"The coop is always locked except for a small opening for the chickens to go into at night/when laying eggs." Seriously? Chickens ROOST at night, not lay eggs. The door is to be unlocked to let them in at night to roost, then locked. The next morning, the door is to be unlocked to let them out, etc. The small opening is for nocturnal predators to get into the coop.
I even had a favorite hen killed in the coop by something that reached in, grabbed her, and ate everything that could be pulled through the bars. I guess it was a coon. Anyway, unless they are kept in a super snake-proof and coon-proof coop, chickens are never safe.
