Dryland elephant shrew

Dryland elephant shrew
Dryland elephant shrew ( Elephantulus intufi )
Systematics
Superordinate : Afrotheria without rank: Afroinsectiphilia Order : Elephant jerk (Macroscelidea) Family : Elephant jerk (Macroscelididae) Genre : Elephant shrews ( Elephantulus ) Type : Dryland elephant shrew
Scientific name
Elephantulus intufi
( A. Smith , 1836)

The dryland elephant shrew ( Elephantulus intufi ), also known as the dryland elephant shrew , is a species of the elephant shrew genus . It has the long, trunk-like nose and short front and long hind legs that are typical of all representatives of the elephant shrews. The habitat comprises dry, semi-desert-like landscapes in south-western Africa , which, however, require a certain vegetation as a prerequisite for the presence of the species. The nimble ground dweller feeds mainly on insects and uses more or less clearly defined grazing areas, which are interspersed with hiding places and contain various places to stay, for example for sunbathing. Males and females form monogamous pairs that last a lifetime, but joint activities outside of mating are rare. A litter consists of one or two young animals that are not being raised by the father. The dryland elephant shrew was scientifically introduced in 1836 and its population is not considered endangered.

description

Habitus

The dryland elephant shrew is a smaller representative of the elephant shrews . It reaches a total length of 21.1 to 27.2 cm. Of this, 9.7 to 14.2 cm are accounted for by the tail, which corresponds to or slightly exceeds the length of the rest of the body (105%). The weight varies between 35 and 62 g. A pronounced sexual dimorphism is not recognizable. Investigations of 116 individuals from Namibia showed a total length of on average 23.5 cm for males (tail length 12.1 cm) and 23.7 cm for females (tail length 12.1 cm). Body weight is also relatively similar for both sexes. Male animals are about the same weight with an average of 45.9 g as females, which weigh around 45.7 g. Typical of the species are the large head with the trunk-like elongated nose and the very short front legs compared to the hind legs. The fur is dense and soft, the individual hairs are up to 12 mm long, show a dark gray color and have a yellowish-brown tip. The fur on the back and the top of the head appear overall yellowish-brown, but it is tinted pale on the sides. In general, individuals from the western range are lighter in color than in the eastern. The belly side and the chin are light gray to whitish in color. The ears are 22 to 25 mm long and have rounded tips. Long, whitish hairs appear on the inside of the auricle, behind the ears there are golden brown spots of color. The large eyes are completely framed by a whitish eye ring. The tail is dark on top and lighter on the underside. The hair here is short and whitish in color, with black tips on the top of the tail. The hair length increases towards the tail end, but no hair bush is formed as is the case with the western cliff elephant shrew ( Elephantulus rupestris ). The hands and feet are each five-pointed and have short claws. The thick skin pad on the rear soles of the feet shows a brown color, in contrast to the black in the eastern cliff elephant shrew ( Elephantulus myurus ). The rear foot length is 29 to 39 mm (average 33.7 mm).

Skull and dentition features

The skull has a length of 34 mm and a width at the zygomatic arches of 19.5 mm. The nasal bone becomes about 13 mm long. The tympanic bladder is only slightly swollen. The dentition consists of 40 teeth and has the following tooth formula : The incisors of the upper row of teeth are all about the same size, the canine is pointed. The second and third lower premolars are missing the additional, rear (third) cusp, as occurs in the closely related western cliff elephant shrew. As with this, the upper second premolar is designed in a molar shape and thus resembles the posterior molars. The length of the upper row of teeth from the first incisor to the last molar is around 17.5 mm. ${\displaystyle {\frac {3.1.4.2}{3.1.4.2}}}$

distribution

Distribution area (brown) of the dryland elephant shrew

The distribution area of ​​the dryland elephant shrew is in south-western Africa from the north-western and northernmost parts of South Africa , over large parts of Namibia with the exception of the coastal areas of the Namib to southwest Angola and the southern and central parts of Botswana . It is adapted to particularly dry, savannah to semi-desert- like landscapes with less than 200 to 450 mm annual precipitation. Because of this, low bush vegetation and thin grass covers on firm or sandy soils dominate the inhabited habitats . There must be a certain number of hiding places so that the species does not appear in completely open areas. The population size is unknown, but the density can vary significantly due to the strongly fluctuating environmental conditions in south-western Africa. However, the species is considered to be relatively common locally. Much of the range overlaps with that of the western cliff elephant shrew, which, however, needs rockier regions. This sometimes leads to confusion between the two species, especially in areas where the preferred landscape areas appear together. In the east, the range of the dryland elephant shrew is bordered by the areas of the eastern cliff elephant shrew and the short-nosed elephant shrew ( Elephantulus brachyrhynchus ). In the central Kalahari , the dryland elephant shrew is the only representative of the elephant shrews.

