Changes needed after disease from domestic sheep puts another Washington bighorn herd at risk

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.

October 21, 2020 Update: The Cleman Mountain bighorn herd has also now testived positive for the M. Ovi. bacterial disease

This week, the Washington Department of Fish and Wildlife killed a dozen bighorn sheep from the Quilomene Herd near Vantage after a domestic ewe infected with bacteria that causes fatal pneumonia was spotted among the wild sheep.

While the 12 wild sheep killed by the state have since tested negative for the disease, transmission to other animals in the herd may still have occurred, and significant public resources will be required for monitoring, including helicopter surveys.

“This event confirms an intolerable pattern of wildlife being harmed by private livestock at great public cost,” said Mitch Friedman, Conservation Northwest Executive Director. “This is not the first time that Washington’s bighorn sheep have been put at risk or even entire herds wiped out by disease from domestic sheep, including on public lands.”

“It has happened enough that we have lost confidence that the livestock producers have sufficient control to prevent future disease transmission that could jeopardize the survival of bighorn sheep in central Washington,” said Friedman. “We recognize and sympathize with the good intentions and efforts of the ranchers and public agencies, but native wildlife and Washingtonians who cherish them require better than this.”

Conservation Northwest is calling on public lands and wildlife managers to better prioritize protecting Washington’s imperiled bighorn herds, working with domestic sheep producers to greatly reduce the risk of disease transmission on public lands in central Washington. This includes requiring that sheep ranchers who operate on and near the Okanogan-Wenatchee National Forest and Washington Department of Fish and Wildlife (WDFW) State Wildlife Areas report missing stock to state and federal wildlife managers in a timely manner.

The organization is also encouraging Washingtonians to contact the Washington Fish and Wildlife Commission, Washington Department of Fish and Wildlife Director Kelly Susewind and Okanogan-Wenatchee National Forest Supervisor Kristin Bail calling on them to further prioritize ways to reduce disease risks to bighorns from domestic sheep.

According to news reports, the diseased domestic ewe had been wandering unreported for at least two weeks before it was observed by an off-duty Kittitas County sheriff’s deputy near the Quilomene Wildlife Area and Gingko State Park. The ewe was euthanized by WDFW agents on October 6, who have confirmed that they received approval from the sheep’s owner to do so. The domestic ewe tested positive for mycoplasma ovipneumoniae bacteria.

“Given there are only around 1,500 bighorns in Washington today, we can’t continue to lose herds to outbreaks of a fatal disease from domestic sheep,” said Jay Kehne, Conservation Northwest’s Sagelands Program Lead.

“The events this week should encourage public land and wildlife managers as well as livestock producers to reach agreement on ways to reduce disease risks from domestic sheep grazing on public lands,” said Kehne.

At approximately 220 animals, the Quilomene Herd is one of the state’s largest, making up nearly 15 percent of Washington’s entire remaining bighorn population. These wild sheep native to Eastern Washington have been declining in recent years due to disease transmission from domestic sheep, with several herds wiped out and others still at risk.

Domestic sheep and goats can carry mycoplasma ovipneumoniae bacteria with little ill-effect, but the pathogen causes severe pneumonia in wild sheep, which is often fatal and can linger in herds for years. The bacteria is known to aerosolize and direct physical contact is not required for transmission. The disease is considered the greatest threat to bighorn populations in North American today.

From 2009 to 2013, hundreds of bighorn sheep in the Tieton and Umtanum herds were killed as a result of pneumonia outbreaks, with the bacteria likely transmitted from domestic sheep on nearby public land grazing allotments. The Tieton Herd was extirpated, with the last 50 animals culled in an attempt to prevent the fatal disease reaching the nearby Cleman Mountain Herd. No attempts at reintroducing bighorns into the Tieton area have been made due to lingering disease risks from domestic sheep grazing on the Okanogan-Wenatchee National Forest and nearby Washington Department of Natural Resources lands.

The disease is still rampant in the Umtanum Herd, which is popular for wildlife viewing in the Yakima Canyon. Wildlife officials may need to cull the Umtanum Herd in the years ahead to suppress the pneumonia outbreak among sheep in the area.

“Big game hunters, conservation groups, the Yakama Nation and Colville Tribes, and state wildlife officials have long invested in recovering Washington’s bighorn sheep, but a single contact with an infected domestic sheep like we saw this week can put these efforts and entire herds at risk,” said Kehne.

The Okanogan-Wenatchee National Forest has been undergoing an Environmental Impact Statement process to analyze current domestic sheep grazing allotments and explore ways to reduce the risk of disease transmission from domestic sheep to bighorn sheep within their jurisdiction. However, conservationists are concerned that the planning process has been too slow to account for the pressing disease risks to wild bighorns in central Washington.

For more information on bighorn sheep in Washington, VISIT OUR WEBPAGE, WDFW’S WEBPAGE, or the WASHINGTON WILD SHEEP FOUNDATION.