Biology of Seasonal Breeding in Deer

Abstract

Deer are long-lived herbivores, and most species are seasonal breeders. In females, the most energy-demanding phase of the reproductive cycle (late pregnancy and lactation) is timed to coincide with the period of maximum food abundance and quality. In males, the period of fertility is timed to the availability of estrous females. The annual cycle in gonadal activity is generated endogenously and is entrained to a particular time of year by responses to environmental cues; these are principally changes in day length in the cold/temperate zones, and possibly nutrition in the tropics.