Backyard Fowl Keepers

If he's harassing the others nonstop, separating him for a few hours or overnight may help. Just be cautious,isolating too long can make reintegration harder.

Since her behavior is normal, I'd suspect either stress or a temporary imbalance. You could try adding some vitamin D and calcium-rich treats (yogurt, scrambled eggs) to her diet and see if that helps.

If she only goes after humans, she might associate people with something negative. Has she ever been handled roughly or startled by sudden movements?

If you're really concerned, you could try adding a little scrambled egg or mealworms for an extra protein boost.

Sand can be a great option for keeping the coop clean in winter! Look for coarse construction sand rather than play sand, as it drains better and won't compact as easily.

Some breeds are naturally lean.
But if they seem underweight, try free-feeding a high-protein layer feed
You can also add some healthy treats like scrambled eggs.

I had a hen with a similar issue, and it turned out to be a respiratory infection that led to a sinus abscess. A vet helped drain it, and she needed antibiotics for a couple of weeks. If your hen is still eating and active, she has a chance, but don't wait too long to act!

Since you can monitor the coop door remotely, I'd say letting them have the yard is fine. But I'd also set up a game camera to see if predators come around at night.

Sounds like a predator attack, but the lack of feathers or blood is strange. Have you checked for any holes in your coop or fencing?

Ive used plastic totes before and noticed the same issue. Adding more ventilation holes near the top and bottom helped reduce condensation significantly.