Deer whistles -- electronic or otherwise -- do they work?

We recently suggested to readers of one of our sister newsletters that they save their money and not buy so-called deer whistles. Deer whistle? Yes, those devices that affix to the front of your rig and purportedly send out a sound that frightens deer away from the roadside, thus reducing the chances of a deer-vehicle accident. We soon heard from a reader to who took issue with our suggestion.

In part, the reader said there were, "several occasions where I felt they saved my bacon (or is that venison?)." He further asked that if we had some "real proof" that we should publish it.

Deer whistles – or deer horns as they are sometimes called – come in two flavors. A simple, relatively inexpensive version that's activated by the power of wind blowing through the whistle, generated by your vehicle's forward velocity, and a far more costly digital version. Most all operate on the same principle: Generate an "ultrasonic" noise that alerts deer that you're coming. The idea is that when the deer hear the noise, they'll either run away from the noise, or freeze.

Most of these devices are said to produce a sound in the range of 16 to 20 kHz (kilohertz), which is outside our human hearing range. The less expensive 'air powered' whistles typically "require" the vehicle to be traveling at 30 mile per hour or faster to be effective, while the electronic or digital versions simply operate off vehicle produced electrical power, and should therefore be effective at any speed. Most all of the makers of these devices claim that deer can hear the noise up to a quarter-mile away.

To answer the question of whether or not these devices really work as claimed, we turned to the Deer-Vehicle Crash Information Clearing House (DVCIC), a center for research that's a wing of the University of Wisconsin. One of the DVCIC's purposes is to look into research of deer-vehicle problems and make the information more widely available. On their website is an extensive review of studies done on deer whistle effectiveness, and from that review we draw much of our information.

What do we learn from the studies? Several things. First, if these devices are to work as stated, then deer must obviously have a hearing range that detects sounds at these relatively high frequencies. Several studies found that deer simply can't hear sounds at these high frequency ranges – basically, if you can't hear it, neither can the deer. Driving down the road, no matter how "loud" the deer whistle is, the sound is evidently lost on the deer.

But what about the "evidence" that is provided by manufacturers of deer whistles that indicates their devices are so effective? Such evidence is typically based on "before and after" studies, comparing how many deer-vehicle crashes occurred without a deer whistle, versus how many took place when whistles were present. The results of a number of studies were looked at, and they were mixed. Some seemed to indicate that the number of 'deer hits' were reduced with the use of whistles; others showed no such reduction. Part of the reason could be so many factors are involved, for example, the deer population may have been significantly less during the time when whistles were present. Drivers with whistles may have been especially "deer aware," and hence, simply drove smarter in deer country.

But to us, the real tell in this matter was a study undertaken in a wildlife management area of Carbon County, Utah – a haven for wintering mule deer. Two different brands of simple, air-operated whistles were mounted up on a truck, each said to produce a warning sound in the 16 to 20 kHz range. The vehicle was driven past groups of deer at 40 miles per hour. The truck was driven past the deer once to get them used to the sound of the truck, then the whistles were attached, and the rig driven back past the deer. The idea was to compare the response of the deer to the vehicle both with and without the whistles. What constituted a "response," was either a head lift, a change in orientation, running away from, or running toward the truck.

Some 300 observations were made with 150 deer groups. In the first pass, without the whistles, a little more than a third (39%) responded to the vehicle. With whistles installed, even fewer of the deer (31%) the truck's passage. The conclusion was that there was a statistically insignificant difference. Deer simply did not respond to the presence of deer whistles.

While no formal studies of the effectiveness of the high-priced electronic whistles were reported on, it would seem reasonable that by virtue of the fact that deer can't hear the higher frequencies produced by deer whistles, whether the noise is produced electronically or by the passage of air, electronic whistles are just a more expensive investment for no return on your money.

Still, considering the relatively low cost of air-operated deer whistles, some might figure that even without solid evidence that the things work, why not just add that extra layer of "protection"? Here's a question in return: Would adding on that deer whistle perhaps lull the driver into a false sense of protection, thus letting down his or her guard when driving in deer country?