Chimpanzees are nearing extinction in many countries. Of the four subspecies of these great apes, western chimpanzees are the most endangered. Experts estimate that their distribution is now extremely patchy, with 80% of their numbers having declined in the last 20 years. The largest-remaining population is found in the Ivory Coast in Western Africa, with smaller populations in Guinea, Sierra Leone, Nigeria, Guinea-Bissau and Liberia. Poaching and habitat loss are some of the well-known threats to chimpanzees. But a study published last September finds that road developments are exacerbating their population decline. Noise pollution emanating from the construction of roads and poachers gaining access to more remote locations are some of the reasons to blame. A team of primate conservationists have quantified the extent to which roads jeopardize their communities. They say that just about 4.5% of the chimp population are left unaffected by roads. On this episode of the Scienceline podcast, reporter Niranjana Rajalakshmi speaks with primate behavior experts who suggest a few strategies that could mitigate the impact of roads on western chimpanzees. Find more information at Scienceline.org