When a dog mouths a bird, after he picks it up, and starts to come to you mouthing it, follow these rules: Take a strap about a foot long, and calling your dog up to you. strap him across the nose two or three times.
Do this several times a day, at home, till he dodges the strap. Always hold him by the collar. After this send him out for the [.raining sack and when he picks it up say "Hold," and walk toward him and shake the strap at him. He will soon have confidence in you and will know that he will get strapped across the nose. Repeat this several times, then take a dead bird and throw it out, give him the same lesson he had with the sack, and if he offers to mouth the bird, strap him across the nose.
Then take him to the field and send him after a bird and repeat the lesson, if needful; but after a few days you will never have any more trouble with him on that score. The great secret in training a dog is to put him under command and not have him afraid of you.