as with most pups catching the what ever is the most rewarding thing he can do. Here's where "training" comes in. If it were me I'd try and get to the point asap. Here is where a partner would help. Get the dog on a lead. reenforce the point however try and resist woaing him(easier said than done I'm very guilty of that). Have said partner flush the bird and if need be keep him in place with the lead as the bird flies away. Here is where you put on the praise and give him his favourite treat. Make him feel the best thing he can do for you is stand there and look at the bird until released.