Population Dynamics of the White-footed Mouse in Floodplain and Upland Forests

Abstract

Comparative observations of the density and demography of 2 populations of the white-footed mouse (Peromyscus leucopus) were made in a floodplain forest and adjacent upland. There was little exchange of individuals (< 3%) between populations. Fluctuations of density were greater in the floodplain because better recruitment in autumn produced higher densities than in the upland, and poor recruitment in winter and spring produced lower densities. In other respects.sbd.breeding season, adult survival and age structure.sbd.the populations were similar. Contrary to expectations, the floodplain population served as a small source of recruits for the upland rather than the reverse. Recruitment patterns and population fluctuations were probably related to food availability; the best survival of young occurred in autumn after the mast crop had fallen. Poor recruitment in the floodplain was related to extensive flooding. Neither population bred during the coldest months, Dec. and Jan. General food habits of the 2 populations were similar and the proportion of seeds in the diet and fat content of carcasses were high during the most successful recruitment period (autumn). Overall, the 2 populations were surprisingly similar. Greater fluctuations of density in the floodplain, while agreeing with theoretical predictions for an unstable habitat, occurred primarily because the floodplain was more productive in autumn rather than because of poor survival. Floodplain forests should not be considered marginal habitat for these mice.