Although many aspects of white-tailed deer (Odocoileus virginianus) biology and physiology have been studied thoroughly, few studies have examined deer perception. We obtained a behavioral measure of light-adapted visual sensitivity based on performance of 7 deer in forced-choice discrimination tests. We compared intensity thresholds at the short and long wavelengths of their purported visual spectrum. Utilizing an automated training device, we trained deer to discriminate between lit and unlit light-emitting diode (LED) lights expressing monochromatic wavelengths, and recorded performance across a series of decreasing intensities for each wavelength until deer could no longer discriminate the light stimulus. We regressed a best-fit logistic function to each deer's performance as intensity decreased at a single wavelength, demarcated the sensitivity threshold to that wavelength, and compared deer's sensitivity threshold across wavelengths. Our behavior-based sensitivity measurements agreed with previous estimates of white-tailed deer's cone photoreceptor sensitivity. We confirm that these cone photoreceptors contribute to deer behavior, and that deer have a greater perceptual sensitivity to shorter wavelengths and lower sensitivity to longer wavelengths. Our findings also suggest the deer have some sensitivity to ultraviolet light. The visual perception of the white-tailed deer is specialized for sensitivity during their crepuscular patterns, enables detection of predators along their horizon, and is well-adapted for a prey species. © 2014 The Wildlife Society.