Macroscelidea

Sengis

(Macroscelididae)

Class Mammalia

Order Macroscelidea

Family Macroscelididae

Number of families 1

Thumbnail description
Small, mouse-like or shrew-like mammals with long legs and elongated, mobile snouts

Size
Species range from mouse-sized to rabbit-sized, adult body weights ranging 1–160 oz (25–550g), head-and-body lengths 3.5–12.5 in (90–315 mm), tail lengths 3–11 in (80–263 mm)

Number of genera, species
4 genera; 15 species

Habitat
Varied, from tropical lowland and montane forests, to dry savannas, scrub forest and brush, rocky outcrops, and deserts

Conservation status
Endangered: 3 species; Vulnerable: 4 species

Distribution
Central, southern and eastern Africa, and a separate region in northwestern Africa

Evolution and systematics

Elephant shrews, or "sengis," are not shrews at all, despite their long inclusion by taxonomists within the order Insectivora, which does include shrews (family Soricidae). As of 2001, extensive genetic comparison studies, along with morphological studies, strongly support placing sengis in their own order, Macroscelidae, and family, Macroscelididae. Scientific and popular literature are now using the new common name "sengi," from Swahili so as to disassociate the species from the Soricidae shrews.

The same and related genetic and morphological comparison studies support the inclusion of several African mammal orders into the superorder Afrotheria: the sengis (order Macroscelidea); elephants (Proboscidea); manatees and dugongs (order Sirenia); hyraxes (order Hyracoidea); aardvarks (order Tubulidentata); and Afrosoricida (or Tenrecomorpha), including golden-moles (family Chrysochloridae) and tenrecs and otter-shrews (family Tenrecidae).

Although still a widespread, vigorous family of mammals, the glory days of the Macroscelididae were in the past, when there were many more species, including an additional four families. The 15 species that remain are but leftovers of an extensive pan-African radiation of sengis that began as far back as the Eocene Epoch, then peaked during the Miocene and Pliocene Epochs (24 to 2 million years ago [mya]). By 2 mya, all but the present living sengi species had become extinct.

Studies of the teeth of fossil and modern sengis indicate that the earliest ancestral sengis were primarily or exclusively consumers of plant material, some forms gradually changing over the ages to a more insectivorous diet. Present-day sengis eat only animal food, mostly invertebrates, or a combination of that and plant food.

The earliest known fossils in the sengi line are Chambius kasserinensis from the early Eocene of Tunisia and Herodotius pattersoni from the Late Eocene of Egypt (Eocene Epoch: 55 to 34 mya). The dental anatomy of these and other sengi fossils support (but do not confirm) a common ancestry of sengis with condylarths, primitive, extinct ungulate animals that gave rise to numerous lines of more recent and modern ungulates.

There are two subfamilies within the single surviving family of Macroscelididae: Rhynchocyoninae, the giant sengis, with the single genus Rhynchocyon; and Macroscelidinae, the soft-furred sengis, with the genus Elephantulus and the monotypic genera Petrodromus and Macroscelides.

Physical characteristics

Sengis can charm the viewer with their rather humorous and endearing appearance and behavior. The sight of a sengi calls to mind a mouse with long, spindly legs and a mobile, slightly downturned snout varying in length among species. The long legs enable a sengi to walk, trot, run, or hop like a large, long-legged mammal, rather than with the scampering motions common among other small mammals. The body is compact, the head large in proportion. The coat is soft and full. The eyes are large, dark, and limpid, and the long proboscis moves continually in hesitant, circular twitchings. The effect is cute and slightly cartoonish.

The different sengi species share similar body proportions, ranging from mouse-sized to rabbit-sized. The Rhynchocyon species are the largest, with an adult head and body length of 9–12.5 in (235–315 mm), the tail adding another 7.5–10 in (190–263 mm). Adult weights can reach 14.5–15.5 oz (408–550 g). An example of a smaller sengi species is the four-toed sengi (Petrodromus tetradactylus), with an adult head and body length of 7–8.5 in (185–220 mm), tail length of 5–7 in (130–180 mm), and weight of 5–9 oz (150–280 g), but still large in comparison to the round-eared sengi (Macroscelides proboscideus) and other Elephantulus species, that are smaller and more mouselike in appearance, with adult head-and-body lengths of 3.5–6 in (90–145 mm), tail lengths of 3–6.5 in (80–165 mm), and weights of 1–2.5 oz (25–70 g).

Larger sengi species tend toward bright colors and patterns, while smaller species display more camouflaging browns and grays, often closely matching the soil color of a particular area. There is little sexual dimorphism throughout the family.

Sengi limbs feature long bones, the hindlimbs longer than the forelimbs, for cursorial (running) and ricochetal (hopping weith the hind legs) locomotion. The tibia and fibula (lower bones of the hindlimbs) are long and fused, the metatarsals are lengthened, and the ulna and radius (lower bones of the forelimbs) are also long, thus lengthening the stride and contributing to high-speed running and jumping.

Numbers and arrangements of digits vary throughout the family, from the traditional 10 fingers-10 toes arrangement to various reductions and modifications, described below in the species accounts.

The long tail is furless or sprouts bristles that vary in density and texture among species.

