Plumage Development and Breeding Biology of the Glossy Black-Cockatoo Calyptorhynchus lathami

Abstract

Plumage changes from nestling to adult were monitored in four captive Glossy Black Cockatoos Calyptorhynchus lathami (two males, two females). Casual observations were also made on four other captive birds of known age, including an offspring of one study pair. Juveniles of both sexes had spotting on the ear coverts, lost by 18 months old. Spotting on the wings, barring on the ventral surface and under-tail coverts, and bars and yellow on the tail were present in varying degrees in juveniles of both sexes. Spotting and barring on the wings and body was usually lost by 18 months but persisted into adulthood in some females, to varying degrees. The birds lost only half their rectrices at each moult; after the first partial moult at c. 18 months each rectrix was retained for two years. In males, the number and completeness of rectrix bars were reduced with each moult but complete and incomplete bars persisted into the fifth or sixth and seventh years respectively; some unbarred rectrices appeared at 2 1/2  years old. Yellow head feathers in two females appeared at c. 10 months and were numerous at 1 1/2-2 years. Males acquired an epigamic display at 20-22 months.

Data on breeding behaviour and nesting chronology were obtained for the two study pairs and their progeny. Females first laid at 3 years old, in autumn (March-May), and incubated alone. The incubation period was 33 days and the nestling period c. 100 days. Males did not enter the nest hollow or feed chicks.