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Eremitalpa grantiGrant's golden mole

By Jason Roth

Geographic Range

Grant’s golden mole, Eremitalpa granti, is confined to a small section of southwestern Africa, inhabiting southwestern Cape Province and Little Namaqualand in South Africa northward to the Namib Desert in Namibia. The subspecies Eremitalpa granti granti occurs south of Helena Bay to Port Nolloth, while Eremitalpa granti namibensis is found north of the Orange River in the Namib Desert of Namibia. (British Broadcasting Corporation, 2003; Macdonald, 2001; Mills and Hes, 1997; Nowak, 1999; Perrin and Fielden, 1999; Roberts, 1951; Shackleton and Harestad, 2003; Smithers, 1983)

Habitat

Grant’s golden moles dwell in one of the driest and least productive habitats in the world. They are confined to white coastal sand dunes and does not range far inland due to the firmer, more consolidated soil. In Namaqualand they are found on coastal dunes with loose sand and karoo, while in the Namib desert it prefers dunes with scattered clumps of dune grass, Aristida sabulicola, and dry river beds with Acacia stands. (Insectivore Specialist Group, 1996; Mills and Hes, 1997; Nowak, 1999; Roberts, 1951; Seymour, et al., 1998; Smithers, 1983)

Physical Description

Eremitalpa granti is the smallest of all members in the family Chrysocholoridae, with a head and body length and mass ranging from 70 to 85 mm and 16 to 32 g, respectively. There is a degree of sexual dimorphism, with males averaging 73.5 mm and 25.3 g, and females averaging 66.8 mm and 19.8 g. Grant’s golden moles are fusiform, but dorsoventrally flattened, and they lack an external tail. Their fur is softer and generally longer than any other golden mole, although its length may vary seasonally. Hairs on the back generally measure 12 mm and are pale grayish-yellow with a silvery sheen. Hairs on the side are about 20 mm and are paler with a stronger yellow tinge in comparison to the upper hairs. The face and underside are paler to buffy white. Subadults may have a more gray coat and possess pale cheek markings. Eremitalpa granti has short and strong limbs that are medially situated beneath the body. Its foreclaws on the first, second, and third digits are extremely broad, long, and hollowed out underneath – an adaptation for digging. It is the only golden mole that possesses a well-developed fourth claw. Its hind feet are webbed and have a prominent thickened pad placed slightly in front of the heel that is not found in other species. Grant’s desert golden moles lack external eyes, the eyelids fusing at a young age with the skin covering the eyes then increasing in thickness. Their noses terminate in a hard leathery pad which aids in digging while at the same time keeps sand out of the nostrils. The skull of E. granti is distinguishable from Chrysochloris asiatica in that it is smaller, broader, has no temporal bullae, and its first premolar is single-rooted. Its skull length is less than 20.6 mm, its width ranges from 16.0 to 18.2 mm, and its dental formula is 3/3, 1/1, 3/3, 3/3.

Subspecies are generally distinguished by body size, skull dimensions, and hair length. Eremitalpa granti namibensis is often slightly smaller in size with shorter, more colored hair, and a shorter and broader skull than Eremitalpa granti granti. (British Broadcasting Corporation, 2003; Mills and Hes, 1997; Nowak, 1999; Perrin and Fielden, 1999; Roberts, 1951; Shackleton and Harestad, 2003; Smithers, 1983; Stuart, 1995)

  • Sexual Dimorphism
  • male larger
  • Range mass
    16 to 32 g
    0.56 to 1.13 oz
  • Range length
    70 to 85 mm
    2.76 to 3.35 in

Reproduction

Very little is known about the reproduction of E. granti. It is presumably polygnous with seasonal breeding. (British Broadcasting Corporation, 2003; Mills and Hes, 1997; Shackleton and Harestad, 2003; Stuart, 1995)

Meager reproductive records exist for E. granti and authorities disagree on certain aspects such as nest sites/chambers.

Breeding is believed to occur in October and November. The gestation period is not known specifically for E. granti, but for golden moles in general, it is believed to be 4 to 6 weeks. The sand E. granti inhabits is too loose for the construction of nesting chambers common to other moles. Thus, it is debated as to where E. granti gives birth to and raises young. Grant’s desert golden moles burrow down to depths of 50 cm where they rest during the day. Some authorities speculate they give birth in these resting burrows. However, Fielden (1991), reported the excavation of more than 100 rest sites in which no evidence of nest material, permanent burrows, chambers, or tunnel construction was found. Eremitalpa granti is believed to give birth to one to two naked, virtually helpless young. In general, golden moles are believed to wean their young after 2 to 3 months at which time the young are forced to fend for themselves. (British Broadcasting Corporation, 2003; Fielden, 1991; ; Mills and Hes, 1997; Nowak, 1999; Perrin and Fielden, 1999; Shackleton and Harestad, 2003; Smithers, 1983; Stuart, 1995)

