Elephantulus intufibushveld elephant-shrew(Also: bushveld sengi)

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Geographic Range

Bushveld sengis are endemic to the southwestern section of continental Africa ranging from southwestern Angola to the extreme northeastern region of Transvaal, South Africa, including Namibia and most of Botswana. (Corbet and Hanks, 1968; Skinner and Chimimba, 2005)

Habitat

Bushveld sengis are found in arid regions with loose, sandy soils (Tolliver et al., 1989). They are found in dry savanna woodlands with low-lying brush (Corbet & Hanks, 1968) and the sandy flatlands of subdeserts and steppe landscapes (Skinner & Smithers, 1990). (Corbet and Hanks, 1968; Skinner and Smithers, 1990; Tolliver, et al., 1989)

Physical Description

Bushveld sengis bear the peculiar physical characteristics of other macroscelidids, with their small, laterally compressed bodies, narrow elephant-like snouts, large eyes, large pinnae, and long hind limbs, from which the order gets its name (macro = big, sceledia = thigh). The hindlimbs are longer than the forelimbs and adapted for swift, cursorial locomotion. Their incredible stride is enabled by their relatively long ulna and radius, fused tibia and fibula, and elongated metatarsals. Bushveld sengis also use their powerful hind limbs to create thumping patterns in moments of danger or agitation (Grzimek, 2004). Bushveld sengis have a sub-caudal gland (Corbet & Hanks, 1968). Males weigh 35 to 56 g and measure 211 to 249 mm, while females weigh 40 to 74 g and measure 204 to 276 mm (Skinner & Chimimba, 2005). Tail length comprises about 105% of the head and body length, ranging from 97 to 132 mm in males and 103 to 142 mm in females (Skinner & Chimimba, 2005). Bushveld sengis lack sexually dimorphic characteristics (Matson & Blood, 1998) and differ little geographically in average size (Skinner & Chimimba, 2005). (Corbet and Hanks, 1968; Grzimek, 2004; Matson and Blood, 1998; Skinner and Chimimba, 2005)

The dorsal fur has a yellowish hue with long, black-tipped dorsal hairs extending to the rump in a contrasting pattern and bright buff patches behind the ears. These characteristics are shared with western rock sengis (Elephantulus rupestris), along with their tails and black tips on the dorsal surface that give them a speckled appearance. The abdominal fur is white, like that of E. rupestris, with less grey showing at the surface. Though they share many similarities in pelage, bushveld sengis differ from western rock sengis in their smaller size, relatively shorter tail length, and larger, less angular bullae (Corbet & Hanks, 1968). Bushveld sengi fur is also generally paler, with more yellow than that of E. rupestris and can be distinguished by the conspicuous, unbroken white ring around each eye (Skinner & Chimimba, 2005). (Corbet and Hanks, 1968; Skinner and Chimimba, 2005)

Bushveld sengis are often misidentified in the field as western rock sengis, their sister species, due to their sympatric distribution over much of Namibia (Matson and Blood, 1998). Both species bear resemblances that cannot simply be seperated by geographical distribution (Tolliver et al., 1989). Comparing the cranial morphology of closely related taxa reveals a set of plesiomorphies that make morphological distinction between E. intufi and E. rupestris, as well as E. myurus and E. edwardii, even more difficult (Corbet, 1995). These include a sinuous suture between the premaxilla and maxilla, perforations along the posterior edge of the palate, foramina between the squamosal and parietal, and hypertrophy among ventral elements of the bullae (Corbet & Hanks, 1968). Bushveld sengi dentition, with one lingual cusp on the first upper-premolar, and two on the second, distinguish it from other Elephantulus species (Skinner & Chimimba, 2005). (Corbet and Hanks, 1968; Corbet, 1995; Matson and Blood, 1998; Skinner and Chimimba, 2005; Tolliver, et al., 1989)

  • Sexual Dimorphism
  • female larger
  • Range mass
    35 to 74 g
    1.23 to 2.61 oz
  • Average mass
    52 g
    1.83 oz
  • Range length
    204 to 276 mm
    8.03 to 10.87 in

