Cactus mouse

Cactus mouse
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Family:	Cricetidae
Subfamily:	Neotominae
Genus:	Peromyscus
Species:	P. eremicus
Binomial name
Peromyscus eremicus (Baird, 1858)
Cactus mouse range in North America

The cactus mouse (Peromyscus eremicus) is a species of rodent in the family Cricetidae. It is one species of a closely related group of common mice often called deer mice. They are native to desert areas of western North America.^[2]

Description[]

Cactus mice are small cricetid rodents, with large eyes and ears, a pointed snout, and a long monocolor tail. Adults weigh between 18 and 40 grams (0.63 and 1.41 oz). Females weigh slightly more than males and are significantly larger in body length, ear length, length of mandible, and bullar width of skull.

Cactus mice can be identified by having naked soles on their hind feet and almost naked tails, which are usually the same length or longer than the animals' body length. Their ears are nearly hairless, large, and membranous. Their fur is long and soft; coloration varies between subspecies and between different populations.

Color of fur varies from ochre to cinnamon, with white ventral areas, and the sides and top of head slightly grayish.^[3] Females tend to be slightly paler in color than males, while juveniles appear more gray than their parents.

Distribution and diet[]

Cactus mice are found in dry desert habitats, steppe, and mountain foothills in arid regions of the southwestern United States and northern Mexico, as well as islands off the coast of the Baja California peninsula and in the Gulf of Mexico.^[4][5] Low average temperatures and lack of mesquite (Prosopis juliflora) might limit northern expansion.^[3] The cactus mouse occurs sympatrically with four other mice species, including the California mouse, canyon mouse, Eva's desert mouse, and mesquite mouse. The cactus mouse feeds on seeds, mesquite beans, hackberry nutlets, insects, and green vegetation.^[3] Specimens from Southern California have tested positive for hantavirus, however, infections in this species are likely incidental and localized, rather than a common reservoir.^[6]

Behavior[]

Cactus mice, like most muroids, are mainly nocturnal. They have been described as "shy and excitable, and seldom bites when handled". In laboratory studies, cactus mice average a running speed of 13.1 miles per hour (21.1 km/h).^[7]

Compared to other Peromyscus species, cactus mice have a lower metabolism. This is thought to be an adaptation to arid environments, and maintained by lower activity of the thyroid gland. They may enter torpor when deprived of food in the winter, and food and/or water in the summer. Below 15 °C (59 °F), they enter torpor more slowly, which may partially explain their southern distribution. In the laboratory, onset of torpor was observed to occur within half an hour of food deprivation.^[7]

They are important as seed predators and as food for other animals.^[7]

Reproduction[]

The mating habits of cactus mice are currently not well studied, but are inferred from other Peromyscus species to be promiscuous. They mate year around, but more so during warmer months. Unlike other muroids, male cactus mice have a simple penis, rather than a complex one, and females have two pairs of teats, rather than three. The number of teats in the female cactus mouse correlates with the number of offspring they can raise in their arid environment. Females mate after about two months, however, male sexual maturity age is unknown.^[7]

Relationship with humans[]

Cactus mice are ideal laboratory animals since they keep clean, live well in captivity, and have a high rate of productivity. They have been proposed for physiological and genetic studies. There are no known negative effects on humans or human-related activities.^[7]

References[]

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