I have 3 mallards and a number of other birds. They all free range. I was away at my son's birthday party today, when I got home I went out to herd the ducks in for the night. Now I have 4 mallards. I had to check and recheck, yup there is an extra. I am somewhat worried about disease but the new one is the same size and assumable age as my other 3 and I can't tell them a part so now I have a wild duck in the coop. I assume he/she is attempting to talk mine into leaving home Anyways I thought it was strange and that I would share the story!