As deer populations have increased so have their run-ins with automobiles.

I mean that quite literally. Over a million U.S. drivers—1:169 according to a 2014 State Farm® report—will experience a deer-vehicle collision in the next year. That probability doubles from October through December, and the annual total has been rising for years.

It goes without saying that deer rarely survive a confrontation with a car, at least not for long. Human fatalities are less common but they do occur, along with injuries and, of course, damage to the vehicle. Researchers from both the transportation and wildlife management professions continue to evaluate technologies and techniques to reduce or eliminate this road hazard, including road design, wildlife crossing structures, highway fencing and lighting, reflectors and warning signs, driver education, road salt alternatives, mowing and vegetation protocols, and animal avoidance systems.

Vehicle-mounted auditory deterrents, aka deer whistles, are a popular way for motorists to take action. These devices are readily available, inexpensive, and easy to install. Manufacturers tout ultrasonic sound waves that are undetectable by humans but scientifically proven to warn wildlife away from approaching traffic.

(David DuBois)

The data beg to differ.

Deer whistle studies have investigated all manner of factors that could contribute to auditory device effectiveness, such as:​

how far the tones carry (at least 33 yards)

deer ear sensitivity (they can hear just fine and at higher frequencies than humans)

behavior alteration in response to the whistle (little to none in the majority of cases)

effectiveness of various frequencies and volumes (deer were more likely to enter the roadway in response to the lower frequencies)

The results announced by a University of Georgia team were not music to a deer whistle dealer’s ears: “...auditory deterrents do not appear to be appropriate for prevention of deer-vehicle collisions."

(Barbara Groffman)

I can’t say this came as a surprise. From my perspective the whistle concept and, to some degree the study designs, are both flawed.

As any hunter knows, and as research has confirmed, deer have sensitive hearing. Moreover, vehicles make noise as they motor down the road. Even electric vehicles, which are practically mute compared to an internal combustion engine, create wheel and tire noise. When a car is coming the deer know. And while most prey species are cautious about any novel feature in their environment, deer in much of the U.S. have grown from fawn to adulthood with tire song as the soundtrack of their entire lives. They simply don’t perceive the vehicle as a threat once they habituate to the sound and movement. Lastly, keep in mind that deer have evolved to be alert to predators who move as silently as possible when they hunt. Birds whistle while they work. Wolves, coyotes, and cougars do not. Songbirds pose no threat so why in the world would a deer be alarmed by a whistle?

Things known to whistle are not typically terrifying.

The only proven measures drivers can take to reduce the chance of deer-vehicle collisions and lessen the severity of those that do occur are:

Buckle Up - the safest place to be in any accident is inside the car so be sure you stay there.

Slow Down - especially when driving at dawn and dusk in areas known to be rife with deer.

High Beams - at night, in the absence of oncoming traffic, provide the best possible visibility.

Scan Shoulders - you’re more likely to see deer in time to respond if you watch the areas where they congregate.

Don’t Swerve - it’s unlikely you’ll save the animal and you’ll probably make things worse for yourself, your passengers, and other drivers.

And I ain’t just whistlin’ Dixie.

They're even harder to see at night!

Related: Avoid Hitting Deer With Your Car By Practicing These Three Habits.