Golden Moles (Chrysochloridae)

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Golden moles

(Chrysochloridae)

Class Mammalia

Order Insectivora

Family Chrysochloridae

Thumbnail description
Small ears hidden by their fur, short tails, not visible externally; large leathery pads on their noses help them to burrow through the ground; thick, glossy fur, triangular-shaped head with skin covering eyes and leathery pad over nostrils; short, powerful forearms and claws

Size
Head and body length 2.7–9 in (7.0–23.5 cm); weight 0.5–17.6 oz (16–500 g)

Number of genera, species
9 genera; 21 species

Habitat
Burrows beneath a wide range of habitats from sand dunes to tropical forest

Conservation status
Critically Endangered: 4 species; Endangered: 1 species; Vulnerable: 6 species

Distribution
Sub-Saharan Africa

Evolution and systematics

Fossil records for this family date back to the late Eocene (40 million years ago). Traditionally, both golden and "true" moles (Talpidae) have been placed within the order Insectivora. Golden moles have been considered part of a suborder Tenrecomorpha, together with tenrecs.

Molecular studies of phylogenetic relationships now conclude that golden moles fit within a superordinal group called Afrotheria that evolved separately from primitive placental mammals of northern continents. The similarities between moles and golden moles are thus a case of parallel adaptation. Scientists propose that golden moles and tenrecs be placed in an order Afrosoricida—the "African shrew-like mammals."

The family Chrysochloridae is divided into two subfamilies. Chrysochlorinae consists of six genera: Eremitalpa has a single species, Grant's golden mole Eremitalpa granti; Chrysospalax, the giant golden moles, has two species; Chrysochloris, the Cape golden moles, has three species; Cryptochloris, the cryptic golden moles, has two species; Carpitalpa has a single species, Arend's golden mole Carpitalpa arendsi; Chlorotalpa has two species. The subfamily Amblysominae has three genera: Amblysomus, the

narrow-headed golden moles, has five species; Neamblysomus has two species; Calcochloris has three species.

Physical characteristics

Golden moles get their descriptive name from the iridescent golden, blue, purple, or bronze sheen on their brown fur. The skin is tough and loosely attached to the body and the fur has a woolly insulating undercoat.

In common with true moles, golden moles have big shoulders and short, extremely powerful forelimbs, with curved claws suitable for digging. The hind feet have webbed toes, enabling the animals to kick soil backwards effectively. The head, conical in shape, is designed to protect the moles from the substrate through which they push. The nostrils are concealed behind a leathery pad and the vestigial eyes of these blind animals are covered by a thick layer of skin.

Distribution

This is the only mammal family with a southern African center of diversity. Eighteen of the 21 species occur only in southern Africa, with 15 endemic to South Africa. The remaining three species are found in central and east Africa, including Somalia, with A. julianae in southern and eastern Transvaal. Golden moles show a scattered distribution within their range, probably as a result of climatic changes during their evolution which are no longer evident.

Habitat

Although golden moles are adapted for an almost exclusively burrowing lifestyle, they occur in a wide range of habitats. These include sandy deserts, forests, swamps, grassland, and mountains up to 13,000 ft (4,000 m) in altitude.

Behavior

Golden moles are solitary and fight to defend their burrows against intruders of either sex, especially in winter and in less fertile areas where food is in short supply. Dominant individuals may subsume a rival's tunnel within their home range. These animals are, however, tolerant of herbivorous rodents such as mole-rats Bathyergus in their burrows.

Burrowing activity is most intense in summer, when the ground is moist. The moles include chambers for nesting and defecation within their tunnels. The network also features several spiraling bolt-holes, so that the moles can return to the tunnels quickly when surface foraging. These animals have an uncanny ability to head unerringly to a bolt-hole if disturbed, despite being completely blind.

Golden moles have six or seven periods of activity over 24 hours, interspersed with longer spells of rest. Over a considerable temperature range of between 73° and 91°F (23–33°C), they do not regulate their internal body temperature. This thermo-neutrality, together with an unusually low metabolic rate, and an ability to sustain periods of torpidity lasting up to three days, enables golden moles to survive temperature extremes. When torpid, golden moles halve their energy consumption.

