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Browsing Faculty Publications by Subject "elephant population"

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    Comparative demography of an at-risk African elephant population
    (Colorado State University. Libraries, 2013) Wittemyer, George, author; Daballen, David, author; Douglas-Hamilton, Iain, author; Public Library of Science, publisher
    Knowledge of population processes across various ecological and management settings offers important insights for species conservation and life history. In regard to its ecological role, charisma and threats from human impacts, African elephants are of high conservation concern and, as a result, are the focus of numerous studies across various contexts. Here, demographic data from an individually based study of 934 African elephants in Samburu, Kenya were summarized, providing detailed inspection of the population processes experienced by the population over a fourteen year period (including the repercussions of recent increases in illegal killing). These data were compared with those from populations inhabiting a spectrum of xeric to mesic ecosystems with variable human impacts. In relation to variability in climate and human impacts (causing up to 50% of recorded deaths among adults), annual mortality in Samburu fluctuated between 1 and 14% and, unrelatedly, natality between 2 and 14% driving annual population increases and decreases. Survivorship in Samburu was significantly lower than other populations with age-specific data even during periods of low illegal killing by humans, resulting in relatively low life expectancy of males (18.9 years) and females (21.8 years). Fecundity (primiparous age and inter-calf interval) were similar to those reported in other human impacted or recovering populations, and significantly greater than that of comparable stable populations. This suggests reproductive effort of African savanna elephants increases in relation to increased mortality (and resulting ecological ramifications) as predicted by life history theory. Further comparison across populations indicated that elongated inter-calf intervals and older ages of reproductive onset were related to age structure and density, and likely influenced by ecological conditions. This study provides detailed empirical data on elephant population dynamics strongly influenced by human impacts (laying the foundation for modeling approaches), supporting predictions of evolutionary theory regarding demographic responses to ecological processes.
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    Devastating decline of forest elephants in Central Africa
    (Colorado State University. Libraries, 2013) Maisels, Fiona, author; Strindberg, Samantha, author; Blake, Stephen, author; Wittemyer, George, author; Hart, John, author; Williamson, Elizabeth A., author; Aba'a, Rostand, author; Abitsi, Gaspard, author; Ambahe, Ruffin D., author; Amsini, Fidèl, author; Bakabana, Parfait C., author; Hicks, Thurston Cleveland, author; Bayogo, Rosine E., author; Bechem, Martha, author; Beyers, Rene L., author; Bezangoye, Anicet N., author; Boundja, Patrick, author; Bout, Nicolas, author; Akou, Marc Ella, author; Bene, Lambert Bene, author; Fosso, Bernard, author; Greengrass, Elizabeth, author; Grossmann, Falk, author; Ikamba-Nkulu, Clement, author; Ilambu, Omari, author; Inogwabini, Bila-Isia, author; Iyenguet, Fortune, author; Kiminou, Franck, author; Kokangoye, Max, author; Kujirakwinja, Deo, author; Latour, Stephanie, author; Liengola, Innocent, author; Mackaya, Quevain, author; Madidi, Jacob, author; Madzoke, Bola, author; Makoumbou, Calixte, author; Malanda, Guy-Aimé, author; Malonga, Richard, author; Mbani, Olivier, author; Mbendzo, Valentin A., author; Ambassa, Edgar, author; Ekinde, Albert, author; Mihindou, Yves, author; Morgan, Bethan J., author; Motsaba, Prosper, author; Moukala, Gabin, author; Mounguengui, Anselme, author; Mowawa, Brice S., author; Ndzai, Christian, author; Nixon, Stuart, author; Nkumu, Pele, author; Nzolani, Fabian, author; Pintea, Lilian, author; Plumptre, Andrew, author; Rainey, Hugo, author; De Semboli, Bruno Bokoto, author; Serckx, Adeline, author; Stokes, Emma, author; Turkalo, Andrea, author; Vanleeuwe, Hilde, author; Vosper, Ashley, author; Warren, Ymke, author; Public Library of Science, publisher
    African forest elephants - taxonomically and functionally unique - are being poached at accelerating rates, but we lack range-wide information on the repercussions. Analysis of the largest survey dataset ever assembled for forest elephants (80 foot-surveys; covering 13,000 km; 91,600 person-days of fieldwork) revealed that population size declined by ca. 62% between 2002-2011, and the taxon lost 30% of its geographical range. The population is now less than 10% of its potential size, occupying less than 25% of its potential range. High human population density, hunting intensity, absence of law enforcement, poor governance, and proximity to expanding infrastructure are the strongest predictors of decline. To save the remaining African forest elephants, illegal poaching for ivory and encroachment into core elephant habitat must be stopped. In addition, the international demand for ivory, which fuels illegal trade, must be dramatically reduced.
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    Will elephants soon disappear from West African savannahs?
    (Colorado State University. Libraries, 2011) Bouché, Philippe, author; Douglas-Hamilton, Iain, author; Wittemyer, George, author; Nianogo, Aimé J., author; Doucet, Jean-Louis, author; Lejeune, Philippe, author; Vermeulen, Cédric, author; Public Library of Science, publisher
    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.