Mapping the Elephants of the 19th Century East African Ivory Trade with a Multi-Isotope Approach.

East African elephants have been hunted for their ivory for millennia but the nineteenth century witnessed strongly escalating demand from Europe and North America. It has been suggested that one consequence was that by the 1880s elephant herds along the coast had become scarce, and to meet demand, trade caravans trekked farther into interior regions of East Africa, extending the extraction frontier. The steady decimation of elephant populations coupled with the extension of trade networks have also been claimed to have triggered significant ecological and socio-economic changes that left lasting legacies across the region. To explore the feasibility of using an isotopic approach to uncover a 'moving frontier' of elephant extraction, we constructed a baseline isotope data set (δ13C, δ15N, δ18O and 87Sr/86Sr) for historic East African elephants known to have come from three distinct regions (coastal, Rift Valley, and inland Lakes). Using the isotope results with other climate data and geographical mapping tools, it was possible to characterise elephants from different habitats across the region. This baseline data set was then used to provenance elephant ivory of unknown geographical provenance that was exported from East Africa during the late nineteenth and early twentieth centuries to determine its likely origin. This produced a better understanding of historic elephant geography in the region, and the data have the potential to be used to provenance older archaeological ivories, and to inform contemporary elephant conservation strategies.Funding: This research was funded by a European Union Marie Curie Excellence grant (MEXT-CT-2006-042704) awarded to PJL for the Historical Ecologies of East African Landscapes (HEEAL) project (http://cordis.europa.eu/project/rcn/83961_en.html). Additional funding came from the Worldwide Universities Network Research Mobility programme and the Smithsonian Institution Fellowship programme awarded to ANC. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Note: This funding was not held by UCAM