The influence of food availability, quality and body size on patch selection of coexisting grazer ungulates in western Serengeti National Park
John Bukombe
A G , Andrew Kittle B , Ramadhan B. Senzota C * , Hamza Kija D , Simon Mduma A , John M. Fryxell B , Flora Magige C , Cosmas Mligo E and Anthony R. E. Sinclair F
+ Author Affiliations
- Author Affiliations
A Biodiversity Program, Tanzania Wildlife Research Institute, PO Box 661, +255, 23113 LEMARA, Kikwakwaru ‘A’, Arusha, Tanzania.
B University of Guelph, Department of Integrative Biology, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada.
C University of Dar es Salaam, Zoology and Wildlife Conservation department, PO Box 35064, +255, 14113 Kijitonyama, Mwenge, Dar es Salaam, Tanzania.
D Tanzania Wildlife Research Institute, PO Box 661, +255, 23113 LEMARA, Kikwakwaru ‘A’, Arusha, Tanzania.
E University of Dar es Salaam, Botany Department, PO Box 35065, +255, 14113 Kijitonyama, Mwenge, Dar es Salaam, Tanzania.
F Beaty Biodiversity Centre, Biodiversity Research Centre, 2212 Main Mall, Vancouver, BC Canada V6T 1Z4, University of British Columbia, Vancouver, Canada.
G Corresponding author. Email: bukombe2017@gmail.com
Wildlife Research 46(1) 54-63 https://doi.org/10.1071/WR18072
Submitted: 16 February 2017 Accepted: 24 October 2018 Published: 11 January 2019
Abstract
Context: Differences in body size and mouth morphologies influence dietary resource separation among savanna ungulates, and this influences their distribution across landscape.
Aim: The aim was to understand the influence of body size and mouth morphology differences on both diet and patch selection by ungulate species in western Serengeti. Two hypotheses were tested: (1) for ungulate species, the relative body sizes and muzzle widths (mean muzzle width range: 3.1- 9.85) relate directly to food biomass, and to quality of diets selected in the wet season when food is abundant; (2) in the wet season, if food is not limiting, similar-sized species should exhibit greater dietary niche overlap than ungulate species that differ greatly in body size and muzzle width; moreover, similar-sized species exhibit less dietary niche overlap than ungulate species that differ greatly in body size.
Methods: In the western Serengeti ecosystem, road transects and direct observation were used to obtain data on the distribution and diet of five ungulate species namely buffalo, zebra, wildebeest, topi and impala; which have of varying sizes (range: 70–630 kg) feeding in three different vegetation types. Grassland biomass, structure, nutrient content and ungulate use were measured at sites along transects.
Key Results: Results indicated that large-bodied ungulates utilised patches of greater food abundance compared with those of smaller ungulates. Body mass was also negatively correlated with diet quality, so that smaller animals ate higher protein and lower-fibre foods, as predicted. Diet niche overlap (niche similarity) showed a strong positive relationship with body mass differences among ungulate species, in support of the second of the two predictions from this hypothesis, namely that dissimilarly sized species could eat the same food.
Conclusion: Overall, the results suggest that in this savanna system, variation in ungulate body size influences resource separation even in the food-abundant wet season, and that this helps multiple species to co-exist.
Implications: Implementing more focused conservation strategies will improve wildlife habitat quality by integrating fire as a forage management tool with grazing preferences to promote forage heterogeneity in protected areas.
Additional keywords: dietary resource separation, dissimilarly sized ungulate species, distribution patterns, Savanna herbivores, Tanzania.
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