Credit: Trinity College Dublin and Okinawa University Graduate Institute of Science and Technology
A collaborative team of ecologists, led by a team from Trinity College Dublin, is using animal noise recordings to assess biodiversity in the subtropics of Japan. The team evaluated how effective these acoustic surveys were in accurately identifying the wild and wonderful Okinawan animals in different acoustic conditions – and discovered that the continuous choruses of native cicadas mask the true diversity of the area.
The work just published in the journal Environmental indicators, Confirms the great potential of sound surveys to characterize the biodiversity of habitats while also highlighting some of the major potential pitfalls.
Many scientists believe that we are now experiencing the sixth mass extinction in Earth’s history, which was largely driven by human actions and our exploitation of the environment, but there is a general consensus that it is not too late to stop the decline in biodiversity if we act now. However, we need to know what species (and how many) are present in any given habitat before designing conservation programs.
Acoustic surveys – simple sound recordings of animal sounds in a habitat – provide the ability to record large amounts of data. They can do this relatively inexpensively and easily, since recording devices can be left unattended once set up. This technique also means that researchers do not need to spend long periods in inhospitable or dangerous habitats, species are more likely to be counted because they will not be afraid of human presence, and the data can be very sensitive because each species makes unique sounds.
However, the new research shows that consideration must be given to ambient conditions, with the time of day, season, proximity to urban areas, and human activity all likely to overlap to varying degrees with the recordings, such that some species cannot be heard.
Interestingly, on the subtropical island of Okinawa off the coast of Japan, the constant noise of cicadas has the greatest effect in masking the sounds, clicks and chirps of hundreds of native animals.
Study lead author Samuel Ross is a PhD candidate at Trinity College of Natural Sciences. He said:
“ In total, we used about 230 hours of audio recordings from a wide range of habitats across Okinawa to gain insight into the area’s biodiversity, to characterize how it is changing near urban areas, and most importantly, to assess how effective the diverse sound recording and evaluation techniques are in extracting information. Trusted “.
“You also expect the weather to be important, as high winds and rain affect the information we can get from the recordings, and human noise pollution is a problem as well. However, it is the cicadas that really affect the quality of such assessments during the summer months in Okinawa.” “.
To date, most of the bioacoustic surveys have been conducted in the tropics, but this field is rapidly developing and these monitoring technologies will prove useful in Ireland, which provides homes for a number of famous endangered animals.
Many Irish creatures have cultural significance and their ability to calm and inspire, while other research opens our eyes to the power of the acoustic environment to influence mental health.
Samuel Ross added:
“These methods are still relatively new and the possibility that we can monitor biodiversity using only sound recording equipment is really exciting. I see this as the next frontier in assessing the state of the world’s ecosystems.”
The study was led by Samuel Ross and Ian Donohue, associate professor of zoology, at Trinity, who work closely with colleagues at the Okinawa Institute of Science and Technology (OIST), including Professor Evan Economo and Dr. Nick Friedman, who run an island-wide systems monitoring project. Okinawa using environmental sound.
Dr. Friedman added:
“The forests in Okinawa are really noisy when the cicadas go out. The sound they make is very loud, it is at least annoying if not painful. It hides a lot of different species in the forest because they don’t really care about contacting each other while the cicadas go. Knowing that helps us Develop a strategy for how to use sound recordings to measure biodiversity or track ecosystem health.