Traffic Noise Cuts Gibbon Morning Songs Near Malaysian Highway — SkimNews
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- Benjamin Galea of Universiti Sains Malaysia recorded white-handed gibbon morning calls at three Malaysian sites during 2023–2024 and found the highway-adjacent group called in just 36% of recordings, compared with 84.6% at a hiking-trail site and 71.4% at a quiet seaside location.
- The study, not yet peer-reviewed, found that within individual sites, the estimated odds of calling decreased as background noise rose — a dose-response pattern linking noise levels directly to vocal output.
- The hiking-trail gibbons sang more than the quieter beachfront group, likely because they lived nearer to a neighboring group (prompting territorial calls) and sat deeper inside the forest where vehicle noise intruded less, per Galea.
- When the highway gibbons did call, 93.3% of their vocal phrases came in solo-song contexts, raising the possibility that traffic noise made it harder for mating pairs to hear and coordinate with each other.
- The white-handed gibbon is listed as endangered by the IUCN, with the global population believed to have declined more than 50% over 45 years due to habitat destruction, hunting, and the pet trade.
- Supervisor Nadine Ruppert of the Chinese Academy of Sciences' Xishuangbanna Tropical Botanical Garden warned that forest fragments can look physically suitable yet still inflict chronic noise stress, arguing habitat quality must be measured by what animals experience, not just what trees remain.
Why it matters: For an endangered species whose population has fallen more than 50% over 45 years, losing even part of their daily calling behavior could undermine territory defense, mate attraction, and pair coordination — functions the IUCN already flags as critical. The 36% calling rate near highways versus 84.6% in quieter forest shows that 'intact-looking' forest fragments in urbanizing Malaysia may be acoustically degraded habitat in disguise, complicating conservation planning in places like Kuala Lumpur where gibbons persist in small, road-bordered patches.
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