I have a young mallard drake. He lives with my chickens. This morning I heard him hee haw, like a donkey but I wasn't sure that I really actually heard it so I just went on my routine. But then I saw him arch his neck and do it again. Has anyone ever heard of this? He is a quirky little duck but I just want to make sure it isn't a cough or something serious. I will try to get it on video if I can. Anyone?