Faculty of Natural and Agricultural Sciences
School of Biological Sciences
Department of Zoology and Entomology
Selected Highlights from Research Findings
Giraffes are well known for their unusual height, and they generally feed high in the tree canopy above the height that other herbivores can reach. Text-books use the giraffe’s elongated neck as an example of evolution by natural selection caused by competition between different species for the same leaves. We have investigated whether foraging competition can explain why giraffes feed mostly on leaves high in trees, and why males feed higher in the trees than females. Giraffes receive more leaves per bite by foraging high in the tree, and we showed that this was because smaller browsers like steenbok and impala deplete leaves at lower heights. Therefore, competition appears to drive the giraffes to forage high in the trees, providing the first real experimental evidence that the long neck of the giraffe might have evolved as a consequence of competition, providing support for the previously untested text-book example of natural selection. Our ongoing work is investigating whether cow giraffes force bulls to forage high in the tree by indirect competition in a similar way.
Contact person: Prof EZ Cameron.
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