For decades habitat loss has been the key threat for wildlife in tropical rainforest ecosystems but a new study finds that ground dwelling mammal and bird communities are more impacted by illegal hunting using indiscriminate snares than they are controlled 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 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.
“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.
Because hunting in the Annamites is primarily accomplished by the setting of indiscriminate wire snares, the findings of the study have implications for other landscapes in Southeast Asia, which currently are facing an ever-increasing snaring “epidemic”. In this respect, the levels of defaunation found in the rainforest study sites in the Annamites by the researchers could offer a foreboding glimpse into the future of biodiversity across the wider Southeast Asian biodiversity hotspot.
The study’s findings also have positive implications for conservation. Datuk Mashor Mohd Jaini Director of the Sabah Forestry Department notes, “These results show that logging concessions can be safe havens for mammal and bird communities, particularly if sustainable forest management protocols are applied, following principles of forest certification standards”.