The Fragmented Forest

Edge Effects

The plight of many forest-nesting songbirds has brought into question the benefits of certain traditional wildlife management techniques. For example, historically land managers were trained to "develop as much 'edge' habitat as possible because wildlife is a product of the places where two habitats meet" (Giles 1971). Creating edges increases local diversity by attracting game species such as rabbits and deer, as well as a variety of nongame bird species such as Song Sparrows and Northern Cardinals. We now know, however, that forest-interior species may disappear from areas that contain extensive edge habitat. Gates and Gysel (1978) proposed the idea that edges may serve as "ecological traps" for some breeding birds by providing a variety of attractive habitat characteristics, while at the same time subjecting the birds to higher rates of nest predation and parasitism. Evidence from numerous studies indicates that the detrimental effects of an edge can extend from 150–300 feet (45–90 m) into the forest interior.