A new study carried out by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) in cooperation with the World Wide Fund for Nature Vietnam (WWF-Vietnam) and the Sabah Forestry Department of the Government of Malaysia suggests that for ground dwelling mammal and bird communities, illegal hunting using indiscriminate snares may be a more immediate threat than forest degradation through selective logging. The researchers conducted a large scale camera-trapping study to compare several forest areas with logging concessions in Malaysian Borneo and protected areas in the Annamites ecoregion of Vietnam and Laos known to be subjected to illegal hunting. The results, published in the journal “Communications Biology”, show severe defaunation in snared forests compared to logged forests.
While both habitat degradation and unsustainable hunting have long been known to negatively affect animal communities in tropical rainforests, no study had directly compared how these threats compare in their severity in terms of losses of mammal and bird biodiversity at landscape scales. The result was that both logging and hunting negatively affected ground-dwelling mammal and bird communities, and unsustainable hunting had more severe effects on these communities. Overhunted sites in the Annamite Mountains of Vietnam and Laos had a higher proportion of species extirpated than the degraded sites in Borneo. Even species which persisted in the landscape subjected to illegal hunting had smaller distributions than similar species in the logging concessions.
“We had a unique opportunity to investigate the complex mechanisms of these defaunation drivers and compare their relative severities,” says Andrew Tilker, doctoral student at the Leibniz-IZW and Asian Species Officer at Global Wildlife Conservation, one of the lead authors of the paper. “Our rainforest study sites in Malaysian Borneo are degraded through logging but have experienced little hunting, whereas our rainforest study sites in the Annamite Mountains are structurally intact but are subjected to extremely high illegal hunting pressure. Because the two study landscapes generally have similar habitats and faunal communities, it was an opportunity for us to investigate to what extent these defaunation drivers differ in their impact on tropical rainforest faunal communities.”
“These findings are not only interesting from an academic perspective, they also have implications for conservation work”, says Dr Jesse F. Abrams, postdoc at the Leibniz-IZW and co-first author. “Our results show that maintaining habitat quality as a means of protecting tropical biodiversity is, by itself, insufficient.” The researchers suggest that, whilst both defaunation drivers should be addressed to maintain tropical biodiversity, in some cases it may be more prudent to focus limited conservation resources on addressing overhunting rather than habitat degradation.