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Georychus capensisblesmoles(Also: Cape mole rat)

By Nicole Whipple

Geographic Range

Cape mole rats are found in the southwestern and southern parts of the Cape of Good Hope Province in South Africa. (Nowak, 1999)

Habitat

Details of the habitat of this species are lacking in the literature. They apparently occur in areas where the soil is hard, and where tubers are available for food. They can be destructive to tuber crops, so they must be found in agrigultural areas. (Nowak, 1999)

Physical Description

Georychus capensis has a body length of 150 to 205 mm with a tail addint and additional 15 to 40 mm. Body mass averages about 181.8 g for males and 180.0 g for females. There is variation, however, and individuals may weigh as much as 350 g. (Nowak, 1999; Reichman and Jarvis, 1989)

These animals have short limbs and a thick-set body. They have long, thick, fluffy pelage that can completely conceal the tail. The tail looks flattened due to hair along the sides. (Nowak, 1999; Reichman and Jarvis, 1989)

They are buff to buff-orange in color with a lighter underside. The hands, feet, and tail of G. capensis are white and they have black or dark brown markings, with white spots on the face. The ears are round with thickened skin and there is a reduction of the eyes, ears and tail due to their fossorial existence. (Nowak, 1999; Reichman and Jarvis, 1989)

The claws are relatively weak (considering they are burrowers) and both the claws and front feet are not well adapted to digging. (Nowak, 1999; Reichman and Jarvis, 1989)

The incisors are used to loosen the dirt and the claws and front feet are used to move the loosened soil. The incisors are prominent and are not grooved. (Nowak, 1999; Reichman and Jarvis, 1989)

It is normal for cape mole rats to have 3 pairs of mammae but 4 are not unusual. (Nowak, 1999)

  • Sexual Dimorphism
  • male larger
  • Average mass
    181 g
    6.38 oz
  • Average mass
    181 g
    6.38 oz
    AnAge
  • Range length
    150 to 205 mm
    5.91 to 8.07 in
  • Average basal metabolic rate
    0.637 W
    AnAge

Reproduction

Information on the mating system of G. capensis is not available. However, the beginning to the breeding season is signaled when males begin drumming. This behavior is apparently intended to signal females. (Nowak, 1999)

Breeding in cape mole rats occurs from August to December. Males call the females by drumming with their hind feet. This drumming usually occurs in June and marks the beginning of the breeding period. Gestation lasts 44 days. Females experience a postpartum estrus and can produce two litters during the season. (Nowak, 1999)

Cape mole rats produce an averag of 5.9 young per litter, although they may produce as few as 3 and as many as 10. Young are unfurred at birth, measure 30 to 40 mm, and weigh between 5 and 12 g. (Nowak, 1999)

The young develop quickly. Their eyes are open and the fur has grown in completely by the age of 9 days. By 17 days of age, young mole rats can eat solid food. Siblings become aggressive to one another, and disperse from their home by 60 days of age. Adult size is reached by the age of 260 days and young of the previous year breed before their first birthday. (Nowak, 1999)

  • Breeding interval
    These animals breed only during the months of August to December, and can produce up to two litters during that time.
  • Breeding season
    Breeding takes place between August amd December.
  • Range number of offspring
    3 to 10
  • Average number of offspring
    5.9
  • Average number of offspring
    5
    AnAge
  • Average gestation period
    44 days
  • Average gestation period
    44 days
    AnAge
  • Average weaning age
    17 days
  • Average time to independence
    60 days
  • Average age at sexual or reproductive maturity (female)
    10 months
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    304 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    10 months
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    304 days
    AnAge

There are usually 3 to 10 young, born naked. The young are 30 to 40 mm long. The are weaned around the time they start eating solid food, at 17 days of age. No reports of male parental care exist, so it is likely that all care comes from the mother, who provides her offspring with protection, grooming, and milk. (Nowak, 1999)

  • Parental Investment
  • no parental involvement
  • altricial
  • pre-fertilization
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female

