Will Elephants Soon Disappear from West African Savannahs?

Philippe Bouché,Philippe Lejeune,Jean-Louis Doucet,Cédric Vermeulen,Aimé J. Nianogo,Iain Douglas-Hamilton,George Wittemyer,Brian Gratwicke

doi:10.1371/journal.pone.0020619

Philippe Bouché, Philippe Lejeune + Show 6 more

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https://doi.org/10.1371/journal.pone.0020619

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Abstract

Precipitous declines in Africa's native fauna and flora are recognized, but few comprehensive records of these changes have been compiled. Here, we present population trends for African elephants in the 6,213,000 km2 Sudano-Sahelian range of West and Central Africa assessed through the analysis of aerial and ground surveys conducted over the past 4 decades. These surveys are focused on the best protected areas in the region, and therefore represent the best case scenario for the northern savanna elephants. A minimum of 7,745 elephants currently inhabit the entire region, representing a minimum decline of 50% from estimates four decades ago for these protected areas. Most of the historic range is now devoid of elephants and, therefore, was not surveyed. Of the 23 surveyed elephant populations, half are estimated to number less than 200 individuals. Historically, most populations numbering less than 200 individuals in the region were extirpated within a few decades. Declines differed by region, with Central African populations experiencing much higher declines (−76%) than those in West Africa (−33%). As a result, elephants in West Africa now account for 86% of the total surveyed. Range wide, two refuge zones retain elephants, one in West and the other in Central Africa. These zones are separated by a large distance (∼900 km) of high density human land use, suggesting connectivity between the regions is permanently cut. Within each zone, however, sporadic contacts between populations remain. Retaining such connectivity should be a high priority for conservation of elephants in this region. Specific corridors designed to reduce the isolation of the surveyed populations are proposed. The strong commitment of governments, effective law enforcement to control the illegal ivory trade and the involvement of local communities and private partners are all critical to securing the future of elephants inhabiting Africa's northern savannas.

Highlights

Overexploitation of African elephants (Loxodonta africana) over the past two centuries has resulted in serious range reduction, local extirpation, and large scale declines of this keystone species [1,2,3,4]
The Central African portion of this range has experienced rapid human population growth and related land use changes, the major threats in this region are unregulated deforestation and road development that facilitates the penetration of hunters into former pristine habitat [2,3,4]
In the last ten years, 4 of 13 populations in Central Africa have been surveyed by aerial counts (Table S1, Fig. 3), representing 10% of the elephant population of Central Africa

Summary

Introduction

Overexploitation of African elephants (Loxodonta africana) over the past two centuries has resulted in serious range reduction, local extirpation, and large scale declines of this keystone species [1,2,3,4]. Declines have accelerated in the last four decades [5,6] This conservation disaster has been largely over-looked in part due to the contrasting context of growing elephant populations in other regions of Africa [5,6]. The West African portion of this range has long carried the largest and some of the fastest growing human population of the continent [3,8] Many of their original habitat have been transformed into agro-pastoral areas. The Central African portion of this range has experienced rapid human population growth and related land use changes, the major threats in this region are unregulated deforestation and road development that facilitates the penetration of hunters into former pristine habitat [2,3,4]

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