Bighorn sheep are an iconic part of Idaho’s natural heritage and are valued by wildlife enthusiasts, tourists and sportsmen. These iconic animals roam the rugged terrain of the Middle Fork and Main Salmon Rivers, Hells Canyon, the White Clouds Wilderness, and the Owyhee Canyonlands. For many river runners and backpackers, spotting a herd of bighorn sheep perched high up on a canyon wall is the highlight of their trip.

Bighorn Sheep are in Decline

Prior to the mid-1800s, bighorn sheep were the most abundant big game species in Idaho. Unfortunately, these majestic animals are in decline. In the last few decades in central Idaho, number of Rocky Mountain bighorn sheep have decreased from 10,000 to fewer than 1,600 today. Many of the remaining sheep exist in isolated herds consisting of fewer than 100 individuals and are at increased risk of becoming extirpated. Bighorn sheep are now classified as a sensitive species by the Forest Service and BLM.

Disease Affecting Bighorn Sheep

Scientists attribute most of the decline in bighorn sheep numbers to a pneumonia-like disease. Domestic sheep and goats carry this disease and are resistant to it, but the disease can be fatal to bighorns. Young bighorn rams venture on forays for 20 miles or more in search of new herds and mates. Because both species of sheep are naturally gregarious, they can interact and transmit disease when they both occupy the same range. Rams that have contacted domestic sheep or goats on such forays can infect their own entire herd upon their return. In 2004, 80% of the lambs in Hells Canyon died from a disease outbreak.

The Solution Is Simple

Best management practices by herders to prevent contacts between these species have not proven effective. The solution is relatively simple: don’t graze domestic sheep or goats, or hike with pack goats, on public land where bighorn sheep live. This means that ranchers who haven’t adjusted operations in decades may have to adapt and find new pastures for their private sheep operations. There are numerous backcountry destinations without nearby bighorn sheep populations that are suitable for use by pack goat enthusiasts. Other pack stock, such as horses and mules, do not pose a disease risk, and these pack animals can allow recreationists to enjoy the experience of a pack support trip in bighorn sheep habitat.

We work to ensure that Idaho’s bighorn sheep herds expand into historic habitat where there aren’t conflicts with domestic sheep and goats.