Bighorn Sheep

Washington’s vulnerable wild sheep: working to conserve the bighorn

When you think of the animals that Conservation Northwest works to protect and restore, what comes to mind? You may have a mental image of wolves, grizzly bears, or fishers. While it is true that our organization has placed emphasis on recovering historically-persecuted and locally extinct carnivores in Washington, through our Sagelands Heritage Program we’re also working to help conserve a different kind of native species, one of the hoofed variety: the bighorn sheep. 

Take action by sending a message to the Okanogan-Wenatchee National Forest and Washington Department of Fish and Wildlife calling on them to do more to protect bighorn sheep from disease

Entire bighorn sheep herds have been wiped out by disease in central Washington, and now a dozen have been killed and hundreds more are at risk after an infected domestic ewe wandered for weeks. Public land and wildlife managers must take steps to further reduce disease risks from domestic sheep to Washington’s imperiled bighorn herds.

Bighorn sheep in Washington. Photo: WDFW

News on bighorn sheep

Bighorn sheep in the West

Not to be confused with mountain goats (which have white coats and spiky horns), the bighorn (Ovis canadensis) is the largest wild sheep in North America, sporting fawn-colored coats and dense, tightly curled horns that display status and age. A large ram can over 300 pounds, and his horns up to 30 pounds – more than the weight of all his other bones combined. As with some other ungulate species, rams and ewes typically inhabit separate herds. Rams travel in bachelor groups and fight for mates in the fall by using their horns and thick skulls to crash into each other head-on.

Three subspecies of bighorn sheep exist in North America, including the Rocky Mountain (or mountain) bighorn (O. c. canadensis), and the endangered California bighorn ( O. c. sierrae) and desert (O. c. nelsoni) bighorn. Only Rocky Mountain bighorn sheep are found in the Pacific Northwest. Two other closely-related species of mountain sheep, the Dall sheep (O. dalli) and Stone sheep (O. dalli stonei), reside in western Canada and Alaska.

Bighorns once numbered around 1.5 – 2 million throughout the American West at the beginning of the 20th century. Today, some 70,000 exist throughout the Western states. Historic overhunting, habitat loss and, most significantly, the spread of the pneumonia pathogen from domestic sheep to wild herds led to the extirpation of bighorns from Washington by the mid-1920s. It is only thanks to reintroduction efforts that our state once again has this native species roaming our landscapes, but the threat of disease from domestic sheep still looms over their long-term recovery.

As the West was settled with landowners and livestock ranchers, the onset of domestic sheep grazing in close proximity to wild bighorn herds led to the transfer of the pneumonia bacteria Mycoplasma ovipneumoniae from the former to the latter. Domestic sheep and goats can carry the pathogen with relatively minor effect, but bighorn sheep, who never evolved immune systems that could effectively combat it, are unable to withstand this non-native pathogen.

The disease is now the greatest threat to bighorn populations in North America. More on the disease from the Wild Sheep Foundation is also available here.

Bighorns in Washington

Today, around 1,500 mountain bighorns range in approximately 18 herds scattered across parts of Eastern Washington, particularly in the Hells Canyon country in the southeast corner of our state, the drier eastern slopes of the Cascades into the Columbia Basin, and in the Okanogan Highlands.

From 2009 to 2013, hundreds of wild bighorns from the Tieton and Umtanum herds in Yakima and Kittitas counties were wiped out by the m. ovi. bacteria, likely transmitted from grazing allottments on nearby U.S. Forest Service and state public lands.

Bighorn herds in Washington state. Some of these herds have since been extirpated by disease from domestic sheep. Map: WDFW.

The remaining 50 wild sheep in Tieton Herd had to be culled by state wildlife agents in order to prevent disease transmission to the Cleman Mountain Herd, which remains at risk of infection from domestic sheep grazing. The disease continues to be present in the Umtanum Herd—popular for wildlife viewing in the Yakima River Canyon—which has been declining and may require further state culling to prevent disease spread.

The U.S. Forest Service is also considering how to best ensure bighorn viability on National Forest land. The Okanogan-Wenatchee National Forest is undergoing an Environmental Impact Statement process, which would analyze their current domestic sheep grazing allotments and explore ways to reduce the risk of disease transmission from domestic sheep to bighorn sheep within their jurisdiction. A public meeting was held last year to kick off the discussion on this forest, and the analysis has been prioritized to begin in Fiscal Year 2018. Our Forest Field Program is closely engaged in discussions preparing for this upcoming process.According to the Washington Department of Fish and Wildlife’s (WDFW) bighorn lead Rich Harris, WDFW has focused on building partnerships with small-scale domestic sheep owners to decrease the spread of pneumonia from their backyard flocks to bighorn sheep. This work includes the creation of a pathogen-free sheep flock owned by WDFW and located at the Washington State Penitentiary. Still in its early stages, this pilot project will allow willing sheep owners to replace pathogen-carrying sheep in their flock with pathogen-free sheep from WDFW’s herd, which will be cared for and managed by trained incarcerated individuals at the penitentiary. Swapping out pathogen-carrying sheep in flocks when possible is one step towards healthy coexistence between domestic sheep and bighorn herds.

At Conservation Northwest, the conservation and recovery of bighorn sheep overlaps several of our program areas. Through our Washington Connected Landscapes Project, we released a scientific analysis showing current needs to maintain and restore habitat connectivity for bighorn in our state. Our newly expanded Sagelands Heritage Program will also aim to reduce barriers to bighorn movement and promote higher habitat quality, and we’ve been working to restore important bighorn habitat in the Mt. Hull area of Okanogan County.

A bighorn ewe and lamb herd spotted through a scope in Hell’s Canyon. Photo: Laurel Baum

“Bighorn sheep are an iconic species across the West, and they face real challenges to survival and recovery from small isolated populations in our state and disease,” said Conservation Northwest’s Conservation Associate Jen Watkins. “There is no easy answer to their conservation, but we are committed to rolling up our sleeves to work with all stakeholders in identifying solutions that ensure generations to come have a chance to view them in the wild.”

Through dialogue, support, and collaboration with wildlife and land managers, we’re doing our part to make Washington a viable home for bighorn sheep for years to come.

There is a lot of work still to do, and Conservation Northwest will continue to advocate for and find solutions to maintain healthy populations of all native wildlife – including bighorn – in our region.

For more information on bighorn herds in Washington, visit WDFW’s webpage. We also reccomend the Wild Sheep Foundation and their local chapter the Washington Wild Sheep Foundation.

Bighorn sheep in Okanogan County, Washington. Photo: Linda Apel