The chances of you seeing a mouse are low unless you are a night owl. Mice are most active at night and they move fast. You are much more likely to see signs of a mouse in the house than you are to see the mouse itself.

Here’s what to look for:

Droppings
Mice excrement is about the size and shape of a grain of rice and is dark brown to black in color. Look for excrement in cabinets and cupboards, drawers, behind trash receptacles and along baseboards.

Urine Pools and Trails 
Mice use urine to mark territory. You can sometimes see drops in a line pattern leading to a hiding place and also something called a “urinating pillar” which is a mound of debris including grease and dirt that is mixed with urine.

Nibble and Gnaw Marks
You might see evidence of chewing on boxes, bags and other food containers as mice try to get access to food. Pet food is a favorite, as is, believe it or not, soap. You might also see tooth marks on wood and sawdust nearby. A mouse may be trying to keep his teeth sharp.

Mouse Nests
Look for soft, fuzzy piles of material, paper or grass gathered into a pile. Mice will build cozy nests any place they can find a quiet place to hide, such as behind appliances, in walls, drawers, and cabinets that are rarely used. Nests can also be found in upholstered furniture, and even inside toasters and blender housings. Since a mouse can fit through an opening as big around as a pencil, you might be surprised where they end up.

You might hear a mouse stirring when your house is quiet at night, or scratching inside a wall. You might see dirt marks and smudges in areas where mice frequently scurry. Some people also report smelling an unusual musky odor.

Freaking Out Pets
Is your dog tracking something behind the trash can? Is your cat agitated and staring at something you can’t see? They might be onto something: maybe a mouse in your house!