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The breeding population of Carnaby's Cockatoo at Coomallo Creek in the northern kwongan (sandheath) of southwestern Australia was monitored from 1969 to 1996. The cockatoos breed in hollows in trees in a belt of woodland through the centre of the study area and feed in adjacent kwongan. During the period, the study area was progressively and rapidly cleared for broad-scale cereal and sheep farming. The area of native vegetation cover was reduced from 90% in 1959 to 25% in 1996.
The number of breeding attempts fell over the period of the study from around 80 attempts in the early part of the study to less than 40 by 1996. The initial decline was due to a combination of loss of habitat and increased mortality of the birds due to the use of wing tags to mark them individually. The subsequent decline was most likely due to loss of habitat.
The importance of the northern kwongan and associated woodland patches to the conservation of animals like Carnaby's Cockatoo that breed in tree hollows is discussed. Unless areas of woodland on private land and adjacent kwongan are afforded more protection, the future for hollow nesting species that feed on native vegetation like Carnaby's Cockatoo is bleak.
INTRODUCTION
CARNABY'S Cockatoo (formerly called the short-billed form of the White-tailed Black Cockatoo) Calyptorhynchus funereus latirostris, occurs only in southwestern Australia in the region receiving more than 300 mm of mean annual rainfall. It has been studied at various intensities at five sites across its range over the period 1969 until 1996. One of these sites was at Coomallo Creek in the northern wheatbelt. This study area was established in 1969 when the area was visited several times during the cockatoo's breeding season and 13 nests were found. From 1970 to 1976 inclusive, the population was studied intensively, both during the breeding season at Coomallo Creek, and outside the breeding season during its movements away from its breeding area. This study was based on birds individually marked with wing (patagial) tags, in addition to leg bands. The results of this intensive phase of the study were published in Saunders (1979a, 1979b, 1980, 1982, 1983) and subjects covered include food, use of hollows in trees, breeding success, nestling growth rates, nest...