Deer horn

A deer horn, or deer whistle, is a sonic generator (whistle) mounted on automobiles intended to help prevent collisions with deer. A Shu-Roo is a similar device used in Australia to scare off kangaroos. The device produces ultrasound, and relies on deers' allegedly acute sense of hearing. Deer are highly unpredictable, skittish animals whose normal reaction to an unfamiliar sound is to stop, look and listen to determine if they are being threatened.

Scientific studies of these devices have indicated that they do not in fact reduce collisions.

Researchers with the Georgia Game and Fish Department and University of Wisconsin–Madison have pointed out several reasons why these devices do not (and probably could not) work as advertised:

• Some deer whistles do not emit any ultrasonic sound under the advertised operating conditions [typically when the vehicle exceeds 30 mph].
• Ultrasonic sound does not carry very well. It does not travel a long enough distance to provide adequate warning, and also is stopped by virtually any intervening object, so any curves in a road will block the sound.
• We know little about the auditory limits of deer, but what we do know indicates that deer hear approximately the same frequencies as humans, and thus if we can't hear it, they probably can't either.
• If deer could hear ultrasound, we do not know that it would alarm them or induce a flight response. Certainly if they heard it on a regular basis, they would get used to the sound and not react to it.

In addition to the Georgia and Wisconsin studies, research by the Washington State University as well as a study by the Ohio State Police Department also indicated the whistles are ineffective. Independent testing carried out by the Department of Zoology at the University of Melbourne reached the same conclusion about shu-roos and kangaroos.^[1]

These results are summarized in the following articles:

• Insurance Institute for Highway Safety Advisory #31
• Whistles and Whitetails
• An article from Road Management and Engineering Journal

See also Shu-Roo.

References

• "Blowing the Whistle on Deer Scare Devices", Farm Journal, Mid-February 1993 issue.
• Schwalbach, Randall P.: Whistles and Whitetails, Deer and Deer Hunting, Nov. 1989.
• Insurance Institute for Highway Safety Advisory #31
• An article from Road Management and Engineering Journal
• research by the Washington State University