The house mouse is one of the most widely distributed and successful mammals in the world. It has dull greyish-brown fur and the tail, which is the same length as the body, is thicker and scalier than that of other species of mice. It is accompanied by a distinctive strong ‘stale’ odour and its presence can easily be detected by means of its droppings. Forms of this species living in association with man (‘commensal’ forms) tend to be larger and darker than ‘wild’ forms, and have longer tails. The voice is a familiar high-pitched ‘squeak’.
House mice are typically active at night, but will emerge during the day if food is scarce. They are extremely agile, with an excellent sense of balance, and are able to jump and swim fairly well. The senses of hearing and smell are highly developed and communication is largely through scent. They have an extremely broad diet, incorporating most human foodstuffs.
In urban situations, territories are usually set up, which males defend aggressively. Breeding tends to occur throughout the year, with five to ten litters produced each year, each one consisting of between four and eight young. The nest is constructed of shredded matter such as paper or cloth and females may share a nest if the population density is high. The young are born virtually hairless, with sealed eyes and ears. They are fully furred after 14 days and weaned after 18 – 20 days, when they begin to emerge from the nest.
House mice are well-known pests, contaminating foodstuffs and grains and carrying a number of diseases and parasites that are transmissible to humans.