Feeding ecology and diet

Golden moles rely on touch, smell and sensitivity to vibration to hunt their food both below and, more rarely, above the soil. Sand-burrowing species, including Grant's golden mole—captured memorably on David Attenborough's Life of Mammals series "swimming" through a sub-surface tunnel—are able to detect vibrations from dune grass in their middle ear. This enables them to head "blind" to vegetation where ants and termites are regular prey. De Winton's golden mole Cryptochloris wintoni surfaces to catch and kill legless lizards (Typhlosaurus) and invertebrates with its front claws.

Foraging behavior is determined by rainfall in other areas. The hottentot golden mole Amblysomus hottentotus eats mainly earthworms and soil insect larvae, taken from burrows near the surface in moist soil, but digs much further underground in dry conditions. Heavy rain and waterlogged burrows force some species to become temporarily terrestrial foragers. Under such conditions, Cape golden moles and giant golden moles root around on the surface for worms and insects.

Reproductive biology

Golden moles are believed to be polygynous and breed during the winter months of April to July. Males and females exchange chirping and squealing calls; the male shakes his head, stamps his feet and pursues the female. Mating generally occurs in the spring, and gestation is believed to last from 4 to 6 weeks. The female makes a grass-lined nest deep in a chamber of her burrow and gives birth to two or three young. She raises the young alone and suckles them for two to three months, then evicts them from her burrow.

Conservation status

Eleven out of 21 species were under threat of extinction, according to the year 2002 IUCN Red List. Destruction of habitat includes poor forestry practices, agricultural development,

livestock overgrazing, and removal of dunes for diamond mining. As human settlements move into golden mole habitats, the animals fall prey to domestic dogs and cats.

Scientists do not fully understand the distribution, status and ecology of this family, because golden moles are crytpic and trap-shy.

Significance to humans

In South Africa, the burrowing activities of golden moles through vegetable plots and grass lawns make them unpopular with some farmers and householders. Many are killed as pests and are sometimes skinned for their glossy fur. Conversely, other farmers appear to favor their presence because of their insect pest diet. Bakiga tribesmen of Uganda use Stuhlmann golden mole Chrysochloris stuhlmanni skins as lucky charms.

Species accounts

List of Species

Hottentot golden mole
Grant's desert golden mole
Large golden mole
Stuhlmann's golden mole

Hottentot golden mole

Amblysomus hottentotus

subfamily

Amblysominae

taxonomy

Amblysomus hottentotus (Smith, 1829), east Cape Province, South Africa.

other common names

English: Narrow-headed golden mole.

physical characteristics

Head and body length 4–5.5 in (10–14 cm); weight 1.4–3.5 oz (40–100 g). Dark red-brown fur, white hairs around ear cavities and vestigial eyes. Four-clawed toes, but mainly digs with only two.

distribution

Southern and eastern South Africa, Lesotho, southern Mozambique.

habitat

Grassland and woodland from sea level to 10,800 ft (3,300 m).

behavior

Some golden moles inhabit areas of peaty soil in mountain or forest regions; others live in escarpment forests, and certain species are favor open areas where there is good grass cover. Some golden moles burrow just below the surface of the ground, while others burrow deeper depending on local soil conditions. In fertile areas, they dig 13 ft (4 m) per day, but in poorer soil they tunnel 40 ft (12.4 m).

feeding ecology and diet

Mainly earthworms and larvae, but also slugs, snails, crickets, and spiders.

reproductive biology

May breed all year round. Known to raise three young per litter.

conservation status

Not threatened.

significance to humans

None known.

