1/24/2011
Division of Wildlife
Gunnison Bighorns Get Preventative Treatment
GUNNISON, Colo. -- In an effort to bolster a formerly productive herd of Rocky Mountain bighorn sheep, the Colorado Division of Wildlife recently vaccinated more than two dozen bighorns near Gunnison against respiratory diseases that have periodically afflicted wild sheep across Colorado and the West.
The respiratory diseases cause lung infections that can kill bighorns.
On Jan. 11, Division biologists used a drop net to capture 27 bighorns in the remnant Taylor Canyon herd and administered antibacterial and antiviral vaccines to each. The sheep were also fitted with ear tags before being released at the capture site.
Gunnison Area Wildlife Manager J Wenum explained that vaccines and other drugs have been administered to Colorado bighorn herds through feed and individual injections in the past. This operation, however, was unique because all but a few of the sheep that comprise the herd were captured. Plans are in place to capture the remaining individuals.
"We hope to isolate, essentially, the entire herd and give them all the same treatment," Wenum said. "This will really help us to see if these treatments are effective. We want to see these animals make it through the winter and we're especially hoping for good survival of lambs born next spring."
A similar operation is being planned for about 20 bighorns in the Fossil Ridge herd, which winters east of Gunnison.
The Taylor herd has historically numbered more than 150 animals, but more recently the population has fluctuated as the sheep have struggled with chronic disease epidemics. Laboratory analysis has identified various strains of bacteria in the herd, which has also been periodically exposed to several deadly viruses. Adult wild sheep seem to develop immunity to these pathogens, but young lambs have a more difficult time coping with infection. Biologists say that reduced lamb survival has significantly depressed the size of the Taylor herd over the last five years.
Three of the sheep captured were lambs that were born last spring. Biologists are optimistic that the young animals will make it through the winter.