Mice are active during the winter months, but the drop in external temperatures forces them to relocate. These small rodents, primarily the common house mouse and the white-footed deer mouse, seek out new habitats that offer protection from the cold. A home provides an ideal environment, transforming a minor outdoor presence into a serious indoor concern as the seasons change.
Winter Survival: The Primary Drivers for Seeking Indoor Shelter
Unlike some other small mammals, mice do not hibernate; they must remain active year-round, requiring a continuous supply of food and a stable body temperature to maintain their high metabolism. When outdoor temperatures plummet, the energy required to stay warm threatens their survival. A heated home offers a perfect microclimate where they can thrive without expending excessive energy on thermoregulation.
The second motivator for this seasonal migration is the scarcity of natural food sources. Seeds, berries, and insects that make up the bulk of a mouse’s diet become inaccessible once snow and ice cover the ground. This forces them to seek out the readily available food stored inside human structures, viewing homes as a reliable, year-round buffet.
A home’s warmth and consistent resource availability also support their reproductive cycle, offering a safe place to breed. A female mouse can produce multiple litters per year, and the shelter of a structure ensures that these large populations can survive and grow unchecked. This combination of thermal comfort and accessible nutrition makes indoor shelter a necessity during winter.
The Vulnerabilities: Common Access Points Mice Exploit
A mouse allows it to exploit even the smallest construction gaps. These rodents can squeeze through an opening roughly a quarter-inch wide, about the size of a dime. Their remarkable flexibility is due to a lightweight skeleton and lack of a rigid collarbone, allowing them to compress their bodies dramatically; if their head fits, the rest of the body can follow.
Many entry points exist at the foundation level, including small cracks in the concrete or gaps beneath garage doors. Utility penetrations are frequent points of entry, as mice follow the pathways created for electrical, gas, or water lines where they enter the structure. Often, the space around these pipes and wires is not adequately sealed, leaving just enough room for a mouse to slip through the exterior wall.
Higher up on the building, damaged ventilation screens, such as those on attic vents or dryer vents, offer access to wall voids and attics. Mice may also exploit weep holes in brick siding or gaps where the roofline meets the fascia boards. Any structural discontinuity that is not sealed with durable material is a potential doorway seeking a winter refuge.
Health Hazards and Property Damage of Indoor Infestations
Once inside a home, mice pose significant risks to human health through contamination from their droppings and urine. The dried waste can become airborne dust, which can trigger allergic reactions and asthma symptoms. Diseases such as Salmonellosis and Hantavirus are associated with mouse infestations, transmitted when people inhale contaminated dust or come into contact with surfaces that the rodents have soiled.
Beyond health concerns, the property damage caused by mice is driven by their need to gnaw continuously to wear down their incisor teeth. This gnawing behavior often targets structural materials and electrical systems hidden within walls. When mice chew through electrical wiring, they create exposed conductors that can lead to short circuits and are responsible for a percentage of house fires.
Mice also shred materials like insulation, paper, and fabrics to create nests. This nesting behavior reduces a home’s thermal efficiency and spreads waste throughout the structure.
The presence of an infestation can sometimes be detected by faint scratching or scurrying noises inside walls or ceilings, often heard at night when the rodents are most active. Small, greasy smudge marks along baseboards and walls, created as mice repeatedly travel the same pathways, are another sign of their successful entry.