The effects of food on midsummer demography of white-footed mice, Peromyscus leucopus

Abstract

At mid-latitudes, white-footed mice (Peromyscus leucopus) breed in spring and autumn with a decrease in breeding activity in July and August. A food supplement of sunflower seeds and oats was applied to two 1-ha live-trapping grids from 1 May to 13 August 1984 to determine if a high quality food supplement would stimulate reproduction in Peromyscus leucopus during the midsummer breeding hiatus. Breeding activity on treatment and control grids was high from May through June, declined considerably from early July through August, and increased again in September and October. Food had no apparent effect on the decline in reproductive activity during midsummer. During the spring breeding season, the number of females was higher on treatment than control grids, but food had no effect on number of males, pregnancy rates, home-range size, length of residence, or body weights. The breeding activity and upper limits of population density are apparently determined by factors other than food.