How bioacoustics helps explore the animal kingdom

An acoustic observatory was opened in Australia last year. She collects the sound landscapes of the wildlife of the Green Continent. Such audio recordings can give no less information about the animal world than video materials. We’ll tell you how bioacoustics helps scientists search for rare species of fauna, and for simple nature lovers to understand what they hear on forest walks.

A photo Free to use sounds / Unsplash

Bioacoustics – a section in zoology, is studying the mechanisms and methods of sound communication in the animal world. Bioacoustic specialists study how animals, insects and birds make sounds and transmit information to each other. These studies help to observe the animals in their natural habitat, track the development and extinction of species, solve applied problems – for example, to drive away birds on the runways.

Why listening is easier

Australian Acoustic Observatory (Australian Acoustic Observatory, A2O) – a project at the intersection of ecology, biology and computer science. Its specialists record sounds in 90 locations across the Green Continent using several hundred highly sensitive sensors. This network encompassed seven of Australia’s widespread environmental regions with a unique combination of landscape and climate conditions, a specific mix of animals and plants. On the A2O map, there are deserts and forests, plains and foothills, arid territories and areas of high humidity.

In such a project can not do with ordinary microphones. A2O uses 400 professional bio-acoustic recorders with the ability to record sound panoramas in FLAC format. In clear weather, they are powered by the sun, at night and with heavy cloud cover – they switch to autonomous power supply (the battery lasts for 1000 hours of recording). Data is written to high-capacity SD cards – they need to be changed at least once a year. how it is seen On the manufacturer’s website, devices are in demand by nature reserves, parks and scientific institutions.

At first glance, such recorders should functionally lose to camera traps and video cameras. But in fact, for research purposes, sound can be much more useful than the clearest picture. Firstly, the lens “looks” only in one direction, and the microphone records a wider sound panorama. Secondly, small animals can hide from the camera in the grass, but a highly sensitive recorder will keep their squeak for researchers. Scientists are able to restore large-scale canvases from audio recordings, look for rare representatives of the fauna on them, note the rise and fall of the population of biological species.

Thus, they will be able to explore remote regions where earlier expeditions appeared several days a year. A2O sensors provide an opportunity to study how animals migrate, respond to natural disasters and less dramatic events (story about the work of the observatory on Australian television)

“We can hear how [в какую-то область] birds come because water appeared there and flowers bloomed on the trees, – tells one of the leaders of A2O, professor at the University of Technology of Queensland Paul Roe. “Or, the call of the frogs that appear in the desert after rain.” Usually we cannot find out what happens to these animals, we cannot predict when they will vote or where they will be. ”

The professor emphasizes that the amount of data collected is not comparable with that that can be obtained in the framework of traditional expeditions: “These will be recordings of entire days, and we will be able to hear how sounds change during the day – from birds singing at dawn to the sound of crickets at night.” The results can be compared year to year to track events in different environmental conditions.

A photo Jaron nix / Unsplash

Five years later, when the project comes to an end, scientists will have at their disposal audio materials with a total duration of 2000 years – this is an audio archive of “continental scale.” To recognize the different participants in the sound panorama and create “acoustic DNA” from Australian wildlife from all this diversity, scientists will use analytical software of their own design. Then the data will fall into the public cloud – as in the panoramas of maps, users will be able to select and listen to any segments on the timeline (part of the audio recordings already available)

Especially under water

Although A2O is one of the most ambitious initiatives in terms of territory coverage, there are already other large projects in the history of bioacoustics. Many works have been devoted to studies of underwater depths, where, as you know, sound travels much faster than through air. For this reason, for many marine inhabitants, acoustics plays an even greater role than for terrestrial animals.

Back in 2000, New Zealand scientists discoveredthat sound waves help orient in the ocean to larvae of pelagic fish that have only recently hatched from eggs. As it turned out, these tiny creatures know how the “coral reef” (the habitat of adults of their species) “sounds”, can cover tens of kilometers on the way to the goal and withstand the ocean currents.

Bioacoustic technologies also help scientists to study the ordered chaos of underwater massifs – to estimate the size of populations, identify different species of fish, and monitor how they fight for survival. Nowadays passive listening considered one of the most environmentally responsible ways of such monitoring. Moreover, this technique provides high accuracy of observations – unlike deep-sea dives, which break down the barrier between scientists and the object of study and do not always give a correct idea of ​​the behavior of animals.

Marina of the original minds

It would be a mistake to think that all these technologies are used only in scientific research. There are also private projects for ordinary smartphones in the spirit of “Shazam for birds“.

A photo Suzan Kiršić / Unsplash

But organizations don’t have to spend hundreds of dollars on equipment like A2O recorders. Researchers on a budget can afford devices like AudioMoth $ 70-75 without an SD card and batteries – for comparison, for the Solar BAR recorder from the A2O project have to pay $ 1300. Audio data can be processed, in particular, using the system ARBIMON (Automated Remote Biodiversity Monitoring Network) – it has tools for analyzing and identifying wildlife sounds. The main thing is to use the devices for their intended purpose and preliminarily (even before deciding to order something like that) think about the potential difficulties associated with their delivery (or even better, consult with mail specialists and your colleagues who could use analogues).

The same AudioMoth helped track moving birds in Mount Kenya National Park, find rare species of bats on Cuba and Madeira: the funnel ears of the species Natalus primus were considered extinct until scientists came across the areas of their current stay.

Ecologists themselves say that the threshold for entering the world of bioacoustics is now lower than ever. And there is a place for any projects. For example, you can study the “conversations” of plants! That’s right – plants too emit sound waves, both low-frequency and high-frequency. Tracking and analysis of these signals is the basis of an independent discipline – “Plant” bioacoustics.

The audio data that scientists are collecting around the world now represents a huge field for subsequent experiments. And How notes one of the leaders of the Australian Acoustic Observatory, David Watson: “The beauty [этого проекта] in that we will not only analyze the historical data that we are collecting now, but also future generations of scientists – people who may not even have been born. ”

Additional reading from our “Hi-Fi World”:

“Colleagues, breathe more quietly”: why office noise drives us crazy – we discuss research
Concert for a city with an orchestra: who and why records the sounds of everyday life
Like the crack of a fire, the creaking of doors and noise become music
Sound cards as a way to plunge into the atmosphere of an unfamiliar city
“Listen to find a breakdown”: audio recordings of failed industrial machines

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