Research update: road-testing our bat call detection software

Last week we published our latest Bat Detective research update, explaining how we’ve used the data you’ve labelled to improve our algorithms for detecting bat calls in audio data. The next step is to assess how well they perform in real-world bat survey situations – and the best way to do this is to put them into practice on new data. So following last week’s update, this post will focus on examples of where we’ve road-tested our new tools this year.

The first was a two-week garden bat survey we carried out over two weeks in July, in a row of suburban gardens in southeast England. We were testing our algorithms on data collected by two different bat detector types, both of which were deployed outside to collect data autonomously over multiple nights. Alongside some specialised full-spectrum ultrasonic detectors, which are commonly used in acoustic wildlife monitoring research and citizen science projects including the Norfolk Bat Survey, we were also also using some brand new, low-cost acoustic sensors developed by our collaborators in Oxford for a variety of biodiversity monitoring applications (including citizen science). This offered a great chance to test our call detection tools on data from two different types of acoustic sensor.

The videos below show examples of how the algorithms are used on the UK garden survey data. The first shows the distinctive calls of a common pipistrelle passing by the detector, and the second are calls from a noctule, the UK’s biggest bat. Each red line on the spectrogram shows where the algorithms predict a bat call – so you can see in these cases they’re performing well, successfully detecting every echolocation call in these recordings. For each predicted call, the algorithms also calculate a probability of detection – a measure of how likely the sound is to be a bat call, with reference to our training data from Bat Detective. This enables us to set a threshold for call detection – by setting a high probability threshold, this then makes it possible to only detect sounds that are very likely to be a bat call. As we discussed in the last post, this can help to reduce the risk of false positive detections (i.e. falsely thinking there’s a bat call, when actually there isn’t one).

Once the calls have been detected, the next step in the analysis is to classify those calls to species – what bat is that? Doing this requires a second set of algorithms, trained to distinguish between the calls of different species. Our group are currently working on developing these, and incorporating them into our tools, in order to more fully automate the analysis process (and therefore make it faster and more reliable for researchers monitoring bats).

As well as the UK data we collected in July, we’re also now using our call detection tools to analyse recordings collected during a huge bat survey on the Atlantic island of Madeira. There are thought to be three bat species on Madeira, including the endemic Madeira pipistrelle (Pipistrellus maderensis), which is listed as vulnerable on the IUCN Red List. However, little is known about the distribution and abundance of bats on the island, and its relatively small size makes it an ideal study system for an island-wide bat survey.

So a member of our research group (in collaboration with M-ITI in Madeira), has been busy out in the field throughout August and September, deploying full-spectrum bat detectors in locations across the island, which were selected to provide a randomised sample of its full range of habitats and altitudes. A map of the sample sites is shown below, with each blue marker showing where bat detectors have been placed. Now the data have all been collected, we’re starting to use our automated tools to detect bat calls in all the recordings. From there we can start to ask questions about the distribution of bats on the island, and to assess what habitats and locations might be particularly important for conservation.


This is a great example of how the tools we’ve developed using the Bat Detective data can now be applied to understand bat ecology and assist in conservation efforts. Without tools like these, the sheer quantity of audio data collected during a summer-long survey at this level of detail – which clocks up to hundreds of hours of survey-time in total – would be almost impossible to analyse by hand. Keep an eye on the Bat Detective blog in the coming months, as we’ll keep you informed on the last few steps in developing our bat call detector tools for open-source release, as well as letting you know about this and other test-case projects.

Research update: developing new bat monitoring tools with Bat Detective data

Hello from the Bat Detective team! It’s been a busy summer at Bat Detective HQ after an amazing spring with British Science Week and the World Tour. So we’ve been a bit quiet on the blog in the last couple of months while we’ve been working on updating our automated tools and road-testing them on new data. We’re now coming close to having our results ready for scientific publication, and we’ve also had the chance to put our new software tools into practice on analysing some brand new bat survey data. So over the next two blog posts, we’ll be updating you on our progress, explaining where the Bat Detective project is at right now, and showing how we’ve been using all the data you’ve helped us to label.

In this first post we’ll discuss how we’ve used Bat Detective data to improve our automated bat call detection tools, and highlight some of the challenges we’ve encountered along the way. In the next post, we’ll show some examples of where we’ve been testing out our software tools on bat survey data from the UK and Madeira – keep an eye on the blog for that one very soon.

