Just had a good thought – what happens on an original Gilwood box when you use a wren guard? There would not be much ventilation would there, as the opening is covered & would be hot, especially in hot weather?
I have used wren guards on Gilwoods with no problems, I made it go out the 2″ from the furthest edge of the front, not the door if that makes sense. Both times were on Chickadee nestings but I don’t see why it would be any different with bluebirds. I had sides on mine too.
Donna, I guess I questioned this because my boxes are in full sun and it gets very hot inside those boxes in the summertime. I always use Styrofoam heat shield on nests (being sure not to cover my ventilation areas) if they are active in June and further out. Maybe up North there you don’t have the heat we have here in the Midwest in the summertime. But I really think a Gilwood needs that extra top ventilation is you were to use a wren guard, as I always do. But maybe it does still get quite a bit of air even with the guard on – I don’t know. P.S. my wren guard does have sides, but they do not cover up the existing ventilation slots on my boxes.