Nice looking dog! What your dog actually did is what is called a sight point. The reason they instinctually lock up like that is because they don't want the animal to know they are there by not moving. The dog won't move because if they do the bird/animal is going to fly or run. A dog doesn't even have to be a pointing breed to do that.My dog will stop and freeze every time she spots a cat, a bunny, a deer, etc. until I tell her to leave it. When she was a youngster she'd chase,,,,not anymore, though. An actual hunting point occurs when the dog uses its sense of smell,,,,not sight. As soon as they enter the scent zone the dog will get birdy and should lock up on point, not even realizing they are doing it at first. The dog doesn't usually see the bird because it is hidden but they know they shouldn't move. If you want to get your dog to point using its sense of smell you've got to get him out on game birds, wild or pen raised, as much as possible. Using pigeons is a good alternative.In the beginning always run your dog on a long check cord so you can control the creep or if he continues to break once the point has been established when the bird has been flushed. Hopefully after he chases a few he will realize he can't catch them and will become more steady. Once it all comes together for the dog that is the best part about hunting them!