Well, IF I ever had any doubts that heat shields do work on nestboxes in hot weather, I sure don’t have any doubt now. I visited with a BB friend of mine this weekend and she told me that she lost a brood of bluebirds this summer to the heat. They went on vacation and were gone for several days in one of our heat spells. When she got back they were dead. My heart just sunk – I am the one who encouraged her this year to try again with a new Gilwood box in a different location than she had been using, and she actually had 3 different nestings. I had gone over everything, from getting her to use a VanErt in-box trap to shielding the box from the heat. Her box was out in full sun, like mine. She was sick about it also, but lesson learned (the hard way). So people, boxes in full sun in a hot-weather state (like Missouri), please do something about the sun – either use a heat shield or put box in an area where it can get afternoon shade. My backyard where my boxes are is on the west and I can’t situate them anywhere they might get some shade without being too close to the trees.
Great advice Carol! No doubt with the summers getting hotter here in the States, (it was extremely hot here in Pennsylvania as well this summer in July and August), heat shields have become and should be just as important as predator guards on nest boxes. So sorry to hear about your friend’s loss of nestlings from the heat. It truly is heartbreaking and I hope she has better luck next year.