Value of park reserves to migrating and breeding landbirds in an urban important bird area

Increasing urban development threatens not only breeding habitat for migratory landbirds but also critical stopover habitat. The purpose of this study was to investigate the relationship between landbird community composition and land cover in and surrounding urban park reserves in the Mississippi River Twin Cities Important Bird Area (IBA) in order to evaluate this area’s value during both spring migration and summer breeding seasons. This IBA includes a mosaic of residential, commercial, and park reserve land running along the Mississippi River between Minneapolis and Hastings, Minnesota. Using citizen-science data collected at 8 park reserve sites in the IBA between 2007 and 2010, we calculated species richness, diversity, and evenness for the migrating and breeding landbird community at each site and categorized species into three conservation statuses (species of greatest conservation need, native and exotic) and four migratory behavior classes (permanent residents, short-distance migrants, resident neotropical migrants, and en-route neotropical migrants). We used AIC to rank multiple regression models to evaluate how these groupings vary across sites in comparison to the land cover in and surrounding each site. We found that most measures of both the spring migration and breeding communities were negatively related to increased impervious cover. Exotic species and permanent residents were less affected by surrounding land use, while breeding season resident and transitory neotropical migrants were greatly affected. Patterns of landbird richness and density suggest that removing impervious cover within lower quality sites can improve habitat supporting migrating birds.