Thank you both. I never imagined that a land animal would have scaled the wall instead of trying to burrow below the coop. There was NO sign of even an attempt to get in from ground level. The man who built the coop is coming to close the space this weekend but with wire, not hardware cloth...
I was sad to find my 3 young chickens taken from their coop overnight. All that was left of them inside the coop were 3 feet and one wing. Shockingly, it wasn't as bloody as I'd expected but clearly it seems their bodies were taken out mostly in one piece. It was horrible! Nothing burrowed...