Are Cockatoos Aggressive? Here's a Major Mitchell's Cockatoo I have been training and let me tell you about whether or not Cockatoos are aggressive birds.

Cockatoos most typically bite for one of two reasons:
1) They are defensive/scared or don't want to cooperate
2) Mature Cockatoos can be very defensive of territory and mates

It is important that a Cockatoo has a good friendship/relationship with people and not perceive them as a mate.

In either case, The Parrot Wizard's Guide to Well-Behaved Parrots has training methodologies, lifestyle, and advice to minimize biting and aggression from Cockatoos and other parrots.