During the rut, which takes place between April and June, adult impala males establish territories, which they defend by chasing away rival males.
Guttural roars followed by protracted snorts can be heard throughout the day and night, as the dominant male defends his territory against intrusions by neighbouring males. If territorial displays are not effective in fending off rivals, the males resort to horn-clashing duels to determine dominance.
A herd of impala approaches water. For impala, gathering together in a herd has many advantages: many pairs of eyes and ears are constantly alert to danger, and the chances of being caught by a predator are greatly reduced. In the Kruger Park there are approximately 10 000 impala herds with an average herd size of 11 animals.
Impala gather at a water hole in acacia country near Lower Sabie. They have a marked preference for areas where there is a regular supply of water, short grass and dense thickets of shrubs and trees.
These conditions are normally encountered near rivers where a concentration of larger animals, such as elephant and buffalo, further improves the habitat for impala. Impala are prolific breeders and are the most abundant mammal in Kruger, but these medium-sized antelope drink less than one quarter of the water consumed by the Elephants in Kruger National Park.
A redbilled oxpecker removes ticks from a female impala, the smallest of the antelope attended by these birds. Small flocks of oxpeckers clamber about the host cleaning ectoparasites from its hide. When startled, they move to the opposite side of the host, and peer over its back at the source of disturbance. Their noisy, hissing alarm calls help to warn the animals they are perched upon of impending danger.
Kudu are nonselective browsers and feed on no less than 150 species of trees and shrubs. They avoid trees with a high tannin content in their leaves, and favour acacia and combretum species.
Although they prefer the same trees that are sought after by giraffe, competition between the two species is minimised by feeding at different heights. This beautiful large antelope is the most widely distributed of 20 antelope species in Kruger Park, but is most common in the Central Region where its favourite food plants are found in abundance.
Although Kudu drink when water is available, in times of drought they are more susceptible to a lack of adequate browse than they are to a lack of drinking water. The female weighs about 160 kilograms, but males are much larger and weigh on average 250 kilograms.
A kudu bull displays the longest horns of all the antelope that occur in Kruger. At the age of nine months a male kudu sports two short horns, which begin to grow and curve with age to form the corkscrew shape typical of mature bulls.
The record length of 181 centimetres is more than twice that recorded for a close relative, the nyala. There have been several observations of jousting kudu bulls interlocking their spiral horns and being unable to disengage. Unable to disentangle their horns or flee, the helpless contestants soon fall prey to predators.
Herds of female waterbuck and their young occupy a home range that coincides with the territories of several males.
Relative to their small population size, more waterbuck are killed by Lion than any other antelope in Kruger, and 60 to 80 per cent of deaths can be attributed to these predators. Waterbuck are uncommon throughout their range in South Africa and currently number a modest 1 400 in Kruger. They favour open woodland near water.
A male waterbuck, followed by an attentive cattle egret, grazes near the Sabie River. Of the 77 species of African antelope, only the waterbuck has a distinctive white ring around the rump. Grasses of a high nutritional quality and a regular supply of water are both essential habitat requirements for these animals. Cattle egrets, the only members of their family that are not closely dependent on water, feed on grasshoppers and other insects disturbed by large antelope.
The regal sable, arguably the most beautiful antelope in the Park, has specific habitat requirements that include tall grassland and open woodland.
An increase in zebra herds and prolonged drought has caused a considerable decline in sable in recent years. Blue wildebeest favour short grasses and need to drink less than other grazers such as zebra and buffalo. Although wildebeest are dependent on water, the severe drought of 1992/93 had little effect on their population, currently estimated at about 13 000.
A blue wildebeest bull maintains his dominance by means of ritual displays intended to intimidate any intruder. When another bull approaches, the territorial bullís rocking-horse gait and swishing tail†are meant to dissuade his competitor.
If this display fails, the bull drops to his knees and engages in horn-clashing sparring (opposite below). No injuries result from these contests as the impact is absorbed by the bullís solid horn bosses. One of the bulls eventually surrenders and is chased off the territory by the victor. Wildebeest bulls clash at Bangu, an important water hole on the eastern plains. Males are territorial and even where herds migrate over long distances, temporary territories are established.
In the Kruger Park bushbuck are associated with dense riverine bush, and the road between Skukuza and Lower Sabie offers the best sightings. They are solitary antelope and occupy home ranges that often overlap. Unlike most antelope species, bushbuck are exceptionally tolerant of each other and territorial displays are a rare phenomenon.
The smallest of the antelope most commonly seen in Kruger, steenbok show a marked preference for the open plains in the eastern region of the Park, formed on volcanic basalt. There is some sexual dimorphism, with only male steenbok having horns, and the females being slightly larger than the males.
A nyala male displays the stripes and horn shape typical of this antelope family. Nyala occur mainly north of the Letaba River, especially along the Shingwedzi and Luvuvhu rivers. Only males have horns. Females are a reddish ochre in colour and can be confused with young kudu.
The roan antelope is classified as an endangered species in South Africa. Following the harsh drought of 1992/93, roan antelope nearly became extinct in the Park, and the population fell from 452 in 1986 to 44. Kruger mostly contains habitats that are marginal to their requirements, as roan survive better on wetter savannas. They avoid areas of short grass and overutilised areas, and occur only in open woodland with a well-developed cover of tall grass.
By Nigel Dennis & Michael Brett.