Spatial distribution and research trend of illegal activities and the factors associated with wild mammal population declines in protected areas

Abstract

Illegal activities are a persistent problem in many protected areas, but an overview of the extent of this problem and its impact is lacking. We review 35 years (1980-1914) of research across the globe to examine the spatial distribution of research and socio-ecological factors influencing population decline within protected areas under illegal activities pressure. From 92 papers reporting 1048 species/site combinations, more than 350 species comprising mammals, reptiles, birds, fishes and molluscs were reported to have been extracted illegally from 146 protected areas across four continents. Research in illegal activities has increased substantially during the review period but also shows strong taxonomic and geographic biases towards large wild mammals and African continent respectively, suggesting persistent poaching pressures on wild mammals in African protected areas. Population declines were most frequent i) where there was commercial poaching as opposed to subsistence poaching alone, ii) in countries with a low human development index particularly in strict protected areas and iii) for species with a body mass over 100 kg. Habitat loss associated with greater land use change had an additional significant impact on population decline, particularly in the less-strict categories (IUCN III-VI) of protected area across the continents. Overall, these findings provide evidence that illegal activities are most likely to cause species declines of large-bodied animals in protected areas in resource-poor countries regardless of protected area conservation status (i.e. IUCN category). Given the mounting pressures of illegal activities, additional conservation effort such as improving anti-poaching strategies and conservation resources in terms of improving funding and personnel directed at this problem is a growing priority.