Mystromyinae

Diversity

Mystromyinae is an Old World nesomyid subfamily that has a single genus and species, the white-tailed mouse ( Mystromys albicaudatus ).

Geographic Range

Mystromys albicaudatus is found in South Africa and Swaziland.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

These rodents inhabit dry savannahs and semidesert.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland

Physical Description

White-tailed mice are rat-like in overall appearance, with slender limbs and large, prominent ears. Their long, soft fur ranges from brown to buffy-gray on the dorsal surface, with interspersed black-tipped hairs. The ventral surface, feet, and tail are white, and the ears are dark brown. The tail is covered with stiff, short hairs. The head and body length of white-tailed mice ranges from 105 to 184 mm, and the tail length ranges from 50 to 97 mm. They weigh 75 to 111 grams, males tend to be about 20 grams heavier than females (Becker and Middleton 1979). The incisors of mystromyines are pale yellow and the surfaces lack grooves. Mystromyines have no cheek pouches, and they have two pairs of inguinal mammae.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

The mating system of white-tailed mice has not been studied in the wild; however, in captivity, white-tailed mice form monogamous pairs that share in the task of raising offspring.

• Mating System
• monogamous monogamous

Mystromyines breed year-round. Females give birth to an average of three young per litter, after a gestation of about 37 days. The young are altricial; they are born hairless, with their eyes and ears sealed shut, and with their toes fused together. Their ears open after three to four days, and their incisors erupt at about the same time. Their toes separate between 9 and 11 days after birth, and their eyes open at 16 to 20 days. The young can crawl with difficulty at birth, becoming more accomplished by the time they are five to six days old. They can walk by day 20 and run by day 24. The young groom themselves at day 21, and begin eating solid food at day 20. By day 38, the young are completely weaned. Females attain sexual maturity at about five months.

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Young white-tailed mice cling to the nipples of their mother almost continuously for the first three weeks of life. She drags them around with her when she forages. After three weeks, they separate from her for longer and longer periods, and she stops nursing them after another two and a half weeks. Females groom their young, especially after a disturbance. Both males and females carry their young immediately after parturition and protect their young by sheltering them with their bodies and trying to bite intruders.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • male
    • female

Lifespan/Longevity

White-tailed mice live to about six years in captivity; lifespan in the wild has not been reported.

Behavior

White-tailed mice are nocturnal, strictly terrestrial rodents that rest by day in holes or cracks in the ground. Sometimes they shelter in meerkat burrows. They are reportedly most active when it rains.

• Key Behaviors
• terricolous
• nocturnal nocturnal
• motile motile

Communication and Perception

White-tailed mice probably have keen olfactory and auditory abilities, as they have been observed rearing up on their hind legs and sniffing when disturbed. Young mystromyines probably have good senses of smell and touch from birth. They squeal when they are separated from their parents and begin responding to sound at 13 to 15 days of age.

• Communication Channels
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Mystromyines eat insects, seeds, and other plant matter. In captivity, they will eat meat and carrots. Adults have also been observed eating the carcasses of dead offspring.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • scavenger scavenger
• herbivore herbivore
  • granivore granivore
• omnivore omnivore

Predation

Barn owls ( Tyto alba ) are reported predators of white-tailed mice. Other likely predators include other owl species, snakes , and nocturnal mammalian predators Young white-tailed mice cling to the nipples of their mothers continuously for the first few weeks of life, which increases their chance of survival because adult females can more easily evade predators than can immobile neonates. Even after they are no longer nursing constantly, youngsters seek shelter under their parents when alarmed. Parents sometimes defend their offspring by biting viciously.

Ecosystem Roles

Because they are omnivores, mystromyines are primary and higher-level consumers. They are also food for animals at higher trophic levels, such as barn owls .

Economic Importance for Humans: Positive

White-tailed mice are easy to breed in captivity and are therefore used in laboratories for disease research.

• Positive Impacts
• research and education

Economic Importance for Humans: Negative

There are no known negative effects of white-tailed mice on humans.

Conservation Status

White-tailed mice are currently considered endangered by the IUCN; though their range is relatively large, population density is low and populations are highly fragmented. There are protected areas in some parts of the species' range, but habitat loss to grazing, agriculture, and timber plantations is a major threat. Surveys of white-tailed mouse populations and research into their life history characteristics are needed, as is public awareness about their plight.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Allison Poor (author), University of Michigan-Ann Arbor.

References

Becker, S., C. Middleton. 1979. Organ weights and organ body weight ratios of the African white-tailed rat (Mystromys albicaudatus). Laboratory Animal Science , 29(1): 44-47.

Carleton, M., G. Musser. 1984. Muroid rodents. Pp. 289-379 in Orders and Families of Recent Mammals of the World . New York: John Wiley and Sons.

Coetzee, N., A. Monadjem. 2004. "Mystromys albicaudatus" (On-line). 2004 IUCN Red List of Threatened Species. Accessed July 05, 2005 at www.redlist.org .

DeGraaff, G. 1997. White-tailed rat Mystromys albicaudatus. Pp. 156 in The Complete Book of Southern African Mammals . Cape Town: Struik Publishers.

Ellerman, J. 1941. The Families and Genera of Living Rodents, vol. II . London: British Museum (Natural History).

Hallett, A., J. Meester. 1971. Early postnatal development of the South African hamster Mystromys albicaudatus. Zoologica Africana , 6(2): 221-228.

Jansa, S., M. Weksler. 2004. Phylogeny of muroid rodents: relationships within and among major lineages as determined by IRBP gene sequences. Molecular Phylogenetics and Evolution , 31: 256-276.

Lavocat, R. 1973. Les rongeurs du Miocene d'Afrique Orientale. Memoires et Travaux de l'Ecole Pratique des Hautes Etudes, Institut de Montpellier , 1: 1-284.

Michaux, J., A. Reyes, F. Catzeflis. 2001. Evolutionary history of the most speciose mammals: molecular phylogeny of muroid rodents. Molecular Biology and Evolution , 18(11): 2017-2031.

Musser, G., M. Carleton. 1993. Family Muridae. Pp. 501-573 in Mammal Species of the World . Washington, D.C.: Smithsonian Institution Press.

Musser, G., M. Carleton. 2005. Superfamily Muroidea. Mammal Species of the World . Baltimore and London: The Johns Hopkins University Press.

Nowak, R. 1999. Walker's Mammals of the World, vol. II . Baltimore and London: The Johns Hopkins University Press.

Skinner, J., R. Smithers. 1990. The mammals of the southern African subregion . Republic of South Africa: University of Pretoria.

Vorontsov, N. 1966. Taxonomic position and a survey of the hamsters of the genus Mystromys Wagn. (Mammalia, Glires). Zoologicheskii Zhurnal , 45: 436-446.