A sengi's mobile, somewhat flexible snout, which inspired the "elephant" word in the old common name, is both sense organ and tool. When not foraging, a sengi continually moves its snout in a subdued, circular motion from the base, seeking scents. When foraging, a sengi pokes its snout into

crevices or leaf litter, sniffing for food. The nostrils are located at the forward end of the snout. Long sensory vibrissae, or whiskers, arise from the base of the snout.

The senses of smell, vision and hearing are well-developed and highly tuned. The eyes are conspicuously large, dark, and limpid. Most species have a pale ring around each eye. The ears are large in proportion to the head, and in the Elephantulus species, the auditory bulla is almost grotesquely enlarged, to enhance the animal's already acute hearing abilities. The braincase is relatively large, and more complex than that of similarly-sized insectivores.

Sengi bodies are riddled with scent glands, at the base of the tail, soles of the feet, chest, behind the ears, at the corners of the mouth and in the genital and anal regions, with which they mark territory.

Metabolic rates among sengi species are like those in similarly small mammals, not lower or fluctuating, as in shrews. A few sengi species, such as the North African sengi (Elephantulus rozeti), can adjust metabolism and activity to changes in their environments, going into torpor when temperatures or food availability go low.

A sengi lives from one to five years in the wild. The record longevity, held by a captive Bushveld sengi (E. intufi), is eight years and nine months.

Distribution

All sengi species are confined to the African continent, including, for a few species, the island of Zanzibar (but not including Madagascar). The three Rhynchocyon species live in central and eastern Africa. The four-toed sengi (Petrodromus tetradactylus) is widespread through eastern and southern Africa. The round-eared sengi (Macroscelides proboscideus) is found only in southern Africa. A majority of the ten Elephantulus species occur in southern Africa, followed by eastern Africa, excepting the North African sengi (Elephantulus rozeti), found only in Morocco, Algeria, Tunisia, and Libya, separated by the Sahara Desert from all the other sengi species.

Habitat

Genus Rhynchocyon is mostly confined to tropical lowland and montane forests, while all other sengi species live in dry savannas, scrub forest and brush, rocky outcrops, and deserts.

Behavior

Sengis are alert, high-strung creatures with hair-trigger senses and reactions, always primed for escape, fleeing into hiding at the least threat. The enemies of sengis are legion. Snakes, birds of prey, and carnivorous mammals are known predators of sengis. Accordingly, the sengi lifestyle balances the vulnerability of small size, short life-span and low reproductive rate with keen senses, lightning-swift reflexes, and alterations that the sengi makes in its territory to ensure maximum safety.

Sengis sleep or hide in tucked-away shelters, such as rock crevices, burrows, nests and depressions of their own making, or burrows abandoned by other small mammals. Sengimade burrows often include an inconspicuous emergency exit.

Individuals may live alone (except during mating), or as monogamous, pair-bonded male and female, or in small groups. Whether a loner, or one of a pair or group, a sengi patrols its territory constantly. A male-female bonded pair defends its territory "sex-specifically" against other members of its species, i.e., males confront and chase off intruding males, females do likewise to trespassing females.

Active times of day and night vary among species. The Rhynchocyon species are diurnal, while other species tend toward crepuscular (twilight) or nocturnal activity. Some diurnal species switch to nocturnal foraging in exceptionally hot weather, on adequately moonlit nights, or if overly harassed by daytime predators.

Many of the soft-furred sengi species make and maintain elaborate trail systems through leaf litter or grass, with strategically located hiding spots along the way for quick cover from threats. Males and females scent-mark stones and twigs along the trail systems and deposit identifying little heaps of excrement where their path crosses a path in an abutting territory. The animals fastidiously maintain the trails, booting off intruding pebbles, twigs, and leaves with their forelimbs. This behavior keeps the trails open and ready for the sengi to flee along toward shelter in response to threats.

A trail-making sengi marks its trails with little heaps of excrement wherever its path crosses the path of an abutting, same-species territory. If individuals of abutting territories meet at the crossroads, they interract with elaborate threat rituals, ending in a stalemate and truce, or a fight.

Unlike the soft-furred sengi species, the giant sengi species seldom maintain trail systems, but an individual or pair will build a network of leaf nests throughout their territory. The giant species scent-mark their territories but never resort to excremental signatures. There are no elaborate rituals if individuals of abutting territories meet. One simply and pointedly chases off the other, finishing with a nip by incisors to the fleeing hindquarters.

Sengi limbs are built for walking, trotting, and high-velocity running and hopping. Most species go to hopping mode only occasionally, while all are quadrupedal walkers and runners. Sengis walk and run in digitigrade fashion, i.e., on the tips of their fore-digits and hind-digits. When threatened, they prefer to run for a hiding spot, but will go into hopping mode with their hind limbs, tail extended, in extreme danger.

In open country, soft-furred sengis often sunbathe just out-side their home shelters, sitting on their haunches, their senses always alert for the least inkling of a threat, at which point they instantly rouse and flee into hiding.

Some sengi species also "sand-bathe," wallowing in dry sand, a behavior noted in other rodent species. Sand-bathing both scent-marks the immediate territory and serves to clean the fur of accumulated oil, dandruff, and dirt. Established sand-bathing spots are scattered throughout a sengi trail system. Soft-furred sengis also clean their fur with their tongues and scratch with their hind legs, able thereby to reach all parts of their bodies.

