House mice are mainly nocturnal, although at some locations considerable daytime activity may be seen. Seeing mice during daylight hours does not necessarily mean there is a high population present, although this usually is true for rats. Mice have poor eyesight, relying more on their hearing and their excellent senses of smell, taste and touch. They are considered essentially colorblind.
House mice can dig and may burrow into the ground in fields or around structures when other shelter is not readily available. Nesting may occur here or in any sheltered location. Nests are constructed of fibrous materials and generally have the appearance of a “ball” of material loosely woven together. These nests are usually 4 to 6 inches in diameter. Litters of 5 or 6 young are born 19 to 21 days after mating, although females that conceive while still nursing may have a slightly longer gestation period. Newborn mice are naked and their eyes are closed. They grow rapidly and after 2-3 weeks they are covered with hair and their eyes and ears are open. They begin to make short excursions from the nest and eat solid food at 3 weeks. Weaning soon follows, and mice are sexually mature as early as 6 to 10 weeks old.
Mice may breed year-round and a female may have 5 to 10 litter’s per year. Mouse populations can therefore grow rapidly under good conditions, although breeding and survival of young slow markedly when population densities become high.
During its daily activities, a mouse normally travels an area averaging 10 to 30 feet in diameter, seldom traveling further than this to obtain food or water. Mice constantly explore and learn about their environment, memorizing the locations of pathways, obstacles, food and water, shelter and other elements in their domain. They quickly detect new objects in their environment, but they do not fear novel objects as do rats. This behavior should be remembered if faced with a large population of mice in a residential, industrial or agricultural setting. Proper placements of mouse bait is a must if you are to have a successful baiting program.