We evaluated the behavioral responses of white‐tailed deer (Odocoileus virginianus) to 4 colors of wildlife warning reflectors (red, white, blue‐green, and amber) that are purported to reduce the incidence of deer—vehicle collisions. We observed white‐tailed deer behaviors relative to roads before and after installation of wildlife warning reflectors using a forward‐looking infrared camera during 90 observation nights. We concluded that wildlife warning reflectors were ineffective in changing deer behavior such that deer—vehicle collisions might be prevented.

To gain knowledge of visual specializations influencing the behavior of white-tailed deer ( Odocoileus virginianus (Zimmermann, 1780)), we examined gross eye characteristics, structural organization of the retina, and the density and distribution of cone photoreceptors. White-tailed deer possess ocular features similar to other ungulates including a horizontal slit pupil, reflective tapetum lucidum, typical retinal structure, and medium wavelength sensitive cone photoreceptors concentrated in a horizontal visual streak. The tapetum was found to cover the superior portion of the eye and overlapped the horizontal visual streak. Comparisons between fawns and adults did not reveal any differences in retinal thickness, retinal nuclei counts, or cone photoreceptor counts. While M-cones had increased density in the visual streak, S-cones were distributed evenly across the entire retina. Schematic eye calculations of a 0.5-year-old deer indicated a hyperopic eye (+7.96) with a F/# ranging from 5.55 to 1.39 for pupil diameters of 3 to 12 mm. As expected for a crepuscularly active prey species, the visual system of white-tailed deer is specialized for sensitivity in low-light conditions and detection of predators.

: Basic knowledge of white‐tailed deer (Odocoileus virginianus) hearing can improve understanding of deer behavior and may assist in the development of effective deterrent strategies. Using auditory brainstem response testing, we determined that white‐tailed deer hear within the range of frequencies we tested, between 0.25–30 kilohertz (kHz), with best sensitivity between 4–8 kHz. The upper limit of human hearing lies at about 20 kHz, whereas we demonstrated that white‐tailed deer detected frequencies to at least 30 kHz. This difference suggests that research on the use of ultrasonic (frequencies >20 kHz) auditory deterrents is justified as a possible means of reducing deer—human conflicts.

We evaluated efficacy of sound as a deterrent for reducing deer (Odocoileus spp.)–vehicle collisions by observing behavioral responses of free‐ranging white‐tailed deer (O. virginianus) to pure‐tone sounds within their documented range of hearing. Behavior of free‐ranging deer within 10 m of roadways was not altered in response to a moving automobile fitted with a sound‐producing device and speakers that produced 5 sound treatments documented to be within the hearing range of white‐tailed deer. Many commercially available, vehicle‐mounted auditory deterrents (i.e., deer whistles) are purported to emit continuous pure‐tone sounds similar to those we tested. However, our data suggest that deer whistles are likely not effective in altering deer behavior in a manner that would prevent deer‐vehicle collisions.