Light-level geolocation reveals migration patterns of the Buff-breasted Sandpiper

Buff-breasted Sandpipers Calidris subruficollis have a small and apparently declining population, and face threats both during migration and while wintering. To document their migratory patterns, we equipped 62 Buff-breasted Sandpipers with light-level loggers on their wintering sites in Argentina, Brazil, and Uruguay during the austral summer of 2012/2013. A year later, we recovered data from three birds (two females and one male) and tracked their movements for one complete migratory cycle. During northbound migration, all three birds traveled non-stop to Colombia, then to coastal Texas, followed by several smaller movements within the Central Plains, and one last non-stop flight to their breeding grounds in Canada and Alaska. Southward migration was similar except stops in Bolivia and Paraguay were used. Birds took ~1.5 months and 4–7 stops to travel north, and 2–2.5 months and 4–6 stops to travel south. Females each traveled >33,000 km and the single male traveled >41,000 km during their annual migratory cycles. The longer migration distance of the male appears to be a result of him stopping, and possibly visiting leks, at two and possibly three disjointed sites across the Arctic. The most important stopover sites for this species appear to be in Colombia and coastal Texas (north and southbound migrations), and Bolivia and Paraguay (southbound migration only). Additional areas were used in the Great Plains but for less time, including the Eastern Rainwater Basin of Nebraska and the Flint Hills of Kansas. The time spent at stopovers varied between sites and the direction of migration, ranging from 2–4 weeks in Colombia and Texas, and 1–20 days in the Central Plains. Local observations of birds indicate they likely spread over a broad area during stopovers. To fully understand how the species uses the landscape will require more precise locations from additional individuals and systematic ground surveys.