Indexed on: 02 Jun '06Published on: 02 Jun '06Published in: Environmental Management
This study assessed the relationship among land use, riparian vegetation,and avian populations at two spatial scales. Our objective was to compare the vegetated habitat in riparian corridors with breeding bird guilds in eight Rhode Island subwatersheds along a range of increasing residential land use. Riparian habitats were characterized with fine-scale techniques (used field transects to measure riparian vegetation structure and plant species richness) at the reach spatial scale,and with coarse-scale landscape techniques (a Geographic Information System to document land-cover attributes) at the subwatershed scale. Bird surveys were conducted in the riparian zone,and the observed bird species were separated into guilds based on tolerance to human disturbance,habitat preference,foraging type, and diet preference. Bird guilds were correlated with riparian vegetation metrics,percent impervious surface,and percent residential land use,revealing patterns of breeding bird distribution. The number of intolerant species predominated below 12%residential development and 3% impervious surface,whereas tolerant species predominated above these levels.Habitat guilds of edge,forest, and wetland bird species correlated with riparian vegetation. This study showed that the application of avian guilds at both stream reach and subwatershed scales offers a comprehensive assessment of effects from disturbed habitat,but that the subwatershed scale is a more efficient method of evaluation for environmental management.