I have had 3 ducks disappear without a trace. They free range during the day with our chickens and we put them away right before dark. The disappearances have happened randomly every couple of days. No chickens are missing or injured. Just ducks. Any guesses on what it is getting them? Or are they running away…. 

Welcome! It's an old thread and the OP hasn't been on for a while .... but the info may help somebody with a similar issue that stumbles upon the article.