Extirpations of local populations of white-tailed deer (Odocoileus virginianus couesi) within the Sonoran Desert in Arizona are discussed. Seasonal drought is thought to exclude this animal from western Arizona. The recent elimination of isolated populations at the western periphery of the species range is thought to be due to an increase in the incidence and variability of spring drought since 1950. Observed survival rates of white-tailed deer fawns correlated significantly with spring (June) and autumn (November) drought indices.