Lifespan/Longevity

Georychus capensis may live as long as 3 years in the wild. (Nowak, 1999)

Behavior

Cape mole rats are solitary animals as adults. Males and females build separate burrows of which they are extremely defensive. Intruding conspecifics can be detected by changes in air currents. Males use drumming of their hind feet as a territorial signal. Burrow systems of individuals will come close to each other (within one meter) but never intersect. (Mason and Narinsa, 2001; Nowak, 1999)

If strange adults are put together in captivity, they will fight, probably until death unless they are separated. These animals are only social during the reproductive season. (Mason and Narinsa, 2001; Nowak, 1999)

Georychus capensis is mainly a burrowing animal which spends most of its time underground. The incisors are used more for digging than are the claws. Cape mole rats have extensive burrow systems that may underlie 5 to 10 percent of a field. Mounds from excavation of soil may cover 8 to 20 percent of a field. The line of excavation is distinctly marked by the mounds formed where the earth has been thrown out of the burrow by the animal periodically. (Nowak, 1999; Reichman and Jarvis, 1989)

Home Range

The size of a burrow system has not been reported.

Communication and Perception

The most well studied aspect of communication in this species is foot drumming. Foot drumming is used by males to call females during the breeding season, but it can also be used to warn other animals that a burrow is occupied. Foot drumming contains both auditory and seismic components. Seismic vibrations have been shown to propagate at least an order of magnitude better than airborne sound between the burrow systems of G. capensis. It is more sensible that cape mole rats use seismic signals over auditory communication because seismic signals travel better and farther underground. It is not know how detection of seismic waves is accomplished in this species, although it is theorized that it is a form of bone conduction. Vocal communication is used, but usually only when the animals are in close proximity to each other. (Mason and Narinsa, 2001)

Chemical signaling and the sense of smell are probably used as well. Tactile communication occurs between mates, rivals, and between mothers and their young. Although this species has eyes, it is unlikely, given their fossorial existence, that they use many visual signals in communication.

Food Habits

The diet of cape mole rats consists almost exclusively of below ground plant parts, although they have been know to ingest insects, especially ants. The main burrow of G. capensis is used for food storage of tubers, roots, and bulbs. Cape mole rats have been know to bite off the buds of bulbs and tubers to stop them from growing. (Nowak, 1999; Reichman and Jarvis, 1989)

  • Primary Diet
  • herbivore
    • eats sap or other plant foods
  • Animal Foods
  • insects
  • Plant Foods
  • roots and tubers

Predation

No information could be found on predation in cape mole rats. It is likely that these animals do experience predation, probably by snakes, or by other animals capable of entering their burrows or digging them up.

Ecosystem Roles

Cape mole rats feed on tubors and roots and may affect plant communities. Their burrowing behavior probably helps to aerate the soil. (Nowak, 1999)

Economic Importance for Humans: Positive

No information could be found on economic importance of cape mole rats.

Economic Importance for Humans: Negative

Cape mole rats can have a negative impact on agricultural fields and crops. (Nowak, 1999)

  • Negative Impacts
  • crop pest

Conservation Status

Cape mole rats are not listed by IUCN or CITES.

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Nicole Whipple (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Innvista. 2002. "Bathyergidae" (On-line). Invista. Accessed June 01, 2004 at http://www.innvista.com/science/zoology/mammals/bathyerg.htm.

Lovegrove, B., M. Papenfus. 1995. Circadian body rhythms in the solitary cape molerat (Georychus capensis) with some evidence of splitting. Physiology and Behavior, 58/4: 679-685.

Mason, M., P. Narinsa. 2001. Seismic signal use by fossorial mammals. American Zoologist, 41/5: 1171-1184.

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

Reichman, O., J. Jarvis. 1989. The influence of three sympatric species of fossorial mole-rats (Bathyergidae) on vegetation. Journal of Mammalogy, 70/4: 763-771.

van der Merwe, M., A. Bothe. 1998. Incisors as digging tools in molerats (Bathyergidae). Southern Africa Journal of Zoology, 33/4: 230-234.

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