The team have also been up to a few other things in the last few months. Bat Detective’s Rory Gibb (me) gave a project update talk at the Zooniverse’s first ever ecology workshop, where there was some fascinating discussion about how citizen scientists can become increasingly involved in some of the major challenges facing ecology and conservation in future. We’ve also just had a big article on Bat Detective and its sister project iBats published in the latest citizen science-themed issue of Environmental SCIENTIST – the article will be available to read online in the near future, so we’ll share it here when that happens.

Training machines to recognise bat calls: why and how?

In our last research update post a year ago, we explained how advances in machine learning technology have enabled us to train algorithms to automatically recognise bat calls in ultrasonic survey recordings. This is important because newer bat detectors can be deployed in the field for weeks or months, collecting so much audio data that it’s almost impossible to analyse them manually. By making it possible for bat researchers to quickly and reliably find where bat echolocation calls are in these recordings, automated tools are creating exciting new opportunities to study bat ecology, behaviour and conservation at much larger scales than ever before.

Machine learning involves training computer algorithms to automatically recognise bat echolocation calls in recordings, by showing the computer thousands of examples of what they look and sound like. In our last research update we showed how training the algorithms on increasingly large amounts of data from Bat Detective improves their performance. For that reason, and also to include a greater diversity of bat sounds from around the globe, we’ve asked for your help in labelling our World Tour data over the last year. And thanks also to the efforts put in by volunteers during British Science Week, we’ve now got thousands of new bat call annotations to incorporate into our detector tools – so one of our current challenges is exploring the best ways to use all of these new data.

We’ve now got the detector algorithms up and running, and we’re currently testing them out to assess how well they perform. The figure below shows an example of the detector in action on a snippet of audio data from the iBats global bat monitoring programme. The recording is displayed as a spectrogram underneath, with sounds showing up as bright markings. The graph above shows the computer predicting where it thinks the bat calls are – each vertical red line shows where the computer predicts there is a bat call. The height of the red lines tell us how certain the computer is about its predictions, where higher indicates more confident. The green bars show where a human expert has confirmed that bat calls are present – so in this example, the computer has successfully recognised all the bat calls.


Are you sure that’s a bat? The problem of false positives

However, there are still some errors where the computer thinks there is a bat call, when there actually isn’t one (a ‘false positive’). This is a problem for monitoring bat populations, because too many false positives could result in researchers overestimating the true number of bats in an area, which could for example have an impact on conservation efforts. You can see a clear example of these errors in the next figure below, where the computer falsely predicts that the mechanical noises at the bottom of the spectrogram are lots of bat calls.


So to improve this, we’ve also been including non-bat sounds from Bat Detective – those insect calls and mechanical noises you’ve also helped us to find. By training the algorithms to also recognise what bat calls don’t look like, we can significantly improve their accuracy. The image below shows the difference: it’s the same audio clip, but there are now far fewer false positives (red lines).


This is a great example of the importance of testing out these tools on new data from a variety of times, places and detector types. This helps us get a better idea of where they’re under-performing, and how they can be improved before we release them as open-source tools for other researchers to use. So with that in mind, keep an eye on the Bat Detective blog next week for our next research update: we’ll be showing some examples of where we’ve road-tested them on new bat survey data recorded during this summer. We’ll also be uploading a new set of data from Russia – one of our last few World Tour stops – so stay tuned for that.

And a huge thanks again for all your efforts with labeling the data on Bat Detective, both during this year and throughout the whole project – we wouldn’t have been able to get to this stage without your input, and it’s really exciting to see the work of our community of volunteers starting to produce results.

Bat Detective arrives in Japan, our next World Tour stop

Welcome to the latest stop on our World Tour! We’re now in Japan, after spending the last two months uploading data from Australia and New Zealand to the Bat Detective site. Firstly, a massive thanks from the Bat Detective team for all your efforts in listening to and classifying our data so far this year – thanks to the amazing efforts of citizen scientists during the World Tour as well as British Science Week back in March, we’ve got a much larger dataset of labelled bat calls to train our automated algorithms with, and the results are improving.

