Common Mice

Size: The house mouse is small, its body rarely exceeding two inches long and one ounce in weight.
Color: It is usually gray in color but some individuals may appear darker.

Introduction:

Mice are more numerous than rats and are more widespread throughout urban and suburban communities. A mouse can be distinguished from a young rat since the rat's head and feet will be overly large in relation to its body.

Mice are small RODENTS, and like all rodents they possess gnawing teeth. The word mouse, however, has no distinct meaning beyond that in scientific classification systems. It has been applied loosely to many rodents simply because of their size and superficial similarities, such as a somewhat pointed snout, a slender and sparsely haired tail, relatively conspicuous ears, and an elongate body. (The word rat is used in an equally loose way for larger rodents of similar appearance.) In addition, many small rodents with distinctly different characteristics have also come to be known as mice. Among them are the short-tailed field mice, or field voles, Microtus; the pocket mice, family Heteromyidae; the jumping mice, family Zapodidae; and the squirrellike dormice and related forms, families Gliridae, Platacanthomyidae, and Seleviniidae. Many of these animals carry a variety of viral, bacterial, and parasitic diseases . Mice associated with humans also have considerable economic impact through crop damage, destruction of trees, and food contamination.

Garlough and Spencer (1944) noted the word "mouse" can be traced to the Sanskrit word musha which is derived from a word "to steal." Mice were well known to the ancient Greeks and Romans and were featured prominently in their art and literature. This cosmopolitan rodent is believed to have come originally from Central Asia. It is now found throughout the world from the tropics to the Arctic and Antarctic.

Linnaeus originally named the house mouse Mus musculus. Later, taxonomists cosidered that two subspecies of house mice had been introduced from Europe into the New World: Mus musculus domesticus and M. m brevirostris. Especially in the Midwest these two forms came into contact and interbred. Taxonomic "splitters" came to recognize several hundred verieties.

In recent years opinions have been revised again, and you are likely to see Mus domesticus cited in technical papers. Some specialists now want to reserve M. musculus for those mice in Eastern Europe. However, continuing to use our present technology (i.e., M. musculus) seems to me the appropriate and least confusing course of action.

Identification

Newborn mice are extremely small, blind, pink and naked, except for short vibrissae. They weigh between 0.02 and 0.03 ounces. After two weeks, the eyes and ears open, and the young mouse is fully covered with hair, makes short trips from the nest and begins feeding on solid food. At four months of age an adult mouse weighs about 25 grams, slightly less than 1 ounce. Eaton and Cabell (1949), on studying laboratory mice, state: "Young mice may be moved from their dam at three weeks of age and the dam rebred. A female is not usually productive after 15 months, but may live much longer. Male mice have been known to live as long as 2-1/2 to three years."

Feeding Patterns

While mice are nibblers and feed many times in many places, they have two main feeding periods. They eat at dusk and just before dawn, interspersed with many other feeding bursts approximately 3/4 to 1-1/4 hours apart. They have to consume about 10 to 15 percent their body weight every 24 hours. When water is available, they drink.

Southern and Laurie (1946), who studied the house mouse in grain stacks in the field, make the following notes about the water requirements of house mice: "Unlike rats, mice do not feed to forage outside a rick for water; in captivity they live in good health on a diet of wheat, which itself contains about 15 percent of water, though they will take a small amount more if it is provided. This is generally less than 1 ml per day, and this quantity would be easily obtained on the outside in the form of dew or rain. This probably accounts for most mice in a rick visiting outside, and for the readiness with which they take poison bait mixed with water."

Social Behavior

Women's liberation has a long way to go in the world of house mice. Each male mouse stakes out a territory and guards it. Within the territory can be several females and lower ranking males. While the dominant male is busy defending his territory, the female mice may be "getting acquainted" with lower ranking males. Female mice will often mate with more than one male. A mouse's territory depends upon a number of factors, including number of mice in the entire structure and arrangement of materials within the structure. The more mice present, the less territory each has. Some mice can remain in a desk or pallet for an entire lifetime, but it is important to keep in mind that the mouse is climbing up and down within the materials stored on the pallet or in the desk. Mice entering an already occupied territory are not welcome and are driven off. When mouse populations swell, the mice will seek out rodent bait stations, exposed window ledges and any other area where they can hide from other more aggressive mice.

Mice are cannibalistic and will feed on each other when hungry. Mice caught on glue boards may be partially eaten by other mice. Mice in multiple live traps will often be eaten by other mice caught in the same trap.

Because mice scurry from place to place and deposit fecal droppings wherever they please, the easiest way to determine if mice are present is to locate their droppings. Other signs include gnaw marks, small holes in walls and doors, and the pungent odor of their urine. The easiest way to discern active infestations is to sweep up the droppings and see if new ones appear the next day.