Some observations on the occurrence of three generations of primaries in Common Terns Sterna hirundo

In adult Common Terns Sterna hirundo, the post-nuptial primary moult begins either near the breeding grounds (Cramp 1985) or upon arrival at the wintering grounds (L Underhill pers comm). Moult starts with the innermost primary (p1, numbered descendantly) and all birds initiate moult by October (Cramp 1985, Underhill & Prys-Jones 1986). Common Terns that begin primary moult whilst in European waters suspend moult during southward migration (Ginn & Melville 1983, Cramp 1985) but this may be a less widespread occurrence than first suggested (Ward 2000). […].In adult Common Terns Sterna hirundo, the post-nuptial primary moult begins either near the breeding grounds (Cramp 1985) or upon arrival at the wintering grounds (L Underhill pers comm). Moult starts with the innermost primary (p1, numbered descendantly) and all birds initiate moult by October (Cramp 1985, Underhill & Prys-Jones 1986). Common Terns that begin primary moult whilst in European waters suspend moult during southward migration (Ginn & Melville 1983, Cramp 1985) but this may be a less widespread occurrence than first suggested (Ward 2000). […].In adult Common Terns Sterna hirundo, the post-nuptial primary moult begins either near the breeding grounds (Cramp 1985) or upon arrival at the wintering grounds (L Underhill pers comm). Moult starts with the innermost primary (p1, numbered descendantly) and all birds initiate moult by October (Cramp 1985, Underhill & Prys-Jones 1986). Common Terns that begin primary moult whilst in European waters suspend moult during southward migration (Ginn & Melville 1983, Cramp 1985) but this may be a less widespread occurrence than first suggested (Ward 2000). […].

Robin M. Ward, Eric Wood and Geoff Myers, Ringing & Migration (2004) 22, 63-64