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The African savanna elephant

25 August 2015

 

www.leopard.tvSome 182 types of elephant and 44 genera are known to have existed at some time, but only the Asiatic elephant Elephas maximus, African forest elephant Loxodonta cyclotis and African savanna elephant Loxodonta africana have survived. However, based on some preliminary, but inconclusive, genetic studies it is being speculated that a fourth type of elephant may also occur in the deep forests of Africa and that it developed from the ancient gene pool which also gave rise to the living Asiatic and African elephants. The African savanna elephant developed some 1,5 million years ago in Africa. It was first described scientifically by Blumenbach in 1797 as Elephas africanus based on a molar tooth that was found near the Orange River in South Africa. The name Loxodonta was created by an unknown scientist in 1827 and was derived from the ancient Greek words loxós for oblique (bent) and odont for tooth, while africana refers to Africa. In 1798 a Cape elephant was described as Elephas capensis by Cuvier but this differentiation is no longer valid.

In South Africa, elephants were first mentioned by Vasco da Gama when he visited Mossel Bay in 1497. However, elephants apparently never occurred in the Cape Peninsula. The most southern distribution seems to have been near Tiervlei just west of Stellenbosch, while in 1652 Verburgh saw elephants during an expedition between Cape Town and Saldanha Bay. Elephants also once occurred between the Green and Buffalo Rivers in Namaqualand and around the Orange River. In years of exceptional rainfall a few elephants move south from Botswana into the south-western Kalahari, as do other wildlife. On 10 January 2015 an elephant was seen next to the border with Namibia some 50 km north of the Mata Mata Rest Camp in the Kgalagadi Transfrontier Park before it crossed into Namibia. The most recent previous time that elephants occurred in this park was in February 1997. In 1779, elephants were recorded just west of the Augrabies Falls, and in 1812 Khoikhoi people killed 39 elephants next to the Matlhwaring River north of Kuruman. Elephants were once abundant in the forests of the South Cape into which they fled as early as 1876 to escape from hunting pressure. By 1899 as much as 60 000 kg of ivory was exported per year from South Africa to England, causing the death of thousands of elephants. The current number of elephants in the forests near Knysna is unknown but there may be a remnant breeding population. There also once were large herds in KwaZulu-Natal, and for the pioneer trekkers elephants were a major source of income. Elephants were abundant in the northern parts of southern Africa, but in arid Pre-Namib and Namib Desert they have adapted their morphology and behaviour to be able to cope with life in an arid environment.

A typical savanna elephant bull has a maximum shoulder height of 3,42 m and weighs from 5500 to 6000 kg as opposed to 2,62 m and 4000 kg in a cow, but the heaviest known bull weighed 6560 kg. Because of the heavy head, the forelegs are larger and more rounded than the hind ones and the footprint of the forefoot is rounder than the rear one. The soles of the feet have creases and cracks that are unique to specific individuals and can be used to identify individual elephants. The weight of a bull increases throughout his life but the cows reach a constant weight when they are 35 to 40 years old. Because the testes are abdominal and are not externally visible, elephants are members of the Testiconda group of animals. The grey to brown-grey skin is thinnest behind the ears and thickest on the trunk, forehead, legs and back where it can be up to 40 mm thick. The behaviour of dusting themselves or taking mud baths may affect the apparent skin colour. The body is covered sparsely with bristle-like hair and the cylindrical tail is some 1,5 m long but it has a flat end with a tassel of long, black hair.

An elephant lacks sweat glands on the skin but it loses substantial moisture from the skin. There are two temporal glands on the side of the face which increasingly secretes fluid when an elephant experiences stress or when a bull becomes sexually active. The mouth forms a small tout and the trunk has prehensile tips on the bottom and top, consists of hundreds of muscles and has a multitude of uses. The large ears form 20 per cent of an elephant’s surface and each ear has an extensive vascular system through which 5 to 12 litres of blood flows per day to release 75 per cent of an elephant’s heat and allow it to maintain a constant body temperature. The profile of the forehead of an adult bull is more blocky than that of a cow. In addition the cow has two visible teats between the forelegs and a bull’s back is more straight than that of a cow. The age which an elephant can attain is determined by the wear of the six molar teeth which erupt in sequence. The last molar tooth appears when an elephant is 45 years old and it usually is worn away at an age of 60 to 70 years. The top of the pelvic bone protrudes above the body when an elephant is in a poor physical condition.

Elephant cows form breeding herds which are joined by bulls when the cows are in oestrus. The breeding herds are not territorial but each herd has its own range which can be as large as 5527 km2 as in northern Kenya. However, some elephants may suddenly start moving around without any apparent reason to appear in places where elephants have not been known to occur for many years. The small eyes are green or hazel in colour but the eyesight of an elephant is poor although its hearing is acute. Elephants swim well and will walk through shallow rivers with their trunks held above the water. They breed during the summer rainy season in the bushveld of southern Africa. Rutting bulls can become aggressive and secrete fluid copiously from their temporal glands while urine drips from the penis which becomes greenish in colour. In the older bulls the rut can last from two to five months. The bulls usually only breed once they are 35 years old, and the cows from an age of 25 to 60 years depending on their food quality and physical condition. A single calf is born after a gestation period of some 22 months although twins have been recorded. The cow squats when giving birth in isolation, although she may be protected by other cows, and the she seldom eats the afterbirth. At birth the calf of some 0,9 m tall at the shoulder weighs around 120 kg, is pinkish in colour and it has more hair than an adult elephant. The calf usually suckles for two to three years but may continue to do so for up to eight years.

Elephants are mixed feeders and eat a wide variety of roughage. The diet varies from region to region depending on the availability of food plants, and elephants move around seasonally to better food resources and water. They eat a variety of wild fruits such as those of the various types of lala palm Hyphaene, the manketti tree Scinziophyton rautanenii and the marula tree Sclerocarya birrea. At certain times of the year they concentrate on green, palatable grasses that are in seed. They rip the bark off trees and use the bark of the baobab tree Adansonia digitata for its water content. The bark of various types of thorn tree, but especially that of the knob thorn tree Acacia nigrescens and the umbrella thorn tree Acacia tortilis, is eaten as food. Elephants also uproot trees to eat the roots. When too many elephants occur in an area they will eventually destroy the large trees by pushing them over to eat the young leaves. In Tsavo National Park in Kenya an overpopulation of elephants destroyed the vegetation to such a degree that numerous other types of wildlife, among others all the black rhinoceroses, died. In addition, thousands of elephants died of hunger. It is estimated that before the advent of modern man elephants migrated every 200 years or so to give an area which they had destroyed an opportunity to recover.

Elephants drink some 160 litres of water per day and waste another 140 litres or so to bathe and cool off. In the north-west of Namibia they walk 90 m to and fro along deeply trampled footpaths to the nearest water resource and they drink around every third day. They dig for water with their forefeet and tusks in sandy riverbeds and excavate gonas that can be up to 0,8 m deep to reach water under the surface sand. When they are forced to drink brackish water they can die if the salt content is too high.

A cow of ten years old produces a mean of 100 kg of dung in 24 hours. Elephant dung is an ideal microhabitat for the germination of the seeds of certain trees, including those of the camel thorn tree Acacia erioloba. Various types of wildlife will eat the undigested fruit seeds in the dung.


References:

Du Toit, J G 2015. The African savanna elephant. In J du P Bothma & J G du Toit (Eds), Game ranch management, sixth edition. Pretoria: Van Schaik, in press

Skinner, J D & Chimimba, C T (Eds) 2005. Mammals of the southern African subregion, third edition. Cambridge: Cambridge University Press, pp 51 - 59.

 

article by Prof J du P Bothma

 

 

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