I've not had a chicken become prostrate, sick or ill, or die from heat. They have plenty of shady places to hang out when it gets hot, and multiple water buckets. On hot days I check the water frequently, and if it starts to get warm I either replenish it with fresh water or put ice in it. We keep PowerAde bottles in the freezer for this, each about 1/3 full of water, well, ice. When needed I top them off with water, screw on the lids, and put two in each water bucket. I want my girls to stay hydrated and I don't think they drink as much when the water is warm.