Nest-site selection and nest survival of Bachman's Sparrows in two longleaf pine communities

Longleaf pine (Pinus palustris) ecosystems of the southeastern United States have experienced high rates of habitat loss and fragmentation, coinciding with dramatic population declines of a variety of taxa that inhabit the system. The Bachman's Sparrow (Peucaea aestivalis), a species closely associated with fire-maintained longleaf pine communities, is listed as a species of conservation concern across its entire range. Bachman's Sparrow breeding biology may provide valuable insights into population declines and inform restoration and management of remnant longleaf pine forest, but the species' secretive nesting habits have received little attention. We located 132 Bachman's Sparrow nests in the Coastal Plain and Sandhills physiographic regions of North Carolina, USA, during 2014-2015, and modeled nest-site selection and nest survival as a function of vegetation characteristics, burn history, temporal factors, and landscape-level habitat amount. There were distinct differences in nest-site selection between regions, with Bachman's Sparrows in the Coastal Plain region selecting greater woody vegetation density and lower grass density at nest sites than at non-nest locations. In contrast, sparrows selected nest sites with intermediate grass density and higher tree basal area in the Sandhills region. Despite clear patterns of nest-site selection, we detected no predictors of nest survival in the Sandhills, and nest survival varied only with date in the Coastal Plain. Daily survival rates were similar between regions, and were consistent with published studies from the species' core range where declines are less severe. Overall, our results indicate that creating and maintaining community-specific vegetation characteristics through the application of frequent prescribed fire should increase the amount of nesting cover for Bachman's Sparrows.