Paired nest boxes about 6 -7 feet apart on free standing poles with grease for predator protection. Face nest holes away from each box to accommodate both Tree Swallows and bluebirds. Put poles in rough grass edges so machinery won't hit the pole.
This single box is below Red Pine trees in an area where it is not mowed so the box will not be hit by the lawnmower. Grease is used for predator protection. It fledged bluebirds last year.
A 8 inch stove pipe baffle works well at stopping climbing mammals. Use 1/4 inch threaded rod. It will go through the T-bar holes. TSC have them.