Tracking migration routes and overwintering locations of the Western Purple Martin
Dr. Sarah Rockwell, Klamath Bird Observatory
The unique western subspecies of Purple Martin (Progne subis arboricola) is roughly estimated at just 3,500 pairs, and is considered to be of conservation concern. Light-level geolocator studies have revealed that Western Purple Martins appear to use an entirely different overwintering area than the more abundant eastern subspecies (Fraser et al. 2012), but these data come from a small number of individuals breeding in British Columbia, and location data obtained from geolocators are imprecise. A better understanding of overwintering locations and migratory stopover sites used by Western Purple Martins, and potential threats originating during the non-breeding season, are key information gaps needed to target conservation actions. Our objectives are to obtain precise locations of roost sites used during migration and winter, and to use this information to identify international partners and potential conservation actions. In summer 2020, we captured seven Western Purple Martins breeding in coastal Oregon at night while they roosted in nest boxes, and fit them with lightweight archival GPS tags to track their movements. We recaptured one returning female with GPS locations taken through March 2021, including an extended fall stopover in Baja California and overwintering locations in southeastern Brazil. In summer 2021, we captured and GPS-tagged an additional eight martins; information from any returning tagged birds recaptured in summer 2022 will also be presented.