Gymnures and hedgehogs

(Erinaceidae)

Class Mammalia

Order Insectivora

Family Erinaceidae

Thumbnail description
Small, short-legged animals, five toes on each foot, gait plantigrade; muzzle generally pointed, moderately to greatly elongate, eyes small; pelage may be spiny (hedgehogs) or soft (gymnures)

Size
Head and body length: 4–12 in (10–30 cm); tail:0.4–12 in (1–30 cm); weight: 0.5–38 oz (15–1,100 g)

Number of genera, species
8 genera; 21 species

Habitat
Varies from woodland to grassland, deserts and urban parks for hedgehogs; gymnures restricted to humid forests and meadows

Conservation status
Critically Endangered: 1 species; Endangered: 3 species; Vulnerable: 2 species; Lower Risk/Near Threatened: 1 species

Distribution
Europe, Asia, and Africa

Evolution and systematics

Erinaceidae is a small family, containing just 21 species. The fossil record is rather sparse, with a further 21 extinct species described so far. The family appears to have its origins in North America in the mid Palaeocene, about 60 million years ago (mya). American erinaceids went extinct about 5 mya, but not before further lineages had been established in Europe, Asia, and Africa (about 58, 55, and 23 mya respectively).

Modern erinaceids are split into two quite distinct subgroups, the spiny hedgehogs (subfamily Erinaceinae) and the soft-furred gymnures (known most correctly as subfamily Hylomyinae, but also often referred to as Echinosorinae or Galericinae). Within the hedgehogs there are 14 species in five well-described genera. The taxonomy of the gymnures is rather less clear-cut. There are seven species, including the long-eared lesser gymnure (Hylomys megalotis), which was described in 2002. Prior to 1991, there were five recognized genera, but Neohylomys and Neotetracus have since been reclassified as subgenera of Hylomys. As of 2002, Hylomys is the largest genus in the family with five species, but these are highly variable and the expectation is that further revisions will come.

Physical characteristics

The characteristics that describe members of the family Erinaceidae are generally considered primitive. They are typical insectivores—small animals, with short legs and large feet. Feet have five digits, except in some of the African hedgehogs (genus Atelerix) in which the hallux or big toe is reduced or vestigial. All erinaceids walk with a flat-footed "plantigrade" gait. The two bones of the lower hind leg, the tibia and fibula, are fused into one. The tail is hairy and variable in length, the muzzle is elongated—more so in the gymnures than the hedgehogs. The eyes are small, though better developed than those of most other insectivores. The skulls of hedgehogs and gymnures vary quite considerably, from long and narrow to short and broad. All have a small braincase.

As a general rule, hedgehogs are more derived than gymnures, which have retained many characteristics of their early insectivore ancestors. The most obvious difference between the two subfamilies is the coat. While the gymnures and moonrats are covered in pelage of soft fur, the hedgehogs sport a dense coat of narrow spines, starting on the head and covering the back and flanks. The color varies between and within species, but is usually some shade of yellow- or grayish brown to black.

Hedgehogs and gymnures have similar dentition. The dental formula for the family is (I2–3/3 C1/1 P3–4/2–4 M3/3) × 2 = 63–44. The first incisors are large. In gymnures, there are three pairs of incisors in each jaw, while hedgehogs have lost the third lower pair. The muzzle or rostrum of hedgehogs is shorter than in the gymnures, which have retained a narrow, shrew-like snout.

Distribution

The Erinaceidae is now an exclusively Old World family, with representatives throughout Europe, Asia, and Africa. There is also a pronounced geographical demarcation between the two subfamilies—the Erinaceinae (hedgehogs) are widespread, but except for the Chinese hedgehog (Erinaceus amurensis), they are not found with the Hylomyinae (gymnures and moonrats). The latter are restricted to Southeast Asia. Hedgehogs fare well in cool temperate to tropical climates between about 66°N (Erinaceus europaeus) and 34°S (Atelerix frontalis). The gymnures are essentially a tropical and subtropical group, but they live in a wide range of altitudes, from sea level to 11,000 ft (3,400 m) (Hylomys suillus).

