Where and How Are Roads Endangering Mammals in Southeast Asia's Forests?

Habitat destruction and overhunting are two major drivers of mammal population declines and extinctions in tropical forests. The construction of roads can be a catalyst for these two threats. In Southeast Asia, the impacts of roads on mammals have not been well-documented at a regional scale. Before evidence-based conservation strategies can be developed to minimize the threat of roads to endangered mammals within this region, we first need to locate where and how roads are contributing to the conversion of their habitats and illegal hunting in each country. We interviewed 36 experts involved in mammal research from seven Southeast Asian countries to identify roads that are contributing the most, in their opinion, to habitat conversion and illegal hunting. Our experts highlighted 16 existing and eight planned roads - these potentially threaten 21% of the 117 endangered terrestrial mammals in those countries. Apart from gathering qualitative evidence from the literature to assess their claims, we demonstrate how species-distribution models, satellite imagery and animal-sign surveys can be used to provide quantitative evidence of roads causing impacts by (1) cutting through habitats where endangered mammals are likely to occur, (2) intensifying forest conversion, and (3) contributing to illegal hunting and wildlife trade. To our knowledge, ours is the first study to identify specific roads threatening endangered mammals in Southeast Asia. Further through highlighting the impacts of roads, we propose 10 measures to limit road impacts in the region.栖息地破坏与过度捕猎是引发热带森林内哺乳动物种群下降及物种灭绝的两大核心驱动因素。道路建设可成为这两类威胁的重要催化剂。在东南亚地区，道路对哺乳动物的影响尚未在区域尺度上得到充分的文献记录与评估。在制定基于证据的保护策略以最大限度降低道路对该区域濒危哺乳动物的威胁之前，我们首先需要明确各国境内的道路是如何、在何处加剧了其栖息地破坏与非法捕猎活动。我们采访了来自东南亚7个国家的36位哺乳动物研究领域专家，以甄别出他们认为对栖息地破坏及非法捕猎贡献最大的道路。专家们共指出16条已建成道路与8条规划道路——这些道路可能对上述国家117种濒危陆生哺乳动物中的21%构成威胁。除了收集文献中的定性证据以佐证专家们的判断外，我们还演示了如何结合物种分布模型（species-distribution models）、卫星影像（satellite imagery）与动物痕迹调查（animal-sign surveys），从三个维度量化道路所造成的影响：(1) 穿越濒危哺乳动物的潜在栖息区域；(2) 加剧森林转化与破坏；(3) 助长非法捕猎及野生动物贸易。据我们所知，本研究是东南亚地区首个明确识别出威胁濒危哺乳动物的具体道路的研究。此外，通过梳理道路带来的各类负面影响，我们针对该区域提出了10项减缓道路影响的措施。