Bonding with people is usually seen as desirable among pets of any kind…in parrots such often results in a friendly, affectionate bird that readily learns to mimic speech. However, parrots can become extremely protective of the person to whom they have bonded, to the point of screeching at, biting or even launching full scale attacks upon others. Also, as an extension of natural nesting behavior, bonded parrots are also very likely to become territorial, protecting their cage or larger area from intrusions by all except their favorite person.
Natural Parrot Instincts
It is important to bear in mind that bonding in parrots is a deeply ingrained instinct – one that you may be able to manage but which cannot be eliminated. Wild parrots of nearly all species form long term, usually life-long, pair bonds. Pairs spend the vast majority of their time in close contact with one another…even within large flocks, pairs are very evident by their proximity and physical interactions. Most even fly side by side when moving about within a flock. Captive parrots, no matter how many generations removed from the wild, are “hard-wired” to behave in the same manner.
Bonding-related aggression can best be avoided by socializing your parrot, while young if possible, to all members of your household, or to those who regularly visit. The bird will still be “closer” to certain people than others, but may not develop overly-protective behaviors.
An interesting article on the interplay of natural and captive behaviors in parrots is posted at: