Everything you have done has been perfect. You got the swan to a bird vet, domestic or wild, it is still a bird and domestic birds can sustain broken bones. So, having a bird vet is one good step towards the bird's recovery. Second, you kept him warm and inside away from the cold inclement weather. Because he lives on a park and no predators, he is in a great setting for continuing to live out his life whether he flies or not. Once the bones have set, then he will need some rehabilitation to help him regain use of the wing, the veterinarian will be able to help with this. Again, give the swan a good warm wet-down with water on a daily basis to keep his water repellency working and the uropygial gland healthy. Provide him with clean water and a mixture of 1/2 cracked corn and 1/2 poultry pellet placed in a large bowl submerged in water. Place him on straw to keep him warm and from any leg or foot injuries from cold, slippery or abrasive surfaces. Keep him inside until he is water ready and the weather has turned warmer permanently. Release him onto the pond and see how he fares. Then, if he cannot fly, you will need to plan for his permanent winter accommodations for the future just as you have this year. Thanks for taking care of him. The Regal Swan