REPORTING. Noise pollution, biodiversity… Microphones installed in the countryside, to take stock of French forests

Around a hundred French forests were equipped this year with small boxes to capture all the sounds of the natural environment. Report in the French Gâtinais regional park, near Paris.

You may have seen them by chance during a walk. Around a hundred French forests have been equipped with tape recorders in recent months. It is a scientific project called “Sonosylva” led by the Paris Natural History Museum and the French Biodiversity Office. For three years, researchers will be able to listen to the noises that can be heard in the undergrowth. They are triggered for one minute every quarter of an hour, every other day, from spring to fall. A way to assess the state of biodiversity, but also the impact of noise pollution.

To retrieve the memory card from the tape recorder, you have to go deep into the forest, accompanied by Audrey Bulté, project manager at the Gâtinais natural park. She was the one who installed the microphone “March 1, and the idea is to remove it on September 30. We will have enough data for the whole year.”

It is a small, discreet, foliage-colored box, placed on a tree at eye level, “the auspicious tree, since it is in the middle of the forest, we hear the birds singing”. Birds, but also wild boars, are what have been recorded in this Gâtinais forest. “If we listen to these soundscapes, we have another appreciation than through vision”, explains Jérôme Sueur, teacher-researcher at the Natural History Museum, at the origin of the Sonosylva project.

“It’s a bit like having antennas all over France that allow us to listen to the protected forests of France.” At that moment we hear a plane, “it will be recordedspecifies Jérôme. We can, with artificial intelligence systems, quantify the level of noise pollution, and have unpleasant surprises.”

“We can have a forest which seems to be very protected, but which will be polluted by the passage of a plane or a road not very far away, which other living beings will hear, and they can suffer from it.”

Jérôme Sueur, teacher-researcher

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From the forest of Massanne, in the Pyrénées-Orientales, to that of the Reine, in Lorraine, in one season scientists will have amassed a million files, more than 18 000 hours of recording. So much essential data for the French Biodiversity Office.

And these boxes have advantages, unlike the Office observers, assures Nicolas Tronquart, the research project manager. “The interest is that, already, there are no observers, who can disturb living beings, and to be able to be there continuously, whereas an observer does not stay 24 hours a day on his place of listening.”

These eco-acoustic recorders will be removed for the winter and then reinstalled in the spring. Experts hope to be able to carry out this project over the long term to assess the evolution of soundscapes.