William E. Palmer

THE EFFECTS OF FARM FIELD BORDERS ON OVERWINTERING SPARROW DENSITIES

Abstract Wintering birds that use farm fields may benefit from strips of uncultivated, grassy, and weedy vegetation, called field borders. Field borders were established on 4 farms in the North Carolina coastal plain in Wilson and Hyde counties in the spring of 1996. In February of 1997 and 1998, bird numbers on field edges and field interiors, with and without field borders, were surveyed using strip transect and line transect methods. Most (93%) birds detected in field edges were sparrows, including Song (Melospiza melodia), Swamp (Melospiza georgiana), Field (Spizella pusilla), Chipping (Spizella passerina), White-throated (Zonotrichia albicollis), and Savannah (Passerculus sandwichensis) sparrows and Dark-eyed Juncos (Junco hyemalis). We detected more sparrows on farms with field borders than on farms with mowed edges. This difference was most pronounced in field edges where field borders contained 34.5 sparrows/ha and mowed edges contained 12.9 sparrows/ha. Sparrow abundance did not differ by treatment in field interiors. Sparrow density in field borders was intermediate to wintering sparrow densities reported in other studies. These results suggest that establishing field border systems may be an effective way to increase densities of overwintering sparrows on farms in the southeastern U.S. coastal plain.