Sengis are not particularly vocal creatures. Elephantulus and Rhynchocyon species make squeaking sounds, and drum the leaf litter with their hind feet. The four-toed sengi (Petrodromus tetradactylus) makes a cricketlike call. The golden-rumped sengi (Rhynchocyon chrysopygus), the four-toed sengi, and Elephantulus species all rap the ground with their hind feet to sound alarms or for other reasons, doing so in species-specific patterns that vary in regular or irregular rhythms, intervals between each rap, number of raps in a set, and number of sets in a series. Rhynchocyon species and Petrodromus tetradactylus make similar warning noises by rapping their tails against the ground.

Feeding ecology and diet

Digestion in sengis is similar to that of small insectivorous mammals, although ancestral sengis were herbivorous. All sengis prey on invertebrates, mostly insects, while most supplement this fare with fruits, seeds, and green plant material, the one exception being Rhynchocyon chrysopygus, the golden-rumped sengi, which eats only animals, mostly invertebrates. Smaller species of sengis feed mainly on ants and termites.

The sengi digestive tract includes a caecum (analogous to the appendix in humans). This organ has been little studied in the Macroscelidae, and may not be functional in all species. In species in which it does function, the caecum is full of bacteria that break down cellulose in ingested plant matter. The functional caecum is another legacy from the purely herbivorous diets of sengi ancestors. The caecum of some sengi species may also be used to store water for hot, dry months.

Reproductive biology

Mating behavior varies according to whether the male and female of a sengi species are monogamous (for life) or solitary. Males of solitary species, or young males of monogamous species on their first mating run, go in search of rutting females of their particular species by sensing olfactory cues left in scent markings left by females in strategic spots. When a male and female of a solitary species have found each other, they stay together for several days, mate, then go their separate ways. Pair-bonded couples remain together as long as both are alive. They may be strictly monogamous or they may mate with other individuals while always reassuming the original pair relationship. Males take little or no part in direct care of the young.

A female sengi carries four or six mammae, depending on species.

The reproductive systems of female sengis, during mating, show polyovulation, in which anywhere from a dozen to 100 egg cells are released during ovulation, most of which become

fertilized by male sperm and begin cell division, but only one, two, or three fertilized eggs will implant in the uterus, while the rest are expelled. This may be a holdover from past ages when sengi ancestors bore larger litters, as do most mammal species in their size range.

After a gestation period of about 50 days, sengis are born in small litters of one, two, or rarely, three or four young, which enter the world precocial, i.e., with their eyes open, full coats of fur, and able to move about and explore within a few days, often a few hours, of birth. The mother leaves the infants alone most of the time, in a shelter separate from the parents' shelter, coming by only to nurse at fixed intervals, a behavior known as absentee parental care. After five days the mother starts feeding the young mashed insects that she stuffs in her cheek pouches, in addition to her milk.

In about two weeks, the young emerge from their shelter, effectively weaned and able to forage, although they will remain with the mother for three or four weeks, accompanying her as she forages. Eventually, within a month to two months after weaning, the young strike off on their own, or are driven from the territory by the parents, to establish territory of their own, reaching sexual maturity by 40–50 days. A female sengi may produce several litters per year.

Conservation status

The 2002 IUCN Red List of Threatened Species includes seven species of sengis. Vulnerable: Rhynchocyon cirnei, Macroscelides proboscideus, Elephantulus edwardii, and Elephantulus rupestris; Endangered: Rhynchocyon chrysopygus, Rhynchocyon petersi, and Elephantulus revoili.

The main problems besetting sengi species are, for some species, a limited area of distribution, e.g., the golden-rumped sengi, R. chrysopygus, for others, fragmentation of their habitats. Both conditions are caused or exacerbated by humans clearing land for agriculture. Sengis are only occasionally hunted and trapped for food.

Significance to humans

With their mainly insectivorous diets, sengis are significant natural checks on insect abundance that might otherwise negatively affect human health and agriculture. In some areas, people hunt, trap, and eat sengis, although most people find sengi meat distasteful. In Kenya, the golden-rumped sengi, R. chrysopygus, has become a rallying symbol for conservation.

Species accounts

List of Species

Golden-rumped sengi

Rhynchocyon chrysopygus

subfamily

Rhynchocyoninae

taxonomy

Rhynchocyon chrysopygus Günther, 1881, Mombasa, Kenya.

other common names

French: Rat à trompe à croupe dorée; German: Goldrücken-Rüsselhündchen; Spanish: Musaraña elefante de trompa dorada.

physical characteristics

Rhynchocyon chrysopygus, the golden-rumped sengi, and the two other species within the genus, R. cirnei, the checkered sengi, and R. petersi, the black-and-rufous sengi, are the largest species in the family, and about equal in size. The head and body length of an adult golden-rumped sengi runs 9–12.5 in (235–315 mm), the tail adding another 7–10 in (190–263 mm). Adult weight reaches 14.5–15.5 oz (408–550 g).

The fur is fine, yet stiff in texture, and glossy. The ears are hairless and the tail is less furred than the body. The signature characteristic is a large, bright yellow rump patch. Feet, ears, and legs are black, likewise the tail, exept its lower third, which is white with a black tip. The upper body is deep red-brown and black, the undersides paler. There is a scarcely visible vestige of a checkered pattern on the body similar to that of R. cirnei, more obvious in the young.

Both sexes carry a patch of thickened skin, called a dermal shield, under the yellow rump patch, the shield being thicker in the males. The dermal shield may protect individuals when being bitten on that vulnerable spot by same-species rivals. Complementing the dermal shields are the sexually dimorphic canines, 0.26 in (6.6 mm) long in males, 0.18 in (4.6 mm) in females, and probably seeing service during attacks on rivals.

