How to take part in a Group Big Bat Count

Signing up

You can take part with your community group, or book onto a public Big Bat Count.

You will need to be in a team of between 2 and 6 adults with people you know, three adults per team is ideal. Children over 5 are welcome if each is accompanied by an adult.

On this page are sections for:

  1. Before the Big Bat Count – The things you need to do before the night.
  2. On the night preparation – What will happen on arrival at the Big Bat Count?
  3. Taking part in the Big Bat Count – This will all be covered on the night in the briefing, but it helps if you can read this before the night to familiarise yourself and your team with the process.
  4. The Close of the Count night.
  5. After the Count.

1/ Before the Big bat count night

To prepare for your Big Bat Count we ask that you do the following before the count night: (download printable version)

  1. At least one adult (hopefully more) from each team should install the iNaturalist app from the Google or Apple App store on their mobile internet-enabled phone.
  2. Open the iNaturalist app and create an iNaturalist account.
  3. Join the “Somerset Big Bat Count” project in the iNaturalist App. Click below for instructions for your device:
  4. Your local Count organiser may also ask you to join a local iNaturalist project as well.
  5. Please let your count leader know your iNaturalist ID, ideally before the night, but at the latest on the count night before going on the survey. This enables the echolocation recordings made, to be linked up to the iNaturalist records after the night.
  6. It helps with both pre-event communications, and on the night, if the count leader signs everyone up to a WhatsApp, Facebook or email group for the night’s count.

2/ On the night preparation

On the night of the count, the teams of people meet at a central location to collect two bat detectors per team:

  1. The first detector is an ultrasonic microphone (Echo Meter Touch2 – EMT) attached to a tablet that can record and most importantly automatically identify the bat echolocation calls it hears.
  2. The second detector (Magenta) is non-essential and a “nice to have”, and given out to teams of 3 or more. It can be set to the frequency shown on the tablet and allows participants or more to listen to the echolocation calls the bat is making in real-time

Each team is then given instructions and a map showing an area that they can cover. This can be arranged in advance and could be on the team’s local streets, or open space.

During the preparation, the bat group leader will make sure that all teams:

  • Are aware of their area and the survey process to follow.
  • Have the required kit and know how to use it.
  • Have a copy of the “species lookup for the 15 species of Somerset Bats” laminate.
  • Have received the safety briefing, and have at least one hi-vis “BAT survey” vest per team.
  • Are aware all sounds will be recorded, and avoid creating sounds themselves as much as possible. Keys rattling, small change, rustling cagoules, zips .. etc are all common ultrasound sources.

3/ taking part in the Big Bat Count

All the information below will be covered by the Bat Group leader, in the briefing before the event. However, you may want to familiarise yourself with the process in advance by reading below.

The aim is for each team to start the Big Bat Count of their area at Sunset, and then survey for the next hour.

The process each team should follow is: (download printable version)

At the start of the Count

1/ Switch on the tablet by holding the top power “on” button at the top for 5 secs. Swipe up to dismiss the opening Amazon sales screen:

  1. Start the Echo Meter app on the tablet.
  2. Dismiss the location warning.
  3. Plug in the EMT microphone, this is directional so ensure it is always pointing upwards, or towards any bats.
  4. Press the big green round Start button.
  5. At the bottom of the screen are 5 buttons, these need to be configured as follows:
    • Start recording using the round button with a red square 2nd from left. (bat autoID only works when recording).
    • Check the round button with two rainbows in the middle is set to “HET”, rather than “RTE” or “OFF” (peak frequency display only works in HET mode).
    • The grey button 2nd right, with three vertical lines should be dark grey, not light grey (expanded display, always scrolling, impossible to use)
  6. If at any time the Echo Meter app freezes during the night, the quickest way to reset is to restart the tablet. Hold down the top power “on” button and select “restart” onscreen. Then follow steps 1-5 above again.

2/ Switch on the Magenta bat detector, and set it initially to 45kHz

3/ Log into iNaturalist on the internet-enabled phone.

How to carry out the Big Bat Count

  • Aim to cover as much of your area as you can in the next 90minutes.
  • Always stay in public places, footpaths, parks etc. Never enter private land, even to follow a bat.
  • Ultrasound (sounds beyond our hearing) is very common. From cars, to birds and crickets, ultrasound is everywhere. Hence the EMT device will be recording most of the time, and will often come up with no bat detected, or “No ID”
  • Keep moving around your area until a bat is seen or heard, in real life, or via the detectors. These will usually be rhythmic patterns of sound.
  • Once a bat is seen or heard, stop for a minute to:
    1. Watch and enjoy it!
    2. Watch for AutoID species suggestions from the Echo Meter app. Try to always tap the top suggested species (in yellow) when they appear.
    3. Tune the Magenta detector to the peak frequency shown by the line on the EMT (or use the frequency on the lookup card) so you can also listen to the bats echolocation calls.
    4. Record the top bat species (only) in the iNaturalist app using the instructions for your device below:
  • After the minute is up move on again.
  • When a different species bat is next heard, or another minute has passed and the same species bat is heard again, stop again for a minute and record the bat species in iNaturalist as above. It may be a new bat, or you may suspect it is a bat you have seen before doing big circles. Either way, it doesn’t matter, just add a new record, then move on again once the minute is up.
  • Within your area, feel free to follow the direction a bat went in, but try not to go over the same ground too much.

At the end of your count

  • After the 60 minutes are up, stop recording on the tablet using the red “Stop” button at the bottom right of the screen
  • Switch off the Magenta detector and Amazon tablet (press and hold the power “on” button, then select “Power off” onscreen).
  • Return to the central base.
  • Return all the kit to the bat group count leader, and report if any problems occurred.

4/ The close of the count night

All the team’s results are available instantly on the iNaturalist app and website.

Hence the count leader will be able to review and give a debrief talk to include the initial results.

5/ After the count

All the results on the night will be unverified “casual” flight recordings. Some of the species regarded as threatened in iNaturalist may have their locations and time of observation obscured, by moving them to a random point within 10km.

In the days after the count experts from the bat group will be able to review the recordings made on the devices, and for the key bat sightings, upload screenshots and sound files, to allow verification of the species from the recordings obtained by the teams.

These verified records will then be uploaded into iRecord, the dataset used by the Environmental Records Centres.

Big Bat Count


The Somerset Bat Group is grateful to: