I live in CT where it has been very cold at night. My 3 ducks wont go into their coop at night on their own. It is an up-purposed Little Tykes playhouse with hardware cloth over the windows and an acrylic panel over the upper half of the dutch door. I have a rigid foam insulation covered in heavy duty plastic on the ground with at least 5" of straw/hay over that. If I don't go out and herd them in, they will just wander around quacking all night. Why won't they go in on their own?