In the coming months we have a few more World Tour stops before we reach the end of our global bat search. This month we’re in Japan, with a new set of data uploaded to the Bat Detective site that was recorded on car-driven transects during 2010 and 2011 in locations throughout Japan: you can see where the surveys were carried out on the map shown below. We hope you’ll enjoy searching for bats in Japan, and if you have any queries just let us know via the Talk section of the Bat Detective website.

For this month’s blog post, to accompany our Japan data, we’re publishing a short piece written by iBats and Bat Detective’s founder Kate Jones during her 2010 trip to Japan, during which she collected iBats audio data and hosted training workshops for the iBats monitoring program. Scroll down below the map to start reading…


Locations throughout Japan where the data currently hosted on Bat Detective were recorded, during 2010 and 2011.

“I stare slightly queasily down at the tiny but perfectly formed green-tea plantations and rice paddies in the valley far below, as the car winds down the narrow mountain roads of the Mount Fuji highlands in Japan. We stop to try to manoeuvre around an impossibly large truck loaded with locals, and I am struck by the beauty of the mountains surrounding us, lush green forested slopes and azure blue lakes matching the skies overhead.

A crazy expansion of the iBats monitoring program over the past few months has me visiting places and people that I have only imagined. ‘What are you doing in Japan?’ asked the Japanese air attendant politely as I waited for the bathroom on my 11 hr flight to Tokyo. ‘I am hoping to develop a program with local people and scientists to monitor bat populations’, I replied carefully. ‘You see, you can use changes in bat populations like a heart monitor to check the health of nature and the impact of people on the environment’. ‘Bats?’ she squealed, ‘I LOVE bats,’ and proceeded to draw me a map of Japan marked with large crosses where I should visit to see bats. Equally unexpected was finding out at dinner on our first night given by our host, Dai Fukui, that grilled eels are actually very tasty. Especially as tempura with sesame dressing. Yum.

Stuart Parsons, sitting next to me in the car, is looking even more pale than I. Obviously the sake of the previous evening is not going well with Dai’s mountain driving. David Hill on the other hand is made of sterner stuff, alternating between calmly explaining Japanese culture to us in the back and chatting easily to Dai in Japanese in the front. Yesterday was spent exploring caves in the mountains with members of the Japanese bat group (Komori no koui) and listening to horseshoe bats bubbling and warbling over our heads.

In the evening we were introduced to a whole new concept in fieldwork, a ‘mist netting barbecue’. We left the hard work to the local experts and sat around chatting to the group while some of the students brought us mist netted bats for us to look at. The endemic tube-nosed bat (Murina ussuriensis) was especially cute — David’s favorite. Dai explains that he has found this bat hibernating in little tubes it has made in the snow in winter. We drink cold sake and ponder how this bat copes with subzero temperatures. I explain the importance of monitoring to the group and how our acoustic equipment works. Stuart displays the calls in real time from the bats flittering over our heads on his brand new iPad. Whilst outwardly dismissing this gimmick, I am secretly marveling at how Stuart is among the select few in the world that can out-geek me with Apple products.

Although bats are protected in Japan, there is no formalised monitoring of their populations and little general public awareness of the important role bats play in ecosystems. This is a fact that the bat group is trying to change with their awareness-raising activities around Japan every year, culminating in a bat festival in August. The car lurches down the mountain and I see a Bat Conservation Trust sticker on the car in front in our little convoy.

‘Are you a member?’ I ask curiously of the owner, Keiko Osawa, earlier that day, during our lunch overlooking Nagashima Dam. ‘Yes,’ motioning to her husband Yushi, ‘we like getting Bat News’. Yushi is a photographer and they seem to spend most of their time travelling the world photographing fruit bats.

‘Kate San,’ asked the secretary of the bat group Akeiko Mekosa politely. ‘How many members does Bat Conservation Trust have?’. She exclaimed in surprise when I told her over 5000, and said she struggles to get their membership up to 500. The group wants to develop an iBats project here over the next year, and hopes to raise the profile of bats and start its first national monitoring program. Stuart and I are here to help this get started, and to run a workshop on iBats monitoring, volunteer management and acoustic analysis for them.


