A Survey of the South Australian Glossy Black-cockatoo (Calyptorhynchus lathami halmaturinus) and its Habitat

Abstract

The endangered South Australian glossy black-cockatoo (Calyptorhynchus lathami halmaturinus) occurs only on Kangaroo Island, South Australia. A 1993 survey investigated the size, structure and distribution of the population, the quantity and quality of foraging habitat, and the effects of a 1991 fire that burned most habitat on the Island’s west coast. A total of 136 birds was counted, mostly on the island’s western north coast. Among birds identified by age and sex, 90% were adult and there were 1·4 adult males per female. Woodland of drooping sheoak (Allocasuarina verticillata) covered about 0·3% of the island, primarily on the western north coast. Grazing by sheep in much of the habitat reduced but did not prevent sheoak regeneration. Most habitat patches showed foraging signs, but most individual sheoak trees did not. The best predictor of foraging intensity across habitat patches was average seed mass per cone. The 1991 fire burned 14% of the island’s foraging habitat, and no cockatoos were found in the burned areas. The fire killed most sheoaks but not most eucalypts; burned sheoak woodland was regenerating from both seedlings and basal shoots. The results confirm that the population is critically small, and vulnerable to local events such as wildfires. They also suggest that both habitat quantity and quality are limiting factors for the subspecies.