Contour feather moult of Ruffs Philomachus pugnax during northward migration, with notes on homology of nuptial plumages in scolopacid waders

Among the sandpiper family Scolopacidae, the Ruff Philomachus pugnax combin es a large seasonal change in the appearance of the plumage with a very pro nounced sexual plumage dimorphism. Studies on the east and south African wi ntering grounds of Ruffs indicate that before northward migration at least the males moult (part of their basic (winter) plumage into a kind of altern ative plumage. We studied the details of the subsequent moult into a final (supplemental) breeding plumage by quantifying the presence of three feathe r types - (1) winter (basic), (2) striped (alternate) and (3) breeding (sup plemental) - in breast feather samples of 1441 Ruffs captured on staging ar eas in The Netherlands during northward migration in 1993-97. Ruffs arrivin g in March show a mix of winter and striped feathers. In April, the 'breedi ng feather' type appears in both male and female Ruffs, and partially takes the place of winter feathers as well as striped feathers in males, and win ter feathers only in females. The presence of three plumages in Ruffs is th us confirmed for males, but also occurs in female Ruffs and in Bar-tailed G odwits Limosa lapponica. We suggest that striped feathers represent the 'or iginal' alternative plumage feather type of the sandpiper family and that t he showy feathers of the, in the European literature fortuitously appropria tely named, 'supplementary plumage' represent an additional feather generat ion. Such colourful nuptial plumages could thus be derived characters that have evolved independently in several scolopacid genera, presumably under p articularly strong sexual selection pressures.