Frequently Asked Questions
& Troubleshooting

Choosing a square FAQs

My square is taken!

Sorry about that! We want to get the whole island covered and only have enough detectors to cover the 360 squares across all the islands twice between April and October. The project runs for four years, so there will be other opportunities to select the square. Please consider selecting another square – there are a lot to do and we need all the help we can get!

Is my garden the best place for the detector?

No, not necessarily. This is a survey of how bats use the wider environment – where do they forage, what habitats do they use etc. Please choose a suitable spot as close to the centre of your square as possible, or in habitat typical of the square you have chosen.

For example if the land if predominantly agricultural, please choose an agricultural area (but please consult with the landowner!). If you are in town or in a parish center then a garden might be the most appropriate place. 

Do I need landowner’s permission if it is farmland or woodland?

If the land is States owned then you can just go ahead and put the detector up. However if the land is privately owned we would suggest contacting the owner to ask for permission; possibly a neighbour or someone in the area will most probably know who owns the fields etc.

In our experience, most owners are accommodating and are delighted to help! If you are unaware who owns the land you will need to contact the Cadastre department of the States who hold the records. They can be reached on cadastre@gov.gg.

I know I have roosts in my house. With such large squares, you will miss many roosts.

This is not meant to be a survey of roosts. This is a survey of how bats use the wider environment – where do they forage, what habitats do they use. How important are hedges and other edge habitats, woodland, freshwater etc. Gardens will of course be a major part of that. Although this project is not focused on roosts, our acoustic classification system will pick up and identify social calls as well – something other automated classifiers do not do. Social calls, especially if they are at the beginning or end of night can show that a roost is nearby and further investigations can be made.

Booking a detector FAQs

How do I book out a detector?

To book your detector, please click on this link: https://app.bto.org/batmap/batcentres/guernsey

Once you have opened the link, please double click on the location tag of your preferred Bat Centre and then click ‘Book a detector from this centre’.

This will then take you to a page where you can book our your preferred dates for your surveying slot.

You will be able to see at the top of the page below the blue instructions box that it has a drop down and you can select which detector number you would like. All detectors are the same so it doesn’t matter which you book. This is just to keep track of the bookings.

Please click on the date slot you would like to book the bat detector for and then complete the contact details form. The system will then email us with your request and we will be able to accept this for you.

If you could please book out your first surveying slot (between now and mid-July) and also your second surveying slot (from mid-July -October), we would be very grateful so we know how many more slots we may need to add. This will also allow you to book your preferred dates as slots will fill up quickly!

When booking a detector, what is the difference between the detectors listed as 1, 2 & 3 in the drop down?

They are all the same. There are 3 or 4 detectors at each centre, and you can book any one that is available. All the detectors are numbered with unique numbers so if you book detector number 3 from a bat centre and get number 8, do not worry! We will be moving detectors around bat centres as and when they need maintenance.

Can we pick more than one date to give us more then the 4 nights recording in the same place?

No. We want to cover as much of the islands as possible so are asking volunteers to survey each square they pick for 2 booking periods only – once before mid-July and once between mid-July and the end of October. The booking periods are fixed and you would need to return the detector kit on the last day of each period so the next volunteer can use it.

Choosing a spot to put the detector FAQS

Is my garden the best place for the detector?

No, not necessarily. This is a survey of how bats use the wider environment – where do they forage, what habitats do they use etc. Please choose a suitable spot as close to the centre of your square as possible, or in habitat typical of the square you have chosen.

For example if the land if predominantly agricultural, please choose an agricultural area (but please consult with the landowner!). If you are in town or in a parish center then a garden might be the most appropriate place. 

Do I need landowner’s permission if it is farmland or woodland?

If the land is States owned then you can just go ahead and put the detector up. However if the land is privately owned we would suggest contacting the owner to ask for permission; possibly a neighbour or someone in the area will most probably know who owns the fields etc.

In our experience, most owners are accommodating and are delighted to help! If you are unaware who owns the land you will need to contact the Cadastre department of the States who hold the records. They can be reached on cadastre@gov.gg.

My square is quite exposed – is there anywhere we should look to put it specifically? Does the sound of wind interfere with the recordings, in which case should we find a more sheltered spot?

Wind per se will not impact on the recordings, as the detector is triggered by ultrasonic calls. The main impact of wind is that bats will not fly when it is too windy. In exposed squares, which only have, for example, grassland and a  few trees, we would probably recommend placing the detector near the trees, probably with the trees downwind to give a bit of shelter. That way you are covering both habitats, but also giving a bit of shelter to the detector for when it is windy.

Why are you asking people to put detectors in the centre of the square, or in habitat typical of the square?

