Habitat Use of Wintering Henslow\u27s Sparrows (Centronyx henslowii) in Power Line Right-of-Ways

Habitat loss and degradation are the leading causes of grassland bird declines worldwide. The Henslow’s Sparrow (Centronyx henslowii; hereafter HESP) is a grassland bird species of conservation concern that has historically relied on the herbaceous ground-layer of longleaf pine savannas and similar habitats in the southeastern U.S. for food and shelter in the winter. However, due to human development, alterations of habitat, and fire suppression, only fragments of these habitats remain. Over the last decade, surveys have annually documented HESPs using power line right-of-ways (hereafter, ROWs) at several sites in the coastal plain of Georgia as alternative habitat for overwintering. These ROWs share similar vegetative characteristics to pine savannas because they are managed to have low tree cover and because they have a graminoid-dominated ground-layer. However, which micro-habitat characteristics HESPs select, and how much space they use within ROWs has not yet been studied. During the winters of 2019 to 2021, I captured HESPs at three Wildlife Management Areas and attached radio-transmitters to track their habitat selection and evaluate space use within ROWs. I conducted vegetation surveys in used and available habitat in the ROWs to assess which vegetation characteristics (e.g., height, density, composition) HESPs select. I used principal component analysis to reduce the number of vegetation variables and look for correlations among variables. I then used conditional logistic regression and model selection to identify top predictors of HESP habitat use. Statistical analyses showed that HESPs select areas within a ROW with a greater number of forb species, a small percentage of woody vegetation for escape refugia, and high vegetation density at the ground level. HESPs used less space (using 0.14 ha on average) than in longleaf pine savanna habitats, based on comparison with the literature. Based on these findings, I recommend habitat management practices that promote forb diversity, increase food resources, and maintain habitat structure. This study shows that ROWs can be important areas for conservation of overwintering HESPs. With continued management, ROWs can support overwintering grassland birds and could potentially act as corridors between longleaf pine restoration sites