Any dog can be trained to hunt but for the amateur trainer, there will be a lot of frustration for both the trainer/owner and the dog. A good bird dog naturally has 'birdiness' instilled into its gene through centuries of breeding. It takes the trainer very little effort to bring it out but will spend the majority of time teaching the dog how to hunt (one of the reason why gun shyness is so difficult to break; the dog is associating what it wants with what it is afraid of - most trainers will use the dogs natural birdiness to overcome it). A dog without the birdiness has to have it taught or encouraged above its wanting to play and want to chase other game.
Once that is done, they will have to train it to hunt for them and not for itself. It will take a strong trainer and an exceptional smart dog.