Rocky Mountain Bighorn Sheep: From Majestic Mountains to River Gorges

As one of America’s most iconic species, Rocky Mountain Bighorn Sheep symbolize the sheer beauty, strength and spirit of the American west. With specialized hoofs that allow them to make precarious jumps and scale vertical cliffs, Rocky Mountain Bighorn Sheep (Bighorn Sheep) embody an inspiring story of near extinction toward recovery.

With mature male rams weighing in at over 300 pounds, these incredible creatures are the largest wild sheep in North America. Their ability to traverse difficult terrain while having a wide field of vision and highly developed sense of smell make them a formidable species. The horns of rams curl back around their face while female ewes have smaller horns that curve slightly to a point. Male horns can weigh up to 30 pounds and are used to ram one another during mating season to establish dominance. Rams and ewes generally remain in separate herds and usually only meet to mate.  

From Massive Herds to Devastating Declines

Historically, Rocky Mountain bighorn sheep were well distributed across the western United States numbering well over a million animals. However, this once prolific population began a sharp declined in the mid-1800s to early 1900s as a result of over-hunting, loss of habitat due to ranching and development and introduction of domestic sheep that carried devastating diseases. These factors resulted in massive die offs of bighorn sheep and many of the herds residing in lower elevation areas that were near or accessible to human communities were completely wiped out. Accordingly, even with recent recovery efforts, it is now estimated that there are only about 45,000 Rocky Mountain Bighorn Sheep remaining in the U.S.     

Bighorn Sheep Recovery Efforts

With bighorn sheep nearing extinction, in the 20thcentury concerted recovery efforts began by state and federal agencies, Native American tribes, and conservation organizations. These efforts, coupled with reducing the pressure of hunting and disease, helped stimulate population growth as well as increase genetic diversity. In seeking to promote recovery in their original range, reintroduction and habitat restoration programs began in various western states as well as in Colorado’s Rocky Mountain National Park. Collaborating with state and federal agencies, Native American communities played a significant role in the species’ recovery. Tribes like Taos Pueblo in New Mexico worked collaboratively to reintroduce bighorn sheep, which have important cultural, historical and sacred significance to the area’s tribes. The Rio Grande gorge herd, which resides largely in the iconic Rio Grande del Norte National Monument, now is one of the nation’s most prolific herds and a strong example of how important cross-jurisdictional collaboration and management between Native American tribes, federal and state agencies and conservation organizations can be to species recovery. Across the west, efforts to reestablish populations have been ongoing since the early 1900s, with more than 22,000 bighorn sheep being transplanted in over 1,500 separate transplant actions. Although bighorn sheep recovery efforts have been encouraging, the road to recovery is a long with various challenges lying ahead.

The Need for Strong Conservation and Continued Recovery Efforts

Many bighorn sheep populations remain vulnerable to continued threats of habitat fragmentation and degradation, loss of habitat due to human encroachment from agricultural, industrial and residential development, poaching and the spread of disease from domestic sheep.

Out of concern for highly contagious forms of pneumonia, many state game agencies will immediately put down Rocky Mountain Bighorn Sheep if they believe these wild sheep have been exposed to domestic sheep. Major disease related die-offs continue to be a serious problem and conservation of the species remains tenuous as the 60,000 remaining animals often live in small, isolated herds. It has been well established in scientific literature that bacteria transmitted from domestic sheep results in pneumonia-related die-offs for all ages within bighorn populations; this is followed by long-term suppression of lamb recruitment. Unfortunately, these events are not uncommon as all 14 public-land grazing states with bighorn sheep have experienced at least one bighorn sheep respiratory disease die-off in the last 14 years, and most have had numerous events. According to data compiled by the Western Association of Fish and Wildlife Agencies Wild Sheep Working Group, a total of 13,391 animals have been lost to these events since 1980. In addition, this working group estimates that as a result of these respiratory disease events, nearly 11,000 lambs born to surviving ewes died of pneumonia within a few months. While the initial loss of adult animals is significant, it is the ongoing depressed lamb recruitment in the years following respiratory disease events that impedes herd recovery and threatens persistence. Further, complicating the issue is the fact that studies show that crossing roads and highways create high levels of stress in bighorn sheep, which can reduce their resistance to disease and thereby further increase mortality.

Get Involved

To ensure Rocky Mountain Bighorn Sheep continue to make a full recovery, Earth Keepers is asking spiritual leaders to support the inclusion of Bighorn sheep as a “Species of Conservation Concern” in the Forest Planning Process for the Santa Fe, Carson and Rio Grande National Forests. Inclusion as a Species of Conservation Concern creates additional protections and prioritizes the management of bighorn sheep populations within these forests. As noted, a large amount of state, federal and tribal dollars have already been allocated to restoring, re-introducing and studying bighorn sheep within these forests and it is critical that this species continue to be managed with a high level of protection and care. With considerable vulnerabilities, these iconic species deserve special status and protection by the U.S. Forest Service and believe the agency must take an active role in responsible stewardship. Additionally, out of concerns for disease transmission, many environmental non-profits are also actively working with federal and state agencies as well as private landowners to develop proactive solutions to avoid conflicts and encounters between wild bighorn sheep and domestic sheep.