Way of life

Territorial behavior

Dryland elephant shrew in the Kgalagadi Transfrontier National Park in South Africa

The dryland elephant shrew can be active during the day as well as at night, the main times include the twilight phases. She is a ground dweller and moves there as a fast ( cursorial ) runner, sometimes jumping on four feet. The animals often hide in bush-covered regions and are therefore usually difficult to observe and can usually only be recognized by their constantly moving ears and trunk. The individual individuals use activity spaces which, according to studies in the Erongo Mountains, reach a size of 0.47 ha for males and 0.32 ha for females. Over a dozen different hiding spots are distributed over each action area. Occasionally, for example in the event of disturbances, the dryland elephant shrew briefly also occupies burrows that were created by rodents . She doesn't dig her own burrows. Shelters are located under bushes up to 1 m high or in 15 to 20 cm wide crevices. The entrances to the hiding places under bushes are often covered with up to 5 cm thick leaf waste. Special nests inside are not created. Between the individual residence areas such as sleeping and eating places or areas for sunbathing, the animals create paths on which they remove stones and leaves with their front paws. To sleep or to rest, an animal crouches on all fours and puts its head on its front legs. Sleep lasts a maximum of 10 minutes, but the dryland elephant shrew is always attentive in order to jump up alarmed at unknown noises or the like and sniff to find the source of the disturbance.

As is typical of other elephant shrews, the two sexes live in monogamous pairs that often last their entire life. Sometimes bound males also form further ties at the same time as unbound females, but these usually only exist for a short time. They end as soon as the unbound female finds a steady partner. The ranges of the couples either completely or largely overlap. The overlapping of the two districts is greater the higher the population density in an area. There is little overlap with the areas of activity of other couples, so that there may be territoriality. Common activities of the tied animals outside of mating rarely take place, sometimes they meet briefly before they hide and rub each other's noses as a form of contact or take short sunbaths together. Most of the time, however, they use separate places to stay and rest, with only some of them being used alternately by both partners.

The intra-species communication consists of several forms. In addition to scent marks from glandular sects, various sounds are used, such as a high-pitched squeak as a warning or a soft purr. Similar to other types of elephant shrews, the dryland elephant shrew also uses foot drums, the blows of which are generated with the hind legs. The drum series comprises regular sequences with intervals of 200 to 300 ms, into which irregular sequences of shorter duration (mostly less than 50 ms) and varying lengths are interspersed. Overall, it can last from several seconds to minutes.

nutrition

The main diet of the dryland elephant shrew consists of insects , mainly ants . In the Kalahari-Gemsbok National Park in the southern Kalahari, insects represent up to 87% of the consumed biomass. The rest is plant-based. The search for prey takes place mainly in the shelter of tall plants and bushes. Smaller prey animals are eaten immediately, larger ones such as grasshoppers take the dryland elephant shrew into hiding places and eat them there.

The body temperature of the dryland elephant shrew is 33.5 to 37.7 ° C and is relatively stable. The outside temperatures in the habitat vary between 5 and 37 ° C, sometimes cool nights occur. However, in contrast to other members of the genus, no torpor has been found in the dryland elephant shrew during colder periods of the year. These phases are bridged by the species by more frequent sunbathing and stays in warm hiding places, and there is also a narrowing of the blood vessels ( vasoconstriction ). The animals encounter overheating at high outside temperatures of 35 ° C and above with inactivity and greater evaporation of water on the body surface.

