Comparative demography of forest Peromyscus

Abstract

The demography of Peromyscus leucopus and Peromyscus maniculatus was studied from 1979 to 1986 in four deciduous forest sites in Indiana, Virginia, Ohio, and Pennsylvania. In two sites (Virginia and Pennsylvania) the two species were sympatic; at the other two sites, Peromyscus leucopus was the only species present. Peak densities varied greatly among sites (range: Indiana Peromyscus leucopus peak = 30/ha; Pennsylvania Peromyscus maniculatus peak = 120/ha). Except for an apparent synchronous high in 1981, there was no strong temporal concordance of peaks or lows among sites. Breeding seasons were of comparable length at all four sites and typically showed a late summer (August–September) hiatus followed by some fall breeding. There was no consistent relationship among sites between over-winter survival and peak density the following summer or between the percentage of adult females pregnant and peak density. Thus, our data suggest that local processes are more important than regional ones in Peromyscus demography.