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

Resources

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.

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.

IUCN Species Survival Commission, Afrotheria Specialist Group. Web site:

IUCN Red List of Threatened Species—Species information. .

The Life of Mammals, (episode one). BBC Television, 2002

Nowak, R.M. Walker's Mammals of the World Online. Baltimore: John Hopkins University Press, 1995.

[Article by: Derek William Niemann, BA]

The noun has one meaning:

Meaning #1: mole of southern Africa having iridescent guard hairs mixed with the underfur

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)