Description
“Rooibok”, the Afrikaans name, literally meaning “red buck”, is very descriptive of this very elegant antelope. The fact that they are in abundance does not detract from the fact that impalas are one of the most beautiful and graceful antelopes in all of Africa. See Figure 1.
Before we get to hunting this animal let’s learn something about it. A hunter who knows his quarries habits and understands their behaviour will always be more successful.
Adult males, referred to as rams, stand about 90cm tall at the shoulder and weigh about 54kg. Adult females, referred to as ewes, are slightly smaller and have an average body mass of about 41kg. Only the males generally have horns, although there are records of females carrying horns. In the latter, the horns are usually thin, misshapen, and non-typical.
The upper parts of the body are a rich reddish brown colour. From behind the shoulders, the flanks are a pale fawn colour with reddish undertones. The underparts are pure white. There are white patches around the eyes, the inside of the ears, the muzzle, and the throat. There is a dark brown to blackish patch high up on the forehead. A long, narrow, vertical black stripe on either side of the tail stands out in sharp contrast to a pale fawn colour. The legs are long and slender.
Above the fetlocks on the hind legs, one finds an oval patch of black hair, which overlies a glandular area of the skin. The top of the tail is black, this colour narrowing down to the tip and extending along the back as a thin stripe. The tail is white underneath and along the sides. The tips of the ears are black. The insides of the legs are lighter than the outside.
The lyre shaped horns of adult rams bend gracefully back over the head and then sweep forwards and inwards. There are sharply defined ridges around the horns for approximately two-thirds of the length.
Distribution (Southern African sub-region)
Zimbabwe: Widely distributed in the lowland areas but absent from the plateau and eastern districts. Absent in the Brachystegia woodland of the northeast.
Botswana: Confined to the northern, northeastern, and eastern areas with deep intrusions into the dry eastern areas of the Kalahari along fossil river beds that are associated with Acacia woodland or shrubland.
Mozambique: Historical distribution was south of the Zambezi. During the years of civil war, numbers decreased sharply but since the cessation of the war numbers are recovering.
South Africa: Common in eastern and northeastern areas of Mpumalanga, Northern and North West Province, and parts of Kwazulu Natal.
Namibia: Occurs as the sub-species Aepyceros melampus petersi (black faced impala) in the far northwest, west of Etosha pan.
Habitat
Throughout their distribution they are associated with woodland, showing a preference for more open woodland communities. See Figure 2.
In their northern and northeastern distribution in South Africa, they are closely associated with Acacia and mopane (Colophospermum mopane) veld.
In the eastern areas, they can be found in Combretum (bush willow) and Terminalia (silver cluster-leaf) woodland. They generally avoid open grassland and floodplains but will utilize these areas when there is a flush of new green grass. They are partial to transition zones (called ecotones) between open grassveld and woodland. They also tend to avoid montane (mountainous) areas. Impala are dependent on surface water and cover.
Habits
Impala are generally gregarious animals although lone rams are not uncommon – especially during the rutting season when they establish and defend territories for themselves. Competition during the rut can be quite fierce between rival males. Injuries and mortalities may result from fighting and horns are sometimes broken off during battles (See Figure 3).
Common social groupings consist of the following:
Breeding herds – made up of adult male (or males), adult females, and the whole spectrum of younger male and female animals. During times out of the rutting season, adult rams are tolerant of one another and younger males. During these times, there might be a number of adult rams in breeding herds. Smaller breeding herds are sometimes observed without adult males present. The size of impala herds becomes smaller during the rut as the larger herds are split up by competing males. These herds coalesce during the lambing season to form larger herds. This greatly assists in predator avoidance when the lambs are young and vulnerable. There are more eyes to see, ears to hear, and noses to smell. Figure 4 shows the composition of a typical breeding herd.
Bachelor herds – usually consist of males older than two years of age who are chased out of breeding herds or are not capable of or ready to compete with other adults for territory. See Figure 5.
