Charismatic icons of the American West with massive curling horns weighing 30 pounds — more than all the bones in their body combined. Reduced from 2 million to a few thousand by 1900, they've recovered to ~80,000 today.

Also called: Mountain Sheep, Rocky Mountain Bighorn

Native status: Native; recovered locally; threatened by disease

§ Quick facts

SizeBody 1.4–1.7 m (4.6–5.6 ft); shoulder height 90–105 cm
WeightRams 80–145 kg (175–320 lb); ewes 55–90 kg
LifespanWild 10–14 years; oldest documented 24
OrderArtiodactyla
FamilyBovidae

§ Encyclopedia

The bighorn sheep or bighorn is a species of sheep native to North America. It is named for its large horns. A pair of horns may weigh up to 14 kg (30 lb); the sheep typically weigh up to 143 kg (315 lb). Recent genetic testing indicates three distinct subspecies of Ovis canadensis, one of which is endangered: O. c. sierrae.

Source: Wikipedia — Bighorn sheep Licensed under CC BY-SA 4.0

§ Identification

Field marks. Large dark-brown sheep with white muzzle, white rump patch, and white backs of legs. Rams have massive curling horns that can be a full curl by age 8 (some develop "broomed" tips); ewes have smaller, less-curved horns.

Similar species. Dall Sheep (white, northern range). Mountain Goat (white, beard, different horn shape).

Voice. Grunts, bleats, snorts. Ram-on-ram head crashes are audible 1+ km.

§ Diet & behavior

Diet. Grasses, sedges, forbs in summer; shrubs and woody browse in winter.

Behavior. Rams butt heads at speeds up to 32 km/h (20 mph) during the autumn rut — head-butting bouts can last over 24 hours. Massive double-layered skull and a tendon-like ligament connecting the horns to the spine absorb impact forces equivalent to 60 km/h car crashes without concussion. Disease transmission from domestic sheep — especially Mycoplasma ovipneumoniae — remains the leading conservation threat.

§ Range

Mountain ranges of western US and Canada, desert SW

§ Habitat

Steep, rocky terrain — alpine cliffs, canyon walls, desert escarpments

§ Threats

Pneumonia transmission from domestic sheep (devastating), habitat fragmentation, climate-driven drought.

§ Conservation status

According to the IUCN Red List, the bighorn sheep is currently classified as Least Concern.

§ What helps

Support separation between domestic and wild sheep. Donate to bighorn habitat purchases. Maintain quiet around lambing areas (April–June).

Support our work More ways to help

§ Further reading

§ Sources cited

  • Wild Sheep Foundation
  • USDA Wildlife Services
  • Yellowstone Bighorn Sheep Project
  • IUCN Red List 2020