AUTUMN MIGRATION AND BIOMETRICS OF THE COMMON SANDPIPER ACTITIS-HYPOLEUCOS CAUGHT IN THE GULF-OF-GDANSK

Autumn migration and biometrics of the Common Sandpiper were studied a t the Gulf of Gdansk during twelve seasons: 1983-1994 (from mid-July t o the end of September). Based on ringing recoveries, the mean directi on of autumn migration of adults was 214 degrees (+/- 22 degrees) and juveniles 221 degrees (+/- 14 degrees) - but the difference is not sta tistically significant. Bird numbers peaked in the first half of Augus t, when juveniles appeared. Adults had a significantly longer bill and shorter tarsus plus toe and wing than juveniles, although those diffe rences were very small. The body mass of the Common Sandpipers varied from 35 g to 71. g and, on average, juveniles were significantly heavi er than the adults. Juveniles of the Common Sandpiper migrating in the second half of July had longer bills than those migrating in the seco nd half of August. Late migrants were heavier than birds arriving in t he second half of July and in the first half of August.