Assessing risk of predation for the federally endangered Charadrius melodus (Piping Plover) using Falco columbarius (Merlin) movement and habitat data in the Great Lakes Region

Abstract Effective conservation of threatened prey species requires a clear understanding of how predators use space and select habitats. We tracked 32 adult Falco columbarius (Merlin) during the breeding season in the Great Lakes Region to evaluate home range size, shape, and habitat preference in order to inform conservation and management efforts for Charadrius melodus (Piping Plover), a species known to be preyed upon by F. columbarius. Using GPS telemetry and continuous-time movement models, we identified strong range residency behavior and quantified spatial use across individuals (n = 32). Tracked F. columbarius used 99% home ranges averaging 46.3 ± 10.3 km2 in size and 50% core areas averaging 5.3 ± 1.3 km2 in size. Home range size and configuration varied with sex and translocation status, and individuals differed in their spatial complexity and maximum distance from core area to range edge (mean: 7.6 ± 1.0 km). Although most F. columbarius used shoreline habitats, they generally preferred other cover types. However, 25% of individuals preferred shorelines, highlighting variable risk to C. melodus on their breeding range. We also recorded long-distance movements across water, including between the “mainland” and offshore islands. These findings provide a spatial foundation for predicting F. columbarius–C. melodus interactions and identifying high-risk F. columbarius. To support current predator management, we propose identifying and prioritizing individuals based on nest proximity and repeated use of areas near C. melodus for monitoring, translocation, or removal. These actions would be particularly relevant at locations where plovers nest and predator management are most intense.