We all need figures to support our statements. The decrease in African elephants has been in the news recently, and to the reader of these articles the counting of elephants must seem a trivial exercise. Reports of elephant declines always ignore the methods used to count the animals and always assume that it’s just a matter of wearing khaki, getting into a light aircraft in an adventurous act of derring-do, and hanging out of the door shouting out the numbers to someone who writes them down. It’s a little more complicated than that, which is probably why no one talks it about in the deeply unintellectual articles that inform most popular conservation ideas. In fact, it is so complicated that the art of counting wildlife occupies hundreds of pages of the most specialised scientific journals and includes statistical arguments that require a very high degree of scientific expertise to understand. I don’t plan to try and make these methods understandable (and I don’t think I could make them easily accessible to a general readership) but in this weeks post I’d like to discuss some of the methods used to count wildlife and some of the the pitfalls associated with trying to put a number on elephants, lions, wild dogs or any other African wildlife.
One of the first things to keep in mind is that animals live in a defined geographical area. This can often include very large areas, but at some point there is a limit to the area they occupy. The elephants of Africa are not one population. The elephants in Botswana do not walk to Kenya to find a mate. The forest elephants of central Africa may even be a separate species and definitely do not move out of the forests to the savannas to mate with these elephant populations. This is important for counting purposes because a decline in one population in a geographic area does not affect another population. You could wipe out all the elephants in Kenya and it would not affect the elephants of Botswana one iota. Botswana elephants would continue increasing in number as they currently are doing. Did the death of hundreds of thousands of people in Asia and the Indian Ocean islands in the Tsunami of 2004 affect the population of Sweden or Canada? Of course not – and the same applies to elephants or any other species for that matter. A huge effort was made conserving Lichtenstein’s Hartebeest in the Kruger National Park and Zimbabwe, but the species thrives in large numbers in Zambia and the efforts to conserve the species where its numbers are low has no bearing on areas where populations are high. This has implications for sustainable use of these resources – if numbers are declining in one region then there are local ecological, social and political reasons for this and these are more than likely different in other regions. I’ll have more to say on this point later.
So how do you count wildlife? Most wildlife scientists accept that there is no way to produce an accurate count of wild animals across a large landscape. There is always an error associated with the count, and a confidence level associated with the error. We may, for example, be 85% certain that we have counted between 1000-1224 elephants in a particular area. This is about as accurate as you can be (the actual figures may differ) so when you see articles saying that there are 1543 lions in a country – it’s simply impossible to be that accurate and whoever reports these figures is not reporting them properly.
Direct counts are where the animals themselves are counted either from the air or from the ground. Aerial surveys either sample a manageable area and extrapolate the results to a wider area, or attempt a total count where it is assumed that all animals are seen. Total counts are only possible in relatively small areas of about 1000 square km for highly visible animals like elephants. I simply do not believe you can attempt a total count of lions for example, across a very large landscape. Lions are well camouflaged and difficult to see from even a few metres away in thick grass. Indirect counts use signs of animals like dung and feeding activity to infer numbers. In the forests of central Africa it is impossible to use direct counts because the habitat is too dense, and much of it inaccessible due to war and civil conflict. Estimates of elephant numbers in the central African rainforests must be taken with a pinch of salt – I don’t accept that anyone has a figure or a trend that is reliable. Ultimately there is tradeoff when your count wildlife – you either aim for accuracy which always has wide confidence limits associated with it, or you aim for precision, preferably at regular intervals so that you can establish population trends.
This leads us onto what is achievable when you try to count wildlife. The most important outcome is that you can establish population trends. However, to do so you must use the same methods regularly (every year) in the same area and at the same time of year. Once you have a few years data you can start to produce a graph which shows, within the constraints of accuracy and confidence limits, whether the population is increasing or declining. You can’t count wildlife, but you can establish trends over time.
Managing populations of wildlife depends on having data on numbers and this depends on proper wildlife survey techniques. If we are to allow local African people to use wildlife for their own purposes we need to establish trends so that an off take can be calculated. At the moment this process is not performed in most areas of Africa, the surveys are not regular or consistent enough to establish trends of population increase or decrease. Elephants receive a lot of attention and it may be possible to establish regional trends but those who try and put a single figure on the number of elephant in an area do not understand the process of counting wildlife. Those who use these figures to make political points are simply using incorrect information. Africa is not one country and elephants do not live in one giant herd spread across the continent. The conservation lobby should stop trying to oversimplify the argument about elephant decline and focus instead on regional trends and the social and political problems associated with decline in these regions. In southern Africa elephant populations are managed very well. In east Africa elephant populations are managed very badly and their elephants are in decline.
Leopards are notoriously difficult to count. I’ve been working in the bush for many years and only seen leopards a few times. My guess is that they are far more abundant than anyone realises. An example of this comes from hunting leopards in the south east low veld of Zimbabwe. In areas where there were only two leopards on licence every year, hunters consistently shot two leopards every year for many years. When the hunting quota was doubled to four leopards a year the hunter had no problem in shooting four leopards every year for at least 8 or 9 years that I know of. This means the population of leopards in the areas was able to support this off take without declining. I used to travel the area regularly and I only ever remember seeing a leopard once in about 10 years! They were there in abundance, but very difficult to see without using baiting and patient techniques to lure them out. The availability of remote cameras which are triggered by movement has shed light on the distribution of animals where they were formerly thought to be extinct. Until a few years ago no one would have imagined that there were cheetahs in the Sahara desert. However, camera traps have photographed these animals recently and there appears to be a breeding population in northern Niger. How many are there? That’s the million dollar question. A few years ago everyone would have said none – but now the population is estimated at around 200. The truth is no one knows, and it’s impossible to know. With extensive sampling we may reach a stage where we can say that we are 70% certain there are between 120 and 240 cheetahs in the Sahara. That’s how I’d like the figures to be quoted – because you can’t count wildlife.