Grey call drake is breathing heavy... I can hear some wheezing when I hold him close. He has lost interest in swimming, but still follows the group and will self groom. He feels very light and is a little off balance. he looks top heavy and holds his tail up while his crop is closer to the ground. He struggles weakly and quacks weakly when I catch him. Eyes and nose are clear, feathers look good; the top ones are fluffed out though. He is a young adult. His poop is a small amount & soft, barely formed. Temp out lately is in the upper twenties...lower 30's. No other duck or chickens have such symptoms. They free range and have cracked corn and pellets. Duck folks, any ideas? I hope I posted this in the right section; I thought I might get better results here.