I've shared our Cockatoo story before... but here again is my behavioral slant:
We had been told that the beautiful Umbrella was up for adoption at the pet store. Told the older couple owners had passed away. I think--
Abby had been sitting on the 'old lady' when she passed [Abby DOES NOT LIKE me to have my glasses off, and would begin small biting me if I would fall asleep w/ her on me].. Because, she acts TOTALLY DIFFERENT w/ my hubby-- when he's taken his glasses off, she becomes extremely compassionate and goes to comfort him, snuggle. Especially when he wipes his eyes.
And if I rub his back--- she attacks me. [rubbing his hand or head is ok].
I think-- the kids tried to take care of the birds, but because of no experience, tried to force her to come up w/ a stick [she's terrified of sticks, small ladders, anything elongated], and would throw pop cans at her [she viciously attacks them].
There are other minor observations... but just think of the circumstances surrounding a behavior [noise, lighting, etc]...