Habitat

As a group of small, "primitive" animals, the erinaceids, and especially the hedgehogs, exploit a surprising diversity of habitats, from mangrove forest to stony desert, urban parks to alpine meadows. In all cases, the main limiting factors are the availability of suitable daytime shelters and food—especially of invertebrate prey. A hedgehog has a fairly small home range with an approximate 120-yd (110-m) radius from its nest. The nest is built in dry litter under tangles of hedge or bush, rock crevices, termite mounds or underbuildings. The hedgehog chatters, snorts or softly growls if its range is invaded by another animal. The gymnures live predominantly in humid forests, but this is more indicative of the availability of suitable food in such places than of their intolerance of dry habitats.

Behavior

For the most part, erinaceids are nocturnal; although the Malayan moonrat (Echinosorex gymnura) and lesser gymnure (Hylomys suillus) may also forage by day. Species living in temperate zones may be forced to begin foraging before sunset in mid-summer. As a general rule, erinaceids are terrestrial, living and feeding at ground level. Most are competent climbers and swim well—E. gymnura may even be least partially aquatic. Digging ability varies, but some species, such as the Indian and the long-eared hedgehogs (Paraechinus micropus and Hemiechinus auritus) are very good burrowers.

Most members of the Erinaceidae are able to enter torpor and thus tolerate bad weather and seasonal food shortages by hibernating in winter or estivating during droughts. Hibernation of the European hedgehog, (Erinaceus europaeus), in colder parts of its range may last six or seven months, during which the heart rate drops from about 188 beats per minute to around 22, and body temperature may fall to just 1°C (34°F). Prolonged hibernation puts enormous strain on the animals reserves of stored fat and those that do not put on enough weight in the fall will not survive.

All the well-studied species are essentially solitary and territorial as adults. Small groups of three or four have been reported for some species, but these probably represent females with subadult young of the year. Fights are seemingly rare, but individuals may react aggressively to threats, giving rapid hissing snorts. Interestingly, an almost identical sound is produced

by female hedgehogs during courtship, presumably in response to close approach of another individual, the male.

All erinaceids use scent to mark their home range, but olfactory cues appear to be particularly important for the gymnures, several of which have a strong musky odor that is obvious even to the human nose. Among the other senses, hearing is apparently most sensitive, while eyesight is not particularly acute. One of the most distinctive and unusual aspects of erinaceid behavior is "self-anointing," an activity performed by all species of hedgehog. Apparently triggered by olfactory cues such as strong-smelling or noxious plants or chemicals, this behavior starts with the animals licking or chewing the source of the smell, and producing copious amounts of frothy saliva. The saliva (and presumably with it the chemical trigger, whatever it may be) is then spread over the spines with quick flicks of the tongue and distinctive jerking movements of the head. Presumably the spines provide a surface area from which scent can be dispersed, but so far there is no really satisfactory explanation for the function of self-anointing. Theories range from attracting mates to deterring predators or repelling parasites, but none stand up to rigorous investigation or satisfactorily account for the diversity

of trigger substances or the wide range of situations in which animals will suddenly devote all their attention to this odd behavior.

Gymnures are relatively secretive animals, while hedgehogs, with the benefit of their spiny defenses, are more bold. When a hedgehog is threatened, it curls itself into a tight ball by means of well-developed abdominal muscles that act like the cord on a drawstring bag. The head, feet and tail are all tucked away and the spines are erected, presenting a potential predator with nothing but a puzzling spiky ball. Some predators, including badgers and foxes, learn the art of unrolling hedgehogs and may become specialist hedgehog eaters.

Feeding ecology and diet

All hedgehogs and gymnures feed primarily on insects and other invertebrates including worms, spiders, and terrestrial mollusks. Being larger than most other members of the order Insectivora, some are also able to take some larger prey, including reptiles, amphibians, and in some cases small mammals. Hedgehogs are also rather notoriously fond of birds' eggs—the introduction of the European hedgehog to islands including New Zealand has proved disastrous for populations of ground nesting birds. Most species will also consume non-animal matter such as fruit, seeds, and fungi.

Several species of hedgehog sometimes eat venomous animals such as vipers, scorpions, and bees, as well as toxic beetles and spiders, with no apparent ill effects. Their resistance to adder venom can be up to 40 times that of laboratory mice, and they can consume the beetle toxin cantharidin in quantities equivalent to 3,000 times the dose toxic to humans.

