The house mouse (Mus musculus) is a highly adaptable, opportunistic omnivore whose survival revolves around finding a consistent source of calories. Their small size and high metabolism mean that the question of what they eat when there is no food is a matter of immediate life or death. In environments shared with humans, these rodents exploit unconventional materials to meet their constant need for energy and maintain their unique dental structure. Their ability to scavenge extends far beyond simple crumbs and discarded scraps.
Standard Diet and High Metabolic Requirements
A house mouse relies on a diet of seeds, grains, and human food debris, consuming about 10 to 15 percent of its body weight daily. This constant caloric need stems from their high surface-area-to-volume ratio, which causes rapid heat loss. This physiological trait necessitates a speedy metabolism to maintain body temperature and energy levels.
Because of this accelerated metabolism, mice cannot survive long without sustenance. They can only go without food for a maximum of two to four days before their bodies shut down. They are compelled to eat frequently, involving constant nibbling rather than large, infrequent meals.
Consuming Non-Food Items for Survival
When traditional food sources are depleted, mice scavenge non-traditional household items, driven by hunger and a separate biological need to gnaw. Their front incisors grow continuously, sometimes up to 0.4 millimeters per day. This forces them to chew on hard materials to file their teeth down and prevent painful overgrowth. This gnawing instinct means they will attack materials that offer no nutritional value simply for dental maintenance or to gain access to a potential food source.
Materials containing trace amounts of fats or proteins become temporary survival food. Items like soap and paraffin candles are targeted because they contain animal fats or oils that mice can metabolize. They may also chew on old leather items, which are composed of collagen, a protein. Similarly, certain types of animal-based glues used in older furniture or book bindings contain protein traces and can be ingested.
Fibrous materials like paper and cardboard are also consumed, though they provide little caloric energy. Mice chew through these items because they may be contaminated with food residue, grease, or starches used in manufacturing. Even materials like foam or fiberglass insulation are chewed through, creating tunnels for nesting or movement. The chewing of electrical wiring is also common, satisfying the need to gnaw on the plastic or rubber casing, which creates a significant fire hazard.
Water Sources and Limits of Survival
While the need for calories is constant, a mouse’s need for freestanding water is minimal if it can find moist food. They can survive for a month or longer without drinking free water by extracting sufficient moisture from their diet. However, if all sources of moisture and food are removed, the survival time drops drastically.
In a domestic environment, mice find indirect water sources everywhere, extending their ability to wait out a food shortage. Common sources include condensation on cold pipes, leaky faucets, and pet water dishes. High-moisture foods, such as fresh fruits or vegetables, can eliminate the need for direct drinking. The availability of water is a major factor in determining how long a mouse can survive a lack of solid food.
Securing Areas Against Extreme Scavenging
Understanding a mouse’s desperation is the first step in effective prevention, as traditional food security alone is insufficient. All grain products, seeds, and pet food must be stored in heavy, tightly sealed containers made of metal or thick plastic, not cardboard boxes that are easily gnawed. Beyond food, all non-traditional sources that satisfy their gnawing instinct need to be addressed.
Paper clutter, old cardboard boxes, and stored fabrics should be removed or secured to eliminate nesting and gnawing material. Utility areas must be inspected to eliminate water sources. This includes insulating cold pipes to prevent condensation and promptly repairing any dripping taps or leaks. Finally, any holes or gaps larger than a dime should be sealed with gnaw-resistant materials like copper mesh or sheet metal, as soft sealants and insulation are easily chewed through.