The snout is reinforced within by a row of 30 rings of cartilage similar to those in a human larynx.

Golden-rumped sengis, like the other species in this genus, have only four toes on front and hind feet, missing the pollex ("thumb") and hallux ("big toe").

distribution

R. chrysopygus is found with certainty only in the Arabuko-Sokoke Forest Reserve on the coast near Mombasa, Kenya.

habitat

The Arabuko-Sokoke Forest is a 155 mi² (400 km²) block of moist and dry coastal tropical forest, the largest surviving fragment of an indigenous forest type that once extended along the east coast of Africa from northern Mozambique to southern Somalia. The forest reserve encompasses 109 acres (44 ha) of the Gedi Historical Monument, while a 2.3 mi² (6 km²) bloc has been set aside as Arabuko-Sokoke National Park. The forest is under consideration as a World Heritage Site. An estimated 20,000 individuals of R. chrysopygus inhabit the entire forest.

behavior

Golden-rumped sengis are diurnally active. Monogamous pairs hold territories sex-specifically, one pair per average territory of 4.2 (1.7 ha), the neighboring territories contiguous, or abutting on one another. Individuals exude a pungent odor from a gland behind the anus, with which the animals mark territory. Both sexes scent-mark territory.

Individuals sleep in shelters made up of small pits lined and covered with leaves. The animals build new shelters every few days, digging out a hollow in the soil, upholstering it with litter leaves and roofing it with more litter leaves into a blanket 3 ft (0.9 m) across. A finished shelter is almost unnoticeable. The monogamous pair builds shelters in the early morning, when leaf litter is moist from dew and less likely to make rustling sounds as the sengis move leaves into place. There may be 10 such shelters in a territory. Individuals of a monogamous pair stay in separate shelters. An individual sleeps in a crouching position, head tucked under forequarters, ready to instantly awake at the sounds of a predator trodding on the edge of the leaf blanket, dashing up through the blanket of leaves and away.

The garishly bright, golden rump may seem a liability in such a vulnerable creature, but it does have a defensive function: its brilliance and motion are likely to catch the attention of a possible predator and tempt it to close in, too early and from too far. The predator, on the hunt, spotting the bright rump patch from a distance, reacts and moves, thus producing slight sounds that the sengi's alert ears can pick up as early warning to facilitate its escape. On sensing the predator in this way, a golden-rumped sengi will slap its tail loudly against the leaf litter, communicating to the approaching predator that the sengi is aware of its presence, is ready to flee, and is too far away to be worth the predator's efforts. If the predator decides otherwise and the sengi chooses to flee, its noisy boundings over the leaf litter warns its mate and young that a predator is in their territory. A golden-rumped sengi in full flight is a memorable sight. The gait has been compared to the stotting, or running in a series of high leaps, of gazelles.

feeding ecology and diet

The golden-rumped sengi is the only sengi species that eats exclusively animal food, mostly invertebrates of many sorts, including earthworms, millipedes, insects, and spiders, using its long, flexible snout to poke through leaf litter in search of edibles.

Golden-rumped sengis share a commensal relationship with the red-capped robin-chat (Cossypha natalensis). A red-capped robin-chat will follow a foraging golden-rumped sengi or pair through the forest, feeding on scraps of invertebrates left behind by the sengi.

reproductive biology

Golden-rumped sengi sexes mate for life, yet take opportunities to mate with lone individuals. The species breeds throughout the year. Females give birth to a single young after a gestation period of 42 days. The youngster remains in the nest for two weeks, then emerges as a fully weaned individual. It follows the mother while she forages, but is able to fend for itself after five days, although it stays in the parents' territory until establishing its own, anywhere from five to 10 weeks after weaning. Having secured a territory with a mate, an individual can live up to five years.

conservation status

Rhynchocyon chrysopygus is listed as Endangered in the 2002 IUCN Red List of Threatened Species. That status is due to its limited range and restriction to the forest floor (it cannot climb and does not burrow), the latter condition rendering it vulnerable to wild predators and domestic or feral dogs. People living in areas adjacent to the forest hunt and trap sengis for food, while clearing forested land along its edges.

A support group, "Friends of the Arabuko-Sokoke Forest," made up of Kenyan and foreign individuals and institutions, works actively to protect the forest. The group publicizes, encourages ecotourism, and involves local people in conservation and in using forest products in sustainable ways.

significance to humans

Golden-rumped sengis are hunted for food by locals. From the viewpoint of conservation, they are symbols of a unique and vanishing ecosystem and of the wisdom of protecting it.

