Autumn migration and biometrics of the Common Sandpiper Actitis hypoleucos caught in the Gulf of Gdansk

Abstract

Autumn migration and biometrics of the Common Sandpiper were studied at the Gulf of Gdańsk during twelve seasons: 1983-1994 (from mid-July to the end of September) . Based on ringing recoveries, the mean direction of autumn migration of adults was 214° (± 22°) and juveniles 221° (± 14°) -but the difference is not statistically significant. Bird numbers peaked in the first half of August, when juveniles appeared. Adults had a significantly longer bill and shorter tarsus plus toe and wing than juveniles, although those differences were very small. The body mass of the Common Sandpipers varied from 35 g to 71 g and, on average, juveniles were significantly heavier than the adults . Juveniles of the Common Sandpiper migrating in the second half of July had longer bills than those migrating in the second half of August . Late migrants were heavier than birds arriving in the second half of July and in the first half of August.