FEMALE AGGRESSION AND THE MAINTENANCE OF MONOGAMY - FEMALE BEHAVIOR PREDICTS MALE MATING STATUS IN EUROPEAN STARLINGS

Any reduction in the fitness of a breeding female induced by the settl ement of additional females with her mate creates a conflict between t he sexes over mating system. In birds, females are often aggressive to wards other females but few studies have been able to quantify the imp ortance of female-female aggression for the maintenance of monogamy. T his study of the European starling, Sturnus vulgaris, quantifies male and female behaviour towards a potential prospecting female, presented in a cage during the pre-laying period, and relates it to the subsequ ent mating status of the male. A solitary breeding male was given the opportunity to attract an additional mate, which almost half of the ma les did. No biometric characters of the male or female were related to the subsequent mating status. Males demonstrated mate-attraction beha viour towards the caged female but the behaviour of the male did not p redict the Likelihood to attract an additional female. However, the pr oportion of time that the female spent near the potential settler was related to mating status, indicating that females that reacted more st rongly towards a potential female competitor maintained their monogamo us status. These results suggest that female behaviour may play an imp ortant role in shaping the mating system of facultatively polygynous s pecies.