Perception Channels: tactile ; chemical
Unlike other members of Macroscelidea the habitat (rocky outcroppings) of E. myurus is not subject to great amounts of human disturbance.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
The Rock Elephant Shrew is host to numerous parasites, many of them ticks which carry human and zoonotic diseases. Of the ticks in greatest abundance, Ixodes rubicundus and R. punctatus 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 from toxic excretions (Fourie et al 1992).
Negative Impacts: causes or carries domestic animal disease
Studies of E. edwardii have found a form of larval malaria not normally found in humans, prompting research into the possibilities of other Elephantulus species carrying medically important larva. The polyovulation in females and human-like embryological development has prompted several studies of female reproduction in the Rock Elephant Shrew and provides an interesting educational medical research opportunity (Skinner & Smithers 1990).
Positive Impacts: research and education
The Rock Elephant Shrew host a variety of parasites particularly ticks, varying by season. These parasites are vectors for a variety of human and zoonotic diseases (Fourie et al 1992).
As with all living Macroscelidea, the rock elephant shrew is primarily an insectivore though it may also feed on some plant material (Skinner & Smithers 1990). An analysis of rock elephant shrew fecal pellets determined that 60-100% (mean 90%, n=60) of the diet by volume was invertebrate prey while plant material (leaves, stems and grains) contributed 10-40% (mean 10%, n-60) of the total volume. Isopterans and formicids (ants and termites) are the predominate invertebrate prey (42% of diet) for E. myurus but like other elephant shrews a wide variety of other invertebrates are also prey items (Churchfield 1987). Diet remains constant despite changes in season (Churchfield 1987). Churchfield (1987) speculates that while ants and termites are low in individual nutritional value they are found in high-density pockets and thus worth the foraging effort. These invertebrates are caught with the help of the flexible trunk and fore claws (Rathbun 1990). Tubular glands along with the nasolacrimal and lateral nasal gland ducts release secretions on the tip of the bare rostrum that may inhibit the chemical defenses of ants and termites (Woodall 1988)
In mammals, the digestive tract of a small herbivore is typically longer than that of omnivores mostly due to the need to process a greater mass of food poor in nutritional value. Studies of the digestive tract found that the large and small intestine of E. myurus were allometrically shorter than an herbivore of similar size but also posses a functioning caecum, something not found in most insectivores. The shorter intestinal size indicates a primarily insectivorous diet while the caecum and hindgut are most likely used in water resorption to conserve water in the shrew’s arid environment (Woodall, 1987). In this same study Woodall found that the body mass of E. myurus remains constant despite seasonal changes but the digestive tract significantly reduces in size in the winter and increases in the summer. The reduction of the intestines in the winter is accompanied by an observed reduction in activity (Woodall et al, 1989) both presumed to reduce energy costs during this wetter, non-mating season. The enlargement of the intestine in the spring may assist in the increased energetic needs of the mating season as well as help with water resorption during the driest part of the season (Woodall, 1987).
Water conservation is not only increased by these changes in gut morphology but also with the renal structures and urine processing. The renal structures of E. myurus are similar to other xeric-adapted species such as rodents and insectivores and allow for greater urine concentrating thus the loss of less water for waste removal. The urine of E. myurus contains high amounts of allantoin, a conversion product of uric acid and another possible method of water conservative nitrogen waste elimination (Downs 1996).
Foods eaten include: Isoptera (termites), Formicidae (ants), Coleoptera (beetles), adult Graminae, leaf/stem, little seeds, Hemiptera (true bugs), Diptera (true flies), Lepidoptera (butterfiles and moths), Araneae (spiders) and Chilopoda (centipedes).
Animal Foods: insects; terrestrial non-insect arthropods
Plant Foods: leaves; wood, bark, or stems; seeds, grains, and nuts
Primary Diet: carnivore (Insectivore )
Elephantulus myurus is primarily distributed across the Southern African Subregion with its northern limits in Mozambique and southern limits in Orange Free State. They occur in southern Zimbabwe, western Mozambique, eastern Botswana and throughout the Transvaal (Skinner & Smithers 1990, Elephant-Shrew Website 2001).
Biogeographic Regions: ethiopian (Native )
The Rock Elephant Shrew lives primarily in the rocky outcroppings of boulders (koppies) in hilly terrain. Rock Elephant shrews only inhabit formations with plenty of cracks and crevices as they do not nest or burrow. Typically they inhabit areas within or near the boulders that provide adequate cover from predators with either vegetation or overhanging ledges. Another elephant shrew, Elephantulus brachyrhyncus is found in the same region but only among the neighboring sandy flat ground; their habitats rarely overlap (Skinner & Smithers 1990). The climate of the habitat of the rock elephant shrew is semi-arid 8 months of the year (35-40°C in hot summer months) and subzero in winter (Perrin 1995).
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: scrub forest
The lifespan of the Rock Elephant Shrew is not generally well known though the general lifespan of some Elephantulus species is thought to be near 4 to 6 years in the wild and 1.5 to 3 years in captivity (Rathbun & Fons 1990).
Average lifespan
Sex: female
Status: wild: 1.1 years.