Feeding takes place predominantly at night, when the animals may travel some distance along regular pathways, shoving their noses into nooks and crannies and rummaging about in the leaf litter, or sometimes digging into the top layer of soil. Most food is eaten as and when the animal finds it but the Indian hedgehog (Paraechinus micropus) is known to hide excess food in its burrow as an insurance policy against future shortages.

Reproductive biology

Female erinaceids have between two and five pairs of mammae (a maximum of four pairs in the gymnures). Thus the theoretical maximum litter size is 10, but in reality they average between two and five young per litter. Gestation periods range between 30 and 40 days and the young are born blind, helpless, and virtually naked. In the hedgehogs, the first

spines may erupt before birth but they are very soft and unpigmented. Adult-type spines usually begin to grow within the first week of life, and the curling response develops within a few weeks. Care of the young is always the sole responsibility of the mother—males play no part beyond courtship and mating, which is polygynous. The suckling period in hedgehogs is between five and seven weeks, and longevity is up to seven years.

Conservation status

Of the 22 species in the family Erinaceidae recognized here, three are officially threatened. Hugh's hedgehog (Mesechinus hughi) is listed as Vulnerable by the IUCN, the Hainan gymnure (Hylomys hainanensis) and both species of Philippine gymnure (Podogymnura truei and P. aureospinula) are Endangered. The IUCN regards Hylomys suillus parvus as a full species and lists it as Critically Endangered, as well as listing Hemiechinus nudiventris as Vulnerable and Hylomys sinensis as Lower Risk/Near Threatened. The chief threats to these species are habitat fragmentation and modification, for example, logging and agricultural development. The southern African hedgehog (Atelerix frontalis) is considered Rare and is listed on Appendix 2 of the CITES in order to prevent uncontrolled collection for the pet trade.

Significance to humans

Erinaceids have little economic importance. As a group, the gymnures are not well known and have little use to humans save occasional use in laboratory experiments. Hedgehogs, on the other hand, have been used to a limited extent by humans throughout history. The meat of hedgehogs is good, but while most species are sometimes eaten as bushmeat or feature in traditional

country dishes they are not bred in captivity for this (or any other) purpose. There is a strong association between hedgehogs and European gypsies, who not only eat the animal's meat, but also regard it as an ally against malign mochadi entities such as cats and non-gypsy people.

Hedgehog body parts have been used by many cultures in traditional healing, magic and witch doctoring. The meat has been purported to have cleansing properties and various body parts have apparently been used in the treatment of ailments including leprosy, boils, colic and baldness.

Hedgehogs also appear widely in folklore. They are mentioned in the writings of Pliny and Shakespeare and famous hedgehogs include Mrs. Tiggywinkle, the bustling, petticoated washerwoman in the story by Beatrix Potter and Sonic the Hedgehog—the manic blue-spined hero of the computer game by Sega.

Hedgehogs are among the few wild mammals that have adapted to life alongside people in towns. They are kept as pets and are welcome visitors to gardens, where they help out by eating invertebrate pests. Many people put out food specially for hedgehogs and enjoy watching their spiny visitors dining on bread and milk or canned dog food from a saucer on the back lawn.

Species accounts

List of Species

Western European hedgehog

Erinaceus europaeus

subfamily

Erinaceinae

taxonomy

Erinaceus europaeus Linnaeus, 1758, Sweden. Formerly included E. concolor and E. amurensis.

other common names

French: Hérisson de l'ouest; German: Westeuropäisch Igel; Spanish: Erizo europeo.

physical characteristics

Head and body length: 9–11 in (23–28 cm); tail: 0.5–1.2 in (1.5–3 cm); weight: 14–42 oz (400–1,200 g). Large brown hedgehog with short tail. Spines are banded yellow and brown, with pale tips.

distribution

Widespread throughout Western and Central Europe including Great Britain, Ireland, southern Scandinavia and northwestern Russia.

habitat

Deciduous woodland and scrub, grassland and pasture, suburban parks and gardens. Alpine regions below the treeline.

