Over the last six months, I have found four of my hens, varying breeds and ages, that passed away during the night. Three of them had been sitting on eggs, the fourth had never tried to hatch eggs. I check my coop every morning and every evening before bed, and the day before I found their bodies, all these hens had been acting quite normally, active, eating, no symptoms like a cough or discharge or anything. It was like a chicken heart attack or a chicken stroke, except two of them had passed so peacefully that they literally looked like they'd just hunkered down on their roost or nest for the night and died in their sleep. I am heartbroken. I've only cared for this coop for a year but I've developed "attachments" and learned these birds. Two of the hens were great brood hens, and really interesting, interactive hens. I miss them every time I go in the coop. And I feel clueless. What did I miss? What did I do wrong?