Scientists Accidently Find One Solution To Roadkill

May 22, 2018

The deadliest animal in the U.S. isn’t a grizzly bear, a mountain lion or even a western diamondback rattlesnake. It’s a deer. More than 200 Americans are killed each year on our nation’s roads hitting or swerving to avoid this seemingly harmless animal. Around 30,000 or so are injured.

One group of scientists trying to reduce those numbers ended up finding a solution by chance.


Hitting a deer with your car is a fact of life in Wyoming. Jon Oman said he’s hit all kinds of animals. Like the time, he said, “a coyote just darted out of a small clearing in the forest.”

Oman is with State Farm Insurance.

“So there was really no time to stop or doing anything preventative,” said Oman. “It was just reactionary at that point, and of course, rather than swerve, I just ended up hitting it.”

That coyote didn’t survive and Oman’s car didn’t do so well either. Oman says the average auto repair claim for these types of wildlife encounters is a little more than $5,000.

And Oman said hitting a 300-pound deer or a 1,600-pound moose is just part of the problem.  

“Sometimes we end up seeing a bigger safety issue by folks being almost prideful about not hitting that deer, that elk or that moose,” Oman said. “And then of course they, they go off the road, they roll their vehicle, or hit an icy patch or something.”

Wyoming, Utah, Idaho and Montana are considered high-risk states for these events. In fact, Montana is number two in the country for the number of wildlife collisions.

It’s so common there the legislature passed a “roadkill” law that says if you hit an animal you can get a permit to take it home and eat it. 

Corinna Riginos is a conservation scientist with the Nature Conservancy, who studies how to make roads safer for both humans and animals.  She said we know the best way to do it.

“The gold-standard is under-passes or over-passes, or both with plenty of fencing on either side so that the animals have to go and cross the road at those under and over passes and these are 80 to 90 percent effective across the world,” said Riginos.

But they’re also expensive, and not always possible. A flat prairie is easy enough. But that’s not the case on a winding highway along a steep mountain range. That’s when plan B comes into play - wildlife reflectors.

You’ve probably driven by one and not noticed it. They’re basically a series of poles on the side of the road, which Riginos said, “are intended to flash when headlights hit them and warn deer that the car is coming and to make the deer stop and be more cautious about crossing the road.”

Here’s the thing: There have been a lot of studies on these reflectors, but Riginos said the results are mixed and not very impressive.

So Riginos led a team of scientists to develop what they hoped would be the definitive study on whether or not reflectors actually work. They covered up some of the reflectors and left the others uncovered. The idea was to see if the reflectors really made a difference.

“So we covered them with this cheap, easily available and durable material, which just happened to be white canvas bags,” said Riginos.

Then Riginos said they used thermal video footage to look at how the deer were behaving. And to their surprise, the bag-covered reflectors turned out to be more effective than the reflectors themselves.

“We could actually see that in the white bags situation, that the deer were more likely to stop and wait for cars to pass before crossing the road, instead of just running headlong into the road,” said Riginos.

The reflection of headlights on the bags might have simply startled the deer and alerted them to the cars.

Riginos added that, “It’s also possible that that looked to them like their rump patch. A lot of times they raise their tail and show a white rump as a warning sign of a predator or other danger. “

But there is still work to be done.

“I would love to find some partners to take it forward and develop a true technology that does better than the white canvas bags and testing it thoroughly and come up with something lasting and effective,” said Riginos.

For now, Riginos has some advice for drivers: Take it slow where wildlife may be crossing, and keep your eyes on the road.

This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Boise State Public Radio in Idaho, Yellowstone Public Radio in Montana, KUER in Salt Lake City and KRCC and KUNC in Colorado. 

Copyright 2018 Boise State Public Radio. To see more, visit Boise State Public Radio.