Mice, particularly those in natural and suburban environments, readily consume acorns, which are a significant seasonal food source. The annual drop of acorns, often called a “mast,” provides a high-energy resource that many rodent populations utilize to prepare for the colder months. This phenomenon increases mouse activity near homes as they seek out, consume, and store this abundant food. Understanding the appeal of acorns and the behavior of different mouse species is key to managing their presence.
Acorns as a Nutritional Resource
Acorns offer substantial caloric density, largely derived from high concentrations of carbohydrates and fats. A raw acorn contains approximately 41% carbohydrates and 24% fat, making it a rich energy source for rodents building reserves for winter. Acorns also supply essential minerals such as calcium, phosphorus, and potassium, as well as the vitamin niacin.
The primary challenge in acorn consumption is the presence of tannins, bitter plant compounds that can interfere with protein metabolism. Tannin levels vary significantly between oak species; white oak acorns generally contain less than the more astringent red oak varieties. Mice mitigate the negative effects of tannins by preferentially selecting low-tannin acorns or partially consuming high-tannin acorns to avoid the most concentrated parts.
Species Differences in Acorn Consumption
Reliance on acorns depends heavily on the specific mouse species present. Wild mice, such as the white-footed mouse (Peromyscus leucopus) and the deer mouse (Peromyscus maniculatus), are adapted to woodland habitats where acorns form a substantial part of their diet. These species are highly motivated to gather and cache acorns in the fall, using them as a primary energy source to survive the winter. Large acorn yields directly correlate with population increases in these wild mouse species.
The common house mouse (Mus musculus), by contrast, is far less dependent on natural foods like acorns, having evolved to live closely with humans and consume food waste and domestic sources. While a house mouse will consume an accessible acorn, the wild Peromyscus species are the dedicated collectors and hoarders near homes. These wild mice are the ones most likely to carry large stashes of nuts into garages, sheds, and attics as they migrate indoors for warmth.
Why Mice Hoard Acorns
Hoarding or caching acorns is a survival mechanism linked to the seasonal availability of this food source. Acorns drop over a relatively short period in the autumn, creating a temporary surplus that mice must store to cover energy needs during the winter months when food is scarce.
Mice are scatter-hoarders, typically hiding individual acorns in numerous small caches across their territory, though they also create larger stores near their nests. When wild mice move into human structures for shelter, they bring this hoarding behavior indoors. Homeowners often discover caches in hidden spots, such as inside wall voids, behind kick plates, under appliances, or tucked away in shoes. A mouse nest is often located within about ten feet of its food cache.
Practical Steps for Acorn Management
Homeowners concerned about mice attracted by a nearby oak tree can take several preventative steps. The most direct action is to regularly rake and remove fallen acorns from the yard, especially in areas adjacent to the house and garage. This cleanup reduces the incentive for mice to forage nearby.
Addressing potential entry points is necessary to prevent outdoor mice from moving their caches indoors. Mice can enter a structure through an opening as small as a dime, so sealing all cracks and gaps in the foundation, around utility lines, and near doors and windows is essential. Storing items like pet food and bird seed in secure, sealed containers also removes alternative food sources. Maintaining a clear perimeter by keeping grass trimmed and removing clutter, woodpiles, and debris further discourages mouse activity near the structure.