In eastern North America, remnant patches of forest surrounded by open habitat constitute unfavorable habitat for many species of migratory forest birds because of high rates of nest predation and cowbird parasitism. Although most evidence for this relationship comes from 'forest islands' surrounded by residential or agricultural land, even forest patches isolated from other forests by narrow open corridors such as roads and powerline rights-of-way seem to show this pattern. Productive habitat for migratory birds can be maintained by consolidating corridors and routing them along the periphery of forests to retain as much continuous forest as possible. Consolidation of open corridors provides another major advantage: the area along the corridor can provide a large area of suitable habitat for early successional birds, especially species that are shrubland or thicket specialists. Populations of many species of shrubland birds have declined in eastern North America as open habitats have been developed or have grown into forest. Rights-of-way and other areas subject to periodic artificial disturbance may become increasingly important to these species, which probably originally depended on habitat created by large-scale natural disturbances such as fires and windstorms. Relatively stable shrublands with a diversity of shrubland plants and birds can be maintained by selectively removing trees with basal applications of herbicide.
Askins, R. A. 1994. Open corridors in a heavily forested landscape: Impact on shrubland and forest-interior birds. Wildlife Society Bulletin 22:339-347.
The views expressed in this paper are solely those of the author.