Precise direct tracking and remote sensing reveal the use of forest islands as roost sites by Purple Martins during migration

• Published in: Journal of field ornithology 2019-09, Vol.90 (3), p.258-265
• Main Authors: Fournier, Auriel M. V., Shave, Amanda, Fischer, Jason, Siegrist, Joe, Ray, James, Cheskey, Edward, MacIntosh, Megan, Ritchie, Alisha, Pearman, Myrna, Applegate, Kelly, Fraser, Kevin
• Format: Article
• Language: English
• Subjects: Animal behavior; archival GPS; Avain Behavior and Ecology; biologging; Bird migration; Birds; Breeding seasons; Breeding sites; Colonies; Conservation; direct tracking; Ecological aggregations; Forest conservation; Forest management; Forests; Habitat selection; Habitat utilization; Habitats; Interspecific relationships; Islands; Migratory species; Overwintering; Population decline; Predation; Predators; Progne; Progne subis; Radar; Radar data; Remote sensing; Spring; Spring (season); stopover ecology; Terrestrial environments; Tracking; Urban areas
• ISSN: 0273-8570; 1557-9263
• DOI: 10.1111/jofo.12298

Direct tracking methods in combination with remote sensing data allow examination of habitat use by birds during migration. Species that roost communally during migration, such as some swallows, form large aggregations that can attract both avian and terrestrial predators. However, the extent to which they might use patchy habitats that could reduce predation risk during migration is unknown. We tested the hypothesis that Purple Martins (Progne subis) use forest islands (patches of suitable forest habitat surrounded by unsuitable habitat) as roost sites during migration between breeding sites in North America and overwintering sites in South America. We used high-precision (< 10 m), archival GPS units deployed and retrieved during the 2015 and 2016 breeding seasons, respectively, at 12 colonies located across eastern North America. We found that Purple Martins roosted in forest islands more often than expected based on availability during both spring and fall migration. Despite an apparent association with urban habitats by Purple Martins based on observational and radar data in North America during the fall, the roost locations we identified during spring and fall migration were not more closely associated with urban areas than random locations. The use of forest islands during both spring and fall migration suggest that Purple Martins may use these habitats to reduce predation risk during migration. Our results suggest that some species of birds may use similar habitats as stopover sites during migration and that patches of forest habitat may be important conservation targets for Purple Martins and other species. Identifying habitat use during migration represents an important advance in support of full annual-cycle conservation of Purple Martins ana other migratory species with declining populations. Métodos de rastreo directo en combinación con información de sensores remotos permiten examinar el uso de hábitat por las aves durante la migración. Especies que usan dormideros comunales durante la migración, como es el caso de algunas golondrinas, forman congregaciones grandes que pueden atraer aves depredadoras así como depredadores terrestres. Sin embargo, el grado en el cual pueden usar los hábitats fragmentados que pueden reducir el riesgo de depredacion durante la migración hasta el momento es desconocido. Pusimos a prueba la hipótesis que Progne subis usa islas de bosques (parches adecuados de hábitat boscoso rodeado por hábitat inadecuado) como dor