The door in the nest box is just the right size for a wood duck. If you look at my video "Invasion2" ( ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-7B2qfPi881M.html ) at 45 seconds you will see how a duck goes into the west nest box. The East nest box has the same size opening.
