SONG ACTIVITY IN THE CHIFFCHAFF - TERRITORIAL DEFENSE OR MATE GUARDING

It has been suggested that males of passerine bird species sing most a ctively during the fertile period of their mates partly as a paternity guard strategy and partly to maximize their own extra-pair copulation success. This investigation considers whether song is used as a pater nity guard strategy in the chiffchaff, Phylloscopus collybita. The stu dy was carried out in south-eastern England (Wytham Woods, Oxford) dur ing 1993 and 1994. Song rate was calculated as the proportion of a 5-m in period a bird spent singing, sampled either at dawn or at noon. Mal e chiffchaffs did not sing more during the fertile period of their fem ales contradicting the paternity guard hypothesis. During the fertile period, song rate decreased when the female was present, suggesting th at males sing to contact their mates. It is suggested that after the f ertile period song is used to proclaim an established territory to the neighbours. This might also allow the male to re-mate quickly followi ng nest predation or following female desertion or predation, while mi nimizing expensive territorial fights. (C) 1996 The Association for th e Study of Animal Behaviour.