I'm on to using the new generation of rodent poisons now. See they are deer mice here, and they carry Hanta Virus in this area. And they got into the house too. It was creepy enough when they were in the coop and barn.
So I got a great tip from the guy that did the plumbing for the house. Use scraps of electric wire and pipe to make very safe mouse or rat bait stations. I used electric fence wire since I had lots of that, but had him save me the short bits left over on the plastic 2, 3 or 4 inch pipe. Put the bait on the wire and twist it around in the center then put it through the pipe and bend the ends over the ends of the pipe. I use about a foot long hunk of pipe at least, but mostly whatever length it came to me as. Rodents love tunnels so just leave them out anywhere and they go in, especially near walls or ground cover. The other critters can't get directly at the bait as it is suspended in the center of the pipe. If you have any critters that could carry the pipe away wire it down.
I forget the name of the stuff right now, I can get it for you when I'm home, but it's said to be safe for anything but a rodent to eat, it functions by tageting a liver function that rodents have, and they go into a coma. They must head for the nest to go to sleep because I almost never find bodies. The bodies are said to be safe for other critters to eat and I don't have any unexplained poultry losses or sick dogs/cats.
The stuff has been a miracle around here, I went from major damage to my tack daily and a full on house invasion with chewed up siding needing repair to hardly ever seeing the things in a few months of treatment. I was rebaiting weekly till I had control but have moved on to monthly now. I guess I have about 10 stations between around the house, the shed, barns. The stuff is not cheep but well worth the price. The bait stations need to be good rodent holes so that only your rodents will eat the stuff due to the price! I spoke with a biologist that was out in the area doing a raptor survey and she said that they see the stuff out where birds can get at it and they have tested some song birds positive for the active ingredient with no signs of illness, but wonder why anyone would leave that stuff out to feed the birds at the price, but I think its also just irresponsible.
I did have a few problems with Pack Rats and have not seen another so far so hopefully it's working on them too, some of the pipes are bigger so they could get in.