Nesting success of grassland birds in small patches in an agricultural landscape

Abstract

Although conservation theory argues for large habitat patches, most grasslands in the Midwest are small. To assess the influence of patch size and proximity to edges on nest survival, we monitored 816 nests of two grassland-nesting species, Dickcissel (Spiza americana) and Eastern Meadowlark (Sturnella magna), from 1996 to 2000 in a network of grasslands (3142 ha) surrounded by cropland and small patches (<1 ha) of woody vegetation in southeastern Illinois. In this grassland-agriculture matrix, small patch size and proximity to cropland edges did not negatively affect nesting success of these two grassland species of management concern that commonly occur in small patches. Although larger grasslands are necessary to attract area-sensitive species, this work demonstrates the importance of even small grassland patches for nesting habitat in grassland birds. The landscape-scale density of grassland patches in this area may also contribute to the nesting success of these birds. Our results suggest that loss of small grassland patches would have a direct negative effect on population fecundity and an unknown impact through cumulative landscape effects. © 2010 by The American Ornithologists' Union. All rights reserved.