We are asking people to put detectors as close to the centre of the square as possible, or in habitat representative of the square, rather than necessarily in, for example, volunteer’s gardens as we want to get an unbiased survey of what is out there, and not a survey that is biased towards one habitat or another. The detectors label each recording with GPS locations, so are extremely accurate in terms of place. With all the habitat and other environmental datasets that are available, we can be sure of the type of exact habitat the recordings are from, and should be able to deal with any biases that will inevitably occur. We are not after what are seen (rightly or wrongly) as ‘good’ places for bats, but want an unbiased assessment of how bats use Guernsey’s environment (both good and bad!).

I have an area where I see bats. Should I place a detector there?

The Bailiwick Bat Survey is a survey of how bats use the island’s wider environment – where do they forage, what habitats do they use. How important are hedges and other edge habitats, woodland, freshwater etc. The survey is in its second year and we are asking people to select one of the 360 500x500m  squares across the Bailiwick, and place a detector in the square, either as near as possible to the centre of the square, or in habitat typical of the square. We ask them to do this twice per year – before and after mid July.

The result will be a gridded map of hotspots of species presence/activity and will, for the first time, give us a fantastic opportunity to understand how bats (and bush crickets and small mammals) are distributed across the Bailiwick. As the recordings will also have GPS coordinates embedded in the filenames, we will be able to identify the most important habitats for each species. 

We are therefore not necessarily asking people to place a detector near where they see bats, but to try and give us an unbiased a sample as possible. If everyone placed them in their gardens, we would have a fantastic sample of gardens, but that would not tell us much about other habitats.

I have a tree where I’d plan to put the detector – as long as its more than 7′ above the ground can the detector be attached to the tree or a fence?

No. The detector needs to be placed c. 2m away from vegetation so we do not recommend attaching it to a tree. If it is placed too close to vegetation, or flat surface (e.g. the side of a house or a fence) echoes occur and it is very difficult to identify the bats. There is an extendable pole and cable ties included in the kit that should be used to mount the detector on.

Which direction is best to place my detector’s microphone?

Detector and microphone placement is critical for producing high-quality recordings. Please follow the below guidance as much as is practical:

  • Detectors should be deployed on the provided pole at least 5 feet (1.5 meters) in any direction from vegetation or other obstructions.
  • Several species avoid light, so please place the detector away from lighting (e.g. a house with lights) if possible.
  • Where close to water, avoid positioning the microphone directly next to water, to avoid noise reflection from the water’s surface.

Troubleshooting when placing the detector

The ground is too hard. I can not get the pole in the ground.

Please use the supplied ground spike and attach the pole to the spike with cable ties.

My pole keeps collapsing!

This can be a problem. To solve it, please extend each section with a firm pulling and gently twisting motion to lock each section in place.

If I attach the detector to the top of the pole, it is loose.

Please attach the detector with the supplied cable ties as close to the top but ensuring it if firmly fixed and will not twist in the wind.

The memory card in the detector comes loose.

Push the card in until you hear a ‘click’. It should now be firmly in the slot. If still loose, please contact us.

Survey equipment FAQs

Can I leave the survey equipment unattended for the four nights?

Ideally, we ask you keep the detector out surveying for four nights in the same place. If it is on private land, it can be left out all of the time, if you are happy it is safe to do so. If you are not happy to leave the equipment out all night, please put it out late in the evening and pick it up early in the morning.

If you have placed the detector in a public area, there is a laminated project information label that you should attach to the pole to inform inquisitive folk! The kit is invisibly security coded but if you are concerned about leaving the detector outside, please deploy and retrieve the bat detector at dusk/early in the morning.

What is in the bat equipment kit?

The kit is contained in a small plastic box and has everything you need to undertake the survey. It contains:

  1. Full instructions (also downloadable here) and a quick start guide. 
  2. The bat detector
  3. A metal pole for mounting it on (the detector needs to be a minimum of 7 feet up in the air)
  4. A metal stake
  5. A mallet for banging the metal stake into the ground
  6. Two sets of rechargeable batteries
  7. A battery charger
  8. An SD card reader to download the recordings to your computer to upload to us and a spare
  9. A label to attach to the pole stating it is part of the Bailiwick Bat Survey
  10. Reusable cable ties to attach the bat detector to the pole and the pole to the metal stake. 

Can I use my own detector?

Only if you have a Wildlife Acoustics device – i.e. a Song Meter Mini or an SM4BAT bat detector. As this is a Bailiwick-wide survey we are using standardised settings on our full-spectrum bat detectors and so we are asking people to use our detectors so that the effort/data acquisition from each square is the same, and therefore numbers etc are directly comparable. Other bat detectors may vary in the quality of recordings or the ability to pick up species. If you do have a Wildlife Acoustics Song Meter Mini, or a SM4BAT, these can be used and we can provide a standardised settings file to ensure the data will be comparable.

