Male and female red-tailed black cockatoos can be distinguished by the colored markings on their tail feathers – red markings in males and yellow-orange markings in females.

These cockatoos have zygodactyl feet, two toes pointing forward and two toes pointing back, allowing them to climb and grasp objects with one foot while standing on the other.

They are sexually dimorphic: as they mature, males turn solid black while females retain their mottled appearance.