Up here, they say to leave the housing out until September even though there is no activity. It will be spotted during the south migration and the yearlings will recall when they return next year if their original/first housing choice is not available. Regarding housing, as noted in a post above, the plastic gourds have yielded the best results, albeit limited activity overall in our area. We use the oval holes to deter Starlings. Our biggest enemy is the sparrows. We have taken the the old alum Martin house and installed it about 80 ft away on a shorter pole and right next to a tree. We let the sparrows have that one...the Martins aren't much interested because of the height and the proximity to the tree. It has helped alot, but occassionally I have to put the pellet gun to work when they mess around with the gourds. The PM's are pretty darn protective, tho, when they're in a family way. Three years ago, a sparrow got in when they were both out feeding and pecked holes in the eggs and threw a couple out the hole.
