Perception Channels: tactile ; chemical
Although not endangered, numbers of M. minutus have been greatly reduced by modern agricultural methods, such as combine harvesting, spraying, earlier harvesting, and stubble burning. They also seem to have a three-year pattern of population increase and decline. Every third year, the population apparently crashes, only to be rebuilt over the next two years. It is unclear why this happens. (Burton 1969; Fact-File; Macdonald 1985)
IUCN Red List of Threatened Species: least concern
M. minutus consume large amounts of crop yields, either by eating the seeds in the field or feeding on carefully stored grains. Rodent-borne diseases have also been a large influence on the human population, taking more human lives than all wars and revolutions put together. (Macdonald 1985)
In the wild, M. minutus helps keep populations of crop pests down to a manageable level. (Fact-File; Macdonald 1985)
M. minutus eats a variety of seeds, especially grasses, fruit and grain. In the summer, its diet also contains insects and larvae, such as moths, caterpillars, and grasshoppers. It is a very opportunistic feeder and eats whatever is available during the season. In winter, when food is scarce, M. minutus takes advantage of human stores of food and is often found in grain silos or haystacks. In order to facilitate cellulose digestion, these rodents have a large cecum which contains large amounts of bacteria. After the food has been softened and partially digested in the stomach, it passes down through the large intestine and into the cecum, There the cellulose is broken down into digestable carbohydrate constituents. However, absorption can only take place higher in the gut and in the stomach. For this reason, rodents reingest the soft pellets of bacterially digested food after having defecated it. This reingestion allows the digestive system to be highly efficient, assimilating 80 percent of the ingested energy. (Fact-File; Grzimek 1990; Macdonald 1985; Nowak 1983)
M. minutus lives throughout Europe and northern Asia. Distribution ranges from northwest Spain through most of Europe, across Siberia to Korea, north to about 65 degrees in Russia, south to the northern edge of Mongolia. There are also isolated populations in southern China west through Yunnan. (Wilson 1993)
Biogeographic Regions: neotropical (Native )
M. minutus lives in tropical and subtropical regions and prefers habitats characterized by tall grasses. These would include high meadows, reed grass plots, bushland interspersed with grasses,and grain fields. In Italy and East Asia, they also make a home in rice fields. Population density may be very high in favorable environments. Originally, these mice lived in humid regions with high, long-lasting grasses growing near rivers, ponds, and lakes. With the advent of human encroachment, however, M. minutus has been forced to live along roadsides and in crop fields. When the farmer clears his land for the harvest, this mouse is left homeless. The problem is solved by the mouse either forming a shallow burrow in the soil, or finding shelter in the barn or silo. Not all mice are so lucky, however, and many mice die after being rendered homeless. (Grzimek 1990; Fact-File)
Terrestrial Biomes: savanna or grassland
Average lifespan
Status: wild: 1.5 years.
Average lifespan
Status: captivity: 5.0 years.
Average lifespan
Status: captivity: 4.0 years.
M. minutus a small mouse, ranging in size from 55 to 75 mm long, with a tail that is usually 50 to 75 mm long. It has large eyes and ears, which permits it to see the slightest motions and hear the faintest sounds in the darkness. It has a small, blunt nose encircled by vibrissae. The fur is soft and thick, with the upper parts of the body a brownish color with a yellowish or reddish tinge, and the under parts white to buffy colored. The prehensile tail is bicolored and lacks fur at the very tip, and the feet are fairly broad. The feet are specially adapted for climbing, with the outer of the five toes on each foot being large and more-or-less opposable. This mouse can grip a stem with each hindfoot and its tail, leaving the forepaws free for collecting food. It can also use its tail for balance as it scurries along long grass stems. The fur is somewhat thicker and longer in the winter than in the summer. As with other members of its subfamily, M. minutus has moderately low crowned teeth with rounded cusps on the biting surface arranged in three longitudinal rows. The masseter muscle, as well as the lateral muscle of the jaw, are moved forward on the maxillary, providing very efficient, effective gnawing action. The auditory bullae are large, and it is thought that the size of these resonating chambers enables the mouse to detect low frequency sounds carried over great distances, and thus be better able to escape predation. (Burton 1969; Grzimek 1990; Macdonald 1985; Nowak 1983)
Other Physical Features: endothermic ; bilateral symmetry
Average mass: 6 g.
Average basal metabolic rate: 0.201 W.
The female gives birth to an average litter of 5 to 6 young after a gestation period of 21 days. Births take place in "high nests", structures built about 100 to 130 cm above the ground. Construction on these nests begins during the spring and summer breeding season, and one nest is built for each litter of young. These nests are globular in shape, about 60 to 130 mm in diameter. They are formed of three layers of grass blades woven tightly together. The lining consists of finely shredded leaves and grass, which form a soft warm nest for the young. There is often more than one entrance, but these holes are kept closed by the female during the first week after parturition, and males are not allowed into the nest at all. Reproduction is usually concentrated during warmer, drier months, starting around April and ending in September. Females are polyestrous, undergo a postpartum estrus, and under the correct favorable conditions, can give birth several times in rapid succession. Because they have a short natural longevity, females usually live through only one or two reproductive seasons in a lifetime, but in captivity they have been known to experience up to nine. Gestation is about 17-18 days, as is the typical minimum interval between litters. The number of young per litter ranges from 1 to 13, but is usually around 3 to 8. The young weigh about a gram at birth, and are 2 cm long. The young are born naked, blind and altricial, but can hold onto a grass stalk as early as three days after birth. They open their eyes at 8 to 10 days, are weaned and leave the nest at 15-16 days, and reach sexual maturity in 35 days. Maximum known longevity in the wild is 16 to 18 months, with few individuals living past 6 months. In captivity, M. minutus can live to be just under 5 years old. (Burton 1969; Grzimek 1990; Nowak 1993)
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average birth mass: 0.9 g.
Average gestation period: 20 days.
Average number of offspring: 5.2.
Average age at sexual or reproductive maturity (male)
Sex: male: 37 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 40 days.
