Pneumonia in Anaconda Bighorn Sheep may be Concentrated in Olson

Montana Fish, Wildlife & Parks (FWP) continues to assess the status of pneumonia in the Lost Creek (Anaconda) bighorn sheep population in west central Montana, where the disease was first detected on Aug. 20.   Biologists now believe that the disease may be concentrated in and around the Olson Gulch area west of Anaconda.

Since initial detection, FWP crews have surveyed the sheep herd to assess the spread of the disease. On Friday, Aug. 27, a team of FWP wildlife biologists and wildlife veterinarian focused their efforts on the Olson Gulch area and killed ten sheep for examination and the collection of biological samples.

Samples of lung tissue and other samples from these and seven other sheep killed earlier in the week will be sent to a laboratory for culture to try to determine what pathogens are involved in the pneumonia.

There are no known vaccines to prevent pneumonia in wild sheep, or medications that can be practically applied to prevent the death of sick individuals.

About a quarter of the bighorns sampled in Olson Gulch showed visible signs of pneumonia in their lungs, according to FWP wildlife biologist, Ray Vinkey.

“Four bighorns had lungs that were visually diagnostic of pneumonia,” Vinkey said.   “We can’t be sure about the rest of the sheep that we sampled until we have the lab results.”

The 297 bighorns counted in the Anaconda herd on March 25 th are now widely scattered across summer range.

“Even though they are scattered from the Anaconda-Pintlers to the foothills of the Flint Range, we were able to look a lot of sheep from the helicopter last week.   And, we haven’t seen a sheep coughing or acting sick in any location outside of Olson Gulch.   So far, the evidence makes us think that we’ve detected this infection early.” Vinkey said.

FWP plans to keep a close eye on the population in the coming days and weeks, and will kill sheep that exhibit signs of pneumonia in an attempt to slow or prevent the spread of the infection.   Local volunteers have offered their help in watching for sick sheep, and FWP has been in contact with sheep hunters to solicit their cooperation.

Twelve hunters drew coveted licenses to hunt bighorn rams in Hunting District 213 this fall, and 30 hunters drew ewe licenses, but the threat of a pneumonia outbreak places those plans in jeopardy.

“In terms of the biology, we have more rams than we need to sustain the population,” said Mike Thompson, FWP regional wildlife manager.   “That’s a good thing for ram hunters.   Many hunters never draw a ram license, and most who do may never get another chance.   Right now, it looks like we can manage the disease along with ram hunting, and still have enough rams left over for some to survive a full blown pneumonia outbreak.”

Thompson says that ewe hunters may not be as fortunate because ewes are essential to the recovery of the population in the event that a large die-off occurs later this fall and winter.   As FWP waits for the lab results from the sheep it has sampled so far, it will continue closely monitoring pneumonia symptoms in the population to determine whether a hunter harvest of up to 30 ewes can still be supported.   For the time being the sheep hunts are scheduled to go as planned, beginning with the archery season, which opens September 5 th for sheep license-holders—ten days before the rifle season.

FWP cautions sheep hunters across western Montana to cook harvested sheep meat well and contact FWP with any questions about the suitability of the meat for consumption.   There have been no known cases of humans or pets contracting pneumonia from wild sheep, but FWP cautions anyone who finds dead or sick bighorn sheep to leave the animal alone. FWP also encourages the public to immediately report any observations of sheep exhibiting symptoms of an illness or strange behavior.

“A report from a hunter was responsible for the first detection of pneumonia in Olson Gulch,” said Vinkey. “These reports from the public help us determine the extent of the sickness and give us a chance at catching it in its early stages.”

For more information or to make a report, call FWP in Missoula at 406-542-5500.

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