EFFECT OF FOREST PATCH AREA ON POPULATION ATTRIBUTES OF WHITE-FOOTED MICE (PEROMYSCUS-LEUCOPUS) IN FRAGMENTED LANDSCAPES

We studied population densities, sex ratios, adult masses, reproductiv e activity, age structure, and over-summer recapture rates of white-fo oted mice (Peromyscus leucopus) in 15 woodlots of various sizes and th ree continuous-forest sites to ascertain the effects of forest patch a rea on these population attributes. Our study was conducted in west-ce ntral Indiana during spring 1992 and 1993 and autumn 1992. Densities o f white-footed mice were inversely related to forested area. A survey of previous studies conducted at similar latitudes revealed a similar pattern. Extremely high densities (up to 200 adults/ha) were found in small woodlots (<0.5 ha). Mass of adult male mice also was inversely r elated to forest area, and a positive relationship between proportion of adult male mice and forest area was suggested. Ratios of juveniles to adults were positively related to forest area in autumn but not in spring. The proportion of sexually active individuals in the populatio n was not related to forest area, nor were over-summer recapture rates . Our findings indicate that patch area can have dramatic effects on t he structure and dynamics of populations of white-footed mice inhabiti ng fragmented landscapes.