INTRASEXUAL AGGRESSION OF FEMALE COLLARED FLYCATCHERS (FICEDULA-ALBICOLLIS) - COMPETITION FOR MALE PARENTAL CARE

According to the defence of male parental investment hypothesis, mated females benefit from delaying the settlement of female rivals, wherea s secondary females benefit from settling as early as possible. This i s because males invest more in the largest or earliest hatched nestlin gs. In accordance with this hypothesis female collared flycatchers (Fi cedula albicollis) were most aggressive towards a female ''rival'' pre sented in a cage, early in the breeding season. Eviction of competing females is probably costly, therefore aggressiveness of the mated fema le should decrease during the breeding season as the benefit of expell ing competitors decrease.