Every morning, my redfronted macaw actually grabs my finger and appears that she is going to really chomp down on it... lifts the head up and "lowers the boom" on it... (Or so it would appear to a stranger... )
What she is actually doing, however, is regurgitating for me. (Which is the ultimate macaw expression of love.) If I were to pull away when she was regurgitating for me?! It would be like rejecting a lover... and you could expect hurt birdie feelings and possibly even a hard pinch. (Mine have been taught to pinch instead of bite. Still hurts, but it doesn't draw blood.)
A bird that didn't have that training, I would expect would draw blood under those circumstances. "I was being nice to you, and you're being an a--hole!"
CHOMP! Human error. Not the bird's fault. And entirely predictable.
These are emotional, empathic, sensitive creatures. They have feelings, and they don't hold them back. They play. They love. They get mad. They throw tantrums. They are the most toddler-like of all the parrots. Raising a macaw is a lot like raising a human toddler. Positive interaction, Nurturing guidance and boundary setting is the key. Do that, and they are well behaved.
Permissive parenting? They will push the boundaries, and fight you when you go to re-set them. Better to set boundaries, and stick with them, than to try and "re-negotiate." THIS IS HOW WE BEHAVE BIRD!
Too much time in the cage. (They get MAD!) Generally speaking 4 hours a day is minimum. 8 is better. (My cage doors haven't closed in about 12 years or so... but again, I have a bird room, and mine are trained, and can be trusted to be out unsupervised. Many of them? Not so much!)
Not enough attention or interaction? They will find a way to get attention. Even negative attention (deliberately) is better than no attention. They self entertain fairly well, but macaws generally don't tolerate being ignored!
Toys? Give them appropriate things to chew up, and they won't seek out "inapproprate" things to chew up, i.e. windowsills, cabinets, furniture, etc.
It is very easy to inadvertently train a macaw to do things you don't want it to do. Screaming, for example. The bird screams when it wants something - like attention - or food - and you come running over and give it to them...
Guess what?! You just reinforced that he can get what he wants by screaming. "I don't know what happened, but all of a sudden my bird screams!"
Yeah. Stop me if you've heard that one before.
Biting and tantrums. The bird throws a fit, the humans scramble for cover - and guess what - the bird suddenly discovers just how powerful he is! WATCH WHAT HAPPENS THE NEXT TIME HE DOESN'T FEEL LIKE DOING SOMETHING... and if it works a second and a third time? Watch out! You just let the Genie out of the bottle! NOW WE HAVE TO SEE WHICH IS THE DOMINANT MACAW...
Whereas, if the bird throws a fit, and it immediately results in Mr. Towel, and time out... WHO'S THE DOMINANT MACAW IN THE FAMILY?! Hint: It's not the bird!
So, those are the basics.
These are big, goofy, mushy lap birds at heart. Even the otherwise big bad birdie, abused and neglected ones.
When you get the bird home, sit down on the couch with a blanket or a towel on your lap, and some treats, and some wooden toys, and just sit and talk and play with him. YOU JUST WATCH HOW HE RESPONDS TO THAT!
My greenwing hadn't been handled in 8 years when I got her. She's been my best buddy since DAY 4... 4 days, start to finish, to train this bird. That is literally all it took!