My CBR is at 9.5 months now. I have taken him on a few duck hunts and 1 pheasant hunt. He behaves fine and has a good "hunt mode" when there are no other dogs present, but if there are other dogs present, male or female all he wants to do is play with them and/or mount them - males included. He is not neutered (yet). Is this normal behavior because he is still a puppy, combined with him just reaching sexual maturity? Or is there a more serious problem I need to address?

Sounds very typical for a pup of this age, male or female. We advise never hunting a young dog with others unless all dogs are under control and/or on leash.

Here's the chicken!