Hughes, S.S. 2004. The sheepeater myth of northwestern Wyoming. In P. Schullery and S. Stevenson, ed., People and place: The human experience in Greater Yellowstone: Proceedings of the 4th Biennial Scientific Conference on the Greater Yellowstone Ecosystem, 2–29. Yellowstone National Park, WY: National Park Service, Yellowstone Center for Resources.

Krausman, P. R. and R. T. Bowyer. 2003. Mountain sheep (Ovis canadensis and O. dalli). In G.A. Feldhamer, B.C. Thompson and J. A. Chapman, ed., Wild mammals of North America: Biology, management, and conservation. 2nd ed. Baltimore, MD: The Johns Hopkins University Press.

White, P.J., T.O. Lemke, D.B. Tyers, and J.A. Fuller. 2006. Bighorn sheep demography following wolf reintroduction, Short Wildlife communication to Biology.

White, P.J., T.O. Lemke, D.B. Tyers, and J A. Fuller. 2008. Initial effects of reintroduced wolves Canis lupus on bighorn sheep Ovis canadensis dynamics in Yellowstone National Park. Wildlife Biology 14(1):138–146.


Home to the largest concentration of mammals in the lower 48 states.

Bighorn Sheep - Yellowstone National Park (U.S. National Park Service) (2024)


Bighorn Sheep - Yellowstone National Park (U.S. National Park Service)? ›

Bighorn sheep live in a variety of habitats throughout the year though. During the summer, they can be found in meadows, fellfields, and on mid-elevation slopes bordered by cliffs and ledges. In the winter, sheep frequent windswept and south-facing valleys and ridges where forage is blown free of snow.

Where is the best place to see bighorn sheep in Yellowstone? ›

Sheep are commonly seen along the road through the Gardner River Canyon, where visitors should be alert for bighorns crossing between their preferred cliffs and the river where they drink. Summering bands are found in the Gallatin and Washburn Ranges, the Absarokas, and occasionally in the Red Mountains.

How many bighorn sheep are in Yellowstone? ›

In Yellowstone, bighorn sheep occupy rough, tall country where they have good escape routes from predators. According to the Park Service, there are fewer than 500 bighorn sheep in all of the park, with about 250 in the northern range.

What is a female bighorn sheep called? ›

Females, called ewes, have smaller horns that curve slightly to a sharp point within the first four years of life. Ewes and lambs stay together in herds.

What is a group of bighorn sheep called? ›

Bighorns are known for head-to-head combat between males. They can live up to 15 years in the wild. A group of bighorns is called a Herd.

What time of day is best to see bighorn sheep? ›

Depending on the year, there are 800-1000 desert bighorn sheep on the refuge, all of which blend in extremely well with their surroundings. To spot bighorn, use your binoculars or spotting scope early to mid-morning with the sun behind you.

What to do if you encounter bighorn sheep? ›

If you encounter a bighorn ram while hiking, especially during the rut, do not make eye contact, turn slightly sideways and walk away down slope. If you face the ram or are on higher ground the ram may see you as a challenger and charge you.

What are the predators of the bighorn sheep? ›

Predators of bighorns are coyotes, eagles (feed on lambs), gray foxes, bobcats, and mountain lions. To bighorn sheep, domestic dogs look and smell like predators. Predation is not a primary cause of death for bighorns due to their escape terrain and the variety of wildlife these predators prey upon.

How many bison are at Yellowstone? ›

Number in Yellowstone

In recent years, the bison population in Yellowstone has ranged from 3,000 to nearly 6,000—see the current bison population for more details.

What eat bighorn sheep? ›

Q. What are the natural predators of bighorn sheep? A. Mountain lions, wolves, bobcats, coyotes and golden eagles are predators of bighorn sheep.

How long do bighorn sheep live? ›

Peninsular bighorn sheep can live for 10 to 15 years. FEEDING: Sheep graze on a wide variety of plant species. Green, succulent grasses and forbs are preferred, though shrubs and herbaceous annuals and perennials comprise most of their diet, supplemented with some cacti and grasses.

Which states have the most bighorn sheep? ›

Nelson bighorn (Ovis canadensis nelsoni) are the most abunadant of the desert bighorn races and number approximately 13,000. These bighorn are found in California, Nevada, Utah, and Arizona.

What is the rarest animal to see in Yellowstone? ›

The wolverine is probably the rarest animal seen in Yellowstone. The US Fish and Wildlife Service: "Wolverines are the largest land-dwelling member of the mustelid family and are extremely rare in the continental United States.

What are 2 predators in Yellowstone? ›

During your drive-through, you could catch a glimpse of Yellowstone's most common predators:
  • Black bears;
  • Grizzly bears;
  • Coyotes;
  • Mountain lions;
  • Bobcats;
  • Wolves; and.
  • Canada lynx.

Are there mountain lions in Yellowstone? ›

The cougar (Puma concolor), also known as mountain lion, is the one of the largest cats in North America and a top predator native to Greater Yellowstone.

What is an interesting fact about bighorn sheep? ›

The bighorn sheep's keen eyesight, hearing, and sense of smell help it detect and avoid predators. The bighorn sheep is one of two species of wild sheep in North America with large horns, the other being the Dall sheep (Ovis dalli).

Where do bighorn sheep sleep? ›

Bighorn sheep rest at night on steep, rocky slopes, on top of rocky rims, or on a slope between two bluffs. These types of areas give them excellent protection from predators, since they enable the sheep to see in all directions except uphill.

What is it called when bighorn sheep fight? ›

Ram fighting is a blood sport between two rams (large-horned male sheep), held in a ring or open field.

Where are the most bighorn sheep? ›

nelsoni, the most common desert bighorn sheep, ranges from California through Arizona. Mexican bighorn sheep, O. c. mexicana, ranges from Arizona and New Mexico south to Sonora and Chihuahua.

Where to see bighorn sheep in Grand Teton National Park? ›

Bighorn Sheep

Best places to view: Miller Butte, in the National Elk Refuge, primarily during winter. During summer, bighorns can be found at high elevations in the Teton and Gros Ventre ranges that border Jackson Hole.

Where do bighorn sheep hang out? ›

The desert bighorn, Ovis canadensis nelsoni, ranges through the dry, desert mountains of eastern California, much of Nevada, northwestern Arizona, and southern Utah. Across its entire range, the total population is about 13,000.

What national parks have bighorn sheep? ›

  • Meet the Bighorn Sheep.
  • Yellowstone (Wyoming, Montana, Idaho)
  • Owyhee Canyonlands (Idaho, Oregon)
  • Hells Canyon (Idaho, Oregon, Washington)
  • Muellar Ranch (Colorado)
  • Desert National Wildlife Refuge (Nevada)
  • Badlands National Park (South Dakota)
  • Zion National Park.
Jul 30, 2023


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