Ussuri tube-nosed bat, Murina ussuriensis (image reproduced from

Beside me in the car, Stuart is beginning to look more normal and is checking his photos on his new iPad just to annoy me. We chat about his plans for his iBats project in New Zealand next summer (our winter). In contrast to Japan’s forty species of bats, New Zealand only has two. Stuart bristles at my dismissive tone and says that what they lack in numbers they make up in distinctiveness.

I have to agree with him for once — New Zealand is home to the short-tailed bat (Mystacina tuberculata) which spends most of its time in the moist fern-filled forests scampering on the ground hunting for fruit and insects. Although the iBats car-based acoustic monitoring would not be useful to monitor Mystacina as they are confined to deep forest, Stuart sees the potential for using iBats to monitor long-tailed bats (Chalinolobus tuberculatus). He has agreed to trial our new iBats application for the iPhone – you just attach your iPhone to an ultrasound detector and send the recording and GPS information straight to the iBats website. We did a test run in the Fijordland of New Zealand’s South Island in February and apart from us being bitten to death alternatively by sand flies and mosquitoes, it worked perfectly. Long-tailed bats happily flew over the car as we made our way along the transect through Lord Of The Rings country. Stuart is excited about using the technique to better understand the distribution of this threatened endemic species.

We head back up into the clouds with the help of the nice Japanese lady satnav to where we are staying tonight and holding the workshop. The workshop venue is a lodge in the highlands with traditional Japanese style rooms, where the bed is made every night from bedding beautifully folded and organised in wooden cupboards with ornate sliding doors. I’m especially excited about the tales of the Japanese bath houses, with their piping hot plunge pools fed from the surrounding hot springs.

The expansion and interest in the iBats project has been rather overwhelming over the last few months and has seen the team giving workshops in Hungary, Ukraine and most recently Russia, where the vodka flowed a little too easily but the welcome and enthusiasm for the project was amazing. I am overwhelmed by the generosity of the people I have met around the world and their commitment to conserve their bats in the face of conditions much more problematic than those we face. As we stop to investigate the first bat house built in Japan, one of the group asks me where next for the iBats project. Hmmmmm, what about Australia?”

Next World Tour stop, Australia!


Southern free-tailed bat (photo by Terry Reardon, via Adelaide Bat Care)

Welcome to the latest stop on the Bat Detective World Tour! After a month in New Zealand, we’ve reached our next stop, Australia, and we’re now just over halfway through the full tour. We’ve just uploaded a new set of acoustic data to Bat Detective, which was recorded by the iBats project in the Adelaide Hills in 2011. So visit the Bat Detective site now to listen to the data and get searching for Australian bats.

In addition to the World Tour and a busy British Science Week, there’s been lots of activity in the Bat Detective camp in the last few months. In our last blog post we discussed the recently published Mexican bat classification paper by members of our research group, which was widely reported in the BBC and other media.

Following that, this month Bat Detective founder Prof. Kate Jones went out bat detecting on London’s Hampstead Heath with Adam Rutherford, for BBC Radio 4’s weekly science show Inside Science. While listening to the sounds of passing pipistrelles through an ultrasonic detector, they discussed echolocation, the use of acoustics to monitor bat populations, and how with the public’s help we’re building classifier algorithms to improve the effectiveness of bat monitoring both in the UK and globally. You can listen to the programme now, or download it as a podcast, from the BBC Radio 4 site.

And in other recent news, in April our team’s Rory Gibb presented some of the latest findings of Bat Detective’s citizen scientists, as well as our work to develop automated bat call detector software, at the British Bats Research Symposium in London. Stay tuned to the Bat Detective blog in the coming months for further updates about the progress of our research (you can read our last update here) – the efforts you’re putting in to classifying our recordings are making a real difference.

Adelaide Hills, the area where the Australian world tour data were collected

Adelaide Hills, the area where the Australian world tour data were collected

Similarly to the New Zealand audio, our Australian acoustic data are noisier than some of the European and American recordings from earlier in the World Tour: there’s lots more background sound, making it sometimes difficult to distinguish sounds from each other. Keep an ear out for various types of insects, including distinctive rattle-like calls made by crickets and grasshoppers (Orthoptera), as well as calls from a wide variety of bat species.

