Landscape and Edge Effects on the Distribution of Mammalian Predators in Missouri

Abstract

Raccoons (Procyon lotor), opossums (Didelphis virginiana), and striped skunks (Mephitis mephitis) are predators of forest songbird eggs and nestlings. We examined the relative abundance of these predators at landscape and local scales to better understand predation risks. At the landscape scale, we examined the relationship between detection rates of raccoons, opossums, and striped skunks on 25 scent-station routes distributed across Missouri and surrounding landscape characteristics. Raccoon abundance was related to latitude, stream density, and mean patch size of agricultural lands. Opossum abundance was related to stream density, contagion, mean nearest-neighbor distance between forest patches, and latitude. Striped skunk abundance was not related to landscape characteristics we examined. At a local scale, we used sooted-plate scent stations to compare the relative abundance of raccoon and opossums in forest interiors to forests adjacent to agricultural fields, roads, clearcuts, and streams. Raccoons were more abundant in forest edges adjacent to agricultural fields and streams. Opossum abundance varied greatly among years and there was no consistent edge effect on abundance. Local features such as proximity to some types of edge as well as large-scale factors such as landscape patterns in land use may affect predator abundance and potentially sonngbird-nest predation rates.