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INFLUENCE OF RECREATIONAL TRAILS ON

BREEDING BIRD COMMUNITIES

By Scott G. Miller,^1,3 Richard L. Knight,¹ and Clinton K. Miller,^2,4

Abstract. This study investigated the influence of recreational trails on breeding bird communities in forest and mixed-grass prairie ecosystems in Boulder County, Colorado during 1994 and 1995. Species composition, nest predation, and brood parasitism by Brown-headed Cowbirds were examined near and away from existing recreational trails. Results indicated that composition and abundance of birds were altered adjacent to trails in both grasslands and forest ecosystems. In particular, some species like interior forest species did not occur, or occurred in lower densities, near trails than they occurred at a greater distance from trials; whereas some species, mainly generalists like edge species, were more abundant near trails. For the majority of species found in reduced numbers near trails, the zone of influence of trails appears to be about 75 meters (240 ft.). Certain species, exhibited reduced numbers as far as 100 meters (320 ft.) away from trails. Within the grassland ecosystem, birds were less likely to nest near trails. Within both ecosystems, nest predation was greater near trails. It has been previously documented (Hickman, 1990) that avian nest predators were attracted to narrow, open corridors. In forests, the rate of brood parasitism was not influence by trails. No brood parasitism was found in the grassland ecosystem although Hickman, 1990, had documented cowbirds were attracted to nature trails as narrow as 2.5 meters in deciduous forests. Management of natural areas must entail not only proper trail placement, but also recreational management. Consolidation of trails to certain areas (i.e. edges of forests and grasslands) will reduce the fragmentation of large blocks of habitat, maintaining less-disturbed areas for species sensitive to fragmentation. Nature area personnel can inform recreationists of how their activities affect wildlife, and how they can modify their regime of disturbance by staying on trails and keeping pets leashed, to minimize disturbances along the trails.