Remove any dog food bowls from the garage. Some may like to keep their dog's food and water bowls in the garage instead of their home, but this can attract squirrels and mice.
Pack any loose bird, squirrel or other seed in air-tight containers. You may keep the seed you put in bird or squirrel feeders in the garage. However, the smell may lead wildlife to break in. Place the seed in air-tight containers to hold in the aroma.
Close the garage doors whenever you're not moving things in or out. The doors are the easiest way to get in and out of the garage, and mice and squirrels could slip in whenever they're open.
Shut garage windows and keep them closed at all times. Seal them tight with duct tape if any have cracks. Mice can squeeze through even the tiniest openings, so it's important that your garage is sealed tight.
Seal any holes in the garage roof or walls with wooden boards. This is called "exclusion" and it is the equivalent of burglar-proofing your garage. Mice and squirrels will use their amorphous bodies to squeeze through holes up to one-quarter inch wide, so the best course of action is to cover them completely.
Prune trees that have branches over the garage. Squirrels will use these branches to jump down onto the garage roof, where they will find an entrance point. Cut the branches so squirrels have a more difficult time accessing the garage rooftop.
Apply weatherstripping along the bottom of the garage door. A weatherstrip is rubber insulation that will create an airtight seal between the bottom of the garage door and the ground. This will seal off another potential entrance point for mice.
- Use poisons as a last resort. Poisons will entice the squirrels, mice or other rodents into eating them and kill them off hours later. While these may be effective, they also may be inhumane or leave rotting corpses around the garage.