Is the detector any good? One I used in the past had a knob I had to twiddle.

The detectors you mention are older heterodyne detectors. You twist a dial to a frequency range and the detector converts the bats sounds in to something you can hear. In this survey we are using full spectrum detectors which record across the whole frequency spectrum. The detectors we use come from Wildlife Acoustics and the detectors make very high quality recordings which enable us to identify the species making the sounds.

Where I would be able to purchase a basic bat detector from?

In terms of detectors there are lots of different options.

The cheapest would be a heterodyne bat detector. It translates bat noises into something humans can here. You use a dial to move up and down the ultrasonic frequencies and the device will listen and shift the frequency to something you can here. There is no identification or anything like that but  you can at least hear the bats and by tuning into certain frequencies, you will pick up individual species. Cost is less than £100. See https://www.bats.org.uk/about-bats/bat-detectors-1/heterodyne for more details.

Moving up the scale, there is the Echo Meter Touch (there are also Pro versions) for iOS or Android, which is essentially a microphone that plugs in to your tablet/phone. It works well – https://www.wildlifeacoustics.com/products/echo-meter-touch-2-ios

Then finally, there are the full-spectrum devices we are using which just record the sounds. Recordings are very high quality but there is no interactivity. You put it out, and then download the recordings to your computer and then use a classifier to identify the species. You can use ours which also includes small mammals and bush crickets but there are others available. We use the Wildlife Acoustics SM Mini BAT – https://www.nhbs.com/song-meter-mini-bat. A cheap open source option, called the AudioMoth is available – https://www.openacousticdevices.info/audiomoth. Costing c. £100 for the device and a waterproof case they are much cheaper but the sound quality is not as good as the SM family of devices from Wildlife Acoustics.

I just want to record bats in my garden for more than 2 4-night sessions.

In this survey we are aiming to cover most, if not all, of the survey squares on the islands and have to balance the number of nights recording in each square vs the cost and manpower needed to buy and operate enough detectors. Four nights of recording is a good compromise to pick up the species regularly using the survey area at that time. 

If you want to record bats in your garden more , there are some low cost detectors out there and you can use the same identification classifier that we are using. We provide free access/identification up to 100Gb of sound recordings (see https://www.bto.org/our-science/projects/bto-acoustic-pipeline). We are using the Wildlife Acoustics family of detectors which are fairly costly (the Wildlife Acoustics Mini Bat is £650) but they are high end, last for ages and provide excellent recordings. 

At the cheaper end, there is the open source Audiomoth (https://www.openacousticdevices.info/audiomoth) costing c. £100 with a waterproof case from https://www.labmaker.org/collections/earth-and-ecology/products/audiomoth-v1-2-0. The sound quality is definitely not as good as the Wildlife Acoustics detectors, but they are still a good recorder and are very good value for money.

It’s really bad weather! Should I still do the survey?

When the weather is bad, bats prefer to stay nice and cosy in their roost. The detectors are weatherproof but if the weather is truly awful (gale force winds / torrential rain), please do not survey bats.  If the weather is awful for more than 2 nights of your allotted period, please feel free to book additional survey days through the web system.

Technical FAQs

How does the bat detector work?

The Wildlife Acoustics ‘Song Meter Mini Bat’ have settings that  record an hour before dusk and turn off an hour after dawn pre-installed on the detector. When it ‘hears’ a bat, or a small mammal or bush-cricket, it starts recording and saves a sound file (.wav file) on its memory card. These recordings are what we need to analyse to identify which species are present.

Why do I need a smart phone?

We need to know the exact location of where your bat detector is recording. To assist with this we recommend you use the Song Meter Mini Configurator App [Android | Apple]. The app can use its GPS to communicate, via Bluetooth, the exact location (latitude and longitude) to the detector, so your survey recordings will have the correct location attached to them. 

If you don’t have a smart phone, no problem – you can instead assign the correct location to your recordings when you upload your data. 

The Latitude and Longitude must be correct to ensure that the correct analysis is applied to the recordings, and that identifications of species that are ‘rare or unexpected’ are flagged.

How do I upload my recordings to be analysed?

Once finished, take the SD memory card with recordings from the detector, and insert it into the supplied card reader or into an internal SD card reader, if you have one in your computer. You will need to install a small program, called the ‘Desktop Upload Client’, which manages the uploading of sound recordings (with information about the location and dates/times) for processing. It will download the sound files from the SD memory card to your computer and store them safely until your computer finishes uploading them to our servers for analysis.

