I'm a new member as of today, what a great site! I just wanted to comment on the Wooduck house information as I have "been there and done that". If you place your houses on trees you will learn the hard way that its a mistake. By "hard way" let me share what I mean. Nothing gets you from the top of a ladder to the bottom faster then opening a wooduck house with a coon in it! "been there done that" saved ware and tear on the ladder steps as I didn't use them goin down! \:D That tree had one of my "sure fire" coon stoppers on it which was to wrap the tree with sheet aluminum. Closer observation revealed the muddy paw prints some how going up! What I have now for all my houses is a 10 foot 2" dia. galvinized pipe pounded in the mud over water. Then I put a 4 foot piece of a 2 1/2" pvc pipe over that under the house. The pvc rest on another small piece of pvc that gets bolted to the pipe. This way the pvc spins on the pipe so its hard to climb. I mount a floor flange to the bottom of the box and just screw it on top the pole! I have never found any sign of any preditor getting to one since. I do find the owls every year, in one house or another, seems they like a new veiw. Last spring the owls hatched a pair of little guys in one! Lastly, 3" high x 4" wide hole is best and I have had ducks in several size houses I like the size posted here best. Its not cheap or easy but its worth it when you see them fuzz balls following mom.