An outbreak of pneumonia in bighorn sheep from the East Fork of the Bitterroot herd worsened over the past week.
State wildlife biologists collected almost 30 infected bighorn sheep from the area south of Darby. Some of the infected animals were shot in an effort to slow the spread of the disease. Others were found already dead.
“Any hope for a moderate infection rate is waning,” said Craig Jourdonnais, FWP’s Bitterroot-based biologist. “I think we are in full blown die-off mode.”
State wildlife officials confirmed last week that bighorn sheep from the herd were infected with the nearly always-fatal respiratory disease after two rams were discovered dead along the roadside.
In the past, some bighorn herds infected with pneumonia in Montana have seen dramatic die-offs in the 60 to 70 percent range.
The East Fork bighorn sheep herd was established in 1972 when 35 sheep were transplanted there. Last spring, Jourdonnais counted 185 during an aerial survey.
Jourdonnais and other state biologists will continue to cull sick sheep from the herd this week and collect biological samples for testing.
“It appears to be pretty extensive at this point,” Jourdonnais said. “On Sunday, we headed up into nearby draws. We found a lot of coughing sheep.”
The disease is impacting the entire herd.
“It’s an all-age thing,” he said. “We’re finding infected lambs all the way up to mature ewes and rams. It’s across the board.”
Necropsies found lesions on the animals’ lungs. In some of the worst cases, the animal’s lung lining was adhered to the rib cage.
Jourdonnais said he’s found sheep that were too weak to stand. Others in earlier stages of infection are able to take just a few steps before stopping.
“They are laboring just to move,” he said.
The biologist has found a few small herds away from the main wintering area that appear healthy at this point.
“We’re holding out hope that maybe they’ll keep to themselves and not get infected,” he said.
Jourdonnais said the public has been helpful in helping biologists locate the ailing sheep.
“The Doyle family has been top notch to work with,” he said.
Local sportsmen have offered to help collect samples from dead bighorns over the next few weeks.
“Logistically, we can use the help,” Jourdonnais said. “It takes a good deal of time to collect the samples we need.”
The samples are sent to the FWP laboratory in Bozeman where they are used to identify the pathogen that could potentially help biologists locate the source of the disease.
There are no known vaccines to prevent pneumonia in wild sheep.
“At this point, direct removal of infected animals is our best tool,” Jourdonnais said. “We’re going to try to contain it as best we can.”
It’s a bad time of the year for the disease to show up in bighorn sheep. The rams are in the rut and are on the move.
“They are highly social animals,” Jourdonnais said. “They are touching each other, licking each other and combating with each other. Behavior-wise they are not helping themselves at all.”
State wildlife biologists collected almost 30 infected bighorn sheep from the area south of Darby. Some of the infected animals were shot in an effort to slow the spread of the disease. Others were found already dead.
“Any hope for a moderate infection rate is waning,” said Craig Jourdonnais, FWP’s Bitterroot-based biologist. “I think we are in full blown die-off mode.”
State wildlife officials confirmed last week that bighorn sheep from the herd were infected with the nearly always-fatal respiratory disease after two rams were discovered dead along the roadside.
In the past, some bighorn herds infected with pneumonia in Montana have seen dramatic die-offs in the 60 to 70 percent range.
The East Fork bighorn sheep herd was established in 1972 when 35 sheep were transplanted there. Last spring, Jourdonnais counted 185 during an aerial survey.
Jourdonnais and other state biologists will continue to cull sick sheep from the herd this week and collect biological samples for testing.
“It appears to be pretty extensive at this point,” Jourdonnais said. “On Sunday, we headed up into nearby draws. We found a lot of coughing sheep.”
The disease is impacting the entire herd.
“It’s an all-age thing,” he said. “We’re finding infected lambs all the way up to mature ewes and rams. It’s across the board.”
Necropsies found lesions on the animals’ lungs. In some of the worst cases, the animal’s lung lining was adhered to the rib cage.
Jourdonnais said he’s found sheep that were too weak to stand. Others in earlier stages of infection are able to take just a few steps before stopping.
“They are laboring just to move,” he said.
The biologist has found a few small herds away from the main wintering area that appear healthy at this point.
“We’re holding out hope that maybe they’ll keep to themselves and not get infected,” he said.
Jourdonnais said the public has been helpful in helping biologists locate the ailing sheep.
“The Doyle family has been top notch to work with,” he said.
Local sportsmen have offered to help collect samples from dead bighorns over the next few weeks.
“Logistically, we can use the help,” Jourdonnais said. “It takes a good deal of time to collect the samples we need.”
The samples are sent to the FWP laboratory in Bozeman where they are used to identify the pathogen that could potentially help biologists locate the source of the disease.
There are no known vaccines to prevent pneumonia in wild sheep.
“At this point, direct removal of infected animals is our best tool,” Jourdonnais said. “We’re going to try to contain it as best we can.”
It’s a bad time of the year for the disease to show up in bighorn sheep. The rams are in the rut and are on the move.
“They are highly social animals,” Jourdonnais said. “They are touching each other, licking each other and combating with each other. Behavior-wise they are not helping themselves at all.”
