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Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Assessing the feasibility of density estimation methodologies for African forest elephant at large spatial scales
Author(s): Laguardia, Alice
Gobush, Kathleen S
Bourgeois, Stephanie
Strindberg, Samantha
Abitsi, Gaspard
Ebouta, Fabrice
Fay, J Michael
Gopalaswamy, Arjun
Maisels, Fiona
Ogden, Rob
White, Lee J T
Stokes, Emma J
Keywords: Abundance estimate
Camera trap
Density estimation
Survey methods
Line transect survey
Loxodonta cyclotis
Non-invasive genetic sampling
Spatial capture-recapture
Issue Date: Jun-2021
Date Deposited: 7-Apr-2021
Citation: Laguardia A, Gobush KS, Bourgeois S, Strindberg S, Abitsi G, Ebouta F, Fay JM, Gopalaswamy A, Maisels F, Ogden R, White LJT & Stokes EJ (2021) Assessing the feasibility of density estimation methodologies for African forest elephant at large spatial scales. Global Ecology and Conservation, 27, Art. No.: e01550.
Abstract: Effective wildlife management requires information on population status and distribution. Survey methods that provide estimates of these population parameters can vary greatly in effort required, area covered, precision of estimates, and cost. Trade-offs are required, because increasing precision and area coverage generally requires increasing field effort and incurs a higher cost. We compare DNA- and camera trap based-spatial capture-recapture approaches (DNA-SCR and CT-SCR) to the widely-used, dung-based line transect distance sampling (LTDS) method to assess their performance when applied to three relatively large populations of forest elephant Loxodonta cyclotis (>500 individuals), in order to evaluate their feasibility for future use at national and regional scales. Six of the nine surveys had a coefficient of variation below 20%; area coverage via DNA-SCR and LTDS was comparable and greatly exceeded that of the CT-SCR as applied; overall cost was highest for the LTDS surveys compared to the other two methods. We designed a new metric with which to compare survey methods: an integrated feasibility index (IFI). This combines three typical survey components: total area covered, level of precision achieved, and cost. The IFI suggests that DNA-SCR and LTDS are equally acceptable in terms of the combination of the three survey components, and that either survey method is suitable for large (national or regional) spatial scales for forest elephant density estimation. CT-SCR provides more precise estimates, but has double the IFI, due to the high cost per km2. DNA-SCR in particular, given the improvements highlighted in this study, is now being used at a national scale in Gabon. In conclusion, we recommend that the use of these spatial capture-recapture (SCR) methods, and their development, continue. Future findings and improvements should be compiled across studies to ensure their robust evolution as an option for monitoring the African forest elephant across its range and inform strategies and action for its conservation.
DOI Link: 10.1016/j.gecco.2021.e01550
Rights: This article is available under the Creative Commons CC-BY-NC-ND license ( and permits non-commercial use of the work as published, without adaptation or alteration provided the work is fully attributed. For commercial reuse, permission must be requested.
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