Mountain Goat

An adult mountain goat and a kid overlooking vast sky and mountains
Mountain goats are not native to the Greater Yellowstone Ecosystem.

NPS/Diane Renkin


Descendants of mountain goats (Oreamnos americanus) introduced in southern Montana mountains during the 1940s and 1950s established a population in the park in the 1990s and have reached a relatively high abundance in the northeastern and northwestern portions via the Absaroka and Gallatin mountain ranges. Investigations of paleontological, archeological, and historical records have not found evidence that the mountain goat is native to Greater Yellowstone.

Many people consider the goats a charismatic component of the ecosystem, including those who value the challenge of hunting them outside the park. But the colonization has raised concerns about the goats’ effects on alpine habitats. Competition with high densities of mountain goats could also negatively affect bighorn sheep, whose range overlaps that of mountain goats.

Black track of a mountain goat
Mountain goat track

Nonnative species

Number in Yellowstone

208 in and adjacent to Yellowstone.

Where to See

  • Infrequently seen; northeastern and northwestern portions of the park in alpine habitat.
  • Winter: steep, south-facing slopes, windblown ridgetops; Spring: south- and west-facing cliffs; Summer: meadows, cliffs, ravines, and forests.

Behavior and Size

  • Mature male (billy) weighs 300 or more pounds; female (nanny) weighs 150 pounds.
  • Young (kids) born in late May–June.
  • Females usually begin to breed at 2½ years.
  • Live in precipitous terrain.
  • Both sexes have horns; females curve less and are thinner and sometimes longer than males.
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    Mountain goats live in alpine habitats. Studies of alpine vegetation in the northeast portion of the park during 2002 and 2003 suggest that ridge top vegetation cover is lower, and barren areas along alpine ridges are more prevalent in areas that have received relatively high goat use. Studies by Idaho State University and the National Park Service during 2008–2010 suggest goats are affecting the soil chemistry of sites they inhabit by increasing the availability of soil nitrogen through deposition of urine and feces. Soil rockiness may be increasing slightly over time at sites with high goat presence, but no largescale effects have been detected so far with respect to vegetation (species, community structure).

    Colonization of suitable habitats south of The Thunderer and along the eastern park boundary within the Absaroka Mountain Range appears to be occuring, with a larger number of groups with females and young observed on Saddle Mountain and on Castor and Pollux peaks during recent years. Mountain goats were not surveyed in 2016 due to poor flying conditions for survey aircraft.

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    Yellowstone is being invaded by mounain goats. This non-native species poses a threat to Yellowstone's alpine as well as bighorn sheep.

    A wolf standing on a snowy bank near brown grass howls


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



    Laundré, J.W. 1990. The status, distribution, and management of mountain goats in the Greater Yellowstone Ecosystem, final report. Pocatello, ID: Idaho State University, Department of Biological Sciences.

    Lemke, T.O. 2004. Origin, expansion, and status of mountain goats in Yellowstone National Park. Wildlife Society Bulletin 32(2):532–541.

    Lyman, R.L. 1998. White goats, white lies: The abuse of science in Olympic National Park. Salt Lake City: University of Utah Press.

    Schullery, P. and L. Whittlesey. 2001. Mountain goats in the Greater Yellowstone Ecosystem: A prehistoric and historical context. Western North American Naturalist 61(3):289–307.

    Varlet, N.C.L. 1996. Ecology of mountain goats in the Absaroka range, south-central Montana. MS. Bozeman, MT: Montana State University.

    Last updated: October 23, 2017

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