Land & Environment

Deer-vehicle Collisions May Rise as Temperatures Fall

By Brad Plothow, from the Hard News Café
LOGAN — The driver ahead of you slows as he winds up the canyon. In your haste, you veer left and try to pass.
Only then do you realize why the driver let up on the gas.
You spot the deer around the time it connects with your car grill, killing the animal and sending you to the hospital.
This is one of myriad scenarios where the migratory tendencies of wildlife meet head-on with people's commuting habits. Terry Messmer, Utah State University extension wildlife specialist, has seen the aforementioned example first-hand, and he worries that vehicle-deer collisions could be on the upswing as winter sets in.
That's because as the snow line moves down the mountains, so will the deer.
But cold weather and deep snow aren't the only factors that spur deer to meander city-ward. From Hyrum to Richmond, Cache Valley's towns have been built along the deer population's historical migration paths, said Chris Peterson, a graduate student who has studied these issues for five years.
"We have basically three highways in this valley, and all three of them cut right through migratory routes," Peterson said. "Anytime you're driving through any one of the canyons (near Cache Valley) you're driving through the only habitat the deer have."
Deer typically migrate in the spring and in the fall, or when food or water is scarce.
Unlike elk, which are perpetual nomads, deer are territorial. They like to stake out specific areas, and they meander from the mountains to the valley as the temperature changes. The routes the animals take puts them right in harm's way. Their biannual treks take them along the base of Cache Valley's eastern mountains, so to get to town they use the same thoroughfares as vehicles: Logan, Green and Blacksmith Fork canyons.
The result is a disaster in the making for deer herds when autumn sets in.
About one in three deer deaths in Utah are auto-related, said USU research associate Patty Cramer. In addition, about 30 percent of all deer-vehicle collisions result in the animal's death, and that figure was as high as 50 percent as recently as 2002, Peterson said.
But simply slowing down while driving through the animals' migration territory could prevent most auto-related deer casualties, Peterson said.
When motorists adhere to road signs that warn them of deer, auto-animal accidents can be decreased by 70 percent, according to a three-year study cited by Messmer.
In addition, the added reaction time by slowing to 40 to 45 miles per hour can reduce collisions "ten-fold," Peterson said. The extra seconds afforded by slower speeds can be critical if a motorist encounters deer, which have a tendency to stop in their tracks when they spot oncoming traffic.
Drivers sometimes get the "doe in the headlights" look from deer as a result of the animals' instincts and learned behavior.
Even most humans freeze momentarily when danger is present, Peterson said, and so do deer. Also, if deer perceive oncoming vehicles to be predators, the animals' natural tendency is to limit its movement in order to remain undetected.
Peterson said it's also possible that deer don't even perceive moving vehicles as threats. Many deer have grown accustomed to seeing cars zipping around, and until they get hurt or chased by one, they assume the autos are friendly.
"If you grew up next to your neighbor who whole life and than one day he leaped out and attacked you, you'd be like, 'What the heck?'" Peterson said.
"That's how it is with the deer and cars."
As the snows set in, deer will spend more time near roads because warmth from auto exhaust allows vegetation to stay alive longer. This means deer will be more apt to enter roads from the shoulder, a hazard that motorists often overlook. And it's not always the first deer one sees that gets hit; where there's one deer, there are likely to be others, Messmer said.
Besides the eastern canyons, many deer deaths from cars occur in Cache Valley near U.S. Highway 91's mile markers 8 and 9, Cramer said. This is because landowners near the highway often leave their gates open, so deer meander onto the roads, but can't find their way back through the gates -- they are, in essence, trapped on the highway.
Some efforts have been taken to mitigate the presence of deer on the highway. U.S. Highway 91 has four underpasses -- at mile markers 14, 12, 8 and 5 -- to allow deer to walk under the road. These tunnels -- which are roughly three meters high and four meters wide -- are made of corrugated steel, and deer can be trained to use them.
Still, the best way to avoid a potentially deadly encounter with a deer is for drivers to ease off the gas pedal, Peterson said. Doing so could save the lives of deer and people alike as they tread the same territory this fall.
A deer-vehicle accident

COLLISION: When an animal such as a deer hits a car, it's bad for both. One in three deer deaths in Utah is caused by a vehicle. / Photo courtesy of Terry Messmer


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