On Oct. 1, a domestic sheep was seen at the Ginkgo Petrified Forest State Park mingling with several wild bighorn sheep. So why is it a big deal for a domestic sheep to be hanging around wild sheep, you ask? Two words…Mycoplasma bacteria. Domestic sheep can carry it and pass it on to wild sheep, where it becomes pneumonia. This pneumonia caused a massive die-off in the bighorn herd living in Hells Canyon along the Snake River in 1995. Another outbreak struck the Umtanum herd in the Yakima River Canyon in 2010, killing dozens of sheep and in 2013 the entire Tieton herd west of Naches either died from pneumonia or were put down by WDFW officials to prevent the disease from spreading to neighboring herds.
The bighorn sheep in this area are from the Quilomene herd. There is a southern sub-herd, numbering some 50 animals that lives near Vantage, and a larger group of bighorns that live in the Colockum Wildlife Area and north towards Malaga in Chelan County. Numbering 220 to 250 sheep in total, the Quilomene is one of Washington State’s largest bighorn herds.
As for the domestic ewe, it belonged to an area rancher and it may have been missing for up to two weeks. It’s unclear how it got to the state park near Vantage. Andy Walgamott, Editor of Northwest Sportsman Magazine, reported the ewe may have wandered there from a US Forest Service grazing allotment. Brock Hoenes, the Ungulate Section Manager for WDFW, says it is possible that ewe did come from there but it’s also possible it wandered in from a closer Washington Department of Natural Resources grazing allotment or maybe even from the home ranch for the animal. A spokesperson for the Okanogan-Wenatchee National Forest said they investigated this and determined the ewe did not stray from one of their grazing allotment sites but from private land.
The ewe in question was killed by WDFW officials on Oct. 6. Unfortunately, that ewe tested positive for mycoplasma bacteria. This triggered an immediate reaction by WDFW. On Oct. 12, twelve bighorn sheep in close proximity to the ewe were killed and tested for the presence of this pneumonia causing bacteria. On Oct. 15 results came back and all 12 of the sheep came back negative. During the next week, the herd will be monitored and additional bighorn sheep will likely be live-captured and tested.
Hoenes is hoping if the bacteria did spread to the herd it will be limited to the southern sub-herd. However, Hoenes pointed out that the bighorn rams are in the rut and on the move, looking for mates, so it’s possible several rams from the southern sub-herd will head north to breed with other sheep from the greater Quilomene herd. If the greater herd is infected, this could be disastrous. Not only does the pneumonia strike down a significant number of sheep, but it also causes a reduced survival rate for any lambs born in the near future.
Asked how fast this disease spreads, Hoenes replied “Pretty fast. In captive experiments bighorn sheep contracted it in 48 hours. It’s highly contagious”. There is no treatment or vaccine to help the bighorns who contract this disease. However, based on the results of the initial testing on the 12 rams that were killed, Hoenes said he is “cautiously optimistic” the bacteria did not spread from the ewe to the herd.
When asked if the unnamed owner of the contagious ewe is facing any fines or penalties, Hoenes told me WDFW does not have the ability to do that. However, Chase Gunnell, Communications Director for Conservation Northwest, says their organization, “will be calling for action from USFS, DNR and the sheep producer, including changes to grazing leases to require notification of missing stock. We hope a voluntary agreement can be reached to reduce disease risks from public lands grazing allotments.”
In the meantime, here’s hoping the Quilomene herd dodged an infectious bullet. We’ll let you know more about this situation if it changes.