Impala (Aepyceros melampus) are one of our most successful antelope species in south Africa, and one of the more commonly viewed species on Gondwana while on safari.
The graceful impala is often overlooked as it is so often seen. However it is one of the most adaptable antelope species making it also one of the most successful. Impalas have excellent senses, with large ears for detecting sounds easily and large eyes positioned on the side of the head for good peripheral vision. When an Impala detects danger, they will give off a loud snort to warn the rest of the herd.
Impalas have an interesting social structure. Impala females and their young live in breeding herds called ‘clans’ which consist of 30-120 individuals. Young males share this territory with their mothers until they reach maturity where they start to wonder off and eventually join a bachelor herd. Males form bachelor herds for the purpose of safety. During mating season males within these herds become increasingly intolerant of one another. While females that are in oestrous are present the males engage in defending small territories through physical challenges. During the ‘rut’ the males can be heard vocalising roars and snorting sounds at nearby males.
Impalas are fastidious groomers and spend a large amount of time caring for their shiny coats. Individual as well as reciprocal grooming of one another occurs in the herd. This is possibly because Impala favour habitats in transitional areas which usually see high animal traffic, and which result in high parasite loads.
The Impalas breeding strategy is fascinating. At the beginning of autumn, the onset of winter triggers a testosterone increase in mature male Impalas. They separate from their bachelor groups and start to rigorously compete with one another to set up breeding territories. Males choose good recourses as a priority when selecting their territories. They set up small territories and defend them by thrashing bushes with their horns and using piles of dung.
Fighting and horn clashes establish dominance between males. The males also become very vocal while they define their territories and ward off other males. Males herd females by circling them and directing them into their territories. All this induces the adult females into oestrous and mating follows. During mating season males become weak and loose condition due to lack of feeding and constant territorial battles. For this reason, males only hold their territories with the females for a short period of time. In early summer all the females give birth at the same time after 6, 5 months gestation.
When born, impala lambs are hidden away for the first two weeks. All the impala ewes give birth together and the sudden increase in numbers of new lambs ensures their survival. It is believed that Impalas are able to stall their births in order to wait for the rains, however this has not yet been proven. It is possible that due to the fact that babies ate hidden for so long, that if the babies are born before the rains that the females abort the foetus or the lambs die before anyone notices. Impalas need good source of water in order to thrive and if the lambs are born before the rains there is a good chance that they won’t survive. The lambs that are spotted later in the rainy season are probably those that were born after the first rains of summer. This would contribute to their ecological success as only the fittest survive.