The breeding biology of the Glossy Black-Cockatoo Calyptorhynchus lathami on Kangaroo Island, South Australia

Glossy Black-Cockatoos on Kangaroo Island nest in large hollows in eucalypt s, primarily Sugar Gums Eucalyptus cladocalyx, and usually near their princ ipal food trees. A single egg is laid between late January and late July. I ncubation is about 30 days and the nestling period 90 days. Nestling growth rate is slower than for other cockatoo species. Without protection most ne sts are likely to be pre dated by Brushtail Possums Trichosurus vulpecula. With protection the probability of an egg resulting in a fledgling increase s from 23% to 42%. However, competition from Little Corellas and Galahs, al ready occurring at a small pro portion of nests, may become a significant t hreat in the future. Eggs laid before the end of March are more likely to s ucceed than those laid from April onwards. An equal sex ratio among nestlin gs contrasts with a ratio of about two males to each female among adults su ggesting a greater mortality of females after fledging. Protection of nests against possums and management of competing cockatoos are recommended as m easures required to secure the population on Kangaroo Island and to allow i ts return to mainland South Australia.