We have 3 backyard hens that are about 6 years old. I came home from work today to a dead hen lying directly under their hanging water container. I watched back video and at about 4 in the morning the hen came out of the coup, got a drink of water then went back in the coup. A few minutes later the same thing. Then she did it again this time taking a drink, poofing up for a few seconds, them immediately lied under the water container. She appeared to die quickly because she never moved again. She was lying stomach down and head down into the ground. Any idea of what happened? It's not normal of them to be up that early. The others were still in the coup sleeping. It was cold last night (maybe 40 degrees) but we had a lamp on in the coup. We were thinking of putting some blankets around the coup to try and keep it warmer tonight. Is that a good idea? Thank you. It's my first time here.