Checkered sengi

Rhynchocyon cirnei

subfamily

Rhynchocyoninae

taxonomy

Rhynchocyon cirnei Peters, 1847, Quelimane, Bororo District, Mozambique.

other common names

English: Giant sengi; French: Rat à trompe à damier; German: Geflecktes Rüsselhündchen; Swahili: Njule madoa.

physical characteristics

The checkered sengi is similar to the golden-rumped sengi in size specifics (adult head and body length 9–12.5 in (235–315 mm), tail adding another 7–10 in (190–263 mm). Adult weight 14.5–15.5 oz (408–550 g). The animal can justly be proud of its unique pelt design: several dark stripes, on each side, running the length of the body, broken into squarish spots of alternate chestnut and off-white, or whitish and dark brown. The main coat color is yellowish to dark brown. In some populations, the distal portion of the tail is white.

distribution

R. cirnei lives in northern and eastern Democratic Republic of the Congo, Uganda, southern Tanzania, northeastern Zambia, Malawi, and northern Mozambique.

habitat

Checkered sengis prefer dense, lowland and montane tropical rainforest.

behavior

Individuals may live alone, in pairs or in small groups, are active during daytime but are occasionally nocturnal. Pairs or groups vocalize constantly to keep in touch with one another, and tail-rap the ground when alarmed.

feeding ecology and diet

Checkered sengis forage for invertebrates on the forest floor in the daytime, alone or in small groups, maintaining group cohesion by continually uttering squeals and squeaks. They make little conical depressions in the soil during their grubbings, offering a sign diagnostic of their presence. The diet is mainly insectivorous, with some emphasis on ants, but they may help themselves to small mammals, birds, bird eggs, mollusks, and other animal foods on occasion. While rooting, the sengis ingest a good deal of dirt, which apparently passes through them with little harm.

reproductive biology

Specifics of reproduction are similar to that of the closely related golden-rumped sengi. The litter nest is an inconspicuous heap of leaves in a shallow ground depression. The female bears a single, precocial young.

conservation status

The 2002 IUCN Red List of Threatened Species lists R. cirnei as Vulnerable. The main problem facing the species is deforestation.

significance to humans

None known.

Round-eared sengi

Macroscelides proboscideus

subfamily

Macroscelidinae

taxonomy

Macroscelides proboscideus (Shaw, 1800), Roodeval, Oudtshoorn Division, Cape Province, South Africa.

other common names

English: Short-eared sengi, jumping shrew; French: Macroscelide d'Afrique du sud, rat à trompe d'Afrique du sud; German: Kurzohr-rüsselspringer; Afrikaans: Ronde-oorklaasneus.

physical characteristics

The round-eared sengi is among the smallest of the living sengi species. The adult head and body length runs 3.5–4.5 in (95–115 mm), the long tail adding another 4–5.5 in (97–135 mm). Adult weight is 1–2 oz (30–50 g). The body fur of the animals is long, dense and soft, hued orange, brown, or gray on the upper body or dorsal area and whitish on the underparts or ventral area. The tail bears coarse, black fur. The skin at the base of the tail is pink or dark. The limbs bear short, white fur. The body fur is two-colored throughout, the tips of hairs colored and the bases dark. Fur colors vary widely throughout the range of the species.

All four feet have five toes each, and on the hindlimbs, the hallux, or equivalent of the big toe, is set off from the others. All the digits have small, dark claws.

The head bears large, limpid, dark eyes that lack the pale, surrounding ring seen in other sengi species. The characteristic long, mobile snout is covered with short, white fur. The nostrils, at the nether tip of the snout, are set in dark, wet, furless skin. The ears are rounder and shorter than in other sengi species, and are backed and bordered by fur, providing signs diagnostic of the species. The skull has almost grotesquely inflated auditory bullae, or inner ear chambers of bone, indicating the importance of hearing in the species. The female has six mammae.

distribution

Round-eared sengis live throughout Namibia, Cape Province in South Africa, and southern Botswana. In Great Namaqualand, South Africa, the ranges of the round-eared sengis and Elephantulus rupestris, the Western rock sengi, overlap.

habitat

The preferred habitat for Macroscelides proboscideus is desert, semidesert, and scrub forest.

behavior

Despite also being called "jumping shrews," round-eared sengis rarely jump, preferring to walk or run, carrying their tails horizontally. They can run with speeds up to 12.4 mph (20 km/h), quite impressive for such a small creature. Individuals hide in sparse grass cover or bushes, and can quickly burrow into the sand for protection.

Individuals live solitarily in home ranges that may reach 2.5 acres (1 ha) and include foraging areas and way-shelters. The shelters are short burrows located under stones, roots, or bush. Sengis can and will enlarge their refuge rapidly by digging. The burrows have a main entrance/exit and an emergency exit, the latter inconspicuous. Round-eared sengis also take refuge in deserted shelters of suricates (Viverridae) or gerbils (Gerbillidae), fastidiously cleaning their new homes of sand, gravel, and other detritus.

During the day, round-eared sengis may nap in the sun, sitting on their haunches, still alert for the slightest hint of danger. They also sand-bathe, wallowing in pre-established patches of dry sand, to scent-mark and to clean their coats.

feeding ecology and diet

Round-eared sengis are primarily crepuscular (twilight) and nocturnal foragers. They start foraging at twilight, then continue through most of the night, sniffing with their mobile snouts in crevices between stones, under roots, and in carpets of fallen leaves. Although mainly insectivorous, with a preference for ants and termites, they also eat other small invertebrates and plant material, including roots, shoots, and berries. The round-eared sengi can be considered a functional omnivore, since at least half of its food intake is often plant material, balanced by invertebrate food.

reproductive biology

Although solitary most of the time, individual males and females pair up in the mating season and stay together for several days, defending their territory sex-specifically. There is a distinct breeding season, in August and September, which are warm, wet months in southern Africa.

