Inter-specific pairing in Scaup and Tufted Duck

Abstract

In seven years observations on very large numbers of Scaup and Tufted Ducks at Myvatn, Iceland, sixteen mixed pairs have been seen. In fourteen the male was a Tufted Duck. Two such males were accompanied by both a female Scaup and a female Tufted Duck. Tufted Duck x Scaup pairs are probably more frequent than Scaup x Tufted Duck for two reasons: there is a greater excess of males in the Tufted Duck population and, because that species forms pairs and breeds earlier than the Scaup, unsuccessful male Tufted Ducks can more easily find unpaired female Scaup.