Songbird Responses to Land Preservation Within Southern New England Cluster Subdivisions

Abstract

Cluster subdivisions were designed to protect open space in response to rapid rates of conventional development. One of the proclaimed benefits of preserving open space within cluster subdivisions is the provision of habitat for native wildlife, but this has rarely been evaluated. This study examined songbird response to the amount of land protected within cluster subdivisions in Rhode Island (USA). We selected 11 sites along a gradient based on the relative amount of land protected within a site (% land under a conservation easement; %CE). We used nonparametric multivariate statistics to compare songbird communities between protected and developed areas within subdivisions and regression analyses to relate bird abundance and community metrics to %CE. Songbird communities differed significantly between protected and developed areas within cluster subdivisions. Songbird richness and diversity both peaked between 73-74 %CE, while densities of forest interior and human intolerant species increased with increasing %CE. Ovenbird, Veery, and Pine Warbler most typified high %CE sites and were found most often in protected areas far from development edges. This study demonstrates that cluster subdivisions need to preserve approximately 70-75% of the original undeveloped parcel of land in order to maximize songbird diversity. A higher percentage should be preserved in large contiguous blocks to further benefit forest interior species. This suggests that proposed regulations that require Rhode Island subdivisions to protect at least 50% of a parcel's buildable land may not be adequate to enhance bird diversity or preserve species that depend on large contiguous blocks of forest interior habitat.