The social and behavioural dynamics of colony expansion in the Bell Miner ('Manorina melanophrys')

Abstract

Bell Miners ('Manorina melanophrys') are cooperatively breeding honeyeaters that defend colonies from potential predators and competitors. Despite extensive study of the social organisation of Bell Miners, little is known about the social dynamics of expansion of colonies and establishment of new territories in this species. We took advantage of an individually marked, molecularly sexed and genotyped study population to examine the social dynamics of two extensions of the range of a colony. These observations indicated colonisation of new areas by colony members was accomplished via two different pathways, either the efforts of a breeding pair and its pre-existing contingent of helpers, or a group of unmated males. Only the former bred, with greater numbers of individuals related to the breeding pair acting as helpers in new areas initially. Most colonists were males that lacked a breeding position. Ultimately both expansions of the colony proved to be temporary, with colonists returning to their former home-ranges after six months.