Walters J. (1979) The onset of the postnuptial moult in the Common Tern Sterna hirundo near Amsterdam. ARDEA 67 (1-2): 62-67

A study of the onset of the moult of remiges and rectrices in the Common Tern was conducted near Amsterdam in 1977 and 1978. Two methods were used: registration of primary and rectrix moult scores in breeding birds and collection of newly shed feathers. Special attention was paid to the identification of the feathers collected. The conclusions on the onset of the moult in this species in Stresemann & Stresemann (1966) are generally confirmed and the following more precise and additional data could be obtained. The primary moult started with p.1 on 3-6 July, followed by the first p.2 on 6-10 July. The first p.3 were recorded 10-15 July, the first p.4 18-22 July and the first p.5 on 31 July. No p.6 was found, but the numbers of terns still present in August were low. A few outermost secondaries were recorded from 17 and 18 July onwards. The moult of the rectrices started just before the primary moult in early July. On average - but with exceptions - the order of moult was t.l, t.2, t.3, t.6, t.4 and t.5. The first t.6, t.4 and t.5 were collected in the second week of July. The majority of Common Terns started to moult after the fledging of their young or after unsuccessful breeding, but in July 20% of the late breeders had beginning moult in the primaries and as many as 71%had started tail-moult.