i know we have big rats outside, that's a given. But only having problems in one pen. We have a playhouse coop there, which i had wanted to have placed on a foundation of pavers. My shed mover dude insisted it's better to set it on posts, so air circulation can get underneath. Well, guess what else is now underneath? i have been backfilling rat tunnels almost every morning from under that coop into the pen. Got mad last week and dug down a foot then out a foot. Laid down hardware cloth, covered with heavy rocks, then put the dirt back. All was fine until this morning. Now, another tunnel from an industrious rat that made it under the hardware cloth. i'm pondering throwing rat bait into the tunnel tonight. Although i worry about secondary poisoning, i just don't know what else to do. i don't have the strength to dig down to China to lay a longer length of hardware cloth, although the rats probably do. i just need them dead. i wish i had listened to myself and insisted on placing that playhouse on a secure foundation. Now, i probably have a ton of rats partying under there.