Reproduction

In Botswana and northern South Africa, pregnant females have so far only been observed in the period from August to February or March. This falls in the warm and humid season of the region and would speak for a seasonally restricted reproductive phase, as is the case with the Eastern Cliff elephant shrew. Investigations in Namibia, on the other hand, revealed indications that reproduction was not tied to specific annual periods and climatic conditions, so that here it occurs more or less all year round. The sexual act is relatively short and takes around 30 seconds. The gestation period is 50 to 52 days. A litter consists of one or two young animals. The newborns weigh around 10 g each and, like other representatives of the elephant shrews, are relatively well developed at birth. They remain in their own hiding place, separate from the mother and father animals. The mother only visits her irregularly to suckle, which is known as the “mother's absenteeism system” and is typical of elephants. The sire does not look after the offspring. The young animals gain around 1 g in body weight every day. Solid food is consumed for the first time at three weeks, and the young are weaned after five weeks. At around two to two and a half months they reach the weight of adult animals. Life expectancy in the wild is unknown; animals kept in human care lived up to nine years and three months, which is the highest figure among elephant shrews.

Predators and parasites

The main predators are the barn owl and the horned puff adder . When encounters, the dryland elephant shrew quickly flees into areas with protective grass cover or into hiding places. Ticks such as Rhipicephalus appear as external parasites .

Systematics

Internal systematics of elephants according to Heritage et al. 2020  Macroscelididae     Macroscelidinae     Macroscelidini    Galegeeska      Petrodromus      Petrosaltator      Macroscelides   Elephantulini    Elephantulus   Rhynchocyoninae    Rhynchocyon

The dryland elephant shrew is a species from the genus of elephant shrews ( Elephantulus ), which comprises a total of nine species. These inhabit large parts of southern and eastern Africa . The elephantulus belong to the family of the elephant shrew (Macroscelididae) within the same order of smaller (Macroscelidea), a group, African endemic occurring mammals. The order is differentiated today with the Rhynchocyoninae and the Macroscelidinae in two subfamilies. In the Rhynchocyoninae only the proboscis dogs ( Rhynchocyon ) are placed, the subfamily is thus monotypical . The habitat of these largest representatives of the elephants are densely forested habitats . In addition to the elephant shrews , the Macroscelidinae also includes the proboscis ( Petrodromus ), the North African elephant shrew ( Petrosaltator ), the Somali elephant shrew ( Galegeeska ) and the species of the genus Macroscelides . They are mostly considered to be inhabitants of more arid and more open landscapes and occur both in savannahs and in desert-like regions. According to molecular genetic studies, both subfamilies separated from each other in the Lower Oligocene , about 32.8 million years ago. Beginning with the Upper Oligocene around 28.5 million years ago, the Macroscelidinae became more fragmented.

Internal system of elephant shrews according to Smit et al. 2011  Elephantulus    Elephantulus fuscus      Elephantulus fuscipes      Elephantulus rufescens      Elephantulus brachyrhynchus      Elephantulus rupestris      Elephantulus intufi      Elephantulus myurus      Elephantulus edwardii      Elephantulus pilicaudus The representation here neglects the positions of Petrodromus , Petrosaltator , Galegeeska and Macroscelides , all four of which are currently deeply embedded in Elephantulus , making the genus of elephant shrews paraphyletic .

Historical representation of the dryland elephant shrew from 1839

In addition to the general relationships between the elephants, the molecular genetic analyzes also showed that the elephant shrews currently form a paraphyletic group, as Petrosaltator , Petrodromus and Macroscelides are currently still deeply embedded in the genus Elephantulus . However, the genetic studies support the close relationship of a group of South and East African species. Within this group, the western cliff elephant shrew ( Elephantulus rupestris ) is the closest relative of the dryland elephant shrew. A clade consisting of the red-brown elephant shrew ( Elephantulus rufescens ) and the short-nosed elephant shrew ( Elephantulus brachyrhynchus ) acts as a sister group . This common family group can also be assigned a clade of other, predominantly South African species, consisting of the eastern cliff elephant shrew ( Elephantulus myurus ), the Cape elephant shrew ( Elephantulus edwardii ) and the Karoo cliff elephant shrew ( Elephantulus pilicaudus ), which was only newly described in 2008 ) composed. The ancestors of this large community of species may originally have lived in eastern Africa. Around 11.5 million years ago at the beginning of the Upper Miocene there was a clear aridization of the continent, which is regarded as the reason for the emigration of these early representatives of the elephant shrews towards the south and south-west and thus to the current areas of distribution. A further fragmentation of the elephant shrews was caused by a renewed desiccation of the landscapes of southern Africa in the transition from the Upper Miocene to the Pliocene around 6 million years ago.