Reproduction

The mating system of bushveld sengis can be characterized as density-dependent monogamy (Rathbun & Rathbun 2006). Bushveld sengis form facultatively monogamous pairs and mate during the months of August to March (Skinner & Smithers 1990). Mating takes about 30 seconds from intro-mission to withdrawal (Tripp 1972). Pairs are composed of a male and female that share exclusive, overlapping home ranges in which the female’s territory is often contained within the male’s home range. (Skinner & Chimimba 2005). If male density is low in the area, a male bushveld sengi will expand his home territory to overlap with that of a widowed female’s, temporarily forming a polygynous association until an unpaired male begins associating with her. As they display weak pair-bonds, male mate guarding and same-sex aggression are the adaptive behaviors that ensure a stable monogamous mating system (Rathbun & Rathbun, 2006). (Rathbun and Rathbun, 2006; Skinner and Chimimba, 2005; Skinner and Smithers, 1990; Tripp, 1972)

Female bushveld sengis polyovulate, meaning they produce more ova than can be implanted in their uterus, a process that allows for higher rates of pregnancy as well as competitive selection for the most viable offspring (Birney & Baird, 1985). Polyovulation also allows for postpartum estrus and successful fertilization in as few as 24 hours after giving birth. Though they produce multiple ova, bushveld sengis only give birth to 1 to 2 precocial offspring per litter (Tripp, 1972). (Birney and Baird, 1985; Tripp, 1972)

  • Breeding interval
    Bushveld sengis have been observed in captivity to breed in intervals of 64 to 70 days with a gestation period of 50 to 52 days and female infertility cycle that lasts 14-15 days (Tripp, 1972).
  • Breeding season
    It has been observed that bushveld sengis in Botswana and Transvaal mate during the warm and wet months from August to March, while observation in Namibia suggests they breed year-round (Skinner & Chimimba, 2005).
  • Range number of offspring
    1 to 2
  • Average number of offspring
    1
  • Range gestation period
    50 to 52 days
  • Range weaning age
    3 to 5 weeks
  • Average age at sexual or reproductive maturity (female)
    11 months
  • Average age at sexual or reproductive maturity (male)
    6 months

Although bushveld sengis form monogamous social and mating pairs, parental investment can be described as uni-parental monogamy, with females rearing the offspring and males having little direct contact but indirect paternal assistance before and after birth through behavioural territoriality, mate guarding, and trail cleaning (Rathbun & Rathbun, 2006). Though scarcely observed in the wild, it has been noted that Macroscelides mothers assume responsibility for feeding and rearing their offspring in an “absentee maternal care system” (Olbricht, 2008: 20), leaving their offspring for long periods of time soon after giving birth at a site that is not their normal home base. In one observation period, bushveld sengi mothers left their offspring during the day, returning at night to nurse for two minute intervals repeatedly. During the same observation period, contact between males and their offspring occurred only once during sun bathing in overlapping territory (Rathbun & Rathbun, 2006). In captivity, weaning has been observed to take three to five weeks, with the mother gradually substituting masticated insects for milk. Bushveld sengi young were also observed to increase in weight by about a gram a day for 2.5 months until they reached adult size (Tripp, 1972). (Olbricht, 2008; Rathbun and Rathbun, 2006; Tripp, 1972)

  • Parental Investment
  • precocial
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • male
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female

Lifespan/Longevity

Due to the cryptic behavior of bushveld sengis, there is little observational data (wild or captive) to assess longevity. The average lifespan of other Elephantulus species is estimated to be approximately 4 to 6 years in the wild, and 1.5 to 3 years in captivity (Rathbun & Fons, 1990). (Rathbun and Fons, 1990)