Grant's desert golden mole

Eremitalpa granti

subfamily

Chrysochlorinae

taxonomy

Eremitalpa granti (Broom, 1907), Cape Province, South Africa.

other common names

English: Desert golden mole.

physical characteristics

Head and body length 3.0–3.3 oz (7.6–8.6 cm); weight 0.5–1.0 oz (16–32 g). Pale gray-yellow fur covers body and eyes; belly is more yellow.

distribution

Coastal dunes in Cape Province, Little Namaqualand in South Africa, and the Namib Desert.

habitat

Sand dunes.

behavior

Nocturnal. Burrows under sand just below the surface during the day.

feeding ecology and diet

Nocturnal forager in search of termites, ants and spiders. Also eats geckos, beetles, and legless lizards.

reproductive biology

Digs deeper tunnels in which the female raises at least one young. Presumably polygynous.

conservation status

Vulnerable according to IUCN criteria.

significance to humans

None known.

Large golden mole

Chrysospalax trevelyani

subfamily

Chrysochlorinae

taxonomy

Chrysospalax trevelyani (Günther, 1875), Cape Province, South Africa.

other common names

English: Giant golden mole.

physical characteristics

Head and body length 5.0–6.8 in (12.5–17.5 cm); weight 3.8–5.0 oz (108–142 g). Red-brown fur, lighter on belly. Eyes are covered by hairy skin. Nose is tapered and pink.

distribution

Eastern Cape Province, South Africa.

habitat

Flat or gently sloping ground in damp forests.

behavior

Makes small mounds above the entrances to tunnels. The only species to show complex social behavior, because several animals may share burrows in winter.

feeding ecology and diet

Earthworms and other forest invertebrates taken underground. Feeds above ground when tunnels are flooded.

reproductive biology

Probably polygynous or promiscuous. Female raises one or two young in summer.

conservation status

Endangered according to IUCN criteria.

significance to humans

None known.

Stuhlmann's golden mole

Chrysochloris stuhlmanni

subfamily

Chrysochlorinae

taxonomy

Chrysochloris stuhlmanni Matschie, 1894, Ruwenzori region, Uganda.

other common names

None known.

physical characteristics

Head and body length 3.5–5.5 in (9–14 cm); weight 2.6 oz (75 g). Dark brown-green fur, appears iridescent. Front feet have long thick claws, hind feet are webbed.

distribution

Tanzania, Uganda, Kenya, Democratic Republic of the Congo, Cameroon.

habitat

Can live in highland forests up to 9,180 ft (2,800 m).

behavior

Burrows just below surface. May make overland movements at night.

feeding ecology and diet

Invertebrates, especially beetles, larvae, and worms. Forages on surface when soil is waterlogged.

reproductive biology

Two young, raised during rainy season of April–July. Presumably polygynous.

conservation status

Not threatened.

significance to humans

Skins kept as lucky charms in Uganda.

