Grassland bird and raptor inventory of Harpers Ferry National Historical Park, 2022

Harpers Ferry National Historical Park (NHP) includes grassland habitats that are maintained for the interpretation of historic Civil War battles. In 2022, as part of the National Park Service Inventory and Monitoring program, the University of Delaware conducted a grassland bird and raptor inventory in the park. The goals of this inventory were to determine the grassland bird use of Harpers Ferry grasslands during Spring and Fall migration, estimate the abundance and daily nest survival for focal breeding species, and determine the raptor use during migration. We established and used multiple avian sampling techniques to address these goals including distance sampling using line transects, mist-netting to capture passerine birds, point counts, hawk watching, and nest searching and monitoring. We conducted this inventory during the annual cycle starting in March 2022 and completed the sampling in October 2022. During the course of this effort, we detected 111 species using the Harpers Ferry grasslands at some time during the year. We found that the park is supporting migrating and breeding grassland birds and that the avian species composition changes over the course of the annual cycle. During migration, we detected focal grassland bird species including Bobolink, Savannah Sparrow, Grasshopper Sparrow, and Eastern Meadowlark. During the breeding season, we located and monitored Eastern Meadowlark and Grasshopper Sparrow nests with adequate sample sizes to estimate daily nest survival. We found that Eastern Meadowlark daily nest survival was relatively high (99%) and was influenced by the proximity of the nest to a forested edge. We recommend the park focus on Eastern Meadowlark and Grasshopper Sparrows as these two species used the park during both Spring and Fall migrations and successfully fledged young during the breeding season. The park could attempt to maintain or enhance Eastern Meadowlark and Grasshopper Sparrow use of the park during all stages of the annual cycle but especially during the breeding season. This could be achieved by continuing to keep the existing breeding areas intact through delayed mowing (no mowing from 15 May – 15 July), removing tree lines and woody or non-native vegetation to increase the perceived openness and grassland patch size, and continuing to monitor the effects of any management actions that may influence grassland bird use of Harpers Ferry NHP. Grassland birds are a national conservation priority so any sites that have the capacity to maintain or enhance these declining habitat specialists should do so. Grassland birds provide an opportunity to integrate cultural and natural resources as these birds were most certainly present prior to, during, and after the Civil War Battles that Harpers Ferry was established to commemorate.