discussion / Acoustics  / 6 November 2023

Bird Acoustic Surveys: Comparison with traditional transect methods

Baker Consultants Releases Whitepaper Comparing Traditional & Ecoacoustic Bird Survey Methods

Baker Consultants is pleased to announce the release of its latest ecoacoustics white paper. The paper is the accumulation of years of commercial and academic research from sites across the UK. We hope it will increase awareness of ecoacoustic methods and advance the wider adoption across the consultancy, research and conservation sectors.

This paper discusses nine sites where we have compared the use of both traditional transect and passive acoustic bird survey methods with the aim of assessing the value and benefits of pairing these two methods together. Our research revealed that in two thirds of cases, the ecoacoustic methods recorded a higher species diversity than by using traditional walked transect surveys alone. In two of our examples from the English Midlands the ecoacoustic surveys recorded 50-59% more species overall.

It was notable that some of the species that were only detected by ecoacoustic methods, were rare species of high conservation concern. The article discusses the densities used for deploying ecoacoustic detectors. It is important to note that traditional transects always recorded at least one – and an average of 9.33 species – that were not detected at all using static recorders alone, therefore they are not considered a replacement for traditional surveys.

Our overall findings are that the traditional and ecoacoustic surveys should be used alongside each other to provide a more comprehensive and robust assessment of sites. This study has demonstrated that the use of a combined approach enables assessors and site mangers to more accurately determine the true ornithological value and importance of their site(s). The benefits can be particularly seen where crepuscular or nocturnal species are important considerations, as passive recorders are much more effective at detecting these species than human survey effort alone.

Carlos Abrahams, Director of Ecoacoustics and lead author of this white paper, commented; “We hope this research provides the foundation for wider adoption of passive ecoacoustic methods for bird surveys. We use this approach for all of our commercial work as the quality of the additional data is invaluable. It has helped our clients to assess the constraints and opportunities on their sites with a level of detail and confidence that has not be possible before from traditional bird survey methods alone.

You can download a copy of the whitepaper here and it is also available on the British Ecological Society’s Applied Ecology Resources portal here:  


Note that Baker Consultants will be attending this year’s CIEEM Autumn Conference in Liverpool (22nd & 23rd November) where we will be discussing this whitepaper, alongside our research into soil bioacoustics and the recently released Good Practice Guidelines for Long-Term Ecoacoustic Monitoring in the UK. Please come along to these sessions these if you would like to learn more about our innovative work in this emerging area. Click here to find out more.

Thank-you for sharing this study, I read it with interest! I was wondering, in doing this study did you also get a feel for how these methods compare in terms of time and costs and required skills? As a practitioner I am still a bit worried about the amount time required for set up, maintenance, data management, species identification, and analysis.