I got a dog at about the same age she is a purebred GSP on the first trip I didn't think she would be able to find a bird in a closet. Gave her time and bird contact and now I wouldn't trade her for anything and she is a bird finding machine. Most dogs have hunting instincts in them it just needs to be brought out. I encourage you to keep taking him out with you and make things positive. No pressure to do anything involved with birds until he is ready. Try to get into as many birds as you can, game farms can be fun for the dog with lots of contact and smells. I think with time yoiu may find a decent gun dog in your rescue.