The Effect of Supplemental Food on Life-History Traits and Demography of a Tropical Mouse Peromyscus mexicanus

Three populations of the tropical mouse Peromyscus mexicanus were provided with supplemental food for 1 year (July 1988-June 1989) and demographic and lifehistory characteristics were compared to mice from three control populations. 2. Supplemental food had no clear effect on population density. 3. Juvenile recruitment was greater on fed than unfed grids. 4. There was no difference between fed and unfed populations with regard to age structure, sex ratios, immigration or survival. 5. Fed females produced their first litters at an earlier age than unfed animals and had half as many failed breeding attempts as unfed females. 6. There were no differences in litter size at weaning, interbirth interval or juvenile survival to sexual maturation between fed and unfed females. 7. Food did not influence the total number of litters a female produced per year or during her lifetime. 8. Fed females reproduced earlier but disappeared from the study area sooner than unfed females: there was no difference in the length of the reproductive life span of fed and unfed females. 9. There was no difference between pups born on fed and unfed grids with respect to post-weaning growth rates and age and weight at sexual maturation. 10. The reproductive response to food addition did not vary with female body mass or litter parity