Forest elephant movement and habitat use in a tropical forest-grassland mosaic in Gabon.

Emily C Mills,John R Poulsen,Connie J Clark,Peter Morkel,J Michael Fay,Lee J T White,Christopher Beirne,Amelia Meier

doi:10.1371/journal.pone.0199387

Emily C Mills, John R Poulsen + Show 6 more

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https://doi.org/10.1371/journal.pone.0199387

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Abstract

Poaching of forest elephants (Loxodonta cyclotis) for ivory has decimated their populations in Central Africa. Studying elephant movement can provide insight into habitat and resource use to reveal where, when, and why they move and guide conservation efforts. We fitted 17 forest elephants with global positioning system (GPS) collars in 2015 and 2016 in the tropical forest-grassland mosaic of the Wonga Wongué Presidential Reserve (WW), Gabon. Using the location data, we quantified movement distances, home ranges, and habitat use to examine the environmental drivers of elephant movements and predict where elephants occur spatially and temporally. Forest elephants, on average, traveled 2,840 km annually and had home ranges of 713 km2, with males covering significantly larger home ranges than females. Forest elephants demonstrated both daily and seasonal movement patterns. Daily, they moved between forest and grassland at dawn and dusk. Seasonally, they spent proportionally more time in grassland than forest during the short-wet season when grasses recruit. Forest elephants also traveled faster during the short-wet season when fruit availability was greatest, likely reflecting long, direct movements to preferred fruiting tree species. Forest elephants tended to select areas with high tree and shrub density that afford cover and browse. When villages occurred in their home ranges elephants spent a disproportionate amount of time near them, particularly in the dry season, probably for access to agricultural crops and preferred habitat. Given the importance of the grassland habitat for elephants, maintenance of the forest-grassland matrix is a conservation priority in WW. Law enforcement, outreach, and education should focus on areas of potential human-elephant conflict near villages along the borders of the reserve. GPS-tracking should be extended into multi-use areas in the peripheries of protected areas to evaluate the effects of human disturbance on elephant movements and to maintain connectivity among elephant populations in Gabon.

Highlights

Poaching of forest elephants, Loxondonta cyclotis, for ivory is decimating their populations [1]
Elephants are free-roaming in the area and the reserve is well protected–no elephants had been poached within Wonga Wongue Presidential Reserve (WW) from 2014 to 2016
Forest elephants spend most of their time in forest, but selectively use grassland during nighttime hours and during the short-wet season, when young grass shoots provide browse

Summary

Introduction

Poaching of forest elephants, Loxondonta cyclotis, for ivory is decimating their populations [1]. Between 2002 and 2011, populations in Central Africa decreased by 62% and lost 30% of their geographical range due to global demand for ivory [2]. With forest elephants under intense poaching pressure, information on their habitat use, movements, and ecology is necessary to maximize the effectiveness of conservation efforts. Movement ecology can provide insights into species’ resource requirements—food, water, and space—and elucidate temporal and spatial patterns of habitat use. Using global positioning systems (GPS) technology, animal movement studies have guided management strategies for a variety of terrestrial species [5], including identifying critical habitat for endangered species [6,7] and understanding resource-driven animal migrations [8]. Movement data from wide-ranging animals, such as wolves and elephants, have provided the empirical basis for identifying and securing movement corridors, between large, protected wilderness areas [11,12]

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