It is wrong for a person to bite, but in the bird world biting is an accepted means of communication. Although a bird's bite can sever another bird's toe or worse, many bites do little, if any damage to another bird. The bird receiving the bite has thick down and glossy outer feathers that cushion a bite or even cause it to glance off the bird completely. Humans, however, are not equipped with protective feathers. Bites come in direct contact with skin causing welts, bruising, or cuts.
Bites range from a gentle pinch to bone crushing.
I receive about three good bites a year. This is usually my fault for not following my own advice. My troupe, The Amazing Amazons, is asked daily to do many behaviors that put me in a vulnerable position. Although the Amazing Amazons are known for their performing abilities, they are also known for their good dispositions. As many as 250 people held them after a single performance.