There are around 14 species of microbat (echolocating bats) found within the Adelaide region. They include the Southern free-tailed bat (Mormopterus planiceps, pictured above), a relative of the well-studied free-tailed bat species found across the Americas, as well as the little forest bat (Vespadelus vulturnus), which is only found in south-eastern Australia and is one of the continent’s tiniest mammals (often weighing less than 4 grams). Also found in the Adelaide area – including in the city itself – are much larger fruit bats such as the grey-headed flying fox (whose population in the area is reportedly growing due to migration from elsewhere in Australia). However, since these do not use ultrasonic echolocation, you won’t be able to hear them in our recordings.

Thanks very much for all your efforts in classifying the New Zealand data, and we hope you’ll enjoy searching for bats in these Australian recordings. As ever, if there’s anything you find that you’re unsure about, just use the Talk section to flag it up and discuss with other members of the Bat Detective community.


Bat Detective New Zealand: our latest World Tour location

Welcome to New Zealand, the latest stop on the Bat Detective World Tour! As of today we’ve just uploaded a new set of audio data to Bat Detective, recorded along survey transects on New Zealand’s South Island. You can see the locations of the surveys on the map below, and visit the Bat Detective site now to get searching for bats.

Prior to this we’ve spent the last month hosting audio data from iBats Mexico, which was neatly timed to coincide with the publication of the latest automated bat call classifier from members of our research group – a classifier for Mexican bat species. As with our results from the algorithms we’re training with Bat Detective data, it’s another example of how advances in machine learning technology are increasingly enabling the development of tools and systems for effective acoustic monitoring of bats (as well as biodiversity more broadly). You can find out more about the Mexican classification tool and how it will assist in bat population monitoring via some great coverage in the media, including in Science and an interview with our group’s Dr. Veronica Zamora-Gutierrez and Prof. Kate Jones on the BBC.


Locations on South Island, New Zealand, where iBats data were recorded

Bats occupy a unique space in the ecology of New Zealand, since they are the country’s only endemic terrestrial mammals – before humans settled the islands, the only mammals native to New Zealand were three bat species (the greater short-tailed bat, lesser short-tailed bat and long-tailed bat) and several species of marine mammal. Since human settlement this has changed, with invasive mammalian predators (such as rats and cats) driving massive declines in the populations of endemic birds and bats. Indeed, the last sighting of the greater short-tailed bat was in 1967, and it is now believed to be extinct, while New Zealand’s other two bat species, the lesser short-tailed (pictured below) and long-tailed bat, have both experienced major declines and are priorities for conservation.

The acoustic data on Bat Detective New Zealand, recorded on South Island in 2010, are much noisier than lots of the recordings you’ll have previously heard on Bat Detective. Many clips have a great deal of background noise and static, in addition to distinctive bats and unique rattling insect calls. Although this can make it challenging to determine what sounds you’re hearing, it’s very useful to include data like these while training algorithms to automatically find bat calls – this will help improve the algorithms’ ability to detect bat echolocation calls in even the most noisy of real-world acoustic recordings. This will make them more useful for surveying bats in naturally noisy and complex acoustic environments, such as urban areas where there is lots of human-generated sound, or highly biodiverse (and therefore very loud) rainforests.

We hope you’ll enjoy helping us search for bats in our New Zealand data, and as ever if you’re struggling to figure out whether a sound is a bat, an insect, or something else, you can use the Talk page to flag it up and discuss it with us and other users.


Lesser short-tailed bat (photo via New Zealand Department of Conservation)


Welcome To Mexico, our latest World Tour location!

Welcome to Mexico! After our exciting hiatus for our British Science Week classifications target (which you helped us to hit comfortably), we’re now back on the road for the next stop on the Bat Detective World Tour. This time we’ve headed south, from our previous location in New York to tropical Mexico. Today we’ve uploaded a new set of data collected in 2008 during audio surveys in several locations on the Yucatán Peninsula, so head across to the Bat Detective site now to begin listening and classifying bat calls.

These data were recorded by a team that included Bat Detective’s founder Prof. Kate Jones, and include surveys around the city of Merida, the capital of Yucatán, as well as the Mayan historical sites Edzná and Calakmul, both of which are located in the jungle and are areas of special archaeological as well as biological interest.

