The common house mouse (Mus musculus) is an opportunistic omnivore, meaning its diet is defined less by preference and more by immediate accessibility. They consume both plant and animal matter, prioritizing sources that deliver the most energy. This dietary flexibility, combined with a high metabolism, drives them to seek out and consume calorically dense materials found in human structures.
The Omnivorous Nature of Mice: Preferred Food Sources
Mice possess a highly efficient metabolism that necessitates a consistent intake of energy-rich foods, consuming approximately 10 to 15 percent of their body weight daily, which amounts to about four to five grams of food for an adult. Their natural, preferred diet in the wild consists heavily of seeds, cereal grains, and fruits, which provide the high carbohydrate content they require. When house mice inhabit buildings, their diet shifts to reflect the most available high-energy sources, including dried goods like oats, rice, and wheat products.
Mice prefer soft grains, such as soft wheat and canary seed. They are also attracted to human food items high in fat and sugar, including pet food, sugary snacks, and chocolate. To maintain nutritional balance, they consume insects, carrion, and other animal protein sources. This focus on caloric density means they will bypass lower-energy items like lettuce for a small piece of nut or grain.
Beyond Nutrition: The Necessity of Gnawing
The destructive behavior often associated with mice is not primarily driven by hunger but by a biological imperative related to their dental structure. Like all rodents, mice have a pair of sharp, chisel-like incisors on both the upper and lower jaws that grow continuously throughout their lives. These teeth can grow at a rate of up to 0.4 millimeters per day.
To keep these incisors filed down and prevent them from overgrowing, mice must constantly gnaw on hard, abrasive materials. Their teeth are durable, allowing them to chew through many hard substances. This mechanical necessity leads them to damage non-food items, including plastic piping, insulation, wood structures, and electrical wiring. This gnawing often leads them to new food sources or nesting areas.
What Mice Avoid and Dietary Dangers
While house mice are opportunistic, their diet does have limits, and certain compounds are actively avoided or pose a threat. Naturally, they tend to avoid strong, pungent odors, such as concentrated mint, which can act as a natural deterrent. Highly acidic foods, like citrus fruits, can cause digestive distress and are usually sampled and then ignored.
Mice are physiologically incapable of vomiting or burping, making carbonated beverages and certain toxins particularly dangerous. Foods that are spoiled or moldy can be toxic, as some molds produce mycotoxins that are harmful to them. Securing common household items like chocolate, which contains the toxic compound theobromine, and ensuring food is not left to spoil are practical steps to limit their access to both their preferred foods and potential hazards.