Red-tailed Black Cockatoo
Calyptorhynchus banksii

Red-tailed Black-cockatoos are found over much of Australia with several populations: subspecies banksii is found in northern NSW and Queensland; macrorhynchos across much of the north of the country and mixing with banksii around the Qld-NT border area; samueli in northern to central WA with a few smaller populations inland; naso in southern WA (also known as the Forest Red-tailed Black-cockatoo) and finally graptogyne in a small area of western Victoria and eastern SA, which is endangered. The major differences between the subspecies are the body size and the size of the beak. The first photo here is of subspecies naso, which is also known as the Forest Red-tailed Black-cockatoo and has a large beak and the second is likely of banksii. They are large birds at 50-65 cm, with the males being larger. The males are all black on the plamage apart from the red tail panel, while the females have yellow spots and a yellow to orange tail panel, such as in these females pictured below. They can form large flocks when foraging for food and water and breed in hollows in eucalypts.
 

1: Victoria Dam, Lesmurdie, WA, 30/09/2012.
2: Georgetown, Qld, 11/03/2012.