Behavior

Bushveld sengis are active day and night, with increased activity early at dawn and dusk, suggesting they are crepuscular. They tend not to spend much time in the open, preferring to move in the cover of bushes (Skinner & Chimimba, 2005). Males and females form monogamous social and mating pairs but live, forage, and sleep separately within home ranges that overlap to varying degrees. A male associates with one female by extending his home territory to encircle hers, marking his territory with scent glands in the soles of his feet. There have been observed instances of males and females interacting other than when mating, but these are characterized as moments of resource gathering, such as at a shared sun basking site. Pairs tend to center their activity well away from other areas of potential overlap with neighbors, as they are known for behaviors of same-sex aggression (Rathbun & Rathbun, 2006). Bushveld sengis prefer shelter underneath dense, low brush, or abandoned burrows, building networks of clearly defined pathways radiating outward from their shelter and connecting different sites within their territorial home range (Skinner & Chimimba, 2005). Bushveld sengis use their forelimbs to create and maintain these pathways by clearing debris from dense, brush littered habitats. They have also been observed to display trail cleaning behavior in captivity (Tripp, 1971). Trails serve as anti-predator measures, allowing them easy escape routes to a shelter site when being pursued (Rathbun and Fons, 1990). Multiple shelter sites are established within home ranges and can be used for birthing, sun basking, and sleeping. In the wild, bushveld sengis were observed sleeping for 1 to 10 minutes crouched on all four legs. When agitated or antagonized, they drum their hind feet in both regularly (every 200 to 300 ms) and irregularly spaced patterns (Rathbun & Rathbun, 2006). (Rathbun and Fons, 1990; Rathbun and Rathbun, 2006; Skinner and Chimimba, 2005; Tripp, 1971)

Home Range

Male home ranges average 0.61 ± 0.35 ha; female home ranges average 0.34 ± 0.11 ha. (Rathbun and Rathbun, 2006)

Communication and Perception

Bushveld sengis communicate with each other via nose-nose contact. In observed encounters between males and females in the wild, heterogeneous pairs touched the tips of their elongated snouts together before going separate ways (Rathbun & Rathbun, 2006). They also use their long noses as a probe when foraging and for sniffing the air (Grzimek, 2004). Bushveld sengis communicate via foot drumming and squeaking as well (Rathbun & Rathbun, 2006). (Grzimek, 2004; Rathbun and Rathbun, 2006)

Food Habits

Bushveld sengis are primarily insectivorous, feeding on ants, termites, and other small invertebrates, supplementing their diet seasonally with some plant material. (Rathbun, 1979; Rathbun, 2009)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts

Predation

Bushveld sengis construct a network of pathways radiating from their burrows for easy evasion of predators. In combination with their strong hind limbs adapted for a half-bound gait, they are able to swiftly and sharply escape predation from owls and hawks. When they feel threatened they may foot drum (Rathbun, 1979). Though there is not much data on predators of bushveld sengis, they are prey of carnivorous birds like owls and hawks, as well as other medium-sized desert predators, such as snakes and carnivorous mammals. Bushveld sengi remains have been found in South African barn owl (Tyto alba) pellets. (Rathbun, 1979)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Bushveld sengi ecosystem roles are not well documented. They use abandoned burrows as home sites and create runs consisting of arranged or cleared debris in dry brush or desert landscapes (Skinner & Chimimba, 2005). Although they do not have much contact with human populations (Stuart et al., 2008), bushveld sengis are hosts to immature Rhipicentor nuttalli, a species of ixodid tick that is known to paralyze dogs (Fourie et al., 2005). (Fourie, et al., 2005; Skinner and Chimimba, 2005; Stuart, et al., 2008)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Interactions of bushveld sengis with humans are rare, with the exception of overlapping territories in grazing lands, in which they have negligible impact (Stuart et al., 2008). (Stuart, et al., 2008)

Economic Importance for Humans: Negative

There are no known adverse effects of Elephantulus intufi on humans.

