They have reusable black plastic snap traps. If you buy the bigger tubes of pvc, you can place the trap inside[chickens can't reach it] and place the tube along the walls. Or if you know where they are getting in, close it off, place tubes w/ends covered and a trap inside. If you use poison, you will have to have it covered, tube, box, ect so the chickens can't get in. Something like a gel and heavy box so it doesn't spill out and the chickens can't flip it over. If you get a cat, you'd have to know it's chicken safe. Whacking a cat on the butt when it's still young and stalking a chicken will get it to leave them alone. Did that w/one of my cats, she doesn't even look at the chickens, even chicks that run around. But mice, she just goes nuts over, doing her best to get at them and the nests. Shes a tiny cat though, a rat would prolly scare the crud outta her.