Lone rams – these are usually adult males who establish and defend territories during the rut. See Figure 6.
Impala are predominantly diurnal (day active) with some nocturnal activity. They will seek out shade during the hotter parts of the day. When approached impala will first watch the intruder carefully and move off slowly if the intruder approaches closer. If approached to within the flight distance they will scatter in all directions, leaping in graceful arcs or running away at great speed.
They are easily capable of clearing a 2m high obstacle or jumping a horizontal distance of 12m.
Mortality
Impala adults fall prey to predators such as leopards, wild dogs, cheetahs, and lions (see Figure 7).
Young animals are killed by jackals and larger raptors such as martial eagles. Impala are also susceptible to diseases such as foot and mouth, bovine tuberculosis, and anthrax. Mortalities sometimes result during cold weather, especially if accompanied by rain.
Impala rams that participate in the rut are usually in poor condition by the end of winter and have high parasite loads at this time. See Figure 8.
They are usually at their weakest and most prone to disease and predation during this period.
Impala have a close association with red-billed oxpeckers. In exchange for providing the oxpeckers with food, the birds provide an early warning system for the impala (see Figure 9).
Impala often associate with zebra and wildebeest which mutually assists with danger surveillance.
Feeding and drinking
Impala are both browsers and grazers. See Figure 10.
The ratio of browse to grazing will depend on availability and time of the year. Impala are very partial to new green grass which will emerge after a burn or early during the rainy season. Small branchlets and leaves of Acacia species make up a large percentage of the diet. The seed pods of certain species such as Acacia tortillus (umbrella thorn) are much sought after when available.
The browse of Combretum spp. (e.g. bushwillow), Boscia spp. (e.g. shepherds tree), Grewia spp. (e.g. raisin bush family), Ziziphus spp. (e.g. buffalo thorn), Meytenus spp. (e.g. spike thorn), and Dichrostachys spp. (e.g. sickle bush), and many others will be utilized. Leaves that have fallen to the ground from species such as Colophospermum mopane (mopane) and Spirostachys africana (tamboti) are commonly eaten during dry months of the year.
Grass species which are commonly found in the diet include, amongst others, the following: Digitaria eriantha (finger grass), Themeda triandra (“rooigras”), Cynodon dactylon (couch grass), Eragrostis spp. (love grass), and Urochloea spp. (signal grass). The presence of these species in stomach contents will vary according to location, availability, and season.
They can survive for short periods without water by licking dew and from the moisture content of their plant diet.
Impala usually stay within about 8km of the nearest available surface water They can survive for short periods without water by licking dew and from the moisture content of their plant diet. When water is available, adults will drink about 2.5 litres and usually drink during the day. They will drink from rivers, dams, or pools of rainwater. See Figure 11.
Reproduction
In South Africa breeding occurs during the autumn months of April to May.
During this time territorial males will be seen tirelessly herding female breeding groups and attempting to keep them within the confines of their demarcated territories. The males show interesting behaviour at this time – they approach females with their head outstretched, top lip often curled back (referred to as “flehmen” – see Figure 12), and tail flared.
During the rut territorial rams will evict competing males and also, at times, young males older than two years. Rams are strongly territorial during the rut and serious fights sometimes erupt between rival males which often result in serious injuries and even death.
Dominant males mark territories by depositing dung in latrines referred to as middens and by rubbing their foreheads on grass and shrubs (see Figure 13).
The rut is a good time for bowhunting impala as the territorial males, which are often good trophies, become less vigilant, and can also be called in by mimicking their snorting and guttural vocalizations.
The lambing season begins in November, peaks in December and tails off in January. Impala lambs are soon on their feet and running with the herd after birth. Young lambs form nursery groups which are looked after by a few adult females at a time whilst the remainder of the “moms” are off feeding. See Figure 14.
Now we know something about impala we will look in Part 2 at the actual hunting of this species.
