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Hunting is a major threat to wildlife particularly in tropical regions. A systematic large-scale estimate of hunting-induced loss of animal species was lacking so far. A study published in Science on April 14 fills this gap. Hunting accounts for 83 and 58% declines in tropical mammal and bird populations.

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An international team of ecologists and environmental scientists found that mammal and bird populations within 40 and 7 km of hunters’ access points, such as roads and settlements. Additionally, the team found that commercial hunting had a higher impact than subsistence hunting, and that hunting pressure was higher in areas with better accessibility to major towns where wild meat could be traded. PBL co-operated in this study to further underpin the Global Biodiversity Model (GLOBIO), which is used to inform international policy makers on biodiversity.

The researchers synthesised 176 studies to quantify hunting-induced declines of mammal and bird populations across the tropics of Central and South America, Africa and Asia. The study was led by Ana Benítez-López, who works at the department of Environmental Science at Radboud University in Nijmegen. She cooperated with researchers from the Netherlands Environmental Assessment Agency (PBL), the universities of Wageningen and Utrecht in the Netherlands and a colleague from the School of Life Sciences, University of Sussex.

Higher hunting pressure around villages and roads

There are several drivers of animal decline in tropical landscapes: habitat destruction, overhunting, fragmentation etcetera. While deforestation and habitat loss can be monitored using remote sensing, hunting can only be tracked on the ground. The expert team wanted to find a systematic and consistent way to estimate the impact of hunting across the tropics. As a starting point, the researchers used the hypothesis that humans gather resources in a circle around their village and in the proximity of roads.

As such, hunting pressure is higher in the proximity of villages and other access points. From there the densities of species increase up to a distance where no effect of hunting is observed. ‘We called this species depletion distances which we quantified in our analysis. This will allow us to map hunting-induced declines across the tropics for the first time’, according to de main researcher Benítez-López.