Impala

Impala - Life on the Fringe

With its sleek reddish coat, long legs and lyre-shaped horns, the impala is perhaps the most elegant of all African antelope. But sadly - due no doubt to its abundance in most Southern African wildlife reserves - it is practically ignored by safari-goers (and even many guides) after the first sighting. A closer examination of the impala's lifestyle and ecology does, however, reveal a truly fascinating animal. Its abundance in many regions is largely due to its adaptable diet, for it is both a grazer and a browser (most herbivores are one or the other). With a diet that includes fresh green grass, acacia foliage, seed pods, pioneer herbs unpalatable to most other herbivores, and even dry leaves, impala favour the so-called "ecotone" or fringe habitats, where savannah meets woodland, or where grassland meets savannah.

No Close Relatives

The majority of African antelope belong to tribes or groups of related species but the impala is one of a kind (although claims have been made for affinities with hartebeest). Among a variety of anatomical and behavioural specialities, the distinctive "fetlock glands" are perhaps the most conspicuous. These tufts of black hair on the hind legs cover scent glands which release a pheromone (chemical) under certain circumstances (such as when being pursued by a predator). Such signals allow members of a group to stick together while escaping through dense cover.

Only male impala have horns and these reach their full length and thickness at about four years of age. Members of the East African population (centred in the Serengeti-Mara) possess considerably larger horns than their Southern African counterparts and this has been attributed to the need for males to display and fend off rivals on a more regular basis (due to less clearly defined dry and wet seasons).

Residential Clans

Impala favour specific areas - ecotone with plenty of grass and acacia, well-drained soil, fairly flat terrain and reasonable proximity to drinking water being among their needs - and individuals and groups are faithful to the same small area, year after year. Females form "clans" of between 30 and 120 individuals that occupy areas of suitable habitat with a "core area" of between 80-180 hectares. Several groups can and do overlap beyond the core areas. Lambs are born in a synchronous fashion - all females in an area dropping within two or three weeks - in the rainy season (November in Southern Africa) when food and cover is most plentiful. Mothers keep their lambs hidden for the first couple of days after birth, but the youngsters then join others of a similar age in "crèches" within the herd. Males over one year live in "bachelor herds", often in separate areas from the female herds, with the dominant individuals breaking away to set up territories in proximity to female herds.

Passion Under the Moon

At the end of the wet season (May in Southern Africa) when the days become shorter and the nights cooler, male impala enter a period of "rut". Individuals of four years or more challenge each other in noisy, boisterous challenges in a struggle to gain and hold a territory. The explosive barking call of the rutting males has frightened the wits out of more than a few trailists and campers, for it is often mistaken for the roar of a lion! The competing males put all their energy into the rut, often loosing condition (less time is spent eating) and many preoccupied individuals are taken opportunistically by predators. The males which succeed in holding a territory will not have it for long - the job of rounding up, mating and chasing opponents is tiring! - and they must "make hay while the moon shines". Research in Zimbabwe has shown that impala are influenced by the lunar cycle, with almost all mating taking place in the period between full moons! The average territorial tenure of one male over a breeding herd was found to be just under three months in the Serengeti-Mara, but just eight days in one detailed Zimbabwe study.

Camels of the Bushveld

Although they are rarely found far from water, impala are actually able to survive without a drink for months on end in summer and for up to a week in the dry winter months. During the rainy season they feed primarily on green grass (70% moisture content) - and in winter they mostly nibble green foliage of trees along watercourses and drainage lines; there is enough moisture in these food sources to meet their requirements. When water is available - such as at artificial waterholes - impala will drink daily, but they could survive without it. Among other water-saving devices employed are the drinking of dew from dry grass on early mornings, and by licking water from their own coats after drizzle. And even when they do actually drink, impala require just one and a half litres per day.

Agile and Athletic, but Favoured by Carnivores

Impala are extremely agile and are capable of spectacular leaps and raised kick-backs. The detection of a predator (or a false alarm!) can send a herd into a mad scatter, with individuals leaping above and across one another, nimbly avoiding thorny branches and rutted ground. Long jumps of up to 11 metres have been recorded and individuals have been seen to clear 3 metre high obstacles!

Despite their great leaping abilities, impala form the bulk of the diet of all large carnivores excepting lion, which generally prefer larger prey. Their habit of feeding on habitat fringes does give them quick access to cover, but seems also to favour the stalking techniques of predators. Leopard favour females and younger males, but larger leopards are able to capture the heavy males. Wild dog packs in the Kruger typically take two or more impala per day, only occasionally varying their diet to include young kudu, grey duiker and steenbok. Spotted hyena take a large number of lambs and packs are capable of running down an adult. Cheetah in the Kruger and Okavango take a large number of Impala, although those in the Serengeti-Mara prefer to hunt gazelle in open plains where they can make maximum use of their speed and agility. Martial Eagles and jackals prey upon the lambs, while Nile Crocodile and African Rock Python are a threat to all ages.

Excellent Viewing Opportunities

Although impala are often abundant, they are certainly one of the most interesting and attractive of African antelope. To see and hear the males strutting their stuff during the rut, or the creches of tiny infants during the wet season, is always a memorable encounter. Excellent viewing and photographic opportunities can be had at almost all CCAfrica lodges, with the landscapes of Phinda Private Game Reserve, Londolozi Private Game Reserve, Ngala Private Game Reserve, Bongani Mountain Lodge (all in South Africa), Sandibe Okavango Safari Lodge, Nxabega Okavango Safari Camp (both in Botswana), Kichwa Tembo (in Kenya), Grumeti Serengeti Tented Camp and Klein's Camp all supporting good numbers.

Posted: Mammals by CC Africa, Date: 21 November 2006