Impalas are one of the most abundant antelope species in the Kruger National Park and are over-looked most of the time as they might be too ‘common’ to find interesting. Most of us go out there in search of big cats and forget about the important role that impalas play in the ecosystem. Scientist believe that an impala is the perfect antelope as it is highly adaptable, have an impeccable sense of hearing, good eyesight and is a very attractive creature. Impalas fall into their own tribe called Aepycerotini, different from similar antelopes that are classified as gazelles.
Even though it seems like any other antelope species, impalas display unique characteristics such as; the black coloured scent gland situated above the hoof of each hind leg. It is believed that these fetlock glands release a chemical pheromone when activated by a high kick, this is thought to lay a scent trail to help herd members stay together when chased by a predator.
Impalas are sometimes jokingly referred to as the ‘Mc Donald’s’ of the bush even displaying the ‘M’ on their backsides, impalas are preyed upon by many predators such as lions, leopards, hyenas, wild dogs, cheetahs, crocodiles and even martial eagles. On various occasions impalas have helped the game rangers within Mjejane Game Reserve find predators by their very distinctive alarm call. The loud snorting sound of herd members are usually a good indicator of a predator nearby, the whole herd will face the direction the threat is coming from. Find out more about Mjejane here:
Figure 1: Impalas on high alert after spotting two lionesses nearby. Mjejane Game Reserve
Impalas have complex, but flexible social structures. The social groupings change throughout the year, normally herds consist of a territorial male with numerous females and the previous year’s offspring, including males younger than four years; territorial males do also defend areas without permanent females; non-territorial males and juvenile males form bachelor herds. Over the last few weeks most of you on Mjejane Game Reserve and Kruger National Park would have noticed male impalas vocalising continuously and running around with their tails raised exposing the white fluff underneath chasing either males or females, this is what is called the rutting season.
The deep guttural grunting and loud roars can be heard from over a kilometre away, the roars last for up to two months and a territorial ram can roar nearly 200 times an hour. The roaring and herding of females assists in triggering and synchronising oestrus in ewes. Males start sizing each other up during March and by April most males will have a four to eight-hectare resource-rich-patch to hold and defend. The females are attracted by the resources and the male tries to keep the females in his area for as long as possible, by the end of the breeding season females would have been mounted by several males, this strengthens the gene pool.
Figure 2: Two males sizing each other up before the battle. Mjejane Game Reserve
Synchronized oestrus means synchronized births, this takes place during the rainy season, seven months after mating, usually between November-January. Fawns are born only a few weeks apart; these mass births mean that less fawns are killed as predators are unable to catch them all. In September a secondary rut takes place, this produces ‘laat lammetjies’ as you would say in Afrikaans, which means fawns are born much later than the rest, the reason for this is still unknown.
Figure 3: Mother with few day old fawn. Mjejane Game Reserve
Although impalas outnumber all other herbivores in the Kruger, it was not always the case. Large numbers of impalas were hunted in the 19th century when the Selati railway was constructed, numbers increased after the area became protected. The reason impalas thrive has to do with their feeding habits, they are mixed feeders changing between browsing and grazing depending on seasons and by keeping good company with other herbivores such as zebra, wildebeest and giraffe, it increases their chases of spotting or hearing predators.
Figure 4: Impala and zebra keeping an eye on a male lion nearby. Mjejane Game Reserve
Impalas may seem ordinary and uninteresting to most people, but they are key role players within ecosystems as they shape vegetation structure. They are an important resource for most of our predators and will cause dire effects to savanna ecosystems if removed from it. So, once in a while, stop and watch a herd of impala and be grateful for their sheer number and the significant role they play in the bush.
Reference:
M. Reardon 2012; Shaping Kruger, Chapter 2, p31-45.