Last week when I checked the nest box, I expected it to be empty. To my surprise, there were four almost fully grown bluebirds crammed into the box. They are all gone now, and probably left shortly after I checked the box.
We ended the nestbox season at Mariton fledging out 11 bluebirds , 13 Tree Swallows and 13 Black-capped Chickadees. Not bad for 25 nestboxes in marginal habitat.