KLEPTOPARASITISM DURING COURTSHIP IN A COMMON TERN COLONY: EFFECT ON ITS BREEDING PERFORMANCE

GARCÍA GERMÁN OSCAR; BECKER PETER H; FAVERO MARCO

Conferencia; 46 th Annual Meeting of the Animal Behavior Society; 2009

Kleptoparasitism is a well known foraging tactic used opportunistically by many seabirds. There is ample literature describing the behaviour but little is known during the early stages of the breeding cycle. Terns offer an excellent opportunity to study such effects since males bring food (courtship feeding) to females early in the season. The study was conducted in a Common Tern Sterna hirundo colony (Banter See, Germany) where most of the breeding terns are marked with rings and transponders. We predicted that those frequently stealing food during courtship feedings should show higher reproductive performance in terms of clutch size, egg volume and laying date. We compared the breeding performance between a group of kleptoparasites, a group of non-kleptoparasitic parents (honest group) and a control group. No significant differences were found in the clutch sizes. Kleptoparasites laid significantly larger eggs. Laying date in the kleptoparasitic group was significantly earlier compared with the other groups. This study indicates that kleptoparasitism during courtship period has an effect on reproductive parameters of Common Terns, enhancing fitness of kleptoparasitic parents.