A chicken... Didn't see that one coming not to sure on what that says about Harry's character unless it's actually a cockatrice
Author's response
Google "banty rooster" and click on "Images for banty rooster" then scroll down until you find the photo of a small one perched on someone's hand. Notice the unkempt black tail feathers? That's Harry!
Except for the eyes. I'm pretty sure that Harry's form has green eyes.
If magical Animagus forms were permitted, I would have made Harry a Phoenix, but rules are rules after all, even in an AU fic.