Conservation Status

Bushveld sengis are categorized as Least Concern by the IUCN because they tend to live in South African regions with limited impact from humans, through locally intense grazing, and population fluctuations appear to be caused by natural variations in the environment and not as a result of land use (Stuart et al., 2008) (Stuart, et al., 2008)

Contributors

David Lindsey (author), Yale University, Eric Sargis (editor), Yale University, Rachel Racicot (editor), Yale University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

polygynous

having more than one female as a mate at one time

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

year-round breeding

breeding takes place throughout the year

young precocial

young are relatively well-developed when born

References

Birney, E., D. Baird. 1985. Why Do Some Mammals Polyovulate to Produce a Litter of Two?. The American Naturalist, 126(1): 136-140.

Corbet, G. 1995. A cladistic look at classification within the subfamily Macroscelidinae based upon morphology. Mammal Review, 25: 15-17.

Corbet, G., J. Hanks. 1968. A revision of the elephant-shrews, family Macroscelididae.. Natural History, 16: 1-111.

Downs, C., M. Perrin. 1995. The Thermal Biology of Three Southern African Elephant-shrews. Journal of Thermal Biology, 20(6): 445-450.

Fourie, L., I. Horak, P. Woodall. 2005. Elephant shrews as hosts of immature ixodid ticks. nderstepoort Journal of Veterinary Research, 72(4): 293-301.

Grzimek, B. 2004. Macroscelidea (Sengis). D Kleiman, V Geist, M McDade, eds. Grzimek's Animal Life Encyclopedia, 2 Edition. Gale. Accessed April 12, 2012 at http://www.encyclopedia.com/article-1G2-3406701008/macroscelidea-sengis.html.

Kok, O., T. Petney. 1993. Small and medium size mammals as predators of ticks (Ixodidea) in South Africa. Exp. Appl. Acarol, 17: 733-740.

Matson, J., B. Blood. 1998. Morphological variability and species limits in elephant shrews (Elephantulus intufi and E. rupestris) from Namibia. Mammalia, 62: 77-93.

Olbricht, G. 2008. Aspects of the reproductive biology of sengis (Macroscelidea) in general and the postnatal development of the short-eared sengi (Macroscelides proboscideus) in particular.

Rathbun, G. 1979. The social structure and ecology of elephant-shrews. Zeitschrift fur Tierpsychologie Suppl., 20: 1-77.

Rathbun, G. 2009. Why is there discordant diversity in sengi?” (Mammalia: Afrotheria: Macroscelidea) taxonomy and ecology?. African Journal of Ecology, 47: 1-13.

Rathbun, G., C. Rathbun. 2006. Social structure of the bushveld sengi (Elephantulus intufi) in Namibia and the evolution of monogamy in the Macroscelidea. Journal of Zoology, 269: 391-399.

Rathbun, G., R. Fons. 1990. Modern Elephant Shrews. Pp. 524-531 in Grzimkek's encyclodepia of mammals, Vol. 1, S. Parker Edition. New York: Mcgraw-Hill.

Skinner, J., C. Chimimba. 2005. The Mammals of the Southern African Subregion. Cambridge: Cambridge University Press.

Skinner, J., K. Smithers. 1990. The Mammals of the Southern African Subregion. Praetoria, South Africa: University of Praetoria.

Stuart, C., M. Perrin, C. FitzGibbon, M. Griffin, H. Smit. 2008. "Elephantulus intufi" (On-line). IUCN 2011. IUCN Red List of Threatened Species. Accessed April 12, 2012 at http://www.redlist.org.

Tolliver, D., L. Robbins, I. Rautenbach, D. Schlitter, C. Coetzee. 1989. Biochemical systematics of elephant shrews from southern Africa. Biochemical Systematics and Ecology, 17: 345-355.

Tripp, H. 1972. Capture, Laboratory care and breeding of elephant-shrews (Macroscelididae). Laboratory animals, 6: 213-224.

Tripp, H. 1971. Reproduction in elephant-shrews (Macroscelididae) with special reference to ovulation and implantation. Journal of Reproductive Fertility, 26: 149-159.

Weigl, R. 2005. Longevity of mammals in captivity; from the living collections of the world. Kleine Senckenberg-Reihe Frankfurt, 48: 198-199.