The one or two young are born precocial, able to run a few hours after birth. The female bears and keeps her young in a hideaway separate from the parents' burrow, stopping by once a day to nurse them. The young are weaned at 16–25 days and reach sexual maturity at about 43 days.

conservation status

Due to destruction of its habitat, Macroscelides proboscideus is listed as Vulnerable by the the 2002 IUCN Red List of Endangered Species.

significance to humans

There is no known significance to humans.

Four-toed sengi

Petrodromus tetradactylus

subfamily

Macroscelidinae

taxonomy

Petrodromus tetradactylus Peters, 1846, Tette, Mozambique.

other common names

French: Petrodrome, Rat à trompe tétradactyle; German: Vierzehen-Rüsselratte; Spanish: Petrodromo; Afrikaans: Bosklaasneus; Swahili: Isange.

physical characteristics

The four-toed sengi is one of the larger sengi species, with a head and body length of 7–8.5 in (185–220 mm) and a tail length of 5–7 in (130–180 mm). Adult body weight runs 5–9.5 oz (150–280 g). The fur is long and soft. The coloration above is buffy with an orange or yellow tinge, or brown with a reddish tinge, with a grayish or brownish streak on the sides and flanks. White and reddish brown markings are usually present about the eyes. The underparts are white or red-brown. There are four toes on each hind foot (hence the common name), the first digit (hallux) missing. Females have four mammae.

distribution

Four-toed sengis are widespread, from central Democratic Republic of the Congo and southeastern Kenya through Tanzania, Zambia, Malawi, and Mozambique to the northern Transvaal (South Africa).

habitat

Although sometimes found in semi-arid, rocky habitats, four-toed sengis prefer thickets and undergrowth of dense, equatorial forests.

behavior

The species makes and maintains runways through brush and grass. It has a gait between walking and running, the tail pointed upward, but if alarmed it will break into long jumps with the hind legs. Individuals sleep outside under brush rather than in nests.

Four-toed sengis ground-rap or foot-drum with their hind feet, to sound warnings, invite the opposite sex during mating, and apparently to excite underground ants, which respond with sounds of their own that the sengi can hear and use to locate, uncover, and eat the ants. Individual four-toed sengis vocalize with shrill, cricketlike calls. They do not make nests, but shelter beneath dense vegetation or in random depressions.

feeding ecology and diet

The four-toed sengi is mostly crepuscular, major activity peaking just before dawn and just after nightfall. Their diet consists mainly of insects, particularly termites and ants, but they may add some plant matter to the menu.

reproductive biology

Monogamous pairs defend territories sex-specifically. Breeding occurs throughout the year. The female gives birth to one or two young, each weighing about 1 oz (32 g). The precocial young can run as fast as their parents a day or two after birth.

conservation status

Not listed by the IUCN. The species is so widespread that it seems in little danger of decline.

significance to humans

Some humans hunt four-toed sengis for food.

Short-snouted sengi

Elephantulus brachyrhynchus

subfamily

Macroscelidinae (Soft-furred sengis)

taxonomy

Elephantulus brachyrhynchus (A. Smith, 1836), Kuruman, north Cape Province, South Africa.

other common names

French: Rat à trompe à museau court; German: Kurznasen-Elefantenspritzmaus, Kurznasenrüsselspringer; Spanish: Musaraña elefante hocicorta; Afrikaans: Kortneus klaasneus.

physical characteristics

The weight of an adult short-snouted sengi runs 1.5–2 oz (40–60 g). Average body length is 8 in (210 mm), the tail length about the same. Short-snouted sengis have the mobile snout characteristic of all sengi species, but it is conspicuously shorter and more tapered. The soft fur varies in color, depending on geography and habitat, ranging from reddish yellow to yellowish brown to gray, rendering the animal cryptic in its various habitats. There is a faint white ring around each eye.

distribution

Elephantulus brachyrhynchus lives from northern South Africa and northeastern Namibia through Angola, southern Democratric Republic of the Congo, Mozambique, Kenya, and Uganda.

habitat

Short-snouted sengis inhabit arid and semi-arid environments with wooded bushlands, dense grasslands, and scrub.

behavior

Short-snouted sengis are diurnal and most active during the morning. They are primarily solitary but will occasionally live as monogamous pairs. They run frantically throughout their territory, avoiding areas without ground cover. Short-snouted sengis may dig their own burrows or move into abandoned rodent burrows. They foot-drum, in a regular and irregular pattern, as a warning or to facilitate mating.

feeding ecology and diet

The short-snouted sengi is primarily insectivorous, eating mostly ants and termites, nevertheless taking small amounts of green plant material, fruits, and seeds.

reproductive biology

Some short-snouted sengis live as monogamous pairs. Reproduction occurs throughout the year, decreasing during cool months. The gestation period lasts between 57 and 65 days. The young weigh approximately 0.4 oz (10 g) at birth and reach adult size by 50 days. Usually one young is born, though occasionally litters of two or even three are born.

conservation status

Not listed by the IUCN. Short-snouted sengis, since they live in more or less marginal habitats, need fear little from humans.

significance to humans

None known.

Eastern rock sengi

Elephantulus myurus

subfamily

Macroscelidinae

taxonomy

Elephantulus myurus Thomas and Schwann, 1906, Woodbush, Transvaal, South Africa.

other common names

German: Langschwanz-Rüsselspringer.

physical characteristics

The head and body length range 8–11.5 in (202–290 mm), the tail slightly longer. Adult body weight runs 1.5–3 oz (41–98 g).

