Like squirrels, raccoons and rats, mice build nests in which they deliver and raise their young. True to its name, the house mouse (Mus musculus) is notorious for establishing its nests in human dwellings. If you’ve noticed mouse droppings in or around your home or if you, your family and/or your pet have heard telltale squeaking and scratching behind your walls, you should examine your home for signs of a mouse nest.
What does a mouse nest look like? Mice construct their nests by harvesting materials that are plentiful and readily available. Mice are shy creatures, and they tend to confine their activities to a small radius. In fact, mice are rarely spotted more than 25 feet away from their nests. Paper, fabric, string, fiberglass insulation, mattress and pillow batting and plant material (e.g., straw) can all be easily shredded and transported by mice for the purpose of nest-building. House mice prefer to form their nests into rough, ball-like structures, about four to six inches in diameter. A mouse nest may also look like loose piles of those same materials or like collections of wood chips, pellets and “fill” found in hamster cages and guinea pig enclosures. Mice are not clean animals, and they often leave droppings and scatter bits and pieces of scavenged food around their nests.
How many mice live in a nest? Mice breed often, they breed rapidly and they do not stop breeding unless they are exterminated. Female mice carry their young for about three weeks, and each litter can be five to twelve pups. The average mouse nest can be home to between a dozen and two dozen mice, depending on their age and the presence of other mice in the vicinity. Because mice nest in order to raise their pups, they seek out warm, dry areas that are well protected and close to a food source.
Where do mice like to make their nests? Unfortunately, the average home’s kitchen features many mouse-friendly amenities. If you suspect you have a mouse problem, check behind kitchen appliances, including the refrigerator, freezer, dishwasher and oven. Areas around any gas-powered household appliance that features a pilot light, such as a hot water heater or range cooktop, may also be harboring mice. Concerned homeowners should also check their pantry and all kitchen cabinets, especially seldom-used cabinets located close to the floor. Look for holes mice may have burrowed into your baseboards or drywall, loose nesting materials and droppings (elongated pellets, pointed at both ends, typically no more than one-quarter of an inch in length). Also note any unusual musky, ammonia-like odors, as these may be indicative of urine trails mice use to demarcate their territories.
Prevent mice from making a nest in your house. The best way to keep mice from entering your home is to make sure it doesn’t offer an attractive and cozy place for them to build their nests. Keep your kitchen clean and make sure all packaged foods are securely sealed. Consider transferring boxed and bagged pantry items such as breakfast cereals, flour, sugar, etc., to airtight plastic containers or steel canisters. Don’t allow tempting mouse nesting materials to accumulate in your garage, basement or around the outside of your home. Dispose of empty cardboard boxes, make sure old clothes and linens are stored in rodent-proof containers and keep the landscaping around your home's foundation tidy. Be sure to seal any cracks or gaps around your home’s foundation, in your walls and especially around electrical outlets and pipe fixtures in your kitchen. Some homeowners suggest blocking cracks and open spaces around these common problem areas with a mixture of copper wool and caulk or foam sealant, as mice have difficulty chewing through these materials.