Exploring the Strategies of First Migration in the Subarctic-Nesting Shorebird, Calidris Alpina Hudsonia

Compared with adult conspecifics, juvenile Dunlin undertaking their first migrations experience higher rates of mortality. Despite the significant impact of juveniles shorebirds on population dynamics, little is known about young birds' maiden migrations. For the first time, we present the migratory strategies of juvenile Dunlin (Calidris alpina hudsonia) during their inaugural journeys to non-breeding grounds using the Motus radio telemetry network. We analyze the migrations of adult Dunlin tracked via the Motus system, and compare strategies between age groups. Juveniles preferentially over-wintered in discrete sections of the Eastern Seaboard – sites exclusive to this age demographic. We also elucidate vital juvenile staging sites in Southeastern Ontario, and potential mortality hotspots within Ontario and Nova Scotia. We postulate genetic influences on the migrations of juveniles. Three novel non-breeding sites of adults were documented, in Colombia, Alaska, and Indiana. We also emphasize the ecological importance of select stopover sites along the Atlantic USA.