Sex-biased dispersal is a key mechanism to avoid inbreeding, meaning that species in which both females and males stay at home raise some fundamental questions to the theory of cooperative breeding
All nine Australian fairy-wren species are cooperative breeders: males stay with their parents to help rear the next brood, instead of breeding on their own. Females in most species disperse, which is thought to be the main mechanism to avoid inbreeding. Interestingly, in the red-winged fairy-wren both females and males stay at home, which raises some questions fundamental to the theory of cooperative breeding. For example, why do both sexes stay and help in some species while only one sex does in others? How is inbreeding avoided in the absence of dispersal? Several projects are available to study these and related questions.