HAMILTON - The herd of bighorn sheep in the East Fork of the Bitterroot appears to have survived last winter's pneumonia outbreak.
Montana Fish, Wildlife and Parks biologist Craig Jourdonnais recently counted 87 bighorns in an aerial survey. There are likely more that he didn't see.
Wildlife officials learned the bighorns were infected in November after hunters reported seeing sick animals.
Around the West, similar disease outbreaks have killed as much as
80 percent of infected bighorn herds. Until now, the official response has been to let the disease run its course.
For the first time ever, Jourdonnais and others took an aggressive approach to addressing the outbreak by culling obviously infected bighorn sheep from the herd in an effort to slow the spread of the disease.
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Jourdonnais said the bighorns he spotted during the recent survey "looked tremendous. They responded well to the helicopter. They looked like they were doing well."
The biologist counted 51 ewes, five lambs and 31 rams. Most of the rams were between 4 to 6 years old.
The next test will come this spring when this year's crop of lambs is born. In many cases bighorn lambs born after a pneumonia outbreak don't survive their first year.
A local landowner has agreed to move his small herd of domestic sheep away from the bighorn's winter range after tests showed the domestic sheep carried the same pathogen that appears to have caused the outbreak among the bighorns.
"The landowner has been very responsive," Jourdonnais said. "He agreed to have his sheep tested and then agreed to move them once the tests came back."
The landowner is having a hard time finding a good home for the eight animals. Montana Fish, Wildlife and Parks would like to see them settled at least 15 miles from any known bighorn sheep range.
Jourdonnais said people with interest in providing a home for the sheep can call him at 240-0558.
Both the culled bighorns and domestic sheep tested positive for the pneumonia complex called mycoplasma, which Jourdonnais said was a relatively new strain.
Domestic sheep can carry the pathogen without any harmful effects, but it can be deadly to bighorns. Jourdonnais said no one really understands what causes an outbreak in bighorns to happen.
The pathogen wasn't found in the East Fork herd when bighorns were captured and moved to other parts of the state in 2007.
The pathogen was also different than what was found in other disease outbreaks in bighorn herds at Bonner and upper and lower Rock Creek.
"We found the source of the pathology in the East Fork and it was different than what was found in the other die-offs," Jourdonnais said. "The East Fork appears to be an isolated case."
In Upper Rock Creek, biologists counted about 160 sheep this spring. Last year, they counted twice that many.
"They are finding some that are still coughing," Jourdonnais said. "The jury is still out on that herd."
In Lower Rock Creek, the numbers were a little better. Biologist found about 120 bighorns as compared to about 230 there last year at the same time.
Jourdonnais said the other two Bitterroot herds - at Skalkaho and Painted Rocks - appear to be disease-free. He counted 125 sheep in the Skalkaho area, which is the second-highest count ever.
Ravalli Republic editor Perry Backus can be reached at 363-3300 or email@example.com.