I recently had a hen, who seemed to be top of the pecking order stand around like she was sick for a couple of days and then die. I noticed that she had some feathers on her neck that looked wet and disturbed, like maybe they were getting pulled. She also had a lump of something that could have been mite eggs on her belly. None of the other chickens had any mites or lice, but I dusted them anyway. At the time, I had a rooster and 9 hens in a 8x12 foot coop with a 400sqft run, so they're not crowded. They always have lots of layer feed. They do spill their water all the time, so sometimes they don't have any. (maybe that stresses them?) After the first hen, I had one that got wry neck and then started walking in circles. I suspected that I had some kind of disease, so I cleaned out the coop with bleach and euthanized the hen. Now I wonder if it was from a head injury, instead. (I did have some issues with paralysis in the fall and chickens dying, but they were all from a batch of chicks that I got from the same person, so it could have just been something wrong with those chicks). It's also possible it's marek's or something, but these latest hens don't seem the same as the others. Now this morning, I went out and another hen was standing with her eyes closed and drooped wings like she was in shock. Feathers on her neck/head had been pulled out. I put her in a warm place by herself, but she died. The first two hens that died had just started laying eggs again and were laying every day. the third one had recently been broody, and smashed all her eggs, so I put her back in with the rest of the flock, but that was quite a while ago, now. This has all happened in the last week and a half. Could this be bullying, or some kind of predator? I would expect that a predator would do worse than pull some feathers. My rooster is the gentlest rooster I have ever known. He will never even threaten to jump at me, even if I grab the hens and they squawk like I'm killing them. I don't know if he's gentle with the hens though, he doesn't do anything with them when I'm there, but he's huge and could definitely do damage if he was aggressive. Here are some sad photos of the hen from today.