# Does Foraging or the Avoidance of Predation Determine Habitat Selection by Selective Resident Grazers in the Serengeti Woodlands? A Mixed Strategy with Season

## TL;DR

This study explores how medium-sized grazers in the Serengeti choose their habitats, finding that foraging and predation avoidance drive their decisions differently in dry and wet seasons.

## Contribution

The paper reveals for the first time that medium-sized herbivores use mixed strategies for habitat selection based on seasonal changes.

## Key findings

- Resource availability is the main driver of habitat selection for medium-sized grazers during the dry season.
- Predation risk reduction becomes the dominant factor in habitat selection during the wet season.
- The study provides insights into the dynamics of a globally important savanna ecosystem.

## Abstract

Large herbivores play a central role in savanna ecosystems, structuring plants and feeding predators. As many as 30 species can coexist, from the large elephant to the small dik-dik. Coexistence is based on sharing resources but predation plays an important role for some species. Habitat selection is a key element of resource use: for the large species it is determined by resource availability, for the small ones the risk of predation plays a key role. The determinants of habitat selection by medium-sized species are not well known; the aim of this paper is to discover the features of the landscape and plant structure which determine their choice of habitat. Using detailed measurements of sward structure in the Serengeti we develop highly predictive models of habitat selection for two medium-sized species in the dry season, implying that foraging is the major driver of habitat selection. In the wet season reducing the risk of predation appears to play a dominant role, so these medium-sized species have mixed strategies. Since climate change will modify the resources and predator numbers are affected by disease outbreaks understanding the determinants of the strategies of the herbivores in this globally important system will contribute to effective models, an essential basis for any management actions.

Savanna systems are characterised by a community of large mammal herbivores with up to 30 species; coexistence is based on resource partitioning. In this paper we analyse the features of the landscape and plant structure which lead herbivores to use particular locations, a key to resource partitioning. The processes involved, top-down versus bottom-up, are well known for large species and small ones but not for medium-sized ones. We use two resident, medium-sized species, topi (Damaliscus lunatus jimela) and kongoni, (Alcelaphus buselaphus cokei) in the central woodlands of the Serengeti; selection of habitat by the residents is important for predator-prey interactions and for interactions among the grazers. Using Principal Component Analysis and Multiple Regression we develop highly predictive models which show that resource availability is the critical determinant of habitat selection in the dry season; and reduction in predation risk appears to be important in the wet season. These results show for the first time that habitat selection by the medium-sized herbivores is driven by different strategies in the two seasons. This contributes to understanding the processes involved in the dynamics of this globally important savanna system, a necessary foundation for management.