behavior

Nocturnal and solitary outside breeding season, non-territorial but intolerant of conspecifics; where winters are cold, enters deep hibernation from October–December to March–April; rolls up into spiny ball when threatened; engages in self anointing with frothy saliva.

feeding ecology and diet

Omnivorous, but eats mostly invertebrates such as beetles, larvae, slugs, worms and spiders; also small vertebrate prey, eggs, fruit and fungi. Apparently relishes bread and milk, dog food and kitchen scraps provided by people.

reproductive biology

Probably polygynous. Mates from April to August, the later pairings generally occur if first litter is lost or aborted. Gestation lasts 31–35 days, litter size varies from 2 to 10, and 4 to 6 is normal for most parts of range. Young are born in nest of leaves, blind and virtually naked. First soft, white spines begin to be replaced by adult-type spines between 2 and 7 days old. Young are tended by female only and weaned at 4 to 6 weeks. Sexually mature at 12 months, maximum longevity 7 years (10 in captivity), usually much less.

conservation status

Not threatened; common and widespread. Road traffic and winter starvation are major factors in mortality.

significance to humans

Generally a well-known animal, welcomed into gardens where it eats many invertebrate pests; a popular figure in folklore and children's stories; may be eaten, though the practice of hunting for meat is increasingly uncommon.

Southern African hedgehog

Atelerix frontalis

subfamily

Erinaceinae

taxonomy

Atelerix frontalis (Smith, 1831), Cape Colony, Cape Province, South Africa. Formerly in Erinaceus.

other common names

French: Hérisson Sud-Africain; German: Kap-Igel; Spanish: Erizo enano Africano.

physical characteristics

Head and body length: 7–8.6 in (18–22 cm); tail: 0.8–1 in (2–2.5 cm); weight: 10.5–17.5 oz (300–500 g). Gray-brown to grizzled black fur and spines, with prominent white band from forehead to flanks, narrow center parting in spines on forehead.

distribution

South and east from southern Angola, through northern Namibia, eastern Botswana and western Zimbabwe to eastern South Africa.

habitat

Scrub and savanna grassland, also in suburban parks and gardens.

behavior

Nocturnal and solitary. Hibernation lasts from June to September, slightly less in northern parts of range, will rouse during warm weather. Curls into spiny ball when threatened. Engages in self-anointing behavior.

feeding ecology and diet

Omnivorous, eats invertebrates and small vertebrate prey including beetles, worms, frogs, small reptiles, rodents and birds' eggs, also takes fruit and fungi.

reproductive biology

Polygynous. Females can produce several litters a year, but births peak from October to March (the wet season); gestation lasts 35 days, litters contain 4 to 5 (maximum 10) blind, helpless young. Weaned at 6 weeks, sexually mature at 9 to 10 weeks.

conservation status

Though not officially listed as threatened, it is considered Rare in South Africa by the IUCN and listed on CITES AppendixII. Has suffered from localized hunting/collecting and habitat loss due to agricultural development.

significance to humans

Kept as a pet in some places and hunted for food in others. Generally considered beneficial as a predator of invertebrate pests.

Indian desert hedgehog

Paraechinus micropus

subfamily

Erinaceinae

taxonomy

Hemiechinus micropus (Blyth, 1846), Bahawalpur, Punjab, Pakistan. Formerly also in Erinaceus. Includes Paraechinus nudiventris, considered by some as a separate species.

other common names

English: Pale hedgehog; French: Hérisson du desert Indien; German: Indisch Wüstenigel; Spanish: Erizo del desierto.

physical characteristics

Head and body length: 5.5–9 in (14–23 cm); tail: 0.4–1.5 in (1–4 cm); weight: 10.5–17.5 oz (300–600 g). Pale gray-beige except for dark facial mask.

distribution

Pakistan, western and southern India.

habitat

Desert and semidesert.

behavior

Nocturnal and solitary but generally non-aggressive; digs own burrow and caches food; does not hibernate; engages in self-anointing behavior.

feeding ecology and diet

Hunts insects and small vertebrates, especially toads. Apparently stores excess food.

reproductive biology

Breeds from April to September, litters of 1 to 3 (maximum 6). Probably polygynous.

conservation status

Not threatened. Widespread and common but local populations are increasingly isolated due to desertification and agricultural development. P. m. nudiventris is Vulnerable.

significance to humans

None known.