Eastern rock sengis may hop with the hindlimbs, but most of the time they walk or run about on all fours. There are five digits on each foot with small claws, while the digits of the hind feet, are equipped with digital pads to give them purchase on rocky surfaces. The first digit of the forefoot (as in all species within genus Elephantulus) is set off from the other digits.

The dorsal coat of the animal is brownish gray and soft, while the ventral side is pale gray. The ears and eyes are dark brown, each eye framed by a white ring. Limbs and tail are white on the dorsal sides and devoid of hair on the ventral sides. Black limbs and tail distiguish E. myurus from other Elephantulus species.

distribution

Elephantulus myurus is distributed across southern Africa from western Mozambique in the north to Orange Free State in the south, and in southern Zimbabwe, eastern Botswana, and throughout the Transvaal.

habitat

Eastern rock sengis live in the semi-arid, temperate savannas of southern Africa, most often within heaps of boulders (koppies). The climate is semi-arid and nearly rainless for eight months of the year, interrupted by four months of rains. Temperatures can rise to 95–104°F (35–40°C) in hot summer months, descending to subzero temperatures in winter.

Another sengi species, E. brachyrhynchus, the short-snouted sengi, shares general territory with E. myurus, but E. brachyrhynchus prefers a separate habitat, the sandy, flat terrain surrounding the koppies; the habitats of the two species rarely overlap.

behavior

The eastern rock sengi is primarily diurnal, but shows a good deal of activity at sunrise and sunset. The species avoids activity during the afternoon, the hottest time of day. During the winter months, the animals are less active. Eastern rock sengis do not make nests or burrows, but hide in rock crannies, so that they take up residence only in koppies with generous complements of cracks and crevices. Eastern rock sengi vocalizations and footdrumming may be alarm calls or feints to throw off pursuers. They can run fast and hop if needed, and usually stay near or uunder rocky overhangs.

Although not confirmed, eastern rock sengis probably live as monogamous pairs, sex-specifically defending their territory. The animals forage in areas within or near their koppies, close to vegetation or overhanging ledges, for cover from predators.

feeding ecology and diet

The Eastern rock sengi is primarily insectivorous, but varies its diet with plant material. Ants and termites are the major insect food, making up about 42% of its diet, but it nevertheless helps itself to a broad variety of invertebrate food. The diet remains constant even through changes of season. Individuals snag ants and termites with their snouts in tandem with their fore-claws. Glands within the snout produce secretions that collect on the bare nether tip, which may counterract the chemical defenses of the ants and termites.

The eastern rock sengi has a functioning caecum which may also store water. While the weights of individual E. myurus remain constant throughout all seasons, the digestive tract significantly shortens during the rainy winter, when the animals slow their activities. As the tract shortens, its ability to resorb water decreases. This physiology and behavior restricts needless activity during the cool, non-mating months of winter. The digestive tract lengthens in the spring, and its water resorbtion increases, as the sengis step up their activities for the mating season, their need for more food energy increases to fill the energy demands for reproduction, and their bodies begin hoarding water for the approaching hot, dry summer.

Kidney function aids and abets water retention in E. myurus, the kidney design being similar to that of other mammals adapted to dry ecosystems, allowing increased urine concentration in order to retain water.

reproductive biology

Eastern rock sengis mate between July and January, during which time they use foot-drumming and scent-marking to announce intentions and attract mates. The male reproductive organs increase in size during the breeding season, and decrease size and sperm production somewhat during the nonbreeding months.

The young are born anytime from September to March. Newborns are highly precocial, able to run several hours after birth. Average weight of the young at birth is 0.28 oz (8.1 g). The young remain hidden until they reach about one-third adult size. The parents drive the young away when the latter become sexually mature.

conservation status

No Special Status. The rocky habitat of E. myurus is useless to humans and therefore little disturbed by people.

significance to humans

The eastern rock sengi is home to a variety of parasites, particularly ticks, the specific tick species varying in abundance with seasons. Some of these parasites are vectors for a variety of human and domestic animal diseases. The tick species Ixodes rubicundus and R. punctatus can cause paralysis in domestic livestock, H. leachi is a vector for biliary fever in dogs and Q-fever in humans, and Rhipicentor nuttalli causes paralysis in dogs.

Studies of a related sengi species, E. edwardii, the cape sengi, report on a form of malaria carried by that species that is not normally found in humans, thus rendering the species valuable in malarial research.

Rufous sengi

Elephantulus rufescens

subfamily

Macroscelidinae

taxonomy

Elephantulus rufescens (Peters, 1878), Ndi, Taita, Kenya.

other common names

English: East African long-nosed sengi; French: Rat à trompe rouge; German: Rotbraune Elefantenspitzmaus.

physical characteristics

Adult rufous sengis weigh 1.5–3.5 oz (41–98 g). The head and body length runs 8–11.5 in (202–290 mm), the tail about the same length. The fur is long and soft, the upper coat colored sandy brown, light gray or light orange, while the underparts are white or grayish. A patchwork of white spots and black streaks on the face render the large, dark eyes less obvious.

distribution

A widespread species, the rufous sengi is found in Namibia, the Cape Province of South Africa, and extreme southern Botswana, and from southeastern Sudan, southern and eastern Ethiopia and northeastern Somalia to north and southeast Kenya to central and western Tanzania.

habitat

Elephantulus rufescens lives in open plains, arid lowlands, savannas, deserts, thornbush, and tropical forests. Most individuals, pairs, or groups will take over abandoned rodent burrows for habitation.

