This morning I went out to my chicken shelter and found twelve dead birds inside. Here are the clues... any ideas about what the cause was? What should I do so it doesn't happen again? I had 74 cornish cross that were 8 weeks old. There was a heat index of about 95 degrees F yesterday. They were fine at 3pm yesterday afternoon. I have a 10-12' Salatin-style shelter with metal sides on only 1/4 of it, so there's cross ventilation. I move it every day. The dead birds were some of my biggest - some were 7 lbs. They had food and water when I found them this morning. The dead ones were in the side of the shelter with the food and water - the side without metal sides and roof. The dead ones looked perfectly normal. Heart attacks? They got too hot? Some strange sickness? What do you think?