Next-Door Nature

Motorists are looking for ways to reduce collisions with wildlife, but do "deer whistles" or other acoustic devices really help? (Photo: iStock, used with permission)

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I’m finally able to share some news that has been in the works for several months. Car Talk, one of the most popular shows on National Public Radio, has named me to the newly created honorary position of Animal–Vehicle Biologist. Together, we’ve developed a Wildlife and Your Car FAQ page for their website to address some of the more common questions they’ve received over the years, and I’ve agreed to help as new questions come in. So, in honor of Tom and Ray and all the lackeys at Car Talk Plaza, this week’s blog post is devoted to one particular auto-animal issue.

No matter where you live in the U.S. or whether mule deer (Odocoileus hemionus) or white-tailed deer (Odocoileus virginianus) are the more common species, the potential for a deer–vehicle collision (DVC) continues to increase.

An adult deer can weight between 150–400 pounds. You don’t have to do the math to know when a car hits something that large there’s going to be a lot of damage… to the deer, of course—they rarely survive a DVC—and often to the automobile as well. How much damage the car sustains depends on the size of the vehicle, speed, and a variety of other factors.

The driver and passengers are at risk as well. This may be as a result of the driver attempting to avoid impact, but human injuries also occur when the animal comes through the windshield: dead, or alive-and-kicking.

That’s not a pretty image, I know, but it has to be said.

So I can certainly understand the interest in using acoustic devices—sometimes known as deer whistles—to alert animals that a vehicle is near.  Believe me, I would love to tell you that deer whistles are a simple and inexpensive way to keep cars and deer far from one another. Sadly, that’s not possible.

There have been a number of studies on the subject including a 2008 publication by researchers at Utah State University (USU). Their work suggests devices designed to frighten deer, including deer whistles, are “ineffective.”

Why? The study offers two main reasons: 1) the stimuli can’t be perceived by deer—either the sound isn’t within the animal’s hearing range or it doesn’t travel far enough or it’s blocked in some way; or 2) the sound doesn’t trigger a flight response.

Think about it. Even if deer can hear the whistle, what in their experience would cause them to equate that sound with danger? Aside from the normal wariness caused by anything novel in the environment, why would a deer consider a whistle—or even a car, for that matter—to be cause for alarm? All of their other predators are careful to be quiet, so the kind of sound a deer would equate with danger is more likely to be a twig snapping or leaves rustling. Frankly, there doesn’t appear to be much in the deer’s evolutionary history that would prepare them to be cautious around cars, other than, perhaps, the fact that the vehicles are moving quickly.

This same USU study found that, aside from reducing the deer population, modifying roads and motorist behavior could help to reduce DVCs.  New technologies, including in-vehicle detection systems, look promising but more research is needed.

Meanwhile, what can you do to avoid a DVC?

• BE ALERT—especially during early morning and early evening hours.
• BE AWARE—there’s data behind the placement of those deer-crossing signs so live and learn (and vice-versa)
• BE EDGY—keep an eye out for movement on either side of the road and just beyond the shoulder, especially when driving through agricultural or wooded areas
• BE CALM—slowing down a bit will increase the time you have to respond if an animal does dart out in front of you… and it will lower your blood pressure, too.

You can also visit the Humane Society of the United States website for more information on driving with wildlife in mind.

Have a question about wildlife and other next-door nature? Send an email and the answer may turn up as a future blog post. And don’t forget to “Like” NDN on Facebook!

© 2011 Next-Door Nature— no reprints without written permission from the author.