Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 17, 2025 ...

Amazon sells deer whistles here: Amazon.com: Bell 22-1-01000-8 Black Deer Warning: Automotive

I had a friend from VA who swore by these; but FWIW, the (kinda lengthy) article below (from Wikipedia) makes ya wonder.  Gotta admit though, they are cheap as dirt and they are quite unobtrusive......and hey, they got chrome ones too.

The deer whistle is the most widely studied and scrutinized form of deer-vehicle collision prevention method. Deer whistles are products that attach to a vehicle and act as an alarm system for deer and other wildlife. The manufacturing of deer whistle products has emerged into a multimillion-dollar industry. [11] Their manufacturers advertise that ultrasound, which they say deer can hear but humans cannot is emitted as air passes through the whistle.[9] Most deer whistles are about 2 inches long and are bullet shaped. They cost between $20 and $25 and are designed to be attached to the bumper of a vehicle. When a vehicle moves faster than 35 mph, a whistle sound is induced which is believed to ward off animals from a roadway. The deer whistle is marketed to prevent deer-vehicle collisions.[12] The effectiveness of deer whistles is disputed among agencies because of the conflicting reports available. The study and documentation of deer whistles is generally poor, and a conclusive decision about the effectiveness of the deer whistle cannot be made.[6]

Some research has been published about the function and capability of deer whistles. Deer have an auditory range of two to six kilohertz (kHz), but only a select few deer whistle products have ranges within that of a deer's. Some manufacturers claim that deer can hear the whistle up to a quarter-mile away, but no research has solidified that claim.[13] Another point of concern is that the amount of noise from a vehicle may compromise the clarity of the deer whistle. Because the whistle is vehicle-mounted there is little that can be done about mitigating vehicle noise. Others also argue the whistle's location on the vehicle as being susceptible to dirt and insects which would eventually clog the passageway of the whistle, rendering it useless. The idea of a non-air-activated whistle has been discussed but little research has been done on the effectiveness of such products, and is highly recommended. Deer whistles generally have a questionable level of effectiveness but are advertised as aiding in the prevention of DVCs. A concern amongst studies is the impact the whistle has on the psyche of the driver, and the driver's sense of security.