jyoutz
Super Member
I use Tom Cat bait blocks in a mice bait box. It really keeps the population down, and the dead mice aren’t hazardous to predators. The poison is warfarin, which is a blood thinner often prescribed for human medical use. The blocks contain enough warfarin to cause mice to bleed to death, but the amount retained in the carcasses is too minimal to kill larger predators like owls, etc... I keep these blocks in my barns and carports year round and have much less mice issues now.The best solution I've found for things I have to leave out in the field is to open them completely, hood up, remove any panels that come off easily, provide LED light at night. Mice hate light and visibility. As you've discovered never use any material that supports a mouse nest. I use low wattage LEDs on things I can leave in the shed because there's power. You could put a small solar panel/battery/light combination on the tractor and put it under the hood so it hopefully makes it through the night. You could also put a solar charger on the tractor battery and run a 12v light off of it on a timer so it's only on during dark hours. Have you thought about one of those fabric car port/tent things? I have a half dozen of those, they hold up well and that would allow you to leave the tractor wide open without any rain getting on it.
I'd skip the poison, you can't kill the whole outdoors and too many other creatures die when they eat the poisoned mice.