Mus musculus - House Mouse

Physical Description:

The total length of the mouse body is 160-200 mm. The tail measures 78-94 mm and the hind foot measures 17-20 mm. The average weight of an adult is 15-24 g. The skull length is 20.4 to 22.5 mm with width of 10.4 to 11.5 mm (Cory 1912). This is a small mouse with a slender tapering tail. The tail is hairless, scaled in annulations (circular rows). The ears of Mus musculus are large and naked. The nose is pointed, and the fur is course. The color of fur is brownish yellow on the top and gray to buffed on the underside (Jackson 1961).

Wisconsin Distribution:

Mus musculus is located throughout Wisconsin. It may have originated in China, but is now distributed worldwide and lives commensally with humans. It is thought to be introduced in the U.S. from England, about the time of the American Revolution. There is no record of when it was introduced into Wisconsin. Mus musculus has reached an apparently near stable population throughout the United States, twice as abundant Rattus norvegicus (Cory 1912, Jackson 1961, Kurta 1995).

Ontogeny and Reproduction:

Mus musculus is a short-lived mammal, usually living about two years, longer in captivity. Females average 5 –6 six young per litter. Gestation is 18-19 days. Females are ready to mate again only 12-18 hours after giving birth. They are likely to give birth to a litter every month. Births peak in April-May and again in August- September. If the female resides outside, she may stop breeding in the winter. The young are born naked and blind, and they start resembling the adult population around 14 days. The young are weaned at 3 weeks, and females are sexually mature at 8 weeks (Cory 1912, Jackson 1961, Kurta 1995, Johnson et al. 2001).

Ecology and Behavior:

When living with humans, Mus musculus nest in the walls, in storage areas, or in any protected spot near food. Though rarely seen, evidence of its whereabouts is found near human food supplies include chewed boxes, crumbs and piles of feces. It makes its nest out of rags, paper, or anything else that is soft and can be shredded. Most Mus musculus living with humans are active during the day. In the wild Mus musculus is mostly nocturnal, and live in underground burrows with networking tunnels (Cory 1912, Jackson 1961, Kurta 1995). Scientists have observed a cleaning behavior in the springtime, where Mus musculus move winter debris out of its burrow (Schmid-Holmes et al. 2001). Mus musculus is a great runner (8 miles/hr), climber, jumper (up to 8 inches), and swimmer, but usually stays within 50 feet of its home. Mus musculus is omnivorous and drinks water frequently (it also loves milk). The most common predators are cats, weasels, skunks, and a few raptors. It carries several parasites, both internally and externally. Mus musculus is prone to several diseases, and can spread them to humans (Cory 1912, Jackson 1961, Kurta 1995).

Remarks:

Mus musculus can be confused with genera Peromyscus and Reithrodontomys. Mus musculus can be distinguished by the appearance of the tail and the underbelly is usually never white, the molars are in 3 longitudinal rows of smooth tubular incisors. The other two genera have grooved tubular incisors in longitudinal rows of 2 (Cory 1912).

Literature Cited:

Cory, C.B.  1912.  The Mammals of Illinois and Wisconsin:  176-180.  Chicago.

Kurta, A.  1995.  Mammals of the Great Lakes Region:  183-186.  Michigan: University of Michigan Press.

Jackson, H.H.T.  1961.  Mammals of Wisconsin:  257-261. Madison, WI: University of Wisconsin Press.

Johnson, M.S., S.C. Thomason, and J.R. Speakman.  2001.  Limits to Sustained Energy Intake. Journal of Experimental Biology 204: 1937-1947.

Schmid-Holmes, Sabine, et al.  2001.  Burrows and Burrow- Cleaning Behavior of House Mice ( Mus musculus domesticus).  The American Midland Naturalist 146: 53-62.