We could use poison, I suppose, but I hate to see any creature suffer, and poison is a horrible way to die, even if you are a mouse. Besides, I wouldn't want the chickens to eat a mouse that had died from poisoning. And, they do eat mice, if they can catch them.
Last week, we saw a couple of mice in the chicken coop and decided it was time to set out traps. We normally set the traps in a storage area next to the coop where the chickens can't get in there and disturb them. Tom set 3 traps, baited them with peanut butter and caught 2 or 3 mice. Then one morning when he went to check the traps, they were gone. After searching high and low, he finally found them under a set of steps with partially eaten mice in them. We figured something had found the dead mice and eaten them, but what?. So, Tom got new traps, drilled holes in them and tied string to them while tying the other end of the string to a post.
He is not fully grown, only about half the size of a grown possum. In fact, I'm not sure a grown possum would fit in this trap. He was probably born this spring.
His method of defense was to issue a loud "hissssss" and show off his sharp teeth. At no point did he "play dead" as possums are known to do.
Tom hauled him off several miles to a creek bed where he should find plenty of food and be well away from any houses or chicken coops where he might get into trouble again.
Hopefully, this encounter with humans will have taught him to stay well away from houses and chicken coops. Otherwise, he might not be as lucky the next time.