Mute swans can be found in virtually every state due to owners who do not pinion (render the bird unable to fly as required by state law) their captive swans. We also know of a couple of swan breeders in Oklahoma so they may have had some young feral birds mate with their captive birds and get out prior to pinioning or you just have a swan that came from a feral flock. You can feed him a mixture of cracked corn and poultry layer pellets. Lettuce and bread can be used as treats. We hope this information is of benefit. Please let us know if he stays around. The Regal Swan