Bell miners: Kin-selected helping decisions

Abstract

Bell miners ('Manorina melanophrys') inhabit eucalypt woodlands in southeastern Australia. Living exclusively in large colonies that often comprise hundreds of individuals, they actively exclude other insectivorous and nectarivorous bird species from the entire colony area. Colonies contain from one to a number of social units called "coteries," each consisting of several breeding pairs and an attending assemblage of non-breeding helpers (Clarke 1989). Breeding female bell miners aggressively defend small territories from each other, whereas breeding males and helpers are free to move throughout the coterie to forage or help, and throughout the wider colony when defending it from heterospecifics and potential predators (Clarke and Fitz-Gerald 1994). Most helpers are male, and they help while waiting in their natal coterie for a possible breeding vacancy, which it appears the majority of males eventually obtain (94% of 16 male fledglings, Clarke and Fitz-Gerald 1994).