SPATIAL-ORGANIZATION OF THE COOPERATIVELY BREEDING BELL MINER MANORINA-MELANOPHRYS

Bell Miners Manorina melanophrys are cooperative breeders and occur in discrete colonies. A colony comprised a number of breeding pairs occu pying slightly overlapping foraging ranges that they shared with non-b reeding offspring and immigrants. All nests belonging to a breeding pa ir were built within the pair's combined foraging ranges. Males remain ed in the natal colony until they gained a breeding position, whereas females generally dispersed to another colony. The area of an individu al's foraging range did not vary significantly with its age, sex or br eeding status. Helpers regularly travelled outside their foraging rang es to provision young belonging to a range of different breeding pairs . The individuals helping one breeding pair were not a mutually exclus ive set of individuals from those helping other breeding pairs within a colony. As such the social organisation of the Bell Miner does not f it within current classifications of breeding systems, but closely res embles that of the Noisy Miner M. melanocephala. Bell Miners exhibited extreme interspecific territoriality that resulted in almost total ex clusion of all other avian species from the colony's territory. Males performed more acts of interspecific aggression than females. The extr eme degree of exclusion achieved by Bell Miners may represent a benefi t only attainable through cooperative group-defence of a resource.