INFLUENCE OF RECREATIONAL TRAILS ON BREEDING BIRD COMMUNITIES

We investigated the influence of recreational trails on breeding bird communities in forest and mixed-grass prairie ecosystems in Boulder Co unty, Colorado, United States. during 1994 and 1995. Species compositi on, nest predation, and brood parasitism by Brown-headed Cowbirds (Mol othrus ater) were examined near and away from existing recreational tr ails. Bird species composition was altered adjacent to trails in both ecosystems. Generalist species were more abundant near trails, whereas specialist species were less common. Within the grassland ecosystem, birds were less likely to nest near trails. Within both ecosystems, ne st predation was greater near trails. In forests, the rate of brood pa rasitism was not influenced by trails. No brood parasitism was found i n the grassland ecosystem. Our results may be useful to natural-lands managers who must implement management policies regarding the spatial arrangement of trails and trail-use restrictions.