behavior

Elephantulus rufescens individuals live singly, in monogamous pairs, or in small colonies. They are usually diurnal, occasionally nocturnal. An individual, pair, or group occupies a territory about 0.84 acres (0.34 ha).

feeding ecology and diet

The diet consists mainly of termites and ants, but also includes other invertebrates, shoots, berries, and roots.

reproductive biology

Rufous sengis form monogamous pairs when mating, defending territory sex-specifically. Before mating, individuals leave scent markings along trails by means of their sternal (chest) and other scent glands. Mating takes place throughout the year. The young are precocial, as with other sengi species, and weigh about 0.4 oz (10.6 g) at birth. The mating pair spends minimum time together, the females usually dominant to the males.

conservation status

According to the 2002 IUCN Red List of Threatened Species, E. rufescens is classified as Vulnerable. The most important causes for its decline are habitat loss and fragmentation.

significance to humans

Elephantulus rufescens carries a type of malaria to which humans are immune. The species has thus proven valuable in malaria research.

North African sengi

Elephantulus rozeti

subfamily

Macroscelidinae

taxonomy

Elephantulus rozeti (Duvernoy, 1833), near Oran, Algeria.

other common names

French: Macroscélide de l'Afrique du nord; German: Nordafrikanische Elefantenspitzmaus; Spanish: Musaraña elefante norteafricana.

physical characteristics

The adult head and body length averages about 5 in (125 mm), tail length is about the same, and adult weight is around 1.5 oz (45 g). The fur is soft and often closely and remarkably simulates the local color of the soil, usually some shade of yellowish brown.

distribution

North African sengis live in northwestern Africa, separated from the other species of sengi by the Sahara Desert. This discontinuous distribution of species is probably an outcome of the Macroscelididae having been more widespread throughout Africa in past ages, and in the Sahara region when it was rainier and more congenial. There are two distinct populations of the North African sengi, the main group in Algeria, Morocco, and Tunisia, and a second, small, isolated population in western Libya.

habitat

Open, arid, or semi-arid savanna shrubland, and woodland.

behavior

Little is known about this understudied species. Individuals construct burrows under rocks. They are active during the day, but retire to their burrows during the hottest daylight hours. Experiments have shown that North African sengis will fall into torpor as a response to changes in temperature, cycles of light and darkness, and to lower supplies of food.

feeding ecology and diet

North African sengis are primarily insectivorous.

reproductive biology

Knowledge of reproduction specifics for Elephantulus rozeti is incomplete, but what is known is unusual. The gestation period is at least 75 days, and up to four young may be born in a litter, the most common number being two, but fairly often, three. Females only give birth to two litters per year. In the colder climate of the highlands of Algeria and Morocco, the year's first litters are born starting toward the end of April, but in lowland, warmer Tunisia and parts of Morocco, births begin in March. In other respects, reproductive biology likely accords with the general sengi scheme.

conservation status

Not threatened.

significance to humans

None known.

Resources

Books

Happold, D. C. D. "Small Mammals." In The Sahara Desert, edited by J. L. Cloudsley-Thompson. 251–276, Key Environments Series. Oxford: Pergamon Press, 1984.

Kingdon, J. The Kingdon Field Guide to African Mammals. London and New York: Academic Press, 1997.

Macdonald, David, ed. The New Encyclopedia of Mammals. Oxford: Oxford University Press; Macmillan Publishers Ltd., 2001.

Nicoll, M. E., and G. B. Rathbun, eds. African Insectivora and Elephant-Shrews. An Action Plan for their Conservation. IUCN/SSC Insectivore, Tree-Shrew and Elephant Shrew Specialist Group. Gland, Switzerland: IUCN, 1990.

Novacek, M. "Evolutionary Stasis in the Elephant-shrew, Rhynchocyon." In Living Fossils, edited by N. Eldredge and S. M. Stanley, 4–22 New York: Springer-Verlag, 1984.

Periodicals

Faurie, A. S., E. R. Dempster, and M. R. Perrin. "Footdrumming Patterns of Southern African Elephant-shrews." Mammalia 60 (1996): 567–576.

Perrin, M. R., ed. "The Biology of Elephant-shrews-A Symposium Held During the 6th International Theriological Congress, Sydney, 5 July 1993." Mammal Review 25 (1995).

Rathbun, G. B., and K. Redford. "Pedal Scent-Marking in the Rufous Elephant-Shrew, Elephantulus Rufescens." Journal of Mammalogy 62 (1981): 635–637.

Woodall, P. F. "Digestive Tract Dimensions and Body Mass of Sengis and the Effects of Season and Habitat." Mammalia 51 (1987): 537–545.

Simons, E. L., P. A. Holroyd, and T. M. Bown. "Early Tertiary Elephant-shrews from Egypt and the Origin of the Macroscelidea." Proceedings of the National Academy of Sciences, USA 88 (1991): 9734–9737.

Organizations

Friends of Arabuko-Sokoke Forest, Kenya. E-mail: FoASF@ Bigfoot.com Web site: <http://www.watamu.net/foasf.html>.

Other

Rathbun, G. B. "Elephant-Shrews or Sengis." <http://www.calacademy.org/research/bmammals/eshrews/index.html>

2002 IUCN Red List of Threatened Species. <http://www.redlist.org>

Kevin F. Fitzgerald, BS