  • When you reserve out a bat detector, you will be given a web link which will allow you to register/create a BTO Acoustic Pipeline account and then to add the Bailiwick Bat Survey to your account.
  • Once you have an account, log into your BTO Acoustic Pipeline account and click on the ‘Get the Desktop Upload Client’ web link.
  • Install the correct version (Windows or for Apple Mac) for your computer. Links are given for both.
  • The Desktop Upload Client will make a folder on your hard drive where recordings will be stored temporarily during uploading.

Will 4 nights of recordings in a 500m square pick up all the species that use my square during a season?

Using previous surveys in the UK, we have learnt this amount of effort will give a good idea of the species present, whilst still allowing for broad coverage.

Uploading recordings FAQs

Why do I need to register for a BTO account?

BTO is a partner in the project and provide the technical know how of the survey. To be able to process your bat recordings, we need you to register for BTO Account, so we know who has uploaded the recordings and who to return results to.

How long will it take to find out my results?

Once you upload the recordings, we hope to be able to get back to you with a summary of species recorded within a day. You will receive an email once your results have been processed and are ready to download. 

Troubleshooting when uploading recordings

When I go to upload the files I received the following error “Error refreshing upload queue, please try again. I retried several times but have received the same error.

The easiest way to clear this problem, is to open the desktop app. Cick on ‘File’ and then click on ‘View Pending Recordings Folder’. Delete any folders that are present here. This will delete any folders of recordings that are being uploaded or have become stuck during upload for some reason. Go through the process of uploading the folder of recordings again.

Questions about the science

How were the priority squares chosen?

Across the Bailiwick, there are a total of 351, 500x500m squares where the amount of terrestrial habitat in a square was more than 25%. Other significant pieces of land (Burhou, Lihou, Crevichon, and 6 forts in Alderney) where the amount of terrestrial habitat was less than 25%, added another 11 squares, bringing the total to 360 squares in total across all the islands in the Bailiwick. The grid system we use is based on the Ordinance Survey map of the CIs which, in turn, is based on the global standard UTM grid. 

Guernsey was by far the biggest land area to cover with 276 squares, followed by Alderney & Burhou with 46 squares, Sark and Brecqhou with 28 and Herm & Jethou with 10 squares. These numbers should all add up to 360 squares! 

Covering that number of squares is a big ask, and we had no idea if we would have enough volunteers to cover this number of squares, twice a year (once before mid-July and once after). That equates to 360 squares x 4 nights x twice a year = 2,880 nights of recording. 

We took the immediate decision, for the smaller islands, to go for full coverage but to look again at Guernsey to see if we could prioritise any particular squares as we thought it a bit of a tall order to expect all 276 squares to be covered. There is no way we could get this level of coverage using professional fieldworkers and this is where citizen science really comes in to its own, allowing mass participation by the public to provide an amazing dataset. 

Guernsey’s farmland and semi-natural habitats, are heavily dominated by improved grassland, i.e. pastoral farmland. Improved grassland was the most common habitat in 122 of the 276 squares (44%). Other important habitats for bats such as woodland, scrub, wet meadows, species-rich grassland, freshwater wetlands etc are rarer. None of these other habitats exceeded 40 squares and so we decided we wanted to prioritise these squares to get the best coverage of these other habitats as possible. We therefore decided that we include all the squares that were dominated by these ‘rarer’ habitats as ‘Priority Squares’ (154 squares). This would include much of the cliffs and other coasts, woodland in the south coast and Fauxquetd and Talbots valleys. We also knew the amount of land in a square that was designated as an area Special Scientific Interest (SSI), or an Area of Biodiversity Importance (ABI). Any square that had more than 10% cover of an SSI or ABI was automatically designated as ‘High Priority’. Of the squares where improved grassland was dominant, 26 had more than 10% of the land area covered by an SSI/ABI so were included in the priority sample. but subsample a maximum of 40 of the squares where ‘improved grassland/grass ley’ squares were dominant. 

That left a total of 96 squares dominated by improved grassland. Improved grassland is of course important to survey and we selected 40 squares at random to put into the ‘Priority Squares’. That left a total of 56 squares on Guernsey where the semi-natural habitats were dominated by improved grassland and short-term grass leys were designated as ‘lower priority’. These should all add up to 276 squares!

In my results, how do I interpret the probabilities against the identification for each recording?

Some species are very similar and need manual checking. If you record 500 Common Pipistrelles that is likely to be true, but one other rare bat might be an abnormal call of a common spp.

I have heard some species of bats are very difficult to identify from recordings. How well is the BTO Acoustic Pipeline able to distinguish species?

The pipeline will provide a first automated unverified analysis of recordings and return of results, but it can make mistakes. For this reason, further critical manual checking of the results will be carried out at the end of the season.