Tips from the Wisconsin Humane Society.
At times, animals may wander into your garage when you leave the door open. It is best to just leave the garage door open to give the animal the opportunity to leave. If security is an issue, lower the garage door to within six inches of the ground. You may also consider disconnecting the door from the power garage door opener to prevent unwanted entry by humans.
In other cases animals gain access through pre-existing holes in rotten wood or loose wall or soffit panels. An animal usually opts to take up residence in your garage because she wants a dark, quiet, warm place where she can be undisturbed. Fortunately, it is relatively easy to convince the animal to relocate.
If it is winter, we recommend leaving the animal alone until the season warms. She may have a hard time finding a new home. In cases where there are baby animals, wait until the young are grown and have left the nesting area.
To get an animal to leave on her own, take away what she came for: the darkness, the quiet and any potential source of food. Make the area bright with blinking, flashing or steady lights near the animal. Make sure the light can’t tip over and start a fire! Keep continuous noise in the garage by turning on a radio tuned to a talk or rock station as loud as you reasonably can.
These same techniques can be used for birds after nesting season is complete. Flaps, flutters or flashes will help to keep them away and windsocks, ribbons, foil dishes and wind chimes are very effective. These methods will be more successful than repellent. Always avoid toxic repellents.
Mammals are likely to stay away after sturdy home repairs make their hideout unavailable. To make sure the animal has definitely moved out, cover the entrance with paper. If the paper is undisturbed a day later, solid repairs should begin immediately.
We discourage the trapping and moving of animals. Doing so may cause young to be orphaned and separates the animal from her known food and shelter areas. Also, another animal is likely to move in if the hole that allows the animal access is not properly repaired.