We live in Nebraska and I have three Welsh Harlequin ducks (all fully feathered.) I have a wooden coop with ventilation and used it last year during the cold months. I would make them go inside and lock the box at night (it has alfalfa hay as bedding with no water or food inside the actual box.) The actual pen is enclosed from all sides including the top and it has three strings of electric fencing around it. This summer I left the door to the box open so if they wanted to go inside they could but closed the door to the pen so they would be secure at night. BUT this morning it was 10 degrees outside and they were outside their box (I did not lock them inside last night) and they have a heated waterer. When it gets this cold at night (and it will only get colder!) do I MAKE them go inside their box, or do I let them decide?