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FWP officials investigate cause of dead bighorns

FWP officials investigate cause of dead bighorns


The carcasses of six Rocky Mountain bighorn sheep were discovered this week on a rock slope north of Beartooth Mountain along the Missouri River, said officials with Montana Fish, Wildlife and Parks.

According to Gayle Joslin, the wildlife biologist responsible for the area in which the four ewes and two rams were found, fishermen on the Missouri found two of the sheep on Monday and reported the find to FWP. Personnel from FWP found an additional dead sheep for a total of three. Wednesday, Joslin conducted a helicopter survey of the area and found an additional three dead sheep.

“A couple of the sheep had been dead for a while but we did get a good sample from another sheep,” Joslin said. “We sent the samples to (Bozeman) and it will be probably two weeks before we get the results.”

Keith Aune, supervisor of the wildlife research lab in Bozeman, said his preliminary examination points to an old nemesis of the bighorn sheep.

“We see lesions consistent with the pneumonia complex,” Aune said. “We’re waiting for culture confirmation. When we get that we may be able to identify the specific bacteria or virus responsible.”

Pneumonia complex is a term used to refer to lungworm and a virus or bacteria that combine to weaken the sheep and make them susceptible to pneumonia. Nearly all sheep carry the lungworm in the wild. The pneumonia complex is cyclical in sheep and has been responsible for episodes of large die-offs in wild sheep herds in Montana and other areas where Rocky Mountain bighorn sheep live. The pneumonia complex is often recognizable by chronic cough that persists until death.

The herd affected was transplanted to the Sleeping Giant area in 1992 and 1993. Joslin said that the herd has never been able to maintain the 60 sheep in the population that was hoped for, but in general the herd has been doing well. She also said that sheep swim the Missouri River and walk across on ice to intermingle on both sides of the river. Region 4 sheep are located on the eastside of the river and Region 3 sheep on the west. The intermingling of the sheep may spread the virus or bacteria through both herds.

During Joslin’s helicopter survey Wednesday she counted 30 sheep as compared to a total of 57 sheep she counted in the same area last year. She said a few of the 30 sheep appeared to be in a weakened state.

“The 20 sheep that are unaccounted for doesn’t mean that they’ve died,” she said. “The flying conditions weren’t perfect so we may have missed sheep, but it was important to get out and see what we could before the snow covered the carcasses.”

The news of the Sleeping Giant bighorn deaths comes one week before the FWP Commission is to rule on whether to adopt a tentative proposal for a single either sex bighorn sheep hunting permit in the area where the dead sheep were found.

Joslin said she can’t predict what action the FWP Commission will take on Thursday, but she would like to see the format for the permit in that area established and the issue of the permit delayed until FWP sees how the entire herd of sheep in that area come through the crisis.

The prognosis for the herd depends in part on what virus or bacteria is responsible for the infection but generally the pneumonia complex is bad news for a herd of sheep.

“You can never tell what course something like this will take,” Joslin said. “Usually you get a pretty sizable percentage of the herd that dies and a few survive and over time the herd comes back. That’s the cyclic part. But, sometimes they don’t come back and at that point you have to make the decision whether you want to transplant sheep back into that area.”


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