I've read through most of this thread, and I've wanted to reply to almost every single post. I just want to give hugs and condolences to everyone who've lost chickens to predators.
So far, mine have been lost to dogs. That's it. But, we also have raccoons and opossums that are brash enough to come up on our back deck, that is directly above our chicken coop....I've trapped a coon, and brained a possum, but after reading all this I'm thinking about putting the traps out more often.
I had a dog in my pen, attacking my hens, just recently. Luckily they all survived somehow.