Monitoring Ecosystems through Sound: The Present and Future of Passive Acoustics

Post provided by Ella Browning and Rory Gibb

AudioMoth low-cost, open-source acoustic sensor ©openacousticdevices.info

AudioMoth low-cost, open-source acoustic sensor ©openacousticdevices.info

As human impacts on the world accelerate, so does the need for tools to monitor the effects we have on species and ecosystems. Alongside technologies like camera traps and satellite remote sensing, passive acoustic monitoring (PAM) has emerged as an increasingly valuable and flexible tool in ecology. The idea behind PAM is straightforward: autonomous acoustic sensors are placed in the field to collect audio recordings. The wildlife sounds within those recordings are then used to calculate important ecological metrics – such as species occupancy and relative abundance, behaviour and phenology, or community richness and diversity.

The Pros and Cons of Passive Acoustic Monitoring

Using sound to monitor ecosystems, rather than traditional survey methods or visual media, has many advantages. For example, it’s much easier to survey vocalising animals that are nocturnal, underwater or otherwise difficult to see. Also, because acoustic sensors capture the entire soundscape, it’s possible to calculate acoustic biodiversity metrics that aim to describe the entire vocalising animal community, as well as abiotic elements in the environment.

The use of PAM in ecology has been steadily growing for a couple of decades, mainly in bat and cetacean studies. But with sensor costs dropping and audio processing tools improving, there’s currently a massive growth in interest in applying acoustic methods to large-scale or long-term monitoring projects. As very low-cost sensors such as AudioMoth start to emerge, it’s becoming easier to deploy large numbers of sensors in the field and start collecting data. Continue reading

Bats, Acoustic Methods and Conservation 4.0: An Interview with Kate Jones

At this year’s International Statistical Ecology Conference (ISEC 2018) David Warton interviewed Kate Jones, Chair in Ecology and Biodiversity at University College, London. Their conversation mainly focused on how to classify bats from acoustic data, with particular reference to ‘Acoustic identification of Mexican bats based on taxonomic and ecological constraints on call design‘ by Veronica Zamora‐Gutierrez et al. They also discuss Conservation 4.0!

We’ll have more of David’s interviews from the ISEC coming out over the next few weeks. Keep an eye out for them here and on the Methods in Ecology and Evolution YouTube channel.

Sounding Them Out: A Unique Conservation Tool for Monitoring Bush-Crickets

Below is a press release about the Methods paper ‘Potential for coupling the monitoring of bush-crickets with established large-scale acoustic monitoring of bats‘ taken from the British Trust for Ornithology.

Speckled Bush-cricket © Tom Housley

Speckled bush-cricket © Tom Housley

New research led by British Trust for Ornithology (BTO) and published today in the international journal Methods in Ecology and Evolution, shows how existing bat monitoring could improve our understanding of bush-crickets.

Bush-crickets are a little-known group of insects that inhabit our marshes, grasslands, woods, parks and gardens. Some may be seen in the summer when they are attracted to artificial lights, but as most produce noises that are on the edge of human hearing, we know little about their status. There are suggestions that some bush-crickets may be benefiting from climate change, while others may be affected by habitat changes. But how to survey something that is difficult to see and almost impossible to hear? Continue reading

Issue 7.9

Issue 7.9 is now online!

The September issue of Methods is now online!

This month’s issue contains two Applications articles and three Open Access articles, all of which are freely available.

– Arborist Throw-Line Launcher: A cost-effective and simple alternative for collecting leaves and seeds from tall trees. The authors have also provided some tutorial videos on YouTube.

– ctmm: An R package which implements all of the continuous-time stochastic processes currently in use in the ecological literature and couples them with powerful statistical methods for autocorrelated data adapted from geostatistics and signal processing.

Continue reading

Biggest Library of Bat Sounds Compiled

Below is a press release about the Methods paper ‘Acoustic identification of Mexican bats based on taxonomic and ecological constraints on call design‘ taken from the University College London.

The Funnel-eared bat (Natalus stramineus)

The Funnel-eared bat (Natalus stramineus)

The biggest library of bat sounds has been compiled to detect bats in Mexico – a country which harbours many of the Earth’s species and has one of the highest rates of species extinction and habitat loss.

An international team led by scientists from UCL, University of Cambridge and the Zoological Society of London, developed the reference call library and a new way of classifying calls to accurately and quickly identify and differentiate between bat species.

It is the first time automatic classification for bat calls has been attempted for a large variety of species, most of them previously noted as hard to identify acoustically. Continue reading