Bailiwick Bat Survey

A citizen science project to map bats across the Bailiwick of Guernsey

Are you batty about bats?

The Bailiwick Bat Survey is a citizen science project which aims to improve understanding of local bat distribution and activity. 

We are looking for volunteers to help us map the distribution and activity of the different bat species across all islands of the Bailiwick. The survey season runs from early April until the end of October, so there is plenty of time to take part. 

Anyone can get involved - you don't need to be a bat expert!

Survey Steps



Reserve your 500x500m square to survey using the online survey map.


Book your detector slot here – ideally book for all of your surveys. 


Pick up your detector on your designated day and Get Surveying! 


Upload the data from the detector’s memory card to the BTO app


Return detector and all other equipment to us


Once your data is uploaded and processed you will be emailed the results within 24 hours! 

Step One

Book your square

Click the map to book your square(s)

We ask volunteers to select one (or more) 500x500m survey squares from an online survey map (there are 360 squares available) and to survey it twice this year – once before the 15 July and once after 15 July.

Step two

Book your detector

Bat Centres

Once you have booked a square to survey, you can book a detector from Bat Centres on Guernsey, Alderney or Sark. Click the map to book. 

The Guille Allès Library, the Priaulx Library, La Société  Guernesiaise, Sir Charles Frossard House, Alderney Wildlife Trust and La Société Sercquaise are the 2022 Bat Centres. 

The success of this project is dependent on volunteers picking up, using, and returning the detector to the bat monitoring centre as arranged. Please let us know if you are unable to carry out a survey, so there are not periods when the detector is not being used. Please also report any problems with the equipment as soon as possible.

You can borrow a bat detector kit with all the instructions and equipment you will need from one of our Bat Centres in Guernsey, Alderney or Sark. Twice per year, you place it in the area you choose from our online survey map and it will automatically record the ultrasonic calls the bats make. After 4 nights recording, you then upload the recordings to our website, return the detector kit, and our automated sound analysis will identify each call and send you the results within hours! As a bonus, the analysis will also identify sounds made by bush crickets and small mammals!

What do you need?

  1. A smartphone (iPhone or Android) 
  2. A computer with internet 
  3. An account with the BTO to upload the recorded sound files and receive your results! 
If you do not have a smartphone or computer, please email us & we can help – you can still take part! 

When to survey?

  • You will need to carry out two surveys – once between April and mid-July and once after mid-July and October.
  • Each survey consists of 4 consecutive nights of recordings in your square



How to prepare for the survey, how to set up the detector and how to upload the sound recordings for analysis

Quick Start Guide

For volunteers who have previously taken part in the survey - how to set up the detector and how to upload your data

2021 Report

Find out about the results of the first year of the survey


Frequently Asked Questions & Troubleshooting

If you have any queries about the project or equipment, please check out our FAQs & Troubleshooting page

Email Us

If you can't find what you are looking for, or have any further questions, please email the Project Co-ordinator


"The Survey is an excellent example of what can be achieved - I'd like to see similar done for other species groups - we thought we had a reasonable idea of what was here, but this is eye-opening."
2021 Volunteer
"Engaging in citizen science projects such as the Bat Survey is an excellent opportunity for everyone, young and old, to make a difference to their local environment."
2021 Volunteer
"This has been very interesting. I’ve appreciated the communications from the Bailiwick bat team and I’ve enjoyed learning about the different bats and wildlife across the islands."
2021 Volunteer