What killed my chicken?

[Bonwell]

I have not, as the tunnel was at the very side, appears to be going under the barn. Meanwhile there is a new tunnel, also right by where they lay their eggs, also right at the edge of the wall, so cant follow it. I am now assuming a rat. Its pretty cold here with snow and the ground is frozen, plus I am working 50+ hours a week. But will have to fix the problem. I am no longer worried about the current chickens as they all sleep high, but I am expecting an order of babies the end of March and gonna have to take care of rat problem without danger of harming chickens or cats before then.

This sounds like an Opossum to me. We had one recently dig a hole into our duck pen, they mostly want the eggs, but they will also go for the birds sometimes.