title: The spatial distribution of African savannah herbivores: species associations and habitat occupancy in a landscape context.
abstract: Herbivores play an important role in determining the structure and function of tropical savannahs. Here, we (i) outline a framework for how interactions among large mammalian herbivores, carnivores and environmental variation influence herbivore habitat occupancy in tropical savannahs. We then (ii) use a Bayesian hierarchical model to analyse camera trap data to quantify spatial patterns of habitat occupancy for lions and eight common ungulates of varying body size across an approximately 1100 km(2) landscape in the Serengeti ecosystem. Our results reveal strong positive associations among herbivores at the scale of the entire landscape. Lions were positively associated with migratory ungulates but negatively associated with residents. Herbivore habitat occupancy differed with body size and migratory strategy: large-bodied migrants, at less risk of predation and able to tolerate lower quality food, were associated with high NDVI, while smaller residents, constrained to higher quality forage, avoided these areas. Small herbivores were strongly associated with fires, likely due to the subsequent high-quality regrowth, while larger herbivores avoided burned areas. Body mass was strongly related to herbivore habitat use, with larger species more strongly associated with riverine and woodlands than smaller species. Large-bodied migrants displayed diffuse habitat occupancy, whereas smaller species demonstrated fine-scale occupancy reflecting use of smaller patches of high-quality habitat. Our results demonstrate the emergence of strong positive spatial associations among a diverse group of savannah herbivores, while highlighting species-specific habitat selection strongly determined by herbivore body size.This article is part of the themed issue 'Tropical grassy biomes: linking ecology, human use and conservation'.
authors: Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA anderstm@wfu.edu.
authors: T Michael
authors: 0000-0003-0109-2528
authors: TM
authors: Anderson
authors: Department of Mathematics and Statistics, Wake Forest University, Winston-Salem, NC 27109, USA.
authors: Staci
authors: S
authors: White
authors: Department of Mathematics and Statistics, Wake Forest University, Winston-Salem, NC 27109, USA.
authors: Bryant
authors: B
authors: Davis
authors: Department of Mathematics and Statistics, Wake Forest University, Winston-Salem, NC 27109, USA.
authors: Rob
authors: R
authors: Erhardt
authors: Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN 55108, USA.
authors: Meredith
authors: M
authors: Palmer
authors: Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN 55108, USA.
authors: Alexandra
authors: A
authors: Swanson
authors: Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN 55108, USA.
authors: Margaret
authors: M
authors: Kosmala
authors: Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN 55108, USA.
authors: Craig
authors: C
authors: Packer
mesh_terms: D000349:Africa; D063147:Animal Distribution; D000818:Animals; D001499:Bayes Theorem; D020387:Food Chain; D065948:Grassland; D060434:Herbivory; D008045:Lions; D008322:Mammals / Q000502:physiology*; D008954:Models, Biological; D013636:Tanzania
keywords: Bayesian hierarchical occupancy model; Serengeti; body size; camera trap; food web; predator–prey