OWYHEE COUNTY, ID — Idaho Fish and Game plans to lethally remove a small herd of California bighorn sheep this winter after confirming a pneumonia outbreak in the Reynolds Creek area of southwest Idaho.
The outbreak is caused by Mycoplasma ovipneumoniae (M. ovi), a bacterium that can lead to high mortality and long-term population declines in bighorn sheep. Officials said removing the infected group is intended to prevent the disease from spreading to nearby herds in the Owyhee region.
“This was a difficult decision because no one, including IDFG staff, wants to see these sheep die,” Wildlife Bureau Chief Shane Roberts said. “Unfortunately, it’s the right and necessary decision to protect the larger bighorn population in the Owyhees.”
According to Fish and Game, M. ovi outbreaks often kill about half of infected animals during the initial phase and can significantly reduce lamb survival in subsequent years. Sheep that survive may remain carriers for months or years, increasing the risk of transmission to other herds.
The Reynolds Creek herd is one of several California bighorn sheep herds in the Owyhees and is located about 50 miles from Idaho’s core populations, which total roughly 250 animals. While relatively isolated, some intermingling occurs, posing a risk to broader conservation efforts.
Fish and Game said routine disease monitoring led to early detection, allowing officials to act before the disease spread. Testing of other nearby herds in December 2025 returned negative results.
The agency plans to carry out the removal by helicopter to quickly eliminate the infected herd. Any animals that can be salvaged will be processed locally, with the meat distributed to Idaho residents in need through partner organizations.
