Driving around slowly one afternoon, waiting for a sleepy leopard to wake up and climb the tree that housed her impala kill, we approached an area where I had planned to stop for a sundowner. A herd of giraffes had already decided that they wanted to have some snacks there so we stopped to watch them and browse as a herd of impalas milled about between these elongated supermodels of the bush. Even from a distance, I could see that one impala had a distinctive white patch on the top of her back. I have seen this before in animals in the area, notably a resident kudu cow around Tanda Tula Safari Campthat has a large white patch on her side. This is usually caused by partial leucism, the same condition responsible for the white lions of the Timbavati. Thinking that I had found another example of this, I picked up my binoculars to have a closer look. To say I wasn’t prepared for what I saw would be an understatement.
The patch of fur was indeed white, but that was not the odd part. There was something else coming out of the white patch. Something very recognisable, but something very misplaced. I had to almost check my words when I conveyed to my guests what I was seeing. Just to be sure, I took a photo so I could get a closer look to make sure that I wasn’t jumping to conclusions. As I zoomed in, I realised that I was not seeing things – there was indeed a leg growing out of this impala’s back.
Yes. A leg. A fifth leg.
Both Given and I had the same initial thought process based on our proximity to the leopard’s impala kill. We guessed that perhaps this leopard had walked under the tree housing the dead impala, and by some miracle a leg dislodged itself and fell and landed on this impala’s back, and then somehow stayed in position all day. Oh, and this impala would have needed to have done this whilst not being caught and eaten by the leopard. It was an unbelievable scenario, but one that still seemed more plausible than the fact that this impala had a leg growing out of its back!
Whilst discussing this bizarre sighting with my guests, I postulated a few hypotheses about how this could have come to be, and subsequent research seems to indicate that I might not have been far off. But what I couldn’t answer was the question as to how come no one else had seen this impala before? Although it was a less frequently traversed area of the Greater Kruger,impalas are generally sedentary animals, and as a result, this female likely grew up in and around the area, but had, until now, avoided being seen!
So how did she come to have an extra leg growing out of her back without suffering any other ill effects? Some research suggests that this phenomenon – known as polymelia – is not common, but has been recorded in numerous species, including humans. One of the main causes appears to be the partial development of conjoined twins, where one of the foetus’s has degenerated completely except for the visible limb left on surviving twin. A less common occurrence could be that of a genetic mutation that affects foetal development and results in the growth of an extra limb in a place it shouldn’t be! Based on this impala’s condition, the extra limb – or at least the vestige of it – was not inferring any disadvantage onto it, and I suspect that she will live out as normal a life as any other impala in her herd.
The next morning this naturally spurred on a load of discussions amongst the guides and trackers and talk of female impalas with horns came up. Most of the long-time trackers had seen this once or twice in their time; I too had seen it in an ewe back in 2009. It proved to be an almost prophetic conversation, as that afternoon, whilst driving in a very similar area to our five-legged impala, Given pointed out a female impala, and on top of her head were two vestigial horns! What were the chances of seeing something as rare as that the day that we all sat and spoke about it? So, from now on, the only thing I am going to talk about whilst preparing the coffee trays in the morning will be of seeing a cheetah and her cubs!