Early-summer inhibition of reproduction in wild white-footed mice (Peromyscus leucopus noveboracensis): influence of supplemental food

Abstract

Adults of wild white-footed mouse (Peromyscus leucopus noveboracensis) populations in southeastern Virginia have been shown to be reproductively suppressed during May–July compared with other months of the reproductive season. The gonads and sex accessory glands are also significantly smaller during May–July than at other times of the year. The causes of this early summer reproductive suppression are unknown. In this study, food (Agway 3000) that could not be hoarded was supplied in feeding stations on one-half the 11-ha wooded study area during 1990 and 1991. Food consumption (g) was positively but not significantly correlated with population density (adults/ha) during both years. Population density was higher during 1991 on the food-supplemented area than on the nonsupplemented area, but the statistical significance was marginal. Mice of both sexes living on both areas during 1990 and 1991 exhibited significant reproductive suppression during May–June. Further, mice of both sexes living on both areas during both years had significantly smaller gonads and sex accessory glands during May–June compared with other months of the year. Thus, during both years, surplus food did not prevent suppression of reproductive function in this wild population, and this phenomenon remains unexplained.