We were also working on the mechanisms for the heads. The mother bird will have two levers one to move the head up and down and another to open and close the mouth. The extra head articulation will allow more freedom with the range of expression from the mother bird. For the hatchlings we only gave them mouth articulation has the puppeteer only has one hand controlling the head. We linked up the hatchling's mechanisms with piano wire, and this gives strong lever control so that the mouth can be opened and closed with as little effort as possible.