Long-eared hedgehog

Hemiechinus auritus

subfamily

Erinaceinae

taxonomy

Hemiechinus auritus (Gmelin, 1770), Astrakhan, south Russia. Formerly in Erinaceus. Includes H. a. megalotis, regarded by some as a separate species.

other common names

French: Hérisson à longues oreilles; German: Großohrigel; Spanish: Erizo de orejas largas.

physical characteristics

Head and body length: 6.6–12 in (17–30 cm), tail: 0.6–2 in (1.5–5.5 cm); weight: 8.4–17.5 oz (240–500 g). Long legs and large, mobile ears. Spines are grooved.

distribution

Northeastern Africa, the Middle East and central Asia from northern Libya to the Gobi desert of northern China and Mongolia and including steppe and desert regions of Egypt, Jordan, Israel, Syria, Iraq, Iran, Afghanistan, western states of the former Soviet Union and Pakistan. The Gobi population is apparently isolated from the west by the Altai mountains.

habitat

Semidesert, arid grassland and montane steppe up to 8,200 ft (2,500 m), also frequents parks and gardens in suburban areas.

behavior

Nocturnal and solitary, generally non-aggressive; will dig own burrow where alternative ready-made dens are not available. Hibernates in parts of range where winters are cold, elsewhere may enter facultative torpor during periods of drought or food shortage; self-anoints when encountering certain trigger substances.

feeding ecology and diet

Insects and other invertebrates, also some small vertebrate prey, fruit and seeds. Can survive prolonged periods without eating or drinking.

reproductive biology

Polygynous. Breeding occurs in spring and summer, hibernating individuals mate soon after waking up. Gestation lasts 35–42 days, litter size varies from 1 to 6 (usually 2 to 3 in the Gobi, 5 to 6 in western temperate areas). Weans at 5 weeks, may be sexually mature at 6 weeks. Maximum recorded longevity 6 years.

conservation status

Not threatened; common and widespread.

significance to humans

Occasionally eaten as bushmeat, no real significance.

Daurian hedgehog

Mesechinus dauuricus

subfamily

Erinaceinae

taxonomy

Hemiechinus dauuricus (Sundevall, 1842), Dauryia, Transbaikalia, Russia. At one time also considered to belong to Erinaceus.

other common names

French: Herisson Daurian; German: Daurisch Igel; Spanish: Erizo el Dauryia.

physical characteristics

Records are scarce. Head and body length about 9 in (24 cm); tail about 1 in (2.5 cm); weight probably similar to H. auritus. 8.4–17.5 oz (240–500 g). Longish ears, fur slightly coarse.

distribution

Gobi Desert regions of Eastern Mongolia and northern China.

habitat

Steppe and steppe woodland.

behavior

Nothing is known. May be comparable to Hemiechinus.

feeding ecology and diet

Nothing is known.

reproductive biology

Nothing is known. May be comparable to Hemiechinus.

conservation status

Not threatened.

significance to humans

None known.

Lesser gymnure

Hylomys suillus

subfamily

Hylomyinae

taxonomy

Hylomys suillus Müller, 1840, Indonesia. Includes very rare H. s. parvus, regarded by some to be a separate species.

other common names

English: Short-tailed gymnure; French: Petite gymnure; German: Kleinegymnure; Spanish: Gymnure pequeño.

physical characteristics

Head and body length: 3.5–5.7 in (9–14.5 cm); tail: 0.4–1.2 in (1–3 cm); weight: 0.5–2.8 oz (15–80 g).

distribution

Yunnan Province, China, Myanmar (Burma), Indochina, peninsular Thailand and Malaysia, Sumatra, Borneo, and Java.

habitat

Dense, damp forest from sea level to 11,000 ft (3,400 m).

behavior

Active day and night, moves quickly and nimbly; does not hibernate. Probably solitary, though records of small groups exist—these may represent females with large young. Builds nests of leaves in rock crevices and hollows among tree roots.

feeding ecology and diet

Insects, worms, and other invertebrates found in leaf litter, will also eat fruit.

reproductive biology

Litters of 2 to 3 young born at any time of year. Polygynous.

conservation status

H. s. parvus is Critically Endangered.

significance to humans

None known.

