Bighorn sheep monitoring increases with diagnosis of single case of pneumonia in Mt. Hull herd


This document is provided for archival purposes only. Archived documents do not reflect current WDFW regulations or policy and may contain factual inaccuracies.

News release

Staci Lehman, Public Affairs, 509-892-7853

OLYMPIA - The Washington Department of Fish and Wildlife (WDFW) asks members of the public to report sightings of bighorn sheep that are obviously ill in Okanogan County after a bighorn ram from the Mt. Hull herd was recently confirmed to have died from pneumonia caused by a highly infectious bacteria. While posing no health threat to humans, Mycoplasma ovipneumoniae, known as M. ovi, can decimate bighorn populations and kill lambs for many years, preventing herds from repopulating.

At this time, only a single ram from the herd near the Canadian border has tested positive for pneumonia. Testing on additional animals is currently underway. While WDFW biologists and veterinarians await results, they are partnering with biologists at the Colville Tribes to increase visual monitoring of the Mt. Hull herd. And they are asking for help from the public.

"This is a highly visible herd. These sheep are in orchards and among houses," said WDFW Biologist Jeff Heinlen. "Because we can't be watching all the time, we are asking people to alert us if they notice sheep that appear lethargic, coughing or showing nasal discharge. This helps us assess the health of the herd."

There is also a potential for wandering sheep to pass M. ovi to animals in other herds, such as the Omak Lake herd on the Colville Reservation to the south, the Sinlahekin herd to the west, or herds to the north across the border in British Columbia.

"In 2012 the Colville Tribes conducted a genetic analysis between the Sinlahekin, Mt. Hull, and Omak Lake herds, showing us that the Omak Lake herd was likely founded by individuals from the Sinlahekin herd, but may have been in contact through immigration event(s) with the Mt. Hull herd in the past," said Colville Tribal Biologist Eric Krausz. "We have documented collared bighorn sheep traveling from Omak Lake to Mt. Hull, so we know bighorn sheep from these distinct herds travel back and forth on occasion and likely come into contact with one another."

Because of this, WDFW asks to also be alerted if bighorn sheep are observed in places they aren't normally seen. The Mt. Hull herd's typical range is from approximately Tonasket to the Canadian border north of Oroville. If sheep are seen outside that area, or notably sick bighorn sheep are observed, please call Jeff Heinlen at (509) 826-7372 and leave a message or email

While it is biologically possible for uninfected domestic sheep or goats to become infected by contagious bighorns, cross-species transmission of M. ovi is much more common in the reverse direction. The bacteria typically causes only mild and temporary symptoms in domestic sheep and can reduce growth rates, but serious illness and death is rare. In contrast, most bighorns that become infected due to close contact with domestic sheep or goats succumb to pneumonia, and some that survive pass it to newborn lambs that similarly lack immune protection.

There are approximately 17 bighorn sheep herds across Washington, two within the bounds of the Colville Reservation.

The Washington Department of Fish and Wildlife is the primary state agency tasked with preserving, protecting and perpetuating fish and wildlife and ecosystems, while providing sustainable fishing and hunting opportunities. WDFW manages more than one million acres of public land across the state that is designated for wildlife habitat and public recreation.

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