Between 1932 and 1955, around half a dozen subspecies of the dryland elephant shrew were described, such as E. i. campbelli , E. i. kalaharicus , E. i. mossamedensis or E. i. omahekensis , which were largely based on only a few coat variations . However, the morphological differences within the species are rather small, which is why the various subspecies are generally not recognized today.

Fossil remains of the dryland elephant shrew have so far only come down to us from the archaeological sites of Swartkrans and Sterkfontein . There it was found in several layers ( Sterkfontein Members M4 , M5 and post-M6 as well as Swartkrans Members 1-3 ), the age of which goes back from 2.8 million to 100,000 years ago. Both sites are located somewhat outside of the current range of the dryland elephant shrew, so that it can be assumed that they settled in a larger area of ​​landscape under the sometimes drier climatic conditions at the time. In some layers the species was found there with the much rarer dark elephant shrew ( Elephantulus fuscus ). Their occurrence today is significantly further north.

The first scientific description of the dryland elephant shrew was provided by Andrew Smith in 1836 under the name Macroscelides intufi . Smith gave the plains around Kurrichane in the Marico region in what is now South Africa's northwestern province as a type region . A single individual was available to Smith to describe, his body length was 13.3 cm. He later recognized the very close relationship with the Western elephant shrew. Mostly in the 1950s, some scientists introduced this within the dryland elephant shrew, but this was corrected during a revision of the elephant family in 1968.

Threat and protection

So far, there have been no major threats to the population of the dryland elephant shrew. Their distribution in partly semi-desert arid landscapes leads to only a few conflicts with humans. Locally, for example in Bushmanland in northwestern South Africa, there may be overlaps with grazing animals, and the possible adverse effects on the species are estimated to be rather minor due to the well-known way of life of the elephant. The IUCN therefore lists them as “not at risk” ( least concern ). The dryland elephant shrew is found in several protected areas. It is seldom kept in zoological gardens; in Europe it was bred in the Frankfurt am Main zoo from 1958 to 1970.

literature

• Stephen Heritage: Macroscelididae (Sengis). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 8: Insectivores, Sloths and Colugos. Lynx Edicions, Barcelona 2018, pp. 206-234 (pp. 232-233) ISBN 978-84-16728-08-4
• Mike Perrin and Galen B. Rathbun: Elephantulus intufi Bushveld Sengi (Bushveld Elephant-shrew). In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 268-269
• Galen B. Rathbun: Elephantulus intufi (A. Smith, 1836) - Bushveld elephant-shrew. In: John D. Skinner and Christian T. Chimimba (Eds.): The Mammals of the Southern African Subregion. Cambridge University Press, 2005, pp. 30-31

