Wednesday, September 22, 2010

On highway, mammals lose battle

Increase in prey base deemed reason for spike in road kill

Express Staff Writer

A fox falls victim to a vehicle on state Highway 75 last week. Photo by Willy Cook

For commuters making the drive from Hailey to Ketchum, state Highway 75 can seem less a scenic corridor and more a corridor of carnage.

The amount of road kill has been unusually high this year, according to various state and federal agencies, and the roadway has been littered with voles, raccoons and skunks, in addition to big-game animals such as deer and elk.

Road kill started to spike in early August, when reports surfaced of a substantial number of voles being killed on the highway south of Bellevue.

According to the BLM's Shoshone office, the number of voles has been especially high this year, even compared with last year's substantial numbers. And the higher the vole population, the higher the number of vole fatalities on the highway.

"You can't drive down the highway without seeing those little things scurrying across the road," said Randy Smith, game manager for Idaho Department of Fish and Game's Magic Valley Region.

But vole numbers could have an impact on other highway fatalities as well, Smith said. Increasing reports of dead skunks, raccoons and foxes can be partly attributed to the rise in voles.

"We've had kind of a vole explosion, so there's been an especially good food source," Smith said.

Skunks are omnivorous, which means that while they will eat grass, berries and other plant material, they also feed on small rodents such as voles.

"All the predators, and birds, too, they're having a heyday," said Fish and Game Conservation officer Lee Garwood. "These voles are feeding a lot of things right now."

Both Garwood and Smith said the higher the prey base, the more young predators survive. In the case of the skunks, Smith said, this is the time of year he would expect to see young skunks forging out on their own—young skunks that would not be experienced road-crossers.

Voles can also be credited with a rising bird-of-prey population, Garwood said, and thus a higher number of bird-vehicle collisions.

"It sure seems like we've had a few more birds of prey being struck by vehicles," Smith said.

But voles cannot be blamed for the increase in mule deer and elk fatalities, which Garwood and Smith attribute to a higher number of the ungulates in the area.


Garwood said deer and elk populations are in "pretty good shape," and that he expects to see more collisions as the herds start moving in the early fall. However, these animals are not left on the road after being killed, as are small ones, and thus may be less visible, Smith said.

"We're most concerned about something in the road that might create a safety hazard," he said. "If we ran on every road kill in our region, we'd have to double our staff."

Devin Rigby, District 4 engineer for the Idaho Transportation Department, said his crews sweep state Highway 75 three times a week, but can't always stop if the animal isn't large.

"We typically won't stop just to pick up a small animal off the side of the road unless we have a complaint," Rigby said. "The more we stop, the more we conflict with traffic and the higher risk we have of having an accident."

Rigby said his crews will pick up small animals in more residential areas.

"We're not going to let a carcass decompose in someone's front yard," he said.

Currently, the ITD is working with Fish and Game to develop methods for preventing animal fatalities. Steve Cole, the department's Hailey maintenance foreman, said measures such as overpasses and motion detectors have been successful in other areas.

"We realize that we can't completely stop the kill for the whole length of the road in the valley, but there are areas that have higher instances than others," Cole said.

Katherine Wutz:

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