I have a young lab and she retrieves bumpers and dummies like a champ, Its when she gets a real bird she brings it halfway back and commences to chew it up.

Any ideas on how to break this?

train with frozen birds on land first...

How old?

Poor bird handling with an older dog is not easy to correct, but given time
and the right tools.....it can be done.

To be fair with the dog, teaching and enforcement of proper bird handling
requires a sequential program. One such technique is called Force Fetch.
Here are two, free articles that show the basic process. There are more
recent books and DVDs about FF.

If you can find someone that knows how to force fetch a dog, a good
mentor makes it much easier. Good luck.

Thank you sir.

Ge toyu a pidgen and put a few tooth picks under the wings then tape the bird. She'll bite down a little softer after getting poked. Also have her retrieve a stiff brissel brush.

Its a little dramatic, but a trainer I used kept a frozen duck with nails pounded through it for a specific dog he was force breaking. Painful but effective!!