Mexico is a remarkable country in which to search for bats. It has among the highest bat species diversity found anywhere in the world, as well as some of the world’s most unusual, beautiful and bizarre bat species. Some of our favourites are the spectral bat (Vampyrum spectrum), the largest carnivorous bat in the world; the fish-eating bat Myotis vivesi, which hunts by using its exceptionally large feet to snatch marine fish and crustaceans from the sea; and the banana bat (Musonycteris harrisoni), whose extremely long snout and tongue are ideal adaptations for feeding on nectar from tropical flowers – and lend it its alternative name of trumpet-nosed bat. Other Mexican nectar-eating bats are famous as important pollinators of agave plants – vital for making tequila.

Locations on the Yucatan Peninsula, Mexico, where Bat Detective audio data were collected

Locations in Mexico, where Bat Detective audio data were collected

Another of the country’s best-known bats is the Mexican free-tailed bat (pictured below) which is widespread throughout the Americas and famed for roosting in colossal cave colonies of up to several million individuals. Because of its abundance and visibility, it is fairly well studied; for example one 2015 study, published in the journal Science, found that this species has the remarkable ability to produce interference vocalisations to ‘jam’ rival bats’ echolocation sonar, potentially enabling individuals to improve their own hunting success.

In southern Mexico, as in other tropical regions of the world, bats are even harder to survey than in temperate regions – tropical forests are noisy places, filled with inhabitants occupying their own sonic niches and working to be heard above and around each other. Developing automated bat detector softwares to pick out bat calls from this dense acoustic hubbub, and to then identify those calls to the level of species or species group, requires a lot of labelled input data to train our algorithms.

But it’s worth the exploration, since many of the calls you’ll encounter in tropical Mexico are quite unlike our earlier data from temperate regions such as Europe and New York. So if you’re unsure, use the guide underneath the main classify window to help you figure out what sounds you’re hearing. And as ever, if you have any challenges working out whether a call is a bat or not, just click through to discuss it on the Talk section of the site with us and other citizen scientists. These are some of our favourite recordings to be uploaded to Bat Detective, and we hope you’ll enjoy listening and classifying them too.


Mexican free-tailed bats (photo via Wikimedia Commons)

British Science Week: we did it!


Yesterday was the final day of British Science Week – and we’re now very happy to report that with your amazing help we sailed past our target of 100,000 new classifications over the course of the week. We reached the target on Friday night (to much excitement), and then classifications continued to climb over the weekend – reaching a total of over 110,000! The Bat Detective team would like to extend a huge thank you to all the citizen scientists who participated and contributed their time and energy over the course of the week – your efforts are much appreciated and will make a real difference to our research.

Keep an eye on the Bat Detective blog, Twitter and Facebook during the coming months, and we’ll keep you updated about how our research is going, and explain how your classifications during British Science Week are helping to improve our automated bat detection algorithms for bat population monitoring.

We’d also like to extend our thanks to everyone at British Science Week and the Zooniverse team, as well as everyone who’s been involved in the last week’s bat-themed events, including the Grant Museum, In The Dark Radio, Bat Conservation Trust and all the speakers at the Museum’s bat-themed lunchtime talks.

After that exciting week’s diversion, the Bat Detective team are now preparing to resume our World Tour where we left off – next stop Mexico! We’re preparing to upload some new Mexican data to the Bat Detective site so stay tuned over the next couple of days – hopefully you’ll be keen to continue helping us in our search for bats.


British Science Week and Bat Detective: get involved!


British Science Week 2016 begins this Friday! This year’s citizen science theme is “all things bat-related”, and if you’ve been following us on social media you might have noticed that we’re excited to be one of the week’s main citizen science partners. With the help of both our fantastic current community of citizen scientists and what we hope will be many new recruits, we’ve set ourselves the goal of reaching 100,000 new classifications over the course of British Science Week.

So from Friday 11th March to Sunday 20th March we’re asking for your assistance in helping us to hit our target, by listening for for bats, insects and other sounds on Bat Detective. An extra 100,000 classifications will give us a fantastic boost in useable data for our bat detection algorithms, and will be a great step towards our goal of producing new software for bat population monitoring. We’ll have a counter on the Bat Detective site throughout the week, counting up the number of classifications we’ve managed so far and reminding us of how far we’ve yet to go. So please do get involved during the week and help us reach our goal — your efforts are very much appreciated and are invaluable to our research. To get involved, head to the Bat Detective website at any time and click “Get Searching”.

