a few days ago I went out to the coop to feed the birds and open up for the day. Found one of the hens slouched in a corner, mostly unresponsive. Couldn't stand up, and her eyes kept drooping shut. There was no evidence of a predator attack. I checked her vent, and it seemed OK. I saw no wounds or discolorations, etc. Basically nothing to indicate illness. She was one of the top hens in the peck order, and was well fed. So I seperated her from the rest of the flock and set the hen up in a box with water & feed. A few hours later I check and it was dead . any idea what caused this? If other chickens start dropping dead I know I'll have a problem on my hands. So far all the others look perfectly healthy........they're all the same age, about 1.5 yrs old, and there's no peck order fighting or anything like that.