Listening to the sounds of nature: switching on OIST’s acoustic monitoring network

February 14th is Valentine’s Day, and for birds living in Okinawa it’s the perfect time to start thinking about building a nest. In warm years like this one, the Tree Sparrow (スズメ) begins its breeding season around this time, followed by the Pacific Swallow (リュウキュウツバメ), the Japanese White-eye (メジロ), and the Japanese Tit (シジュウカラ). If you look closely at the eaves of houses around the island, you may notice the swallows beginning their nesting behavior.

Japanese Tit singing near Takeyanbaru; Photo Credit: Sam Ross

Researchers from arilab are monitoring the onset of the breeding season not only for birds, but also for frogs, crickets, and other organisms that communicate with sound. This is accomplished using a new acoustic monitoring network. While testing of this network has been ongoing for the last year, its installation and activation were completed last week, just in time for Valentine’s Day.

Acoustic Recorder; Photo Credit: Nick Friedman

OIST’s acoustic monitoring network produces more audio than scientists can analyze by ear: assuming you listened to the recordings every minute of every day, you would be twenty four years older by the time you finished a single year’s data. To fix this problem, OIST scientists are training computer models to recognize patterns of activity and to detect individual species of birds, frogs, and insects.

Shinji Iriyama, Ayumi Inoguchi, Sam Ross; Photo Credit: Nick Friedman

Written by Nicholas Friedman

Happy New Year! The First Rooster Call of 2017

rooster-call

On a small farm near the botanical garden in Okinawa City, a rooster sang its first song of 2017 – the “year of the rooster”. His was the first song of the dawn chorus, a daily event that arouses every type of bird sound on the island of Okinawa – from the sweet melody of the Ryukyu Robin (Akahige) to the harsh screeching of the Brown-eared Bulbul (Hiyodori).


– The first rooster call of 2017 –

This biological symphony has the sun as its conductor, as the conditions just before dawn are especially favorable for singing: the air is cool, the wind is quiet, and the light is low enough to afford a modicum of safety. For male birds, the dawn chorus provides a time for each individual to broadcast “I am still here”, and to assess which of its neighbors can say the same. For female birds, this can be a convenient time to determine which is the superior songster, or to share in the chorus.


– The dawn chorus –

Arilab’s post-doc Nick uses the rooster and its chorus as a way to monitor Okinawa’s ecosystems. The number of different bird species that join the rooster in its song each morning is an indicator of the ecosystem’s health. A varied and noisy morning suggests a healthy environment, whereas a silent morning suggests that some species have gone missing. The rooster’s song was recorded using a network of automated recorders placed in forests and fields across Okinawa.

– Content written by the OIST media section.

Soundscape of Okinawa during Obon

On top of SLAM traps that collect arthropod samples and weather stations that record physical parameter data, acoustic traps that gather sound data are also set up at various OKEON field sites. The soundscape of the sites differ based on their habitats and their proximity to urban areas, as illustrated by the sounds collected during the period of Obon in Okinawa.

Obon is a Japanese Buddhist custom to honor the spirits of one’s ancestors. During Obon, Bon dance (bon odori) is performed to welcome the spirits of the dead. The bon dance performed in Okinawa is known as eisa. Across different OKEON sites we can hear different eisa dances with different species either in the foreground or the background. For example, in Nago the eisa dance is in the background, with sounds of many cricket species (Hexacentrus unicolor, Cardiodactylus guttulus, Ornebius kanetaki, Ornebius longipennis) in the foreground while in Nakagusuku the eisa song is in the foreground. By contrast, given its well-preserved continuous forests far from civilization, the soundscape of Yanbaru consists only of natural sounds.

Below are the soundscapes of four different OKEON sites during Obon as well as part of their spectrograms:

nago

Soundscape of Nago on the night of Obon, recorded from Nago Castle Park

Link to sound here

nakagusuku

Soundscape of Nakagusuku on the night of Obon, recorded at Nakagusuku Park

Link to sound here

sueyoshi

Soundscape of Naha on the night of Obon, recorded from Sueyoshi Park.

Link to sound here

yanbaru

Yanbaru Forest on the night of Obon, recorded at the Yanbaru Discovery Forest Park.

Link to sound here

Sound data contributed by our Post-Doctoral researcher Nicholas Friedman.