I had two drakes, they are about 6 months old. This morning when I got up to feed them one was missing. The one doesn't fly at all and the one that is missing could only get a few feet off the ground. I know ducks can die if they get separated, and I have a friend that is going to take my remaining duck to put with his flock. I put the remaining duck back in the coop and he has been hissing and biting at me, which he has never done before. I looked to see if there were any feathers or blood anywhere in the yard but couldn't find anything. I live in more of a city area and we don't get very many animals in the yard except the occasional ground hog. I'm worried that he got attacked and killed and that's why my remaining duck is being so defensive. Does anyone know what kind of animal would take a mallard duck and not leave a trace in Northeast Ohio?