Cervids readily adapt to suitable human-altered landscapes and can cause several types of damage, including economic loss associated with landscape and agricultural plantings, human health and safety concerns, and adverse impacts on natural habitats. The need for effective, practical, and nonlethal tools to manage damage caused by elk (Cervus elaphus), mule deer (Odocoileus hemionus), and white-tailed deer (Odocoileus virginianus) has been heightened by the growing prevalence of locally overabundant populations and public demand for nonlethal wildlife management methods. Various frightening devices are available commercially, but most have not been subjectively evaluated. We used consumption measurements to evaluate the efficacy of a specific motion-activated light- and sound-emitting frightening device for urban mule deer and elk. The devices proved ineffective; deer and elk ignored them. As the demand for frightening devices to reduce deer and elk damage increases, it is important that research be conducted to evaluate the efficacy of new devices so that users know what level of efficacy to expect.