To find out how wildlife is doing, scientists try listening

ECUADOR

A reedy pipe and a high-pitched trill duet against the backdrop of a low-pitched insect drone. Their symphony is the sound of a forest and is monitored by scientists to gauge biodiversity.

The recording from the forest in Ecuador is part of new research looking at how artificial intelligence could track animal life in recovering habitats.

When scientists want to measure reforestation, they can survey large tracts of land with tools like satellite and lidar. But determining how fast and abundantly wildlife is returning to an area presents a more difficult challenge, sometimes requiring an expert to sift through sound recordings and pick out animal calls.

Jorg Muller, a professor and field ornithologist at University of Wurzburg Biocenter, wondered if there was a different way.

"I saw the gap that we need, particularly in the tropics, better methods to quantify the huge diversity... to improve conservation actions," he told AFP. He turned to bioacoustics, which uses sound to learn more about animal life and habitats.

It is a long-standing research tool, but more recently is being paired with computer learning to process large amounts of data more quickly.

Muller and his team recorded audio at sites in Ecuador's Choco region ranging from recently abandoned cacao plantations and pastures, to agricultural land recovering from use, to old-growth forests.

They first had experts listen to the recordings and pick out birds, mammals and amphibians.

Then, they carried out an acoustic index analysis, which gives a measure of biodiversity based on broad metrics from a soundscape, like volume and frequency of noises.

Finally, they ran two weeks of recordings through an AI-assisted computer program trained to distinguish 75 bird calls.

"Our results show that soundscape analysis is a powerful tool to monitor the recovery of faunal communities in hyperdiverse tropical forest," said the research published on Oct. 17 in the journal Nature Communications.

"Soundscape diversity can be quantified in a cost-effective and robust way across the full gradient from active agriculture, to recovering and old-growth forests," it added.

Muller believes the tool could become increasingly useful given the current push for "biodiversity credits" - a way of monetizing the protection of animals in their natural habitat.

"Being able to directly quantify biodiversity, rather than relying on proxies such as growing trees, encourages and allows external assessment of conservation actions, and promotes transparency," the study said.