Maybe follow her next time and see where the nest is and get rid of it. About the only way to put a stop to it. And then put up fence when weather gets better. When I first got Muscovy's way back in 2004 I had to crawl under things to get to mine because leaving them out all night isn't even a thought here. So I put large rocks and hardware wire up where they couldn't crawl under, Now since they are fenced in there is no where to hide and they just lay in their houses. Sure makes it alot nicer. Amazing some of the places these girls can get under if they have a mind to. lol
Lol normallythis little Mallard is the best one for laying in the house. I even have them laying in the nesting boxesnow. She was moving pretty fast today to get wherever it is she wants to lay them. She's already back and will stay all day, sleep in pen, and then run off again in am. Going to go look again.