Male whitethroats, Sylvia communis, advertisetheir future contribution to parental care

In altricial species participation of males in parental care enhances reproductive success offemales. How does a female select amate who will allocate time and energy to parental effort?In the whitethroat Sylvia communis, a socially monogamous bird, parental performance ofmales might be predicted on the basis of elaborated song flights displayed in courtship.The correlation analysis revealed that males which advertised intensively needed less timeto attract a female and also their parental performance was better compared to males thatproduced cheaper signals. In the subsequent experiment, we handicapped males by increasingtheir body mass by 5% with a weight attached to tail feathers. Males in the treatment groupreduced the proportion of showy song flights significantly more than controls and their matingsuccess was significantly lower.We conclude that song flights in whitethroats honestly signalmale quality and that the signalling system depends on a dynamic handicap trait whichresponds to a relatively small change in the male.

Konrad Halupka & Marta Borowiec, 2005, Behaviour 143, 1-14