Instead of poisons, use Hav-a-hart trap, snap trap, Rat Zapper, Ultrasonic Pest Repeller…
Another option: Make a dry mixture of 1/2 wheat flour or corn meal, 1/2 plaster of paris. Place in T trap (or other container not accessible to other animals). When the rodents drink water after ingesting the mixture, a hard ball will form in their digestive tracts, and they will die.
Suggestions on Earth Easy website http://eartheasy.com/grow_nat_pest_cntrl.htm#e
1. First, secure any open food sources, especially the compost bin. Sealed compost bins, such as compost tumblers, are recommended if you have rodents in your garden.
2. As a deterrent, soak a rag or cotton balls in oil of peppermint (found at most health food stores), and place in areas of rodent activity. Place under an eve or under a cover that will keep the rain from diluting the peppermint. Rodents are allergic to peppermint and will avoid it. This method is also effective at deterring rabbits.