A wild North American sheep with particularly large horns in males.
Males carry massive horns, while female horns are much smaller and only slightly curved. The brown summer coat becomes paler by late winter.
After pneumonia, summer range may be part of bighorn sheep recovery. A 2019–2021 study compared two Rocky Mountain populations in Wyoming, sampling over 700 vegetation transects and 2,093 forage samples. In the recovering Jackson herd’s core summer range, herbaceous biomass was nearly 2.5 times that on declining Whiskey Mountain range; plant diversity and cover were higher too. Nutrient concentrations in most plant groups showed few clear differences.
The authors suggest that more available, varied forage may support condition and recruitment in herds where pathogens remain. They measured forage available on each range, not sheep-selected diets. They recommend assessing summer as well as winter range in post-pneumonia recovery plans.
IUCN Red List · Least Concern (LC) · Global species-level assessment
The American Society of Mammalogists’ Mammal Diversity Database lists bighorn sheep as Least Concern on the IUCN Red List and links to the 2020 global assessment. Regional herds have had different outcomes: in Wyoming, the Jackson Rocky Mountain bighorn population recovered to about 400 animals after pneumonia die-offs, while Whiskey Mountain remained at roughly one-fifth of its former size. A 2023 study compared the two summer ranges and found greater forage biomass, plant diversity and ground cover in the recovering population. The authors recommend evaluating summer as well as winter range when considering recovery after pneumonia. These are findings about two populations in Wyoming.