Dec 22, 2010 5:38 PM by Bruce Auchly (MT FWP)
Early winter bighorn sheep surveys along the Rocky Mountain Front indicate a drop in sheep numbers, probably due to a variety of factors, according to wildlife biologist Brent Lonner of MT Fish, Wildlife & Parks.
Lonner noted, “While we have not yet found any evidence of disease, it’s probably a combination of things, including disease, weather and predation.”
Rumors had spread this fall that sheep along the Front had contracted pneumonia; that's likely because pneumonia hit western Montana herds earlier this year, and several hundred sheep died or were removed. The last sheep die-off in the Sun River area took place in 1984, but those losses did not compare to the recent problems in western Montana.
Lonner just completed a survey of bighorns on the Front west of Augusta, finding little evidence of emaciated, coughing sheep, which would indicate pneumonia.
“It’s definitely better than what the rumor mill was saying,” Lonner says.
However, overall numbers are down and lamb survival going into the winter appears poor.
“Sheep numbers appear to be down about 35 percent compared to the last three years,” Lonner noted. “The most striking decline is lambs. Out of 386 sheep that I was able to classify I only counted 11 lambs.”
Lonner calculated a lamb to ewe ratio of 5 to 100, which is very low. The recent average has been 31 to 100.
In April, overall sheep numbers were strong, he observed. Since then, some sickness apparently hit the sheep on the Front, along with late spring snowstorms and the usual predator suspects, Lonner said.
Besides a low lamb to ewe ratio, Lonner also noted a 37% overall reduction in the numbers of older age rams, those whose horns curl three-quarters or greater. They are the rams hunters seek most.
Lonner said, “Certain areas appear to have been hit harder than other areas. However, overall ram to ewe ratios appear to be pretty good. I’m still finding decent numbers of younger rams in comparison to the numbers of ewes I’m seeing. And 99% of the sheep I saw appeared in good health.”
For now, Lonner plans to keep watching bighorns along the Front.
“Unfortunately, given my observations thus far and pending more looks throughout the winter and again during the spring sheep surveys,” he commented, “I’m more likely to strongly consider reducing most sheep licenses – ewe and either-sex – at least to some degree. We’ll see.”
Click here to learn more about bighorn sheep on the MT FWP website.
Image above courtesy of MT FWP.