I have large railroad ties that I set around the inside of my coup. (it sits on the ground with no bottom) and these deter the opossums from getting in. Opossums are the biggest threat currently to my chickens. My next step if that didn't work is to put a skirt around the outside Id use hardware cloth.
my feeling is the skirt is better, for two reasons.
1. so much easier to install vs all the digging involved with buried mesh.
2. once the animal starts to dig they might just keep digging deeper they reach the bottom of the mesh and go right under it. Yes, it will slow them down significantly but if they have enough time they still may get in.
I have an apron/skirt made out of pieces of used chainlink fence(probably easy to find free or cheap on CL if it's used). Mine extends maybe 18-20in out from the run fencing. It's wired to the run fencing and to each other, the outer edges/corners are staked down. In about a years time the apron is completely gone from sight, we can mow right over it and never know it's there.
One evening I gave the girls a big pile of scraps that contained meat and some dairy products. I didnt' think to check at dusk and remove what they had not eaten. The next morning when I went outside to collect eggs I was shocked to find that something had tried to dig into the run because of the left over smelly meat/dairy that I left in there. I was soooo relived to get closer and see that the apron had stopped them completely. It did not stop them from digging just from getting in through the hole they made. I can tell from the results that what ever it was(suspect coon) had dug as far as they could reach through the chainlink apron and then no further. I can just picture something out there with their front paw through the chainlink up to the shoulder trying to reach into the run but running out of reach. LOL
Sorry to intrude here, but can you please explain to me what a skirt and apron is? I keep seeing these terms used, but I don't know what they are. Pictures would be wonderful if at all possible. Thank you!