In addition to aiming for this classification target, we’ve also got a week of special bat-related events planned in collaboration with British Science Week and the Grant Museum of Zoology.

These will be taking place throughout next week at the Grant Museum on Gower Street, London, just around the corner from where the Bat Detective team are based at UCL. Throughout the week, from Saturday 12th to Saturday 19th March, the Museum will be hosting a pop-up Bat Detective stand where people can participate, classify calls and help us reach our target. The week’s events will also include lunchtime talks from researchers from Bat Detective and the Bat Conservation Trust, a special immersive audio evening exploring bat echolocation, and a family bat-fun day on Saturday 19th. There’s lots of information at the Grant Museum homepage, which you can find here.

The full set of special events runs as follows. So if you’re in London, come along, get involved and say hello to us — members of the Bat Detective team will be attending or speaking at many of the events. We look forward to seeing you there. And to hear about our progress during British Science Week and keep updated with Bat Detective news, you can follow us on Twitter or Facebook.

Monday 14th March, 1:30pm–2:30pm
Bats at Lunchtime: The London Soundscape (talk)

A talk exploring how scientists at UCL are working to understand the health of London’s biodiversity through listening to its soundscape, including listening to bat calls.

Tuesday 15th March, 1:30pm–2:30pm
Bats at Lunchtime: On Dark Nights (talk)

A talk by researchers from the Bat Conservation Trust, discussing how street lights and other sources of urban light affect the nocturnal lives of bats.

Tuesday 15th March, 7pm—9pm
Bats: In The Dark 

Join In the Dark Radio for an evening of stories told through sound (like a cinema, but without the pictures) at the Grant Museum of Zoology during British Science Week. Enjoy the Museum after hours and listen to hand-picked audio inspired by Bat Detective, an audio visual citizen science project that asks people to identify bat calls. Discover the strange calls of these creatures of the night and find out more about these amazing flying mammals at this exploration of echolocation. This event is ticketed — book a place here.

Wednesday 16th March, 1:30pm–2:30pm
Bats at Lunchtime: Bat Detective (talk)

A talk from members of the Bat Detective team. Learn more about the ideas and science behind the Bat Detective citizen science project, and how the contributions of citizen scientists are helping us to develop tools to reliably identify bat calls.

Thursday 17th March, 1:30pm–2:30pm
Bats at Lunchtime: Bats In The Woods (talk)

A talk by researchers from the Bat Conservation Trust. Woodlands are excellent foraging and roosting areas for bats — learn about efforts to protect these important habitats.

Saturday 19th March, 1pm—5pm
The Brilliance of Bats family day

Bats are taking over the Grant Museum for a mini festival celebrating the brilliance of these flying mammals. Join the Museum for an afternoon of bat-related fun, try batty crafts with finger puppets and origami, take a closer look at some of specimens, hear from scientists investigating bats here in London and discover more about the work of the Bat Conservation Trust. This event is free so there is no need to book, just drop in from 1pm to 5pm.

Bat Detective USA: We’re in New York!

We’ve just landed in North America for the next stop of the Bat Detective World Tour! We’ve spent the last couple of months in the rather warmer climes of sub-Saharan Africa, asking for your help in listening for bat calls in data from Ghana and Zambia. Since the start of the World Tour you’ve listened to over 10511 unique audio clips and classified bats and insects in nearly 2000 of those, labels which will help to make our bat detection algorithms more accurate and robust. You can learn more about how your efforts are contributing to our research and bat population monitoring here, and keep an eye on the blog for future updates about how your work is further improving our automated bat detection software.

Following our time in Africa, we’ve now jetted across the Atlantic to arrive in New York, U.S.A. As of this morning we’ve uploaded a fresh set of audio data to Bat Detective, so visit the Bat Detective site right now to start searching and classifying. These data were recorded by iBats volunteers during surveys both within New York City itself as well as elsewhere in New York State. They cover a variety of urban and non-urban locations, including Central Park in Manhattan, Forest Park in Queens, Pelham Bay Park and Bronx Zoo, as well as Black Rock Forest, a 3,838-acre area of forest specially managed for maintenance of varied habitats and high species diversity. You can see the survey locations on the map below.


