Journal article
Shift in Black Rhinoceros Diet in the Presence of Elephant: Evidence for Competition?
PLoS One, Vol.8(7), e69771
2013
Abstract
In African large herbivore assemblages, megaherbivores dominate the biomass and utilise the greatest share of available resources. Consequently, they are considered a separate trophic guild that structures the food niches of coexisting large herbivores. However, there exists little empirical evidence on how food resources are shared within this guild, and none for direct competition for food between megaherbivores. Using the histological analysis of faeces, we explore this phenomenon for African elephant Loxodonta africana and black rhinoceros Diceros bicornis in the Addo Elephant National Park, South Africa, where the accumulated impacts of elephant have reduced browse availability. Despite being unable to generalise beyond our study sites, our observations support the predictions of competition theory (as opposed to optimality theory) by showing (1) a clear seasonal separation in resource use between these megaherbivores that increased as resource availability declined, and (2) rhinoceros changed their selectivity in the absence of elephant (using an adjacent site) by expanding and shifting their diet along the grass-browse continuum, and in relation to availability. Although black rhinoceros are generally considered strict browsers, the most significant shift in diet occurred as rhinoceros increased their preferences for grasses in the presence of elephant. We speculate that the lack of specialised grazing adaptations may increase foraging costs in rhinoceros, through reduced harvest- and handling-efficiencies of grasses. In the short-term, this may be off-set by an enhanced tolerance for low quality food and by seasonally mobilising fat reserves; however, the longterm fitness consequences require further study. Our data suggest that managing elephant at high densities may compromise the foraging opportunities of coexisting browsers. This may be particularly important in small, fenced areas and overlapping preferred habitats where impacts intensify.
Details
- Title
- Shift in Black Rhinoceros Diet in the Presence of Elephant: Evidence for Competition?
- Authors
- M Landman (Author) - Nelson Mandela Metropolitan University, South AfricaDavid S Schoeman (Author) - University of the Sunshine Coast - Faculty of Science, Health, Education and EngineeringG I H Kerley (Author) - Nelson Mandela Metropolitan University, South Africa
- Publication details
- PLoS One, Vol.8(7), e69771
- Publisher
- Public Library of Science
- Date published
- 2013
- DOI
- 10.1371/journal.pone.0069771
- ISSN
- 1932-6203
- Copyright note
- Copyright © 2013 Landman et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
- Organisation Unit
- School of Science and Engineering - Legacy; University of the Sunshine Coast, Queensland; School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 99448807502621
- Output Type
- Journal article
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