Using remote surveying technology and acoustic analysis tools to infer the impact of infrastructure expansion on bird biodiversity in the tropical rainforests of Brunei, Borneo.

Abstract

Tropical rainforests are the world’s most biodiverse biome but are increasingly threatened by anthropogenic stressors, such as urbanisation. Considering the current biodiversity crisis, gaining a deeper ecological understanding of the effects of such stressors on ecosystems, and the wildlife they harbour, is crucial. Due to its recent linkage to the more developed districts of the country, Temburong, a largely forested region of Brunei, presents an opportunity to collect baseline data to explore how infrastructure expansion impacts biodiversity. Using Autonomous Recording Units (ARUs) and camera traps, we deployed a wildlife monitoring network across current infrastructure expansion gradients in Temburong. Firstly, we examined spatial-temporal changes in soundscapes using the Acoustic Complexity Index and found unexpected results, with higher acoustic diversity at night and in less remote areas. Then, using Kaleidoscope Pro, we constructed and evaluated the performance of six Helmeted Hornbill (Rhinoplax vigil) recognisers – trainable algorithms capable of automatic detection of target calls – with each recogniser trained on different types of audio data. We found that a recogniser trained using a sample of calls of varying quality collected from within the study region performed best. Next, we applied species-specific recognisers and explored the impact of infrastructure expansion on the Helmeted Hornbill and the Great Argus (Argusianus argus), a ground-dwelling pheasant. We found that both species occurred more frequently in areas further from road and buildings, and with higher vegetation biomass. Finally, we compared the detection rates of Great Argus between ARUs and camera traps and found that, despite ARUs having a higher detection rate, using both surveying methods simultaneously provided a more holistic understanding of the species’ ecology. This project showcases the use of two remote surveying technologies, coupled with acoustic analysis tools, to infer the impact of infrastructure expansion on birds in tropical rainforest ecosystems and highlights their contribution to eco-acoustics.