We agree. As long as he has ample water to stay in at night and he has plenty to eat, he will be warm and okay. If this is a wild swan, it is highly unlikely that he will be easily caught to bring inside. So, he will have to survive on his own with the help of all of you. Most northern hemisphere swans are built for tundra conditions, so again, as long as he has water and food, he should be okay. We would change his diet. Give him a mixture of cracked corn and poultry layer pellets. The pellets will provide him with necessary vitamins, minerals and micronutrients that will help him stay healthy. Also, provide him with lettuce so he has some vegetation in his diet. The Regal Swan