I hear the ducks won't voluntarily go into their house to sleep. This could be problem! I have 3 ducks in the shed waiting for their pen to be ready. I have a large dog house for them and will be building a large pen to go around it and also a pond that I'll be putting together (not sure how yet). How can I make the pen predator proof??? I was planning on locking them into the dog house for the night like I lock the chickens up in the hen house at night. We have fox, raccoons, possum, dogs, hawks, owls and snakes here in mass quantities. HELP!