I had some chicks raised by hens that dropped dead one by one. The coop is dusty, but everything else is top-notch. They have clean drinking watering and feed containers, plenty of room, and plenty to eat. There was a chick dead every day.
Now the adult hens are dropping. I don't see anything wrong with them as far as poop or behavior. Sometimes it seems that they're dropping from their perches at night.
I have three pens side by side and all three are having problems. As I'm writing this, I realize the major problem may be the dust, for which I have the things to clean them, though I've never had this problem before after years of chickens. Then again, it's suspicious that the three coops share a common screened wall.
So, I'm tearing my hair out!