Common name / Scientific name / Other common names	Physical characteristics	Habitat and behavior	Distribution	Diet	Conservation status
Gunning's golden mole Amblysomus gunningi French: Taupe dorée de Gunning	Coloration is very dark, smoky brown with a greenish sheen. Head and body length 3.7–5.7 in (9.5–14.5 cm).	Areas of peaty soil in the sheltered ravines of mountains or in forests, escarpment forests, or open areas with good grass cover. Solitary, no particular breeding season.	South Africa, Transvaal, Woodbush.	Worms, larvae, pupae, and insects.	Vulnerable
Zulu golden mole Amblysomus iris French: Taupe dorée zouloue	Coloration of upperparts is dark reddish brown with a bronze sheen. Head and body length 3.7–5.7 in (9.5–14.5 cm).	Areas of peaty soil in the sheltered ravines of mountains or in forests, escarpment forests, or open areas with good grass cover. Solitary, no particular breeding season.	South Africa, Zululand, Umfolozi Station.	Worms, larvae, pupae, and insects.	Not threatened
Juliana's golden mole Amblysomus julianae French: Taupe dorée de Juliana	Coat is shiny, fur is dense, has streamline, formless appearance. No visible eyes or ears. Head and body length 3.7–5.7 in (9.5–14.5 cm), average weight 0.7–2.6 oz (21–75 g).	Drier uplands in open country with sandy soils. Blind. Usually two young are born, sometimes one. As long as the mole is awake, it keeps moving and this keeps body temperature normal. Sleep may be detrimental, as the mole cools off.	Pretoria, Nylstroom/Nylsvley, and Kruger National Park, Transvaal, South Africa.	Invertebrates, such as crickets, grasshoppers, locusts, cockroaches, earthworms, and snails.	Critically Endangered
Yellow golden mole Calcochloris obtusirostris French: Taupe dorée jaune	Upperparts vary from glossy brown to bright golden yellow. Broad yellow or buffy band across top of snout. Sides of face are yellow. Head and body length 3.8–4.3 in (9.7–10.8 cm), weight 0.07–1 oz (20–30 g).	Sandy soils, sandy alluvium, and coastal sand dunes. Stays in burrow systems most of its life. Will burrow deeper if it hears noise at ground level.	Zululand and eastern Transvaal, South Africa; southern Zimbabwe; and southern Mozambique.	Earthworms and insects.	Not threatened
Congo golden mole Chlorotalpa duthieae French: Taupe dorée de Duthie	Upperparts are very dark brown with a green sheen. Underparts are lighter and sides of face are yellowish. Head and body length 3.7–4.4 in (9.5–11.1 cm).	Alluvial sand and sandy loam in coastal areas. Little is known of behavioral and reproductive patterns.	Southern Cape Province in South Africa.	Mainly earthworms and insects.	Vulnerable
Cape golden mole Chrysochloris asiatica German: Kapgoldmull	Shiny coat of dense fur, giving stream-lined, formless appearance. No eyes or ears visible. Head and body length 3.5–5.5 in (9–14 cm), weight 0.8–1.3 oz (25–35 g).	Species is known only from a single specimen collected at Gouna, 87 km (54 mi) east of Calvinia, Cape Province, South Africa. Behavior likely similar to Amblysomus julianae	Western Cape Province and Robben Island, South Africa; perhaps Damaraland, Namibia.	Earthworms, insects, and snails.	Not threatened
Rough-haired golden mole Chrysospalax villosus French: Taupe dorée ébouriffée; German: Riesengoldmulle	Rough hair, streamlined body. Light brown to buff. No eyes or ears visible. Weight 3.8–5 oz (108–142 g).	Dry grassy habitats, particularly meadow-like ground bordering wet marshes. Spends majority of life in chambers and passages in mounds, connected by a system of tunnels.	Transvaal and Natal, South Africa.	Mainly worms and insects.	Vulnerable
De Winton's golden mole Cryptochloris wintoni French: Taupe dorée de De Winton; German: Der De-Winton-Goldmull	Fur is short, soft, and dense. Upperparts drab lead color with violet iridescence. Underparts are lead gray. Head and body length 3.1–3.5 in (8.0–9.0 cm).	White, coastal sand dunes. Generally burrows below surface.	Little Namaqualand, Cape Province, South Africa.	Legless lizards and various invertebrates.	Vulnerable
Van Zyl's golden mole Cryptochloris zyli French: Taupe dorée de Van Zyl	Flat, round body shape. Fur is short, soft, and dense. Upperparts drab lead color with violet iridescence. White facial markings. Underparts are lead gray. Head and body length 3.1–3.5 in (8.0–9.0 cm).	White, coastal sand dunes. Generally burrows below surface.	Northwestern Cape Province, South Africa.	Legless lizards and various invertebrates.	Critically Endangered

Resources

Books

Apps, P. Smithers' Mammals of Southern Africa. Cape Town, South Africa: Struik Publishers, 2000.

Kingdon, J. The Kingdon Field Guide to African Mammals. San Diego, CA: Academic Press, 1997.

Macdonald, D. The New Encyclopaedia of Mammals. Oxford: Oxford University Press, 2001.

Periodicals

Kuyper, M. A. "The ecology of the golden mole Amblysomus hottentotus." Mammal Review 15, no. 1 (1985): 3–11.

Mason, M. J., and P. M. Narins. "Seismic sensitivity in the desert golden mole Eremitalpa granti: A review." Journal of Comparative Psychology 116, no. 2 (2002): 158–163.

Stanhope, M. J., et al. "Molecular evidence for multiple origins of insectivores and for a new order of endemic African insectivore mammals." Proceedings of the National Academy of Sciences USA 95 (1999): 188–193.