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.

Center for Global Conservation Wildlife Conservation Society New York New York United States of America

Center for International Forestry Research Bogor Indonesia

Centre for Tropical Environmental and Sustainability Science and College of Marine and Environmental Sciences James Cook University Cairns Queensland Australia

Centre for Tropical Environmental and Sustainability Science and College of Marine and Environmental Sciences James Cook University Cairns Queensland Australia; Kenyir Research Institute Universiti Malaysia Terengganu Kuala Terengganu Malaysia; Panthera New York New York United States of America; Rimba 4 Jalan1 9D Selangor Malaysia; School of Geography University of Nottingham Malaysia Campus Selangor Malaysia; School of Science Monash University Selangor Malaysia

Department of Husbandry and Ethology Czech University of Life Sciences Prague Czech Republic

World Wide Fund for Nature Malaysia Jalan PJS 5 28 Petaling Jaya Selangor Malaysia

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