The burning question: does fire affect habitat selection and forage preference of the black rhinoceros Diceros bicornis in East African savannahs?

T Michael Anderson,Bente J Graae,Daniel M Griffith,Eivin Røskaft,Frode Fossøy,James D M Speed,Philbert M Ngoti,Mawazo L Nzunda

doi:10.1017/s0030605318000388

Abstract

AbstractThe conservation of threatened species requires information on how management activities influence habitat quality. The Critically Endangered black rhinoceros Diceros bicornis is restricted to savannahs representing c. 5% of its historical range. Fire is used extensively in savannahs but little is known about how rhinos respond to burning. Our aim was to understand rhino responses to fire by studying habitat selection and foraging at multiple scales. We used resource selection functions and locations of 31 rhinos during 2014–2016 to study rhino habitat use in Serengeti National Park, Tanzania. Rhino selectivity was quantified by comparing forage consumption to plant species availability in randomly sampled vegetation plots; rhino diets were subsequently verified through DNA metabarcoding analysis of faecal samples. Rhino habitat use was a unimodal function of fire history, with highly occupied sites having fire frequencies of < 0.6 fires/year and maximum occupancy occurring at a fire frequency of 0.1 fires/year. Foraging stations had characteristic plant communities, with 17 species associated with rhino foraging. Rhinos were associated with, and disproportionately consumed, woody plants, forbs and legumes, all of which decreased in abundance with increasing fire frequency. In contrast to common management practices, multiple lines of evidence suggest that the current fire regime in the Serengeti negatively influences rhino habitat use and foraging and that frequent fire limits access of rhinos to preferred forage. We outline a conceptual model to guide managers and conservationists in the use of fire under variable habitat conditions.

Highlights

Herbivore foraging is hierarchical over a range of spatial scales: individuals select patches within landscapes, where to forage and what plants to consume within patches (e.g. Bailey et al, ; Searle et al, )
We explored the relationship between environmental factors and non-metric multi-dimensional scaling (NMDS) axis scores with a mixed model linear regression using the lmer command in the R package lme ; the best model was selected using Akaike’s Information Criteria (AIC)
Our results show that ( ) rhinos select habitats that burn infrequently, ( ) the plant composition of foraging stations used by rhinos is associated with low fire frequencies and ( ) the abundance of plant species preferred by rhinos decreases with increasing fire frequency

Summary

Introduction

Herbivore foraging is hierarchical over a range of spatial scales: individuals select patches within landscapes, where to forage and what plants to consume within patches (e.g. Bailey et al, ; Searle et al, ). For rare or threatened species, a thorough understanding of how individuals identify and select habitat and forage is required for successful management and conservation. This is especially true when management activities, such as fencing, burning, mowing or chemical application, can be targeted at increasing or restoring habitats or forage that may encourage population growth and stability. Protected by volatile secondary compounds such as alkaloids and phenols (Muya & Oguge, ) Taken together, these studies suggest that rhino selectivity may be aimed at reducing intake of secondary chemical compounds. The effect of fire on browser foraging may depend on the balance between improving foliar quality of plants that regrow after fire and eliminating plants that are preferred by browsers

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