  • Breeding season
    October and November
  • Range number of offspring
    1 to 2
  • Range gestation period
    4? to 6? weeks
  • Range weaning age
    2? to 3? months
  • Range time to independence
    2? to 3? months

Very little is known. It is presumed that the mother provides young with food while they mature. For golden moles in general, it is believed that the mother alone rears the young and suckles them for 2 to 3 months. One source suggests that the young of E. granti are evicted from mother's area when they weigh approximately 35 to 45 g. (British Broadcasting Corporation, 2003; Mills and Hes, 1997; Shackleton and Harestad, 2003; Smithers, 1983)

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

Lifespan/Longevity

Unknown ()

Behavior

Eremitalpa granti is solitary and considered nocturnal. It does not maintain a permanent tunnel system like most moles because the sand it burrows through collapses behind it. Therefore, it is considered by many to be a sand swimmer, constructing new burrows each time it moves. During the day, E. granti burrows to depths of 50 cm and there enters a daily torpor. In these "rest sites," E. granti does not regulate its body, but lowers its metabolism, thus reducing its energy demands. Due to the high energy demands of burrowing in an energy poor environment, this proves to be a vital adaptation. Foraging occurs at night on the surface. Grant's desert golden moles' foraging behavior consists of running on the surface of dunes and periodically dipping underneath the surface using its seismic sensitivity to detect the location of prey. Some individuals have been known to travel up to 5800 m while foraging. (British Broadcasting Corporation, 2003; Cowley, 2004; Insectivore Specialist Group, 1996; Mason and Narins, 2002; Mills and Hes, 1997; Nowak, 1999; Perrin and Fielden, 1999; Seymour, et al., 1998; Smithers, 1983)

Home Range

Eremitalpa granti maintains a relatively constant home range. The mean home range is 4.63 ha, with males having slightly larger home ranges than females. Home ranges generally overlap spatially, while the degree of temporal overlap is yet to be quantified. (Fielden, 1991; Perrin and Fielden, 1999)

Communication and Perception

Eremitalpa granti has extremely sensitive hearing and vibration detection. Morphological analysis of the middle ear has revealed a massive malleus which likely enables E. granti to detect seismic cues. Eremitalpa granti uses this seismic sensitivity to detect prey as well as to navigate when burrowing through sand. While vibrations are used over long distances to detect prey, smell is possibly used over shorter distances.

Eremitalpa granti is seldom vocal, though it does chirrup occasionally and does shriek when agitated. It also has been known to squeal and chirrup during courtship. (British Broadcasting Corporation, 2003; Mason and Narins, 2002; Mills and Hes, 1997; Perrin and Fielden, 1999)

Food Habits

Eremitalpa granti feeds mainly on sand dwelling invertebrates. Termites, Psammotermes allocercus, constitute the majority of its diet. Other invertebrates it consumes are crickets, beetles, ants, moths, spiders, and mealybugs. Eremitalpa granti also eats the web-footed gecko, Pelmatogecko rangei, and legless lizards. (Cowley, 2004; Fielden, et al., 1990; ; Mills and Hes, 1997; Nowak, 1999; Perrin and Fielden, 1999; Shackleton and Harestad, 2003; Stuart, 1995)

  • Animal Foods
  • reptiles
  • insects
  • terrestrial non-insect arthropods

Predation

Due to the nocturnal surface foraging of E. granti, it is often exposed to nocturnal predators. (; Perrin and Fielden, 1999; Smithers, 1983)

Ecosystem Roles

Grant’s desert golden mole plays an important role in controlling desert invertebrate and insect populations. The control of herbaceous insects is particularly helpful for the dune grass Aristida sabulicola. Specifically, termite populations are directly affected by the foraging of E. granti in that termites constitute more than 50% of the mole’s diet. Eremitalpa granti also is an important food source for birds of prey and biodegrading invertebrates. Lastly, the disturbing of the soil via burrowing may prove beneficial for certain reptiles and invertebrates. (Cowley, 2004; Fielden, et al., 1990; ; Mills and Hes, 1997)

Economic Importance for Humans: Positive

Due to E. granti living in such a harsh habitat, it does not have a significant direct impact on humans. Its control of potential pest populations such as termites may be of some economic value. The long, soft, iridescent fur of E. granti may also possess some economic value. (Cowley, 2004; Fielden, et al., 1990; ; Mills and Hes, 1997; Nowak, 1999; Shackleton and Harestad, 2003; Stuart, 1995)

Economic Importance for Humans: Negative

Habitat fragmentation and dune removal by diamond mining poses one of the greatest threats to E. granti. Thus, conservation of the species and restrictions on mining could directly affect the jobs of some people. (Insectivore Specialist Group, 1996; Mills and Hes, 1997; Nowak, 1999)

Conservation Status

Eremitalpa granti is currently listed as vulnerable according to IUCN criteria. Its greatest threat is habitat destruction and fragmentation by dune removal and diamond mining. They are also preyed upon by domestic cats and dogs.

