I wonder if the medicine in cattle tags may be too strong for a dinky chicken. I'm thinking hanging them around the coop defeats the purpose, doesn't the medication leach into the bloodstream, and that is how it functions to deter flies?
Coming in late to this. You made the right choice. I've seen a lot of mind boggling injuries chickens have recovered from here, but a bone break like that is typically a deal breaker.
She will be in good company in that giant coop in the sky. Lots of well loved chickens will welcome her to...
My concern would be your chickens somehow getting ahold of poison, either through eating a poisoned mouse or by the actual poison being carried into the coop area. Weirder things have happened.
It sounds like they aren't very respectful neighbors. All PP's comments are the same I would suggest. Unless you want to get out the frying pan that is....
Kidding!
I will add that Northern Black Racers eat other snakes as well, including venomous snakes. So they eat rats, mice, other snakes, and eggs/baby chicks that aren't securely locked up.
Just relocate this snake, it is very effective rodent control. 1/4 hardware wire around your chicken coop will keep the eggs safe. Well as safe as anything like this. But if possible, don't kill it. Another will just take it's place and it might be a venomous one.
I call chi-yick-EEENS! little baby chi-yick-EENS! and they come hauling ass from what ever little nook they may be stashing their eggs today. Works like a charm.