Yes, Carri – they can. I just had 4 fledge today and we had some very hot (mid to upper 90-‘s for several days while they were in their box. We did manage to get one day of relief in-between about two weeks of very hot weather, and yes, I was worried. But I had foam heat shields on the box with the top shield being very oversized to shade the box better, as it has no shade whatsoever from trees. I’m not sure they would have made it without the shield, however. From what I know and Gin mentioned here, heat related problems are more likely with eggs than hatchlings. P.S. Remember to have proper cross ventilation at the top on the sides of your box, also. Good luck.