I have had chickens in my backyard for 3-1/2 years now(4 summers). I have have had one to die each of the last 3 summers. 2 never really showed any signs of any problems, the other did get sick, but had appeared to get over it, only to die awhile later. The latest was laying well, looked fine, fat and happy. She did show signs of a little runniness (no dis-coloring), but I put it off to too many grasshoppers. She followed me about in the vacant lot behind me and I flushed grasshoppers for her. She would catch a good number and I would catch some that she would take from me. Anyway, dead this morning. Maybe heat (about 98 here yesterday with high humidity). All the hens show a little heat stress but were happy and running for the evening's free range time. Do chickens die from heat often?