There's a lot of reasons birds end up biting people. It's sometimes something like gender, or maybe someone offended them in the past and that person looks like them.
They're so smart, some have mental issues one person said.
It's sometimes tough figuring out what sets them off.
Pako seldom ever bites hard. When I first got him, I was drying my hands with a paper towel, he nipped my neck so hard. I put him in his house and told him bad. I eventually learned he HATES paper towels, even now. I don't know why, he just does.
I wore nail polish one day. He HAAAATED that. He would not step up he, would not stop biting until I took it off. Now I don't wear nail polish. It's a sacrifice for him, but I think I can manage.
** NOTE: If I wore nail polish all the time and I first adopted him, I may have thought he was a forever nippy bird.**
People need to think hard on this fact when they have a nippy bird.
If I didn't learn Georgie was afraid of hands, I would never been able to have him fall asleep in my arms every night. Now he even hops on my shoulder and rests his head under my chin. He's a super sweet bird now. Took awhile to get him there, but it worked out because I didn't give up on him.
I'm just giving examples of how bird's have odd personalities, but aren't bad birds.
There's an amazon that was traumatized at a zoo from a raccoon attack. Was a biter after that. I think it's a paranoia issue.
That's more difficult to tend to, but I think time and patience would prevail.
1year has gone by before Geogie was comfortable enough to walk on my shoulder.
He's really come out of his shell since I've moved him in my room.