What limits the Serengeti zebra population?
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The populations of the ecologically dominant ungulates in the Serengeti ecosystem (zebra, wildebeest and buffalo) have shown markedly different trends since the 1960s: the two ruminants both irrupted after the elimination of rinderpest in 1960, while the zebras have remained stable. The ruminants are resource limited (though parts of the buffalo population have been limited by poaching since the 1980s). The zebras’ resource acquisition tactics should allow them to outcompete the ruminants, but their greater spatial dispersion makes them more available to predators, and it has been suggested that this population is limited by predation. To investigate the mechanisms involved in the population dynamics of Serengeti zebra, we compared population dynamics among the three species using demographic models based on age-class-specific survival and fecundity. The only major difference between zebra and the two ruminants occurred in the first-year survival. We show that wildebeest have a higher reproductive potential than zebra (younger age at first breeding and shorter generation time). Nevertheless, these differences in reproduction cannot account for the observed differences in the population trends between the zebra and the ruminants. On the other hand, among-species differences in first-year survival are great enough to account for the constancy of zebra population size. We conclude that the very low first-year survival of zebra limits this population. We provide new data on predation in the Serengeti and show that, as in other ecosystems, predation rates on zebras are high, so predation could hold the population in a “predator pit”. However, lion and hyena feed principally on adult zebras, and further work is required to discover the process involved in the high mortality of foals.
- What limits the Serengeti zebra population?
Volume 140, Issue 3 , pp 523-532
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- African ungulates
- Population dynamics
- Industry Sectors
- Author Affiliations
- 1. Centre d’Etudes Biologiques de Chizé, CNRS UPR 1934, 79360, Beauvoir-sur-Niort, France
- 2. UMR 5558 “Biométrie et Biologie Evolutive”, Université Claude Bernard LYON1, Batiment 711. , 43 Boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
- 3. Centre for Biodiversity Research, University of British Columbia, 6270 University Boulevard, Vancouver, Canada, V6T 1Z4
- 4. USGS, Northern Rocky Mountain Science Center, Forestry Sciences Laboratory, Montana State University, Bozeman, MT 59717-2780, USA
- 5. Department of Ecology, Evolution, and Behavior, University of Minnesota, 1987 Upper Buford Circle, St. Paul, MN 55108, USA
- 6. Institute of Zoo & Wildlife Research, Alfred-Kowalke-Strasse 17, 10315, Berlin, Germany