SummaryThe conservation status, with special reference to nesting requirements, of the Red-tailed Black-CockatooCalyptorhynchus banksii graptogynein south-eastern Australia (specifically, south-western Victoria) was studied between December 1988 and April 1990. Though the total population size is uncertain, it seems that the subspecies numbers between 500 and 1000 birds with considerably fewer than 200 birds breeding. For feeding, nesting and roosting the birds use three distinct habitats each of which has declined and continues to be under some threat. Twenty-five nests were found in 22 hollows in 21 trees. Seventeen nests were in dead trees and we have stressed the apparent importance of dead trees to the birds' conservation needs.C. b. graptogyneis clearly endangered and in need of more detailed and long-term study of its ecology and demography.