Locations of iBats New York survey data: Black Rock Forest, Forest Park Queens, Central Park, Bronx Zoo and Pelham Bay Park

With its temperate climate, New York lacks the very high species diversity of tropical regions, meaning that the sonic variation and insect noise in these recordings is often lower than in our recent African data. But there are plenty of fascinating bats to be heard. While listening through the data you might encounter any of several bat species found in this region and adapted to its seasonal climate. These include cave and mine-roosting species such as the abundant little brown bat and its larger relative the big brown bat, as well as the Eastern pipistrelle – a cousin of the well-known pipistrelle species you might have encountered in our European recordings – and the large, handsome Hoary bat (pictured below), whose range stretches throughout North and South America.

Bat conservation is currently an important topic in North America, mainly due to the ongoing spread of the deadly fungal disease white nose syndrome (WNS), which has caused large bat population declines in the northeastern US. Named after the furry white fungal mass often seen coating the muzzles and wings of affected individuals, WNS infects hibernating species such as little brown bats during the winter months, and is estimated to have killed over 6 million bats since it was first identified in New York in 2006. Research and conservation activities are ongoing to understand and attempt to contain the spread of WNS, and in response the United States, Canada and Mexico signed an agreement in 2015 to improve co-ordination of bat conservation responses across all three countries.

More broadly, infectious disease of wildlife is a serious and growing conservation threat to multiple species groups. The emergence of white nose syndrome in bats, for example, has parallels with the rapid spread of the amphibian fungal disease chytridiomycosis over the last two decades, which has driven massive declines and even extinctions in global amphibian populations. With most bat species difficult to monitor due to their nocturnal and elusive lifestyles, these challenges further emphasise the need for new tools and technologies to help researchers better understand the impacts of threats such as disease on bat populations – efforts we hope will be assisted by the automated softwares we’re currently developing with your assistance.

We hope you enjoy listening for bat calls in our New York data during this latest stage of the Bat Detective World Tour – click here to start searching. As ever, if you’re unsure about whether a call you’ve heard is a bat or not – or even just want to flag up something unusual or interesting you’ve discovered – click through to the Talk section, where you can discuss it with other citizen scientists and our own researchers.

Hoary bat (photo by J.N. Stuart, used under Creative Commons licensing)

Hoary bat (photo by J.N. Stuart, used under Creative Commons licensing)

Next on our World Tour: Kasanka National Park, Zambia

Happy new year from the Bat Detective team, and welcome to the next leg of our World Tour! Having spent the last month searching for bats in Ghana, we’ve travelled south to Zambia, another country in sub-Saharan Africa with high biodiversity and amazing wildlife. Today we’ve uploaded a new set of audio data to Bat Detective, containing recordings made in Kasanka National Park, which is shown on the map below. Head to the Bat Detective site now to start exploring the new data and classifying calls.

Location of Kasanka National Park, where the Zambia world tour data were recorded

Location of Kasanka National Park, where our Zambia world tour data were recorded

Kasanka is a relatively small national park located in the Lake Bangweulu basin, but has a broad range of habitats and an associated rich array of wildlife species, from famous large African fauna such as hippo and elephant, to a wide diversity of birds and bats. Indeed, like Accra where our Ghanaian World Tour audio data were recorded, one of Kasanka’s most famous wildlife sights is its massive gatherings of straw-coloured fruit bats (Eidolon helvum).

Each year, in November and December, around 1.5 million individuals arrive in Kasanka from the Congo Basin to feed from ripening fruit trees, in one of Africa’s most spectacular wildlife migrations (pictured below). Already known as one of the continent’s most widespread bat species, found from the base of the Sahara desert all the way to South Africa, research in recent years has confirmed that straw-coloured fruit bats are highly mobile and migratory. Recent research taking genetic samples from individuals across mainland Africa found that the straw-coloured fruit bat population is genetically mixed across the entire continent – an indicator of a highly connected population at a huge geographical scale. Indeed, tracking studies have also shown that individuals can travel huge distances, covering up to 370 kilometres in a night.

Fruit bats at Kasanka National Park (photo from

Fruit bats at Kasanka National Park (photo from

Similarly to our Ghana data, however, you won’t hear any fruit bats in these audio recordings from