 Female noisy miners are aggressive towards each other , and one cause of a male @-@ biased sex @-@ ratio in colonies may be the females ' greater intolerance for each other , driving <unk> out of the colony and preventing the immigration of new females . <unk> at the nest is common between males . Adult males begin attacking juveniles when they are around 11 weeks old , and attackers can include males that previously cared for the fledgling . Adult females are less aggressive towards young birds , although mothers do occasionally attack their own offspring , and <unk> has been recorded . There is little male to female aggression other than the ' driving flights ' that form part of the mating ritual . In direct attacks of young birds <unk> are directed at the eye patch . <unk> behaviour has been observed among nestlings , with aggression intensifying after fledging and at times resulting in the death of a sibling . 
