by Dan Stowell, Queen Mary University of London, UK & Jérôme Sueur, Muséum national d’Histoire naturelle, CNRS, Sorbonne Université, Paris, France

Can monitoring sounds help us to meet the world’s biodiversity targets?

Nature sound recordings have been collected for over a hundred years, with an exponential increase since the 1950s. Most such recordings were taken in order to describe and decipher animal communication. However the sounds of animals reveal more than behaviour: they also reflect the structure and functioning of the ecosystem of which the animals are a part.

The practice of deploying remote acoustic sensors in natural environments has been developing for many years, capturing sound both on land and under the water. An acoustic sensor has the advantage that it can capture a wide spatial range (often 360 degrees and about 100 m in terrestrial habitats), and is largely unaffected by occlusion. It can also record continuously or regularly over a long time period and can collect information of a full assemblage of species as it captures all the sounds in the surrounding environment. These properties ensure a high sampling effort with a rather low technical investment.

However, a major limitation in past projects is how to analyse audio systematically and at large scale. Ambient sound recordings can contain evidence for a long list of ecological information, such as: species absence/presence, population density, population structure, community structure, landscape architecture, animal phenology, reproduction period, migration period, species interactions, or ecosystem functions. But it has been labour-intensive to extract that evidence. Benefiting from growth in recent decades of the scale of data capture and processing, the focus in acoustic monitoring can shift to broader ecosystem-level questions, while using audio as a prime source of evidence. This is the main goal of ecoacoustics.

In the context of the United Nations Sustainable Development Goals (UN SDGs), ecoacoustic methods have already been demonstrated to contribute useful evidence, which can complement other evidence sources. Within SDG 14 “Life below water” and SDG 15 “Life on land” these include monitoring threatened species, invasive species, poaching, noise pollution (both on land and below water), land degradation and mountain ecosystems.

We are delighted to introduce the Remote Sensing in Ecology and Conservation special issue “Ecoacoustics and Biodiversity Monitoring“.

The issue is guest-edited by Dan Stowell and Jérôme Sueur, and features 2 reviews and 6 original research articles. The goal we refer to, of using large-scale acoustic data to address ecosystem-level questions, is reflected in many of the articles featured in the issue. The articles cover a variety of habitats from deep sea to tropical forest, and a wide variety of acoustic analysis methods.

Large-scale acoustic methods should now be transferred to application, and used more widely for conservation and management. It is now time to use ecoacoustics as a tool. Acoustic sensors should be included in large scale (i.e. national and international) monitoring programs, in complementary fashion to other standard methods and in particular to design acoustic monitoring into long term programs.