It appears that something rammed or know caked in the door, as the hardware cloth was pushed in (not broken). We can't figure out what did it. It would require a great deal of force to bread that door down and we're not sure if a coyote or raccoon could have done it. That, and the fact that the chickens had been wandering around outside unbothered makes us think it wasn't a traditional predator.
We're wondering if one of the fearless local deer might have tried to kick in the door to get to the feed - has that happened to any of you? We found some fibrous material stuck in the wire - seemed too brittle to be fur. Maybe from a hoof?
Anyway, it's a mystery. There are a lot of chickens in our area and we're not aware of any recent coyote attacks. What might it have been?