Yes, you need to trim his feathers every 3 months so that he cannot fly. Even though he has a mate and should return, he could get lost, find a predator, run into something or become entangled which could seriously injure him or even kill him. Clipping his feathers (on one wing only) will prevent flight. You must check constantly to ensure that the feathers do not grow back without your noticing. The Regal Swan