Mindanao gymnure

Podogymnura truei

subfamily

Hylomyinae

taxonomy

Podogymnura truei Mearns, 1905, Mt. Apo, Mindanao.

other common names

English: Mindanao moonrat, Mindanao wood-shrew, Philippine wood shrew; French: Gymnure de Mindanao; German: Mindanao Gymnure; Spanish: Gymnure de Mindanao.

physical characteristics

Head and body length: 5–9 in (13–15 cm); tail: 1.5–3 in (4–7 cm). Soft gray-brown fur with stiffer guard hairs.

distribution

Endemic to the Philippine island of Mindanao.

habitat

Damp forest at altitudes up to 7,500 ft (2,300 m).

behavior

Little known, probably nocturnal with habits comparable to true shrews (family Soricidae).

feeding ecology and diet

Insects, worms and probably other invertebrates; has been known to take carrion.

reproductive biology

Nothing is known. Probably polygynous.

conservation status

Listed as Endangered by the IUCN because of its small population and declining habitat.

significance to humans

None known.

Malayan moonrat

Echinosorex gymnura

subfamily

Hylomyinae

taxonomy

Viverra gymnura (Raffles, 1822), Sumatra.

other common names

English: Malayan gymnure; French: Gymnure de Malaysie; German: Malaysische Gymnure; Spanish: Gymnure de Malasia.

physical characteristics

Head and body length: 10–18 in (26–46 cm); tail: 6.5–12 in (16.5–30 cm). Coarse, shaggy fur, black on body, pale on face and neck, tail sparsely furred, white towards the tip.

distribution

Myanmar (Burma), Peninsular Thailand and Malaysia, Borneo, and Sumatra.

habitat

Lowland forest and mangroves.

behavior

Nocturnal and solitary. May be partially aquatic. Aggressive towards other moonrats, uses powerful scent from anal glands to mark home range.

feeding ecology and diet

Worms, insects, crabs, shrimps, snails and other invertebrates caught on land and at the edge of water.

reproductive biology

Breeding is apparently aseasonal. Females rear one or two litters a year with an average two young per litter; gestation is 35–40 days. Details of life history are not known. Maximum recorded longevity four years seven months. Presumably polygynous.

conservation status

Not threatened.

significance to humans

None known.

Resources

Books

McDonald, D. Collins Field Guide: Mammals of Britain and Europe. London: Harper Collins, 1993.

Nowak, R. "Hedgehogs and Gymnures (Insectivora; Family Erinaceidae)." In Walker's Mammals of the World, 6th ed. Vol. 1, Baltimore and London: Johns Hopkins University Press, 1999.

Reeve, N. Hedgehogs. London: Poyser Natural History, 1994.

Periodicals

Corbet, G. B. "The Family Erinaceidae: A Synthesis of its Taxonomy, Phylogeny, Ecology and Zoogeography." Mammal Review 18 (1988): 117–172.

Jenkins, P. D., and M. F. Robinson. "Another Variation on the Gymnure Theme: Description of a New Species of Hylomys (Lipotyphla, Erinacaidae, Galericinae)." Bulletin of the Natural History Museum, Zoology Series 68 (2002): 1–11.

Organizations

IUCN Species Survival Commission, Insectivore Specialist Group, Dr. Werner Haberl, Chair. Hamburgerstrasse 11, Vienna, A-1050 Austria. E-mail: [email protected] Web site: <http://members.vienna.at/shrew/itses>

Other

Hedgehog Valley. March 31, 2003. <http://hedgehogvalley.com>.

The International Hedgehog Association. The International Hedgehog Club. January 1, 2003. <http://hedgehogclub.com>.

Stone, David R. "Family Erinaceidae: The Hedgehogs, Moonrats and Gymnures." In Eurasian Insectivores and Tree Shrews: Status Survey and Conservation Action Plan. 1995. ITSES Specialist Group, IUCN.<http://members.vienna.at/shrew/itsesAP95-erinaceidae.html>.

Amy-Jane Beer, PhD