How do zoos like Sea World tame and train their stage performing parrots?

[scottischicken]

How do zoos like Sea World tame and train their stage performing parrots? Do they get the birds as chicks and hand feed them from day 11 so that they become tame and unafraid of people? How do they train adult birds from flying away from their stage?

 

[townchicks]

Most of the zoos do clicker training. A great starting place for you would be the book Don't Shoot The Dog by Karen Pryor