We have a wood duck expert here in MN who just wrote an article in the local sporting paper. He puts his houses on metal poles at a height where he can clean and maintain them without a ladder. He installs those cone shaped critter guards on the pole. They don't have to be over water. He says the important things are like others have said above, clean the house each year and put fresh sawdust or hay. He said nothing about orientation of the house, east, west, whatever. Don't put them in thick trees where they cannot fly directly into the box. He did say that if you have racoons around that they would scare the wood ducks away from houses near the pond. So then you might want to put the houses 100 yards away or in any area where there is an open flight lane especially if you see wood ducks hanging around an area. They will sit up in the trees near where they want to nest. If that area is a long way from the pond that's fine. The ducks will walk a quarter mile if they have to. Then you just wait. I regularly have wood ducks in two of my four houses but not the other two, who knows why. I have one house in which the hooded mergansers lay eggs mixed in with the wood duck eggs. The hen wood ducks hatch them all.

Gotta get back to fishin!