Red-tailed Black Cockatoos are widely distributed throughout Australia. The south-western population, known as the Forest Red-tailed Black Cockatoo (Calyptorhynchus banksii naso), or Karrak in the Noongar language, is listed as vulnerable, with ‘naso’ referring to its large bill. The Forest Red-tailed Black Cockatoo is the smallest of the five races of Red-tailed Black Cockatoo, weighing 600-610 grams with a length of 53-55 centimetres. The sexes are distinct – males have glossy black plumage with clear scarlet tail panels and a black bill; females have pale greyish bills, yellow-spotted heads and wing coverts and yellow-edged feathers on their belly and breast. Juveniles have plumage similar to females. Like other cockatoo species, Forest Red-tailed Black Cockatoos nest in large, rare tree hollows that are becoming increasingly invaded by feral European Honey Bees. Forest Red-tailed Black Cockatoos are now rare to uncommon and are patchily distributed through eucalypt forests and woodlands, although they are now seen regularly in urban areas on the Swan Coastal Plain where they have adapted to feed on the fruits of introduced plants such as the Cape Lilac (Melia azedarach). In the wild Forest Red-tailed Black Cockatoos eat a range of seeds contained in hard, woody seed capsules including eucalypts (Marri. Blackbutt, Jarrah, and Karri), various Proteaceae and Sheoaks (Allocasuarina species). These birds are feeding on the seeds from the woody fruits of the Sheoak Allocasuarina fraseriana in Kings Park in the heart of Perth city in Western Australia.