Motor vehicle collisions have continued to decimate a bighorn sheep herd in the Thompson Falls area, and wildlife officials said the declining population has reached a new nadir and represents an alarming trend.
Montana Fish, Wildlife and Parks biologist Bruce Sterling said he counted only 52 sheep on his annual flight this spring, a figure that pales when compared to the 270 sheep counted in 2008. The numbers reflect the number of sheep observed in the survey, Sterling said, and not the total number of sheep in the population.
Still, the trend is disconcerting to the biologist, who attributed the lion’s share of the decline to highway mortality.
During the four-year period between 2008 and 2012, a total of 110 sheep (50 ewes and 60 rams) were killed by collisions, he said. A total of 107 sheep were killed on Montana Highway 200, while just three sheep were killed by trains. Since 1985, Sterling said 403 sheep have been killed by motor vehicles on the highway and 58 sheep have been killed by trains.
“We have lost 50 breeding or potentially breeding females during this time frame when hunters have taken only five ewes on permits,” Sterling says.
The highway mortality problem has been ongoing for decades, but seems to have grown more serious in recent years, Sterling said, adding that five sheep were taken out in one collision several weeks ago.
Many of the sheep are killed between mile markers 58 and 59 and mile markers 64 and 65, between Thompson Falls and Plains, where the sheep are drawn to salt and minerals along the roadway. The population was once robust enough to withstand the deaths and recover, but as the herd size is diminished and if the mortality trend continues, the future of the sheep is jeopardized.
“Now that we are at a low population level for sheep, each mortality is more critical,” he said.
The Federal Highway Administration, Montana Department of Transportation, Montana Fish, Wildlife and Parks, American Wildlands, and the Foundation for North American Wild Sheep have joined forces in the past to address the problem, but to no avail.
Sterling identified several of the most visible measures that have been taken to reduce highway mortalities of sheep, but said none have proven effective. Flashing yellow caution signs and electronic reader boards have been unsuccessful at convincing drivers to slow down and avoid collisions with sheep. FWP officials have also strategically placed salt blocks in the area to lure the sheep away from the highway, but without much result.
Sterling said the problem will be discussed at an upcoming meeting between officials with FWP and the Montana Department of Transportation on May 10.
Bighorn sheep were native to the Thompson Falls area but were extirpated by over-hunting and disease passed on by domestic sheep. The sheep were re-introduced in the mid 1950s.
Flathead Valley bureau reporter Tristan Scott can be reached at (406) 730-1067 or at firstname.lastname@example.org.