Eremitalpa granti is protected within the Namib Desert National Park in Namibia. However, it is not currently protected in any parts of South Africa. Therefore, the establishment of the proposed Groen River National Park in South Africa is a conservation priority because it would help protect some of the limited habitat of E. granti. (British Broadcasting Corporation, 2003; Mills and Hes, 1997; Nowak, 1999; Shackleton and Harestad, 2003)

Other Comments

Eremitalpa granti, is commonly referred to as Grant’s desert golden mole, or Grant’s golden mole. Some authorities recognize two subspecies of Eremitalpa granti: Grant’s golden moles, Eremitalpa granti granti, and Namib golden moles, Eremitalpa granti namibensis. This report follows authorities that refer more broadly to both subspecies as Eremitalpa granti, though at times some distinguishing information may be provided for each subspecies.

Eremitalpa granti was first discovered by the examination of fecal pellets belonging to Tyto alba. (British Broadcasting Corporation, 2003; Macdonald, 2001; Mills and Hes, 1997; Nowak, 1999; Perrin and Fielden, 1999; Roberts, 1951; Shackleton and Harestad, 2003; Smithers, 1983)

Contributors

Matthew Wund (editor), University of Michigan-Ann Arbor.

Jason Roth (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Ethiopian

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

World Map

acoustic

uses sound to communicate

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.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

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.

insectivore

An animal that eats mainly insects or spiders.

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.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynous

having more than one female as a mate at one time

seasonal breeding

breeding is confined to a particular season

sexual

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

solitary

lives alone

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).

terrestrial

Living on the ground.

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

vibrations

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

viviparous

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

References

British Broadcasting Corporation, 2003. "Grant's golden mole" (On-line). BBC - Science & Nature. Accessed March 17, 2004 at http://www.bbc.co.uk/nature/wildfacts/factfiles/print/641.shtml.

Cowley, C. 2004. "Mammals and Reptiles" (On-line). Clive Cowley's Journey into Namibia. Accessed March 17, 2004 at http://www.orusvo.com/guidebook/content8.htm.

Fielden, L. 1991. Home range and movements of the Namib Desert golden mole Eremitalpa granti namibensis (Chrysochloridae).. Journal of Zoology, 223: 675-686.

Fielden, L., M. Perrin, G. Hickman. 1990. Feeding ecology and foraging behaviour of the Namib Desert golden mole, Eremitalpa granti namibensis (Chrysochloridae).. Journal of Zoology, 220: 367-389.

Insectivore Specialist Group, 1996. "Species Information" (On-line). The IUCN Red List of Threatened Species. Accessed March 14, 2004 at http://www.redlist.org/search/details.php?species=7994.

Macdonald, D. 2001. Golden Moles. Pp. 748-749 in G Bateman, T Allan, M Salad, eds. The New Encyclopedia of Mammals. New York: Oxford University Press.

Mason, M., P. Narins. 2002. Seismic Sensitivity in the Desert Golden Mole (Eremitalpa granti).. Journal of Comparative Psychology, 116/2: 158-163.

Mills, G., L. Hes. 1997. The Complete Book of Southern African Mammals. Cape Town 8001: Struik Publishers.

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

Perrin, M., L. Fielden. 1999. Eremitalpa granti. Mammalian Species, 629: 1-4.

Roberts, A. 1951. The Mammals of South Africa. New York: The Trustees of "The Mammals of South Africa" Book Fund. Hafner Publishing Company.

Seymour, R., P. Withers, W. Weathers. 1998. Energetics of burrowing, running, and free-living in the Namib Desert golden mole (Eremitalpa namibensis). Journal of Zoology, 244/1: 107-117.

Shackleton, D., A. Harestad. 2003. Golden Moles (Chrysochloridae). Pp. 215-223 in M Hutchins, D Kleiman, V Geist, M McDade, eds. Grzimek's Animal Life Encyclopedia, Vol. 13, 2nd Edition. Farmington Hills, MI: Gale Group.

Smithers, R. 1983. The Mammals of the Southern African Subregion. Pretoria, Transvaal, Republic of South Africa: University of Pretoria.

Stuart, C. 1995. Chris and Tilde Stuart's Field Guide to the Mammals of Southern Africa. Cape Town 8001: Struik Publishers (Pty) Ltd.

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