Savanna elephant numbers are only a quarter of their expected values

Ashley S Robson, Morgan J Trimble, Andrew Purdon, Kim D Young-Overton, Stuart L Pimm and Rudi J van Aarde

PLOS ONE, 2017, vol. 12, issue 4, 1-14

Abstract: Savannas once constituted the range of many species that human encroachment has now reduced to a fraction of their former distribution. Many survive only in protected areas. Poaching reduces the savanna elephant, even where protected, likely to the detriment of savanna ecosystems. While resources go into estimating elephant populations, an ecological benchmark by which to assess counts is lacking. Knowing how many elephants there are and how many poachers kill is important, but on their own, such data lack context. We collated savanna elephant count data from 73 protected areas across the continent estimated to hold ~50% of Africa’s elephants and extracted densities from 18 broadly stable population time series. We modeled these densities using primary productivity, water availability, and an index of poaching as predictors. We then used the model to predict stable densities given current conditions and poaching for all 73 populations. Next, to generate ecological benchmarks, we predicted such densities for a scenario of zero poaching. Where historical data are available, they corroborate or exceed benchmarks. According to recent counts, collectively, the 73 savanna elephant populations are at 75% of the size predicted based on current conditions and poaching levels. However, populations are at

Date: 2017
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Persistent link: https://EconPapers.repec.org/RePEc:plo:pone00:0175942

DOI: 10.1371/journal.pone.0175942

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