Traffic noise reduces morning songs of Malaysian white‑handed gibbons

Traffic noise is increasingly disrupting the natural rhythms of wildlife, a new study suggests, with evidence from a Malaysian forest where white‑handed gibbons have become unusually quiet at dawn. The research, conducted by a team of primatologists and acoustic ecologists, focused on two groups of gibbons—Mambang and Walinong—nestled near residential areas and a busy highway. While other populations of the same species in quieter habitats erupt into their characteristic morning songs, the Mambang and Walinong groups produce far fewer vocalizations, their usual “wa‑oo” and “wa‑ing” replaced by the constant hum of traffic.

Field recordings taken at the start of each day revealed a stark contrast between the two settings. In the undisturbed forest, gibbons began their day with a chorus of vocalizations that can be heard from the highest branches, serving as territorial signals and social cohesion tools. In the traffic‑affected site, however, the morning chorus was almost absent, with only sporadic, low‑volume calls detected. The researchers attribute this suppression to the masking effect of continuous road noise, which may interfere with the gibbons’ ability to hear and respond to conspecific calls, potentially affecting mating, territory defense, and group cohesion.

The findings highlight a broader concern about how anthropogenic sound pollution can alter animal behavior and ecosystem dynamics. If traffic noise continues to encroach on natural habitats, it may lead to long‑term changes in communication, breeding success, and survival rates of affected species. Further studies are needed to determine whether gibbons can adapt to these acoustic changes or if mitigation measures—such as sound barriers or traffic regulation—are required to preserve their natural behaviors.