Resource managers confronted with preserving ecosystems for prairie wetland birds in fragmented landscapes require landscape studies that direct conservation efforts over broad geographic regions. We investigated the role of local and landscape factors affecting habitat suitability by integrating remotely sensed wetland and land-cover data with wetland bird habitat models. We linked habitat models with locations of easement and fee-title wetlands to evaluate spatial location and extent of protected, suitable habitat. We also simulated impacts of the loss of small wetlands on suitability of larger wetlands for mobile species that use multiple wetlands. Lastly, we evaluated the efficacy of waterfowl habitat programs in preserving suitable habitat for nongame wetland bird species to recommend strategies for maximizing regional landscape connectivity. Regional databases constructed for this study indicate that easement and fee-title tracts encompass 13.9% (1.2 million ha) of land area and protect 19.8% of the wetlands in eastern South Dakota, USA. Proportion of protected wetlands is highest for semi-permanent (32.3%), intermediate for seasonal (25.6%), and lowest for temporary wetlands (15.8%). A stratified, two-stage cluster sample was used to randomly select 834 semi-permanent and seasonal wetlands that were surveyed for birds in 1995 and 1996. Logistic analyses indicate that habitat suitability for some species (e.g., Virginia rail, pied-billed grebe) is related to local vegetation conditions within wetlands, while suitability for others (e.g., northern pintail, black tern) is related to landscape structure at larger scales. As a result, unfragmented prairie wetland landscapes (i.e., areas with wetland complexes embedded within upland grasslands) provide habitat for more species than isolated wetlands in tillage fields. Models developed from survey wetlands were used to classify habitat suitability for all semi-permanent and seasonal wetlands in eastern South Dakota. Small wetlands are critical components of the surrounding landscape that influence habitat suitability of larger wetlands. Models used to reclassify suitability of larger remaining wetlands after small wetlands (<0.5 ha) were removed indicate that species most vulnerable to loss of small wetlands are vagile species that exploit resources over broad spatial scales. Number of wetlands suitable for northern pintails, a mobile species that uses multiple wetlands within a season, decreased 20.7% when wetlands <0.5 ha were removed. Historic paradigms dictating waterfowl habitat protection efforts also have conserved habitat for nongame bird species. Modern paradigms that acknowledge the importance of small shallow wetlands to breeding waterfowl have shifted the focus of protection towards preserving habitat for species that occupy more abundant seasonal wetlands. Cessation of protection efforts would result in further fragmentation of regional wetland landscapes. We recommend that wetlands be acquired not only to consolidate suitable habitat within protected core areas but also to ensure that core areas coalesce to preserve connectivity among regional wetland landscapes.
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Vol. 21 • No. 1