Effect of coarse woody debris on Peromyscus leucopus population size.

Abstract

Peromyscus leucopus (white-footed mouse) is commonly found throughout Michigan in forested habitats. Recently, a small mammal census discovered a large increase in the numbers of P. leucopus at an experimental plot that produced large amounts of coarse woody debris at the University of Michigan Biological Station in Pellston, MI. We hypothesized that the increase in the amount of downed coarse woody debris at the experimental plot provided high quality habitat for P. leucopus, leading to an increase in the population, and we predicted that traps set at an increasing distance from the experimental plot would be less successful than traps set close to the plot. We set up 3 trapping grids: one in the experimental plot, 1 450 m from the plot, and 1 1150 m from the plot. The mice were assessed for their pelage class, sex, reproductive condition, and mass. Measurements of the amount of downed coarse woody debris and number of trees at each trapping station were also taken. The proportion of traps that caught mice differed among plots (experimental plot: 0.627 mice/trap night, plot A: 0.47 mice/trap night, plot C: 0.74 mice/trap night; χ2=15.44, df=2, p<0.001), but the plot with the largest number of mice was the furthest from the FASET plot, leading to rejection of the hypothesis.