Individual evidence

1. ↑ ^{a b c} J. O. Matson and BR Blood: Morphological variability and species limits in elephant shrews (Elephantulus intufi and E. rupestris) from Namibia. Mammalia 62 (1), 1997, pp. 77-93
2. ↑ ^{a b c d e} G. B. Corbet and J. Hanks: A revision of the elephant-shrews, Family Macroscelididae. Bulletin of the British Museum (Natural History) Zoology 16, 1968, pp. 47-111
3. ↑ ^{a b c d e f g h i} Galen B. Rathbun: Elephantulus intufi (A. Smith, 1836) - Bushveld elephant-shrew. In: John D. Skinner and Christian T. Chimimba (Eds.): The Mammals of the Southern African Subregion. Cambridge University Press, 2005, pp. 30-31
4. ↑ ^{a b c d e f g h i j} Mike Perrin and Galen B. Rathbun: Elephantulus intufi Bushveld Sengi (Bushveld Elephant-shrew). In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 268-269
5. ↑ ^{a b c d e f g} Stephen Heritage: Macroscelididae (Sengis). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 8: Insectivores, Sloths and Colugos. Lynx Edicions, Barcelona 2018, pp. 206-234 (pp. 232-233) ISBN 978-84-16728-08-4
6. ^ ^{A b} C. Stuart, M. Perrin, C. FitzGibbon, M. Griffin (IUCN SSC Afrotheria Specialist Group) and H. Smit (Stellenbosch University): Elephantulus intufi. The IUCN Red List of Threatened Species. Version 2014.3. ( [1] ); last accessed on February 28, 2015
7. ^ Deanna K. Tolliver, Lynn W. Robbins, IL Rautenbach, Duane A. Schlitter and CG Coetzee: Biochemical Systematics of Elephant Shrews from Southern Africa. Biochemical Systematics and Ecology 17 (4), 1989, pp. 345-355
8. ↑ ^{a b c} Galen B. Rathbun and CD Rathbun: Social structure of the bushveld sengi (Elephantulus intufi) in Namibia and the evolution of monogamy in the Macroscelidea. Journal of Zoology 269, 2006, pp. 391-399
9. ↑ AS Faurie, ER and MR Dempster Perrin: Footdrumming patterns of southern African elephant-shrews. Mammalia 60 (4), 1996, pp. 567-576
10. ^ GIH Kerley, MH Knight and T. Erasmus: Small mammal microhabitat use and diet in the southern Kalahari, South Africa. South African Journal of Wildlife Research 20 (4), 1990, pp. 123-126
11. ^ Graham IH Kerley: The Round-eared Elephant-Shrew Macroscelides proboscideus (Macroscelidea) as an omnivore. Mammal Review 25, 1995, pp. 39-44
12. ↑ Colleen T. Downs and Mike R. Perrin: The thermal biology of three southern African Elephant-shrews. Journal of thermal Biology 20 (6), 1995, pp. 445-450
13. ^ Mike Perrin: Comparative aspects of the metabolism and thermal biology of elephant-shrews (Macroscelidea). Mammal Review 25, 1995, pp. 61-78
14. ^ BR Neal: The ecology and reproduction of the Short-snouted Elephant-Shrew, Elephantulus brachyrhynchus, in Zimbabwe with a review of the reproductive ecology of the genus Elephantulus. Mammal Review 25, 1995, pp. 51-60
15. ↑ HRH Tripp: Captive, laboratory care and breeding of Elephant-shrews (Macroscelididae). Laboratory Animals 6, 1972, pp. 213-224
16. ^ Gea Olbricht: Longevity and fecundity in sengis (Macroscelidea). Afrotherian Conservation 5, 2007, pp. 3-5
17. ↑ LJ Fourie, JS du Toit, DJ Kok and IG Horak: Arthropod parasites of elephant-shrews, with particular reference of ticks. Mammal Review 25, 1995, pp. 31-37
18. ↑ Steven Heritage, Houssein Rayaleh, Djama G. Awaleh and Galen B. Rathbun: New records of a lost species and a geographic range expansion for sengis in the Horn of Africa. PeerJ 8, 2020, p. E9652, doi: 10.7717 / peerj.9652
19. ↑ ^{a b c} Hanneline Adri Smit, Bettine Jansen van Vuuren, PCM O'Brien, M. Ferguson-Smith, F. Yang and TJ Robinson: Phylogenetic relationships of elephant-shrews (Afrotheria, Macroscelididae). Journal of Zoology 284, 2011, pp. 133-143
20. ^ Mike Perrin and Galen B. Rathbun: Order Macroscelidea - Sengis (Elephant-shrews). In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 258-260
21. ^ DM Avery: The Plio-Pleistocene vegetation and climate of Sterkfontein and Swartkrans, South Africa, based on micromammals. Journal of Human Evolution 41, 2001, pp. 113-132
22. ↑ Patricia A. Holroyd: Past records of Elephantulus and Macroscelides: geographic and taxonomic issues. Afrotherian Conservation 7, 2009, pp. 3-7
23. ↑ Patricia A. Holroyd: Macroscelidea. In: Lars Werdelin and William Joseph Sanders (eds.): Cenozoic Mammals of Africa. University of California Press, Berkeley, London, New York, 2010, pp. 89-98
24. ^ Andrew Smith: Report of the Expedition for Exploring Central Africa. Cape Town, 1836, pp. 1–68 (p. 42) ( [2] )
25. ^ Andrew Smith: Illustrations of the Zoology of South Africa. Mammalia. London, 1839 (Plate 12) ( [3] )
26. ↑ Zoo animal list ( [4] ), last accessed on June 26, 2015

Web links

Commons : Dryland elephant shrew ( Elephantulus intufi )  - Collection of images, videos and audio files

• Elephantulus intufi inthe IUCN Red List of Threatened Species 2014.3. Listed by: Stuart, Perrin, FitzGibbon, Griffin & Smit, 2008. Retrieved February 28, 2015.