Roads as Ecological Edges: Local and Landscape Influences on Nest Predation of Forest Songbirds

Personnel: Yvette Ortega, David Capen

Cooperators: USDA Forest Service Northeastern Forest Experiment Station, Green Mountain National Forest, Vermont Cooperative Fish and Wildlife Research Unit

Studies of forest fragmentation and avian community composition identify a subset of songbird species whose density and diversity decrease as forest patch area decreases. A frequently cited explanation for this pattern is elevated nest predation rates adjacent to forest edges, and research supports an edge-predation relationship. Although it has been suggested that narrow breaks in the forest may function as ecological edges where predator activity is concentrated, the majority of studies have disregarded interfaces of forest with openings less than 100 meters wide.

This study tests whether nest predation rates are elevated adjacent to forest-road interfaces. The study area is the Moosalamoo Region of the Green Mountain National Forest.

Nest predation rates on transects adjacent to roads and removed from roads were determined using artificial nest techniques. Relationships of these rates to measured habitat variables and densities of songbirds and nest predators are being assessed. The influence of landscape features on observed nest predation rates is being examined. Landscape-level variables generated using GIS techniques include the density and configuration of of non-forested area calculated over varying distances from the sites, and the proximity and density of human habitations.

       Updated: 28 June 2000