. The Impala Of Africa
In swahili Language is Swala
Classification of Impala
Kingdom~ Animalia
Phylum~Chordata
Class~ Mammalia
Order~ Artiodactyla
Family~Bovidae
Tribe~ Aepycyrotini
Genus~ Aepyceros
Species~ Aepyceros melampus.(A.Melampus)
Binomial Name ~ Aepyceros Melampus
Active mainly during the day, the impala may be gregarious or territorial depending upon the climate and geography. Three distinct social groups can be observed: the territorial males, bachelor herds and female herds.
The Behaviour Impala are known to associate with other gregarious animal species such as blue wildebeest Connochaetus taurinus, zebra Equus spp, chacma baboon Pappio ursinus, waterbuck Kobus ellipsiprymnus and giraffe Giraffa camelopardalis, gaining advantage in the sharing of senses needed for the detection of danger. When bred in camp systems sharing with larger game such as sable, roan or wildebeest, impala often get injured or killed from aggressive interaction of the other species at drinking holes and feeding stations. Impala are area-bound and the same group (6-30 animals) is frequently found in the same vicinity; the mean distance for 24 hours movement being 2,5-3 km. Home ranges are stable year round and vary from 200-700 ha depending on the veld condition and the stocking density. Impala are not migratory and roam approximately 8,4 ha/24 hour cycle keeping within 1,6 km from drinking water - they often starve at a dried-up water hole instead of migrating to seek an alternative water source. Feeding is restricted to daylight hours and during hot daylight hours they keep to the shade of trees. Socially mature rams establish temporary
Page 9 of 16 territories of 4-10 ha only during the rut. Bachelor herds form during the rut between January and April, consisting of sexually mature, but socially immature rams. Temporary nursing groups of youngsters that form on the outskirts of the family herds and are accompanied by 1-2 adult ewes. Herds of post-mature rams of 2-4 years that are mostly of trophy quality. Rams reach sexual maturity at 16 months and ewes at 13 months, but social maturity (age of first mating) at 3 years for rams and 1,5 years for ewes. The gestation period is 185-205 days. The lambing season differs with the geographical area, being from October to January in South Africa when 90% of the lambs are born within a short period of 3-5 weeks. Lambs only associate with their mothers for suckling and spend the rest of their time in nursing groups. Dominant rams become aggressive as the rut approaches at the end of January. Declining daylight hours stimulate an increased hormonal production that enables the blubber to accumulate in the neck, enlarging the neck of the male that, in turn, triggers oestrus in the adult ewes. Territorial rams try to retain their family herds generally for a period of 8-12 days and thereafter become weak and displaced by another challenging opponent. After 4-6 weeks the ram loses all of its bodily strength, returns to normal roaming and abandons its territorial behaviour. After 8 years rams become post mature and join small post-mature groups. Natural mating ratio is one mature ram to three mature ewes, giving an annual population growth of 23% at 300 mm annual rainfall, to 48% at >600 mm. The lambing efficiency of two year old ewes is only 60%, in 3-7 year old ewes it is 97% and for ewes >8 years of age it declines to 70-80%. The mean natural lifespan is 8-12 years. A 1 000 ha optimal habitat can sustain 300 impala at an annual rainfall of 400 mm, and 600 impala at 600 mm rainfall. An impala animal-unit (AU) of 50 kg equals 0,17 large stock units (LSU’s) and 0,38 browser units (BU’s). Each impala animal unit requires a minimum of 2-4 ha spatial area in an optimal habitat, with 650 edible shrubs or trees of >80 cm canopy diameter and a sustained canopy height of 50-150 cm. This index can be used to calculate the carrying capacity and animal load for any given land unit after determining the browse composition and density of the colouration.
Distinctive of the black-faced impala is a dark stripe, on either side of the nose, that runs upward to the eyes and thins as it reaches the forehead.
Other differences include the larger black tip on the ear, and a bushier and nearly 30% longer tail in the black-faced impala.
The impala has a special dental arrangement on the front lower jaw similar to the toothcomb seen in strepsirrhine primates,which is used during allogrooming to comb the fur on the head and the neck and remove ectoparasites.
The International Union for Conservation of Nature and Natural Resources (IUCN) classifies the impala as a species of least concern overall.
The black-faced impala, however, is classified as a vulnerable species; as of 2008, fewer than 1,000 were estimated in the wild.
Though there are no major threats to the survival of the common impala, poaching and natural calamities have significantly contributed to the decline of the black-faced impala. As of 2008, the population of the common impala has been estimated at around two million.
According to some studies, translocation of the black-faced impala can be highly beneficial in its conservation.
Around a quarter of the common impala populations occur in protected areas, such as the Okavango Delta (Botswana); Masai Mara and Kajiado (Kenya); Kruger National Park (South Africa); the Ruaha and Serengeti National Parks and Selous Game Reserve (Tanzania); Luangwa Valley (Zambia); Hwange, Sebungwe and Zambezi Valley (Zimbabwe).
The rare black-faced impala has been introduced into private farms in Namibia and the Etosha National Park.
Population densities vary largely from place to place; from less than one impala per square kilometre in Mkomazi National Park (Tanzania) to as high as 135 per square kilometre near Lake Kariba (Zimbabwe).
Distribution and their habits
The impala inhabits woodlands due to its preference for shade; it can also be found on the interface (ecotone) between woodlands and savannahs. Places near water sources are preferred. In southern Africa, populations tend to be associated with Colophospermum mopane and Acacia woodlands.
~Habitat choices differ seasonally – Acacia senegal woodlands are preferred in the wet season, and A. drepanolobium savannahs in the dry season. Another factor that could influence habitat choice is vulnerability to predators; impala tend to keep away from areas with tall grasses as predators could be concealed there.A study found that the reduction of woodland cover and creation of shrublands by the African bush elephants has favoured impala population by increasing the availability of more dry season browse. Earlier, the Baikiaea woodland, which has now declined due to elephants, provided minimum browsing for impala. The newly formed Capparis shrubland, on the other hand, could be a key browsing habitat.
~Impala are generally not associated with montane habitats; however, in KwaZulu-Natal, impala have been recorded at altitudes of up to 1,400 metres (4,600 ft) above sea level.
The historical range of the impala – spanning across southern and eastern Africa – has remained intact to a great extent, although it has disappeared from a few places, such as Burundi. The range extends from central and southern Kenya and northeastern Uganda in the east to northern KwaZulu-Natal in the south, and westward up to Namibia and southern Angola. The black-faced impala is confined to southwestern Angola and Kaokoland in northwestern Namibia; the status of this subspecies has not been monitored since the 2000s. The common impala has a wider distribution, and has been introduced in protected areas in Gabon and across southern Africa.
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