Testing the effects of anthropogenic pressures on a diverse African herbivore community

Milan A Vinks,Wigganson Matandiko,Chuma Simukonda,Scott Creel,Kambwiri Banda,Matthew Becker,Paul Schuette,Ben Goodheart,Clive Chifunte,Carolyn Sanguinetti,Elias Rosenblatt

doi:10.1002/ecs2.3067

Abstract

AbstractLarge herbivore communities around the world have declined steeply in recent decades. Although excessive bushmeat harvesting is thought to be the primary cause of herbivore declines in many ecosystems, the direct effects of anthropogenic pressures on large herbivore populations remain poorly described in most of the systems experiencing decline. To test the extent to which large herbivores are impacted by ecological and anthropogenic factors in a protected area (PA) thought to be experiencing human‐caused decline, we fit distance sampling models to seven years of data from systematic ground‐based surveys in Kafue National Park (KNP) to estimate the population densities and distributions of 10 species of large herbivores, and to test what factors affect these parameters. Population densities of the ten most abundant large herbivores in KNP were substantially lower than those reported for an ecologically similar PA with less poaching pressure. Low densities were consistent across species and areas, though there was ecologically important variation among species and size classes. Densities of larger‐bodied herbivores were greatly depressed relative to smaller species. This pattern has direct and indirect effects on large carnivore populations, with broad implications for the ecotourism and trophy hunting industries. Statistically and methodologically rigorous methods to test the effects of anthropogenic and environmental variables on density and distribution exist, but are rarely applied to large herbivores. To quantify trends in herbivore populations and evaluate the effectiveness of conservation actions, our results show that distance sampling with stratified ground‐based monitoring is an efficient and effective method. In the Greater Kafue Ecosystem (GKE), continued increases in resource protection are needed to facilitate the recovery of an economically and ecologically important large herbivore guild. More broadly, our results confirm that anthropogenic effects on large herbivore distribution and abundance can be strong over wide areas for all species (particularly the larger members of the guild), even in very large PAs.

Highlights

Large terrestrial herbivore populations are facing dramatic population declines and range contractions globally (Ripple et al 2015)
There was substantial overlap across species in the variables that affected density, the anthropogenic variables that were of primary interest (Tables 1, 2)
The second and third most abundant large herbivores were impala and warthog, with mean densities of 6.25 animals/km2 and 2.51 animals/km2, respectively (Table 4)

Summary

Introduction

Large terrestrial herbivore populations are facing dramatic population declines and range contractions globally (Ripple et al 2015). Large herbivore communities in protected areas (PAs) have undergone declines comparable to populations in unprotected areas (Western et al 2009, Craigie et al 2010). These declines are of concern for two major reasons. Large herbivore communities are often a focal point for ecosystem conservation and management, and are flagship species for many PAs (Sinclair and Norton‐Griffiths 1979, Sinclair and Arcese 1995, Bowen‐Jones and Entwistle 2002). Large herbivores provide significant economic and societal value to rural communities, through wildlife‐based economies utilizing tourism, trophy hunting, and game ranching (Gordon et al 2004, Krüger 2005, Lindsey et al 2007)

Methods

Results

Conclusion