Reproductive physiology of the Grey squirrel (<i>Sciurus carolinenis</i>)

Abstract

Abstract The Grey squirrel shows two peaks of litter production in spring and summer, but this does not necessarily mean that all female squirrels have two litters per year. Captive female squirrels do not show regular oestrous cycles, and there is evidence that both the presence of a male and adequate space is necesssary for the induction of oestrus. After day sixteen of gestation, the ovaries are not necessary for the maintenance of gestation. Our studies indicate that the male Grey squirrel has a seasonal period of t esticular regression in the autumn, which may be short‐lived so that full breeding condition is attained by December In some years, localized populations of Grey squirrels may have a prolonged period of testicular regression throughout the winter, with a consequent absence of spring breeding, and there is some evidence that this may be related to available food.