How old is he? Young he'll test limits like any child. It's not uncommon for even gentle, sweeties to become aggressive, sometimes spontaneous. Other birds have similar aggressive showing. Is he nearing sexual maturity? If so then read articles here. All birds are territorial about thier space. You want to discourage the behavior. Somewhere here is an excellent article on a technique called shunning. You basically ignore your bird for a minute. Total ignore, no look, no touch, nothing. I personally leave the room. My CAG knows all the right buttons to push for early forgiveness. The article will explain it better than I can. Pay attention to his body language. Try to identify his tells and triggers. Do something else for a few and return. My avian vet is a firm believer in distraction. Example; Bounce a tennis ball and catch it. He'll see, watch and wonder. I've had my CAG since she was 3 1/2 months over 21 years ago. She still becomes aggressive about her cage. I ignore her. She knows bitting is illegal and settles down. I am very fortunate that she has not bitten me hard enough to break skin. But it still hurts! So shunning. And I make very sure that the trigger wasn't me or something in the room. The trigger can be anything. An example of bird weirdness; I can cover furniture, her cage, bedding with any color excep shades of burgundy or maron. She's tolerant of shirts but chews holes. Reds and other colors ok. So maybe Guava is developing preferences.
