Differential seed predation by rodents in dune and swale habitats of Sturgeon Bay, Michigan.

Abstract

This study will examine the distribution of seed predators and rates of seed predation in dune and swale habitats of Sturgeon Bay, Lake Michigan. The study will focus on the influence of seed predation on three conifer species: white pine (Pinus strobus), white spruce (Picea glauca), and red pine (Pinus resinosa). These species are some of the first trees to colonize the study site. Natural density of these conifers, as well as overall vegetation density, will be correlated with predation rate. Differences in predation rate among conifer types will also be measured to examine the influence of predator choice on the colonization of particular species. Seed predators observed at the study site include thirteen-lined ground squirrels (Spermophilus tridecimlineatus), meadow jumping mice (Zapus hudsonius), and woodland jumping mice (Napaeozapus insignus). White-footed mice (Peromyscus leucopus), formerly the most common seed predators in this system have sharply decreased populations due to an unusually harsh winter. Voles and bog lemmings might also be present during some years, but were absent at the time of the study. The extent and impact of this decrease in seed predator density will also be considered. If predation varies with fluctuations in rodent populations, tree recruitment rates may increase in years with lower rodent densities.