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The University of Southampton
Biological Sciences

AudioMoth: a low-cost, open-source acoustic device for environmental monitoring

Researchers at the University of Southampton’s School of Biological Sciences led the development and field-testing of an acoustic sensor, ‘AudioMoth’, for smart detection of environmental sounds. The open-source device met a need for efficiency and portability in large-scale and long-term monitoring of wilderness habitats with difficult access.

Context

Tropical forests support two-thirds of Earth’s biodiversity, despite covering less than ten per cent of land surface. Over-exploitation of natural resources, including wild meat and forest timber, is recognised as a top five contributor to global biodiversity loss, yet there are almost no data on the prevalence of these activities in forests.

This knowledge gap exists because extraction of meat and wood goes undetected by satellite imagery, and ground-based detectors typically under-report or are prohibitively expensive, and cannot store the vast quantities of data needed to detect rare events.

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Research challenge

In 2014, Professor Patrick Doncaster and Dr Jake Snaddon, both of the School of Biological Sciences, teamed up with Professor Alex Rogers of the School of Electronics and Computer Science to develop and test a low-cost acoustic detector for environmental monitoring.

In December 2017, the team launched the product, AudioMoth, a low-cost, small, power-efficient, smart acoustic detector of environmental sounds such as those from insects, amphibians, birds, bats and humans.

In terms of price and size, AudioMoth outperforms commercial devices with equivalent detection capabilities by a factor of 20.

Global public interest and recognition

AudioMoth is the first device to bring large-scale environmental acoustic detection within the means of conservation organisations and local-scale research projects, achieved with open-source hardware and software.

Its huge potential was immediately recognised on its launch, with a rapid uptake of global interest in the devices by high-profile environmental organisations and authorities.

By 2019, AudioMoths had been deployed by 687 projects across six continents. Prominent applications are detailed below.

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Detection of hunting activity in Belize

At the invitation of the Belize Forest Department (BFD) in 2018, the AudioMoth team field-tested their optimal-deployment and onboard gunshot-detection algorithms across 10 km2 of Tapir Mountain Nature Reserve. The resulting detection of 139 gunshots over the course of 12 months’ uninterrupted monitoring, with 95 per cent detection probability, persuaded the BFD that illegal hunting is an ongoing problem in the reserve. 

Recognising that they lack the workforce of forest rangers to patrol the reserve, the BFD called upon the AudioMoth team to expand the survey across all 25 km2 of the reserve.

Conservation of endangered species

Imperial College London undertook a large-scale deployment of AudioMoths across 360 tropical-forest sites to shape conservation priorities for the highly endangered spider monkey. The same team also developed an open-source acoustic bat call detection and classification tool for the Atlantic Forest of Brazil.

Fauna & Flora International (FFI) bought 20 AudioMoths for monitoring the Critically Endangered Cao Vit gibbon in Vietnam. FFI stated that “AudioMoth has the capability to revolutionise acoustic monitoring of environments, by making it affordable in principle and feasible logistically to flood large areas of inhospitable ecosystems with sensors”.

AudioMoths are also used by the Fundação Príncipe Trust for assessment of the Critically Endangered and endemic Principe thrush on the African island of Principe, and by the international Prusten Project for improving the efficiency of protection for Endangered tigers.

Discovery of new insect species in Brazil

AudioMoths were used to recognise three species of katydid insects (Orthoptera) as new to science. Researchers at the Instituto Latino-Americano de Ciências da Vida e da Natureza and the Museo de La Plata, Brazil, used AudioMoths to detect the species’ unique songs in the UNESCO World Heritage Site of Iguaçu National Park.

Monitoring and survey of the UK bat population

The British Trust for Ornithology (BTO) uses AudioMoth in the world’s first end-to-end system for monitoring bats in the UK, as part of the British Bat Survey. They post AudioMoths to citizen-science volunteers, who deploy them in their local area with an onboard bat-detection algorithm. The 2019 pilot identified over 2 million bat calls.

On a local scale, AudioMoths were used to survey bats for Blackburn with Darwen Borough Council, resulting in a recommendation for the Council to seek a European Protected Species Licence from Natural England.

Associated projects

AudioMoth

Key Publications

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