We found a bird collapsed...?

My brother found a bird collapsed on a road. He promptly took it home for us to examine and care for until it got better (which was pretty dumb to do, because the bird could've had bird flu, and we have dogs at home). I checked online for the symptoms of bird flu, and the bird didn't have any of the visual symptoms (unnatural breathing, ruffled feathers, but since the bird didn't have that red thing roosters and other birds have, we couldn't check for purplish-blue coloring of that red thing). My aunt, a person who could be called an amateur veterinarian (not really a veterinarian, but she has enough knowledge of animals, from her numerous pets that include birds, to be called that), said that the bird probably collapsed from the cold. The bird isn't dead, we determined that, because the bird is breathing properly and reacted to my aunt examining it by opening it's wings, but then collapsing again. Is collapsing from the cold a viable reason, and if so, is covering it in a tiny cloth (the cloth covers the body, but not the head of the bird) to warm it up the appropriate treatment? Or is there still a chance of the bird being infected by bird flu? If so, what are the measures we should take to prevent it from spreading to us?