Rock elephant shrews share many of the features characteristic of the family Macroscelididae including a long, slender trunk-like snout with a small rhinarium housing the nostrils at the distal end. The snout is mobile and the elephant shrew is able to use it to manipulate its environment, forage for food, test the air. It can peel back over the head during vocalizations. The cranium is distinguished by large orbits, quadrate molars, palatal fenestrae and complete zygomatics with large jugals. As in other Macroscelididae, the forelimbs are reduced and the long bones and muscles of the hind limbs are well developed. The locomotive pattern of the shrew is semi-digitigrade. They occasionally hop with the hindlimbs but more often scramble about quadrupedally. There are five digits on each foot with small claws and digital pads on each of the digits of the hind feet. The first digit in the genus Elephantulus is posterior to the other digits. The average mass of the rock elephant shrew is 60 grams with a length of 260mm. The tail is sparsely haired and slightly longer the body. The dorsal coat of the animal is a brownish gray with soft and wholly hair while the ventral side is pale gray. The ears and eyes are brown with a white ring around the eye. The extremities are white on the dorsal side and are devoid of a hair on the ventral side. Black extremities distiguish E. myurus from other species in the genus Elephantulus (Skinner & Smithers 1990, Rathbun & Fons 1990, Nowak 1991). Glands are visible on the base of the tail and near the anus (Faurie & Perrin 1995).
Range mass: 41 to 98 g.
Average mass: 60 g.
Range length: 202 to 290 mm.
Average length: 260 mm.
Other Physical Features: endothermic ; bilateral symmetry
Anti-predator adaptations in the Rock Elephant Shrew include its coloration that blends well into its rocky habitat providing camouflage from predators. Vocalizations and footdrumming mentioned earlier may help deter following by predators and possibly serve as an alarm call. Their morphology gives them the ability to hop and run quickly to avoid danger. Behaviorally, they tend to remain under the protection of the rocky overhangs of their environment and consequently avoid avian predators such as owls and hawks that occasionally prey upon them (Skinner & Smithers 1990).
Known Predators:
The mating system of the rock elephant shrew is thought to be monogamous as with other species within Elephantulus. The relatively small size of the male testis suggests limited sperm competition, and this morphology follows patterns of monogamy in other species (or alternatively, a single male breeding with all females in the group).
Mating System: monogamous
The Rock Elephant Shrew mates between July and January, during which time footdrumming and scent marking may play an important role in attracting mates. Woodall (1987) found that the large and small intestine increased in size at this time, perhaps to provide for increased energy costs in males for reproductive behavior and in females for lactation and pregnancy. Also at this time the female polyovulates or produces multiple (over 12) eggs at each ovulation, even though only one or two will develop (Rathbun & Fons 1990). The size of male reproductive organs increases during the breeding season and the frequency of motile sperm also increases between October and December. This pattern in males is followed in the non-breeding season by a decrease in the size of the seminiferous tubules and testes, and though spermatogenesis continues, the frequency of non-motile sperm increases (Woodall & Skinner 1989). This breeding season corresponds to the seasonal changes from summer to winter. Neal (1995) suggests that the breeding pattern may under a photoperiodic cycle as breeding begins one month after the winter solstice.
The elephant shrew has a discoid placenta with a maternal artery that is symmetrically branching (Rathbun & Fons 1990). The highly precocial young are born with hair and open eyes and are able to run several hours after birth. The mean weight at birth is 8.1 grams and the length at birth is approximately 50mm. The young are driven away from their parents upon reaching sexual maturity (Skinner & Smithers 1990).
Breeding season: July - January
Range number of offspring: 1 to 3.
Range gestation period: 49 to 56 days.
Range age at sexual or reproductive maturity (female): 5 to 6 weeks.
Range age at sexual or reproductive maturity (male): 5 to 6 weeks.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous
The highly precocial young are born with hair and open eyes and able to run a few hours after birth. The young remain hidden until about one-third the size of the adults, thus making parental care difficult to assess. Contrary to the typical pattern in monogamous mating systems of mammals, the males contribute very little to the litter. The young typically remain with their parents until they are sexual mature at 5 to 7 weeks (Rathbun & Fons 1990, Skinner & Smithers 1990).
Parental Investment: precocial ; female parental care
The eastern rock elephant shrew or eastern rock sengi (Elephantulus myurus) is a species of elephant shrew in the family Macroscelididae. It is found in Botswana, Mozambique, South Africa, and Zimbabwe. Its natural habitats are subtropical or tropical dry lowland grassland and rocky areas.[2]
Eastern rock elephant shrews are one of three sengi species known to breed seasonally, during the spring and summer. Environmental factors that influence breeding patterns include temperature, rainfall, and lack of food. Mothers normally give birth to two sets of twins. Their young are known to walk very soon.[3] Although rainfall affects food availability, it does not seem to have direct impact on female E. myurus reproduction. Rainfall and ambient temperature do affect male E. myurus reproduction.[4]
{{cite web}}: Missing or empty |title= (help) The eastern rock elephant shrew or eastern rock sengi (Elephantulus myurus) is a species of elephant shrew in the family Macroscelididae. It is found in Botswana, Mozambique, South Africa, and Zimbabwe. Its natural habitats are subtropical or tropical dry lowland grassland and rocky areas.
