Impacts of removing badgers on localised counts of hedgehogs.

Iain D Trewby,Robbie A Mcdonald,Neil Walker,Gavin J Wilson,Richard Young,Richard J Delahay,C Patrick Doncaster,Andrew Robertson,John Davison,François Criscuolo

doi:10.1371/journal.pone.0095477

Abstract

Experimental evidence of the interactions among mammalian predators that eat or compete with one another is rare, due to the ethical and logistical challenges of managing wild populations in a controlled and replicated way. Here, we report on the opportunistic use of a replicated and controlled culling experiment (the Randomised Badger Culling Trial) to investigate the relationship between two sympatric predators: European badgers Meles meles and western European hedgehogs Erinaceus europaeus. In areas of preferred habitat (amenity grassland), counts of hedgehogs more than doubled over a 5-year period from the start of badger culling (from 0.9 ha−1 pre-cull to 2.4 ha−1 post-cull), whereas hedgehog counts did not change where there was no badger culling (0.3–0.3 hedgehogs ha−1). This trial provides experimental evidence for mesopredator release as an outcome of management of a top predator.

Highlights

Top predators may have far reaching impacts on the ecosystems they inhabit [1,2]
In this study we investigated the relationship between a top predator, the European badger Meles meles and a sympatric mesopredator, the western European hedgehog Erinaceus europaeus, in the UK
The opportunity to experimentally test the effects of a reduction in predator abundance on populations of a competing prey species arose from the Randomised Badger Culling Trial (RBCT) which was a replicated, controlled field experiment to investigate the effect of culling badgers on the incidence of bovine tuberculosis (TB) in cattle [21]

Summary

Introduction

Top predators may have far reaching impacts on the ecosystems they inhabit [1,2]. As a consequence, anthropogenic activities which reduce or remove top predator species may have major and often unintentional effects on the structure, productivity or diversity of the wider ecosystem [1,3]. The majority of studies have not provided experimental measures of how changes in the abundance of top predators result in changes in mesopredator abundance, but rather describe interactions or associations between species [1,6]. The opportunity to experimentally test the effects of a reduction in predator abundance on populations of a competing prey species arose from the Randomised Badger Culling Trial (RBCT) which was a replicated, controlled field experiment to investigate the effect of culling badgers on the incidence of bovine tuberculosis (TB) in cattle [21]. We tested the hypothesis that hedgehog abundance and/or behaviour would change, in line with predictions of mesopredator release, as a result of reductions in badger abundance after culling

Materials and Methods

Results

Discussion

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