Hen died suddenly. Any advice on cause?

[ChickenLoch]

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.

 

[MissE]

40 degrees is not cold for a chicken. It will be -20 here tonight, and there is no heat in the coop.

At 6 years old, I would blame her age. Has she been eating and drinking normally before today? What did her recent poops look like? Was she still laying? If so, when was her last egg. The temp was probably not a factor.

 

[ChickenLoch]

40 degrees is not cold for a chicken. It will be -20 here tonight, and there is no heat in the coop.

At 6 years old, I would blame her age. Has she been eating and drinking normally before today? What did her recent poops look like? Was she still laying? If so, when was her last egg. The temp was probably not a factor.

Thank you. I think she was eating and drinking fine but I haven't really been watching to closely because they are usually always good. They are always active and pecking all around when we let them out to roam the biggest part of the backyard. This chicken had stopped laying over a year ago. All the chicken's poop has always been a little soft from time to time, but I assumed that was normal. On occasion a little liquid-y. We inherited the chickens 3 years ago with the house, and that's how all the chickens were from the start.