The Biology of the Ground Parrot, Pezoporus wallicus, in Queensland. II. Spacing, Calling and Breeding Behaviour

Abstract

The spacing, calling and breeding behaviour of ground parrots in Cooloola National Park was studied over three years. Despite having overlapping home ranges, individual parrots maintain a solitary existence, the inter-bird distance averaging 106 m. No aggressive behaviour was ever recorded. Calling was restricted to before sunrise and after sunset; it comprised whistling notes mostly in variable ascending scales. Four call types were used throughout the year, and three others only in the breeding season. Light intensity appears to be the main factor determining when calling starts and finishes; parrot density influences the rate of calling by individuals. Calling may be used to advertise dominance status and location of an individual. The formation of a dominance hierarchy would enable several birds to use the same area, individual rank determining priority of access to the spatially and temporally variable seed resources. Ground parrots bred in spring, the clutch size was either three or four. Nests were found only on the ground under vegetation in dry parts of heathlands that had not been burnt for at least 3-4 years. Minimum nest density ranged between 1.0 and 1.3 nests per 10 ha. Only the female incubated the eggs, the male provided all food to both the female and chicks. On average a pair produced 1.9 fledglings per nest each year. An unusually high rate of egg failure (22-31%) appears to be typical for this species.