EFFECTS OF HABITAT DISTURBANCE ON BIRD COMMUNITIES IN RIPARIAN CORRIDORS

A study of two watersheds in Central Pennsylvania, an undisturbed, forested (reference) one and a partially disturbed (agricultural and residential) one, was used to analyze bow agriculture and residential development of the riparian corridor affected species richness, abundance, and the structure of guilds of the bird community. Bird species richness and abundance generally decreased with distance from the stream in the disturbed watershed, but remained relatively constant through the reference watershed. At disturbed sites most neotropical migrant birds with specific habitat requirements were recorded only during migration. Although an impoverished bird community can exist in the vicinity of the riparian bank immediately adjacent to the water with < 10 m (30 ft) of natural vegetation, sensitive species will not occur unless an undisturbed corridor > 25 m (82 ft) in width on each bank is present. Presence of narrow 2 m (7 ft) bands of woody vegetation along the stream channel and fence rows seemed to be important in maintaining portions of the bird community in disturbed areas. Land owners and resource managers should be aware of responses by the avian community to small, incremental changes in land use, and try to protect existing stream corridors or restore native vegetation in riparian areas.