LOCAL AND LANDSCAPE-LEVEL FACTORS INFLUENCING BLACK TERN HABITAT SUITABILITY

摘要: Wetlands throughout eastern South Dakota were surveyed (1995-97) for foraging and nesting black terns (Chlidonias niger) to evaluate local landscape factors influencing habitat suitability We 834 randomly selected, semipermanent, seasonal wetlands that stratified by physiographic domain, wet- land density, wetland surface area. A discriminant function model was used in a geographic information system (GIS) classify of all semipermanent Dakota. calcu- lated number suitable, protected combining with easement fee-title tracts the GIS. Black nested 7.8% foraged an additional 17.9% wetlands. Significant variables area, total area within complex, grassland upland matrix. area-dependent species occupied large (f = 18.9 ha) located high-density complexes. typically occurred landscapes where <50% grasslands tilled. Classification rates high (76- 100%), indicating identified unsuitable using landscape-level attri- butes. Characteristics entire must be considered assessments because do not correspond landscape-scale requirements may suitable despite favorable condi- tions. Lower correct classification (22-78%) ponds indicated also is dependent on conditions which from perspective. Suitable tern nest sites regenerating or degenerating vegetation structure rather than dictated substrates. Wetland acquisition programs have 44% terns. Future acquisitions should maintain integrity prairie attributes individual