Guidelines/Standards for terrestrial ecoacoustics studies

Question

Can you provide useful resources about existing guidelines/standards (or even common practices) for terrestrial ecoacoustics studies (recording entire soundscapes, not specific taxa)? More specifically, I'm thinking about:

• sensor type, height, orientation, attach system (e.g. around trees, stick in the ground, ...)
• How to deploy several sensors (minimal distance between them, grid/transect/random positioning, ...)
• Specific things to deal with depending on local conditions (habitat surrounding the sensor, wind, rain, ...)
• recording parameters: schedule, gain, sampling frequency, pre-processing...

Here are a few I already gathered:

• 2017 - WWF Guidelines on Acoustic Monitoring - https://www.wwf.org.uk/sites/default/files/2019-04/Acousticmonitoring-WWF-guidelines.pdf
• 2018 - Bird Bioacoustic Surveys – Developing a Standard Protocol – Abrahams, C. - https://www.researchgate.net/publication/329443381_Bird_Bioacoustic_Surveys_-_Developing_a_Standard_Protocol
• 2019 - Guidelines for the use of acoustic indices in environmental research – Bradfer‐Lawrence, T. – https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/2041-210X.13254
• 2021 - The potential use of acoustic indices for biodiversity monitoring at long-term ecological research (LTER) sites – Andrews, C. and Dick, J. – https://nora.nerc.ac.uk/id/eprint/531301/1/N531301CR.pdf

Answer 1

This is a very broad question, but here are a few other papers that might be of interest. As ever, the right answer will depend on the context.

If you are interested in soundscapes
If you are aiming for short deployments for rapid assessment of whole soundscapes, our guidelines in Bradfer-Lawrence et al (2019) are probably the most comprehensive in terms of the effects of length of deployment and encouraging the use of continuous recording.

If you are aiming for longer deployments for long-term monitoring, then you can record on a schedule, apparently without much loss of information. Have a look at:
Francomanco et al (2021) "Biogeographical and analytical implications of temporal variability in geographically diverse soundscapes" Ecological Indicators https://doi.org/10.1016/j.ecolind.2020.106794

If you are concerned with specific taxa
It probably makes sense to limit your focus. Work from Ollie Metcalf is relevant here:
Metcalf et al (2021) "Acoustic indices perform better when applied at ecologically meaningful time and frequency scales" Methods in Ecology & Evolution https://doi.org/10.1111/2041-210X.13521

Metcalf et al (2022) "Optimizing tropical forest bird surveys using passive acoustic monitoring and high temporal resolution sampling" Remote Sensing in Ecology & Conservation https://doi.org/10.1002/rse2.227

Spatial layout of recorders
If you are aiming to try occupancy modelling, check out the work of Connor Wood, e.g.,
Wood et al (2019) "Detecting small changes in populations at landscape scales: a bioacoustic site-occupancy framework" Ecological Indicators https://doi.org/10.1016/j.ecolind.2018.11.018

Pre-processing
Effect of compressing recordings on subsequent analysis has been looked at by:
Heath et al (2021) "How index selection, compression, and recording schedule impact the description of ecological soundscapes" Ecology & Evolution https://doi.org/10.1002/ece3.8042

There is also a little bit of analysis on the effects of including a low pass filter on acoustic indices values in the supplementary information of our paper:
Bradfer-Lawrence et al (2020) "Rapid assessment of avian species richness and abundance using acoustic indices" Ecological Indicators https://doi.org/10.1016/j.ecolind.2020.106400

Answer 2

On behalf of my co-authors, I'm pleased to announce the publication of new Good practice guidelines for long-term ecoacoustic monitoring in the UK.

The aim of the new guidelines is to advise on the use of the ecoacoustics approach for the collection and analysis of environmental data, offering potential for long-term biodiversity monitoring and ecosystem management.

The guidelines advise on hardware, software and study design choices, providing evidence-based recommendations on deployments, data analysis, and metadata requirements.

You can download the document at: https://www.researchgate.net/publication/368683386_Good_practice_guidelines_for_long-term_ecoacoustic_monitoring_in_the_UK

Answer 3

It might be useful to refer to these two other questions/answers here:

Resources specific to bioacoustics fieldwork in terrestrial settings

What protocol should I use for a general ecoacoustics study (using Acoustic Indices)?

(This second one links to the results of a guidelines questionnaire, available on my GitHub at https://github.com/carlosabrahams/Bioacoustics_Course/blob/f1b6282577a9ace7b085a22ebab4a500e950d8c8/Resources_Reading/UKAN_Questionnaire_Responses_220701.pdf)