Missing a black cat in Norman?

Is anyone missing a male black cat in the Norman area? One showed up at my house last Friday and has not left yet. He has been living between my fence and the neighbor's fence in the three feet of utility easement. I don't know if he is abandoned or if he is just hanging out to mate with the neighbor's cat. He just sits back there and meows at me, and runs when I approach him. It is a huge problem for me to have this cat in my backyard, because of my guinea pig. This is Opossum's house and I do take him outside to eat grass, and can't have a cat attack him. I do stay outside and sit with Opossum, but he is just too afraid to be out any longer than a minute without trying to hide. If anyone knows whose cat it might be or would love to have him as a pet, please let me know. I live between the hospital and Griffin if that helps anyone out.