Ya got one mistake compounding another. You don't have a bird dog, you have a puppy! Your puppy might come when you call it but, a distraction, and it does it in it's own time. You have a puppy that has no need to be given a bird at that young age and it's doing what a lot of puppies do, chewing up something that taste good.

Knock off the birds and let it grow up. If you want to play feach, do it with a small bumper, better yet a large wooden dowel. Teach it all the yard work befor you intro,,,make that re-introduce the bird. Then when you do, make it a frozen bird. I never start a dog on bird work until they are at least a year old, sometimes older.