In sub-Saharan Africa, 50% of the elephants have disappeared in less than forty years. This is the conclusion of an international team of researchers, which has rung the alarm bells in the Plos One journal. It is the outcome of dozens of censuses carried out in several African countries since the beginning of the 1970s. The causes of this carnage are known: the galloping African demography each day whittles away a little more of the territory occupied by wildlife and hundreds of pachyderms each year succumb to the bullets of poachers.

One day, whilst visiting the Akagera Park in Rwanda with his parents, Philippe Bouché saw an antelope burst out just in front of him, bounding away to escape what she believed was a threat. ‘I was six years old,’ remembers the researcher. ‘Since that day I knew that my life was there.’ Thirty-five years later Philippe Bouché still spends a lot of time in Africa, in contact with wildlife. He co-ordinates elephant surveys in this vast area situated between the Sahara desert and Tropical Africa, from Senegal in the West as far as the Red Sea in the East, a savannah area which is in principle a welcoming one for the African elephant.

In principle… According to a study published in the Plos One journal(1), co-authored by Philippe Lejeune, Cédric Vermeulen and Jean-Louis Doucet who work at the Gembloux Agro-Bio Tech (ULg), in the Unit of Forest and Nature Management, the population of African elephants in West and Central Africa has been cut in half since the beginning of the 1970s. ‘There remain a minimum of 7,750,’ estimates Philippe Bouché, who is today a researcher at the Unit. ‘Their numbers were doubtless over double that forty years ago.’ The study has the merit of precisely quantifying and characterising, on a regional scale, a phenomenon which has been experienced at the scale of the whole of the African continent. In the 1960s the censuses were still numbering 1.3 million elephants in Africa. There are probably no more than 470,000 to 550,000 of them today.

It’s not easy to count elephants

Reliable figures? To tell the truth, it is not as easy to count elephants as we might think! There exist various more or less tried and tested census techniques. One of them is foot count. It consists of choosing a sample territory to be examined methodically, counting all the elephants in this area and then extrapolating the figures for the whole of the area. Another ground method consists of counting elephant droppings. One formula, which takes into account the daily dropping number produced per elephant and the degradation rate, allows the number of pachyderms to be deduced.

For foot count surveys, the sample area are rectilinear lines of terrain, called transects, along which teams of two or three people move forward, keeping their eyes peeled, looking for elephants. In the Nazinga game ranch (Burkina Faso) for example, where Philippe Bouché has co-ordinated several surveys in recent years, the 1000 km² territory is sliced into thirty parallel transects, covering a total length of 570 kilometres. Such survey lasts 6 days; 45 people wake up each day at dawn to survey the savannah for several hours before it gets too hot and the animals hide to protect themselves from the sun. ‘A transect,’ adds Philippe Bouché, ‘is a line in the savannah which obviously corresponds to no road or footpath. You have to take your bearings with a compass and GPS to keep to your path. And you always walk against the wind, so that the animals don’t detect you.’

(1) Will Elephants Soon Disappear from West African Savannahs?
 Bouché, Philippe, Douglas-Hamilton, Iain; Wittemyer, George et al, in PLoS ONE (2011)