Author: Amera Natasha Mah
In the tropical rainforests of Malaysia, the night may appear still and silent to an untrained eye. However, for those who listen closely, it holds a symphony of diverse fauna species that come alive in the darkness. Among of them are the nocturnal birds, the elusive residents of the dark that sing in the hours when most of the world is asleep.
In attempt to understand the vocal behaviour of these elusive nocturnal birds, passive acoustic monitoring approach has been used in my study to facilitate the collection of their vocalisations. Bioacoustic Audio Recorders (BARs) were deployed in four lowland forests in Peninsular Malaysia, covering both breeding and non-breeding seasons of these nocturnal birds. Specifically, call types were identified and the respective vocal activity patterns were visualised via sonograms.
These findings are crucial in understanding how these birds utilise and coexist within the same acoustic space where multiple species tend to communicate in the complex forest habitat. Likewise, identifying the time when these birds are most active aids in planning optimal survey periods for effective ecological monitoring.
In my study, the deployment of BARs had facilitated the visualisation of vocal activity patterns of nine nocturnal forest birds in Malaysia, including five owl species, three frogmouth species, and a nightjar species. Among these local resident species were the common Brown Boobook (Ninox scutulata), Collared Scops-owl (Otus lettia), Blyth’s Frogmouth (Batrachostomus affinis), Gould’s Frogmouth (Batrachostomus stellatus), and Malaysia Eared-nightjar (Lyncornis temminckii), the uncommon Oriental Bay-owl (Phodilus badius), Reddish Scops-owl (Otus rufescens), and Barred Eagle-owl (Ketupa sumatrana) as well as the rather rare Large Frogmouth (Batrachostomus auritus). Some of these species, i.e., the Reddish Scops-owl, Large Frogmouth, and Gould’s Frogmouth are Near Threatened species listed in the IUCN Red List.
Recording from the BAR: Calls of Brown Boobook and Collared Scops-owl. Supplied by Amera Natasha Mah
It is hoped that these findings may be able to facilitate future monitoring efforts of these birds, expanding our understanding on their behaviour and ecology especially for those species that are in need of attention.
A part of this nocturnal study has been published in the journal listed below:
Mah, A. N. M. M. A., Puan, C. L., Zakaria, M., & Rahim, A. -K. H. A. (2024). Vocal activity patterns of Malaysian Eared-nightjar (Lyncornis temminkii) in lowland forests in Peninsular Malaysia. Malaysian Forester, 87(2), 277-291. (Link)
Another application of the Bioacoustic Audio Recorder for diurnal recordings is detailed in the journal listed below:
Mah, A. N. M. M. A., Puan, C. L., & Zakaria, M. (2023). Vocal activity patterns of the Changeable Hawk-Eagle (Nisaetus cirrhatus) in Peninsular Malaysia during mid-breeding season. Journal of Raptor Research, 57(3), 1-12. https://doi.org/10.3356/JRR-22-72
Researcher Bio
Amera has used Bioacoustics Audio Recorder (BAR) across several projects, including assessing the vocal behaviour of raptors and nocturnal birds. The BAR has also greatly supported her team’s bird diversity surveys and expeditions, particularly detecting the elusive and shy birds that are missed during the rapid assessments. Its durable structure was capable of withstanding the rain and high humidity of Malaysia’s tropical rainforest, facilitating her team’s ability to carry out long-term monitoring projects and surveys.
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