There are not 5 species of red-tailed black cockatoos (also known as Banksian or Banks's Black Cockatoo), but there are 5 sub-species.
They are:

• South-eastern red-tailed black cockatoo, C. b. graptogyne, (endangered - only found in southwestern Victoria and southeastern South Australia)
• Forest red-tailed black cockatoo, C. b. naso(near threatened)
• C. b. banksii found across Queensland
• Great-billed Cockatoo or C. b. macrorhynchus(found across Australia)
• C. b. samueli found across the central coastal region of Western Australia, and parts of Queensland and western NSW.