Trinity ecologists monitor biodiversity in Japan using acoustic surveys

The research was hindered by human noise pollution alongside “noisy” local cicada insects

Trinity ecologists, as part of a collaborative team, have published new research using recordings of animal noises to assess biodiversity across 23 field sites in a sub-tropical region of Japan. 

The team has assessed how effective these were for pinpointing wild fauna in Okinawa with different sonic conditions. 

The study was part of the OKEON Churamori Project (Okinawa Environmental Observation Network; OKEON 美ら森プロジェクト) in Okinawajima.

Acoustic surveys are audio recordings of animal sounds in a habitat that give an indication of the scale and diversity of wildlife present. They can be instrumented at a relatively low cost, and taking recordings of a landscape and listening back to it allows ecologists to monitor the biodiversity of an ecosystem. 

When listening back on these tapes, ecologists often listen out for the presence of specific species. Using these recordings, scientists can determine which species, and how many, are present, allowing the design of more effective conservation programmes.

Lead author of the study, Samuel Ross, a PhD Candidate in Trinity’s School of Natural Sciences, said that “in total, we used about 230 hours of sound recordings from a wide range of habitats across Okinawa to gain insights into the biodiversity of the region, to characterise how it changes near urban areas, and most importantly, to assess how effective the various audio recording and assessment techniques are in extracting reliable information”.

The ecologists found that human noise pollution and local cicadas have interfered with the ability of scientists to get beneficial information about the landscape. 

The paper, which was published in the journal Ecological Indicators, writes that human-related sounds interfere with animal communication, particularly in the lower frequency range. Additionally, the research shows that soundscapes are dominated by cicada choruses, which disguise the true diversity of the region. 

Dr Nick Friedman, a postdoctoral researcher from Okinawa Institute of Science and Technology, said that the forests in Okinawa are “really noisy when the cicadas are out”. 

“The sound they make is so loud, it’s at least annoying if not painful. It conceals a lot of different species that are in the forest because they don’t really bother calling to each other while the cicadas are going,” Friedman said. 

While the soundscapes utilised in the study are a useful tool at gauging biodiversity in a region, they also have another range of functions. They can provide an insight into the physical landscape and habitat structure of the region, the weather patterns prevalent in the area, and highlight practices like illegal logging that pose a risk to the habitat.

With a better understanding of what can disrupt the data in audio surveys, ecologists can better prepare for the future of studying biodiversity, making greater efforts to protect our environment.

Nina Chen

Nina Chen is the Deputy Sci-Tech Editor for Trinity News, and a Junior Sophister student of Chemical Sciences.