Collection of bat reference calls

Recording kits available for loan!

Help us to build our open-source bat call library and improve our call identification algorithms

The Bat Conservation Trust use an automated classification algorithm developed in collaboration with UCL and University of Edinburgh to classify the large volume of acoustic recordings gathered through some of our passive acoustic monitoring projects.

These algorithms will benefit from being trained on more bat reference calls (i.e. sound recordings of bats definitely identified to species) to improve its classification performance, particularly for woodland bat species. If you know of a roost of a woodland bat species and can get permission to survey it, you can help us collect reference recordings for these species.

Target species

Our target species are listed below; however, we welcome reference calls for all UK bat species.

  • All Myotis species
  • Leisler’s bat
  • Noctule
  • Nathusius’ pipistrelle
  • All UK Plecotus species
  • Barbastelle
  • Serotine

How to take part

You will need to already know the location of a bat roost and be able to get permission to make recordings in the area surrounding the roost as the bats emerge. You will need to know what bat species is using the roost and be confident that there aren’t cryptic species roosting together (e.g. long-eared bat species). You won’t need a Natural England licence and you won’t need to trap bats or enter the roost.

You will also need some experience of recording bats and using time expansion or full spectrum detectors. However, you won’t need to own a detector to take part, you can borrow a recording kit from us.

We will upload a sample of the sound files you share with us to ‘EchoHub: The Bat Sound Library’ website under a CC BY licence, so they can be accessed and used by others in the bat community. EchoHub is an online, community-built, opensource bat sound library that BCT will launch later this year. The library will be free to use, and anyone will be able to upload and download bat recordings.

Survey instructions

1. Select the roost to survey
You will need to already know the location of the bat roost and be able to get access to the survey area easily and safely. Select a roost where bats are definitely identified to species and where there aren’t cryptic species living together.

2. Identify flyways
Carry out an emergence survey before booking the equipment with us in order to identify flyways and to assess if there are suitable locations to position the detectors.

3. Book the equipment kit
Fill in the equipment loan request form to book the equipment.

4. Read the safety guidance
Read the Safety Guidance and complete the Risk Assessment Template ahead of the survey.

5. Carry out the survey
Position the two sets of detectors along flyways in different habitats to maximize your chance of capturing call variability.

6. Return your records
Fill in the metadata spreadsheet and return your records.

If you have questions or need help with any aspect of taking part in this survey, contact Giada Giacomini at ggiacomini@bats.org.u

Resources

Equipment loan request

We have two equipment kits that volunteers can book. Each equipment kit includes two sets of one AudioMoth, one Peersonic and one tripod. We will also provide batteries and SD cards. If you have other detector brands available to you and are happy to use them alongside our equipment kit, you are welcome to do so. We are looking for sounds recorded in full spectrum or time expansion.

You should record reference calls of bats leaving the roost using the two sets of detectors simultaneously. Each set of detectors should be positioned at least 10 meters away from the roost and in a different habitat (e.g. one in a flyway in open space and the other in a flyway surrounded by vegetation) to maximize your chance of capturing call variability.

Equipment loan request form

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