Timing and phenology of Curlew Sandpiper Calidris ferruginea on southward migration through Puck Bay, Poland

Between 1983 and 2000, regular counts were made at three sites on the Puck Bay coast of the southern Baltic Sea, Poland: Reda mouth, Rewa and Jastarnia. Adult Curlew Sandpipers arrived at Puck Bay in the first decade of July. Over many years, the average dynamics of migration showed peak numbers in the second decade of July. At the end of July the number of adults decreased, being observed in small number until the first week of September. The first juveniles reached Puck Bay about mid-August. The main peak in juvenile numbers was observed in the first week of September; single juveniles were recorded until the end of this month. On average, adult males migrated about 10 days earlier than adult females. Males migrated in one wave, while females were in two waves: the first simultaneously with males (about 20–24 June), and the second peaking five pentades later (about 14–19 August). The range of median date of migration was 17 days in adults and 14 days in juveniles. The percentage of juvenile Curlew Sandpipers fluctuated, with peaks at approximately three year intervals, in 1985, 1988, 1991, 1994, 1997 and 1999.