I thought I had lost my australian spotted drake night before last. When I went to lock them in for the night he was nowhere to be found, of course it was dark by the time I missed him so I was tromping around with a flashlight. When I went to let them out I noticed an extra duck in with my muscovies. I had to catch him and put him out to reunite with his woman, who was very glad to see him. A couple of weeks ago the same thing happened with one of my pekins. Before this they have never changed pens, I keep them separate at night to make sure no one gets bullied away from the food and shelter at night. I don't know if this was just a random thing or if they were being bullied so moved.