Biodiversity | Hold the mic to nature

They are avid grunts, squeals, and buzzes. They leave in nature, capture the melodies of ecosystems. In their ears: the soundtrack of declining biodiversity.

“When I was studying, a friend lent me a dictaphone for work,” says Noémie Delaloye. And instead of doing my job, I went to record bird sounds. I liked it so much. This is where it all began. »

For 20 years, the Genevan has been recording symphonies of the living wherever she goes. Choir of kittiwakes in northern Norway. Concerto of laughing frogs in the heart of a Spanish marsh. Nocturne of dragonflies in the Portneuf park in Quebec.

Noémie Delaloye is part of the community of audio-naturalists. These nature lovers explore ecosystems, microphone in hand, headphones in their ears.

Their work led to the creation of a sound library at the National Museum of Natural History (MNHN) in Paris. Available to researchers and the general public, this sound library brings together 24,000 recordings of animal species captured around the world. Unique traces of present and past biodiversity.

Hear climate change

Jérôme Sueur is one of the pioneers of eco-acoustics, the study of the evolution of biodiversity from the sounds of nature. “At a symposium, I met a colleague who was working on estimating biodiversity using mathematical tools,” he says. We pooled our skills and created acoustic indices to estimate the level of biodiversity. »

These indices make it possible to assess the effects of climate change on wildlife. With the disappearance of species, several ecosystems lose acoustic diversity. And in some environments, nature is silent little by little.

To follow the transformations of soundscapes, the eco-acoustician and his team have placed automatic recorders in certain French forests. The machines have been capturing a minute of sound every quarter of an hour for four years.

The researchers are working on a major challenge: to identify, for each recording, all the species present. “It’s complicated because we have a sound mass where everyone speaks at the same time: birds, amphibians, insects…”, explains Jérôme Sueur.

This is where artificial intelligence comes in. Using files from the sound library, the team trains algorithms to recognize different animal sounds.

polluted sounds

Soundscapes play a key role in ecosystems. Evidenced by the variety of attributes that allow animals to hear.

But these landscapes are today invaded by the human imprint. Noémie Delaloye is worried about the increasingly flagrant noise pollution in her recordings. “We feel that there is increasing human pressure,” she laments. There are more and more planes, vehicles, companies that emit noise. And many more recreation areas with speakers that [diffusent] music in the mountains. »

Raphaël Proulx works to better understand the still poorly documented effects of this acoustic pollution in animals. In particular, he studies how fish flee certain environments due to the noise of boat engines. Other research shows that these noises interfere with the echolocation of whales and dolphins, essential to their survival.

“As humans are not under water on a daily basis to testify to this, it is one of the last places where we did not realize the amount of noise pollution that we were doing, estimates the professor at UQTR. And this pollution is very little regulated. We hope that our work will lead to more appropriate guidelines. »

Sensitive by nature

In addition to their usefulness in the world of research, nature sounds have many benefits for humans, according to a study published in 2021 in the journal PNAS: reduced stress, reduced pain, improved cognitive performance, etc.

“People are sensitive to these soundscapes, says Jérôme Sueur. And only with sounds, we can communicate a lot about the quality and beauty of natural environments. »

One of the objectives of audio-naturalism is to use the general public’s sensitivity to wildlife symphonies to raise awareness of the issues surrounding biodiversity. “When a forest is badly managed, or when it is cut down and replaced by plantations, we also lose a lot from an acoustic point of view”, emphasizes the MNHN researcher.

In the case of Noémie Delaloye, this awareness of the public goes through training offered, camps for young people and CDs of her recordings to learn to recognize different species.

The struggle of the audio-naturalist against the decline of biodiversity can take on the appearance of David against Goliath. “But I tell myself that at least, if everyone was made aware, maybe there would be less stupid decisions that would be made,” she concludes.