Listening to the Forest Floor: Discovering Borneo’s Hidden Ground Birds Through Sound

By Sui Peng Heon (Kuamut Rainforest Conservation, Malaysia)

Camera traps, point counts, and line transects have long been the foundation of wildlife surveys in Borneo. Yet despite these well-established methods, some forest-floor species remain mysteriously elusive. Among the most understudied are Borneo’s ground-dwelling birds—a group that quietly moves through the leaf litter but rarely reveals itself to researchers.

Our initial plan was simple: deploy camera traps and study the occupancy of these birds across the landscape. But weeks turned into months, and to our surprise, only one species of ground bird appeared in the footage, while the many other species remain undetected. Their absence forced us to ask difficult questions.

Had they not survived the last round of logging?
Were they hunted out of the area?
Or were they simply too cryptic for our cameras to detect?

That uncertainty pushed us to try a different approach: bioacoustics.

While we have not yet detected some of the rarest species—such as the Bornean Peacock-Pheasant (Polyplectron schleiermacheri) or the elusive Bornean Ground-Cuckoo (Carpococcyx radiceus)—the recordings have begun to reveal the hidden soundscape of Borneo’s forest floor. The charismatic boom of the Great Argus Pheasant (Argusianus argus), the rhythmic tunes of the Pittas and the melodic notes of the Sabah Partridge (Tropicoperdix graydoni) are now emerging from the data, each call shedding light on species that were once nearly invisible to our surveys.

Bioacoustics is opening a new window into the secretive world of Borneo’s ground birds—reminding us that sometimes, to understand what lives in a forest, you must listen as much as you look.