Etosha – Creatures great and small

Text by Hu Berry, Photos by Paul van Schalkwyk

| This article was first published in the Flamingo March 2008 issue. Information has been adapted accordingly.

Among the most often-asked questions by visitors to the Etosha National Park are “Where are the lions?” and “Where are the elephants?”

T hese awesome animals are understandably on the wish list of every tourist. However, Etosha boasts a daunting array of other creatures that pose a challenge for the discerning sightseer. To date no less than 581 different species of vertebrates, that is animals with a spine, have been recorded. They comprise 1 fish (49 during floods), 16 amphibian, 110 reptiles, 340 birds and 114 mammal species. At this stage of our knowledge the number of animal species without a spine, that is spiders and insects, are literally anybody’s guess. But since most visitors come to view the ‘big and hairies’, they are the ones to concentrate on.

Etosha’s mammals are divided into large and small by using the common black-backed jackal, weighing up to 10 kilograms, as a convenient dividing line between ‘big’ and ‘small’. They represent 24 families, including bats, hares, rodents, pangolins, apes, carnivores, aardvarks, rock hyraxes, elephants, zebras, rhinos, warthogs, giraffes and antelopes. The antelope family has the most variety, consisting of wildebeest, red hartebeest, grey duiker, springbok, klipspringer, Damara dik-dik, steenbok, black-faced impala, gemsbok, kudu, and eland. No fewer than 12 species of ruminants digest their food by means of regurgitation and circulation, propelling it through a succession of four complex stomachs. The resultant mix is a refined blend of highly digestible nutrients. This ability to ‘chew the cud’ explains why antelope overshadow other plant eaters on Africa’s savannahs. In addition many antelope species are highly gregarious, providing the herd with many eyes, ears and nostrils to detect danger. Safety in numbers is a common theme for survival on the Etosha plains. Ancestors of the modern antelope appeared about 25 million years ago, adapting so successfully to changes in the habitat that the pressures of natural selection produced 91 different species in Africa, compared to only 3 species of zebra.

The small mammals are less known but occupy critical niches in the ecosystem. They are part of the base of the numbers pyramid. There are many more rodents and bats than wildebeest and zebras, and many more wildebeest and zebras than lions and elephants. The big game may appeal more to tourists and be easier to record on digital cameras, but many of Etosha’s small game have astounding habits and, equally, intriguing names that capture the imagination.

Take for example the insect-eating, tiny musk shrew, which weighs a mere 4 grams. It has all the attributes of a mammal, including a heart and blood vessels, a brain and nerves, a muscular network, a digestive tract, and reproductive organs that enable the nursing mother to secrete literally only drops of shrew milk to its healthy baby, which at birth tops the scales at just over 1 gram. Shrews resemble mice but are not rodents and belong to an entirely different group. They are all characterised by sharply pointed snouts and are armed with needle-sharp teeth to tear up their prey of moths and grasshoppers. Other weapons in the shrew’s armament are the musk glands they carry on their flanks. These secrete hormones to attract the opposite sex, but also make shrews highly distasteful to mammalian predators such as jackals. Unfortunately for shrews, this taste does not deter owls, with the result that shrew remains are often found in owl pellets.

At dusk many animals become active, some creeping, some crawling and some flying. In Etosha certain of these tiny twilight flyers even mate in the air. They are likely to be the diminutive bats you see flitting around rest-camp waterholes at sunset. Another insect-eater, the common slit-faced bat, is only slightly larger than a shrew, weighing 10 grams. Its conspicuously large ears enable it to detect the slightest sound. Using echolocation clicks made in its larynx at the incredible rate of 230 000 vibrations per second, and letting them bounce off objects in its flight path, the bat can detect prey up to 10 metres away. We cannot detect these sounds because our hearing is limited to a range of 20 to 18 000 vibrations per second.

Out on the sun-baked plains of Etosha, often next to the road, the terrestrial ground squirrels provide excellent photographic opportunities, amusing tourists with their antics. The flared bushy tail spreads like an umbrella, shading the body. Indeed, ground squirrels take their family name Scuiridae from the Greek word for ‘shady tail’. They are the smallest Namibian mammal able to endure the sun’s rays throughout the day. When it comes to water-saving, these squirrels are the clear winners. Their kidneys rate among the most effective of any mammal’s, able to concentrate their urine to the extent that they can survive several months without drinking water. Science has baptised them with the generic name of Xerus, which is synonymous for ‘dryness’. Commonly living in close association with ground squirrels, the yellow mongoose, identifiable by its white-tipped tail, provides protection against snakes for the squirrels. To reciprocate this security service, the burrowing squirrels allow mongooses, which don’t possess the sharp digging apparatus squirrels have, to share their burrows.

The animal dividing ‘large’ mammals from ‘small’ ones is ubiquitous in Etosha, as in most of Namibia. Black-backed jackals are regarded by many as the most superbly adapted carnivore in the country. This distinction is awarded because of the ability these animals have to hunt and scavenge, live singly or in packs, be active day and night, and adapt to the presence of humans. In Etosha black-backed jackals have been observed to kill springbok, hunt rodents and birds and insects, and eat carrion, refuse and vegetable matter. They can be highly vocal, penetrating the night air with a chorus of shrill howls, or remaining silent when threatened. Admired by conservationists and reviled by farmers, both friend and foe of the black-backed jackal agree that it will probably survive human pressure long after other large carnivores have been eradicated.