Amazons, macaws and cockatoos are most commonly associated with dominance and mating aggression, which can be quite serious and vicious. Watch for screaming, biting or lunging. Breeding season – late winter through summer – is the time when dominance behavior can become worse. Birds tend to protect their territory and their chosen "mate." If dominance aggression is seen at any stage of the bird's life, it should be immediately stopped. If you prepared to stop aggressive tendencies early, serious injury to you and the bird can be diverted.
For more information, please read the story Mating and Aggression in Birds.