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Bees, the pet hate of elephants
11/21/16

The cleverest will win...

In the last few years, farmers and wildlife managers alike have been endeavouring to develop "soft" deterrents, aimed at discouraging elephants in their attempts to raid crops. Erecting physical or natural barriers, installing electric fences, digging trenches, using sonic or olfactory deterrents (firing chilli-based irritants), the renewed use of traditional techniques combining the use of fire and the collective supervision of the crops, etc. All these methods, particularly in East Africa (faced with pockets of overcrowding), provide more or less encouraging results according to the methods and the precise location of their use. But there is a problem: "We're dealing with a particularly intelligent animal. Elephants learn quickly... Once they have learnt how the deterrent works, they find a solution and aren't afraid anymore". 

It is true that the workings of the human/elephant relationship are complex, in Gabon and elsewhere. And that they are impacted by another, more anthropological, development linked to the living conditions in villages in agricultural areas. "Surveillance of the cultivated plots isn't as collective as before. The presence of humans in the fields, at night, has almost disappeared in favour of a division into individual plots supervised by isolated farmers. A form of individualism has taken over the collective management of agriculture, which offered shared benefits in the past. And a more modern way of life has also established itself, even in the most far-flung forests. The peasants in Gabon are just like our mountain shepherds in Europe: life in the city (or in the valley), connected to electricity and television, is more comfortable than long nights spent protecting flocks against wolves (over here) or crops against elephants (over there)".

Insects against giants

This is where the work of Steeve Ngama comes in, a PhD student at the Laboratory of Tropical and Subtropical Forestry at Gembloux Agro-Bio Tech (ULg) for the past two years, and a researcher at the Institut de Recherches Agronomiques et Forestières du Centre National de la Recherche Scientifique et Technologique in Libreville (Gabon). Drawing inspiration from similar experiments carried out in East Africa, Steeve Ngama tested the installation of special "fences" in Gabon. These fences are actually made from beehives whose bees are believed to scare off elephants. Between November 2011 and February 2013, i.e. a period of 70 weeks, he observed the mammals' behaviour when they approached the dozen or so beehives hanging in the trees just over a metre from the ground. The two species of trees were chosen for their fruit which is particularly appreciated by the elephants: Irvingia gabonensis and Sacoglottis gabonensis. The experiment took part in the Gamba complex, which is home to two national parks (Loango and Moukalaba-Doudou, 1550 and 4500 km2 respectively) whose boundaries are frequently the subject of human/elephant conflicts owing to the high density of these mammals. The repellent species tested was Apis mellifera adansonii, the only widespread Apis type of bee in central Africa. Automatically triggered cameras were installed at a distance of 10 to 20 metres from the beehives to observe the elephants' reaction.

Elephant foret ruche nuit  

"Based on the photographic material collected (8151 photographs), we listed different types of elephant behaviour, ranging from a simple visit to the site to an attempt to approach the beehives or destroy them", Steeve Ngama explains. "We quantified these behaviours by correlating them with the presence of the bees and their activities in the hives (some were empty, acting as control hives). These activities were quantified according to the number of entrances and exits – "movements" – per minute by the bees". The results were highly instructive. "We first observed that the presence of fruit on the trees is indeed a powerful factor of attraction for the elephants, both in terms of the number of visits and their duration. We then observed that the mere presence of the beehives, whether they were active or not, considerably reduced (more than 70 %) both the visits to the site and their duration. However, the most interesting thing is that the elephants seem perfectly capable of understanding and taking into account the hives' level of activity. When the hives experienced entrances and exits of insects greater than 70 movements a minute, the sudden arrival of elephants close to the trees fell by 84 % compared with hives where there was little activity, and the duration of the visit dropped by 92 %. We can deduce that Apis mellifera adansonii clearly has a repellent effect on the forest elephant. It's the first time that this result has been established in relation to this species. Up until now, as regards using bees as a repellent, we only had information concerning the savanna elephant, whose habits are noticeably different from those of the forest elephant". As to why elephants behave in this way, it would appear that it is the buzzing produced by the bees, which the elephants perceive in much wider ranges than ours.

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