You have your sight and your scent hounds. I have a sight hound, he sees something and he is gone, nothing will distract him. If yours is what you think, it's a scent hound, they are not as fast and the particular breed is a barker. They actually do bark when hunting to flush out stuff and for the handler to track them.
This is probably not a dog you want to leave outside because of the barking. I would think that he may be smelling different things and is curious. Have you taken him to explore the area on leash so he can learn what's around him?
They also have nose work classes for dogs in lots of areas. This may help take that energy out and give him a job. For mine we did lure coursing, it was the only thing that would tire him out.
This is probably not a dog you want to leave outside because of the barking. I would think that he may be smelling different things and is curious. Have you taken him to explore the area on leash so he can learn what's around him?
They also have nose work classes for dogs in lots of areas. This may help take that energy out and give him a job. For mine we did lure coursing, it was the only thing that would tire him out.