The deer whistle may be categorized as a communication device. The purpose of these devices is to act as an alarm signal, which fall into three categories (Bradbury and Vehrencamp, 1998): flee alarms, assembly alarms, and alert alarms. Alert alarms do not cause the receivers to flee or to gather but to remain stationary and become observant. If the signal is linear, that is, combines readily with others, it will combine additively without distortion from the sound produced by the automobile. This would be the intent of the deer whistle. All of the alarm devices tested had the same statement regarding the anticipated response of deer to their sonic components and, in general, are viewed as acoustic “attention-getters”, alleged to elicit a response, not of flight but of attentiveness. This would allegedly preclude the animal from bolting in front of the vehicle. In a few cases, the manufacturer’s statement indicated that the device may “startle” the animal; however, most indicated that the animal was likely to acknowledge the vehicle (the sound of the whistle) by remaining still while “looking up and turning its ears.