The unknown offender

[Bizzybirdy]

And would it be harmful to the chickens?

ABSOLUTELY! It will eventually get in and kill them all. Is probably the racoon but possums and skunks also dig. Why didin't you kill it when you saw it?

A racoon will not think twice about mercilessly ripping your chickens apart and they do not deserve such a horrible death. If you cannot shoot it, try to catch it in a trap. In the interim consider putting hot wire around your pen or coop.

 

[gsim]

Groundhog or badger. Trap and shoot. Marshmallows good bait for coons. Do not know what works for badgers or groundhogs. Badgers might like meat, so some cheap lunch meat?

 

[PortageGirl]

Groundhogs have Zero interest in chickens or even chicken feed. It might have dug the original hole is all. They're quite shy and will leave if there's too much activity. I have one way on the edge of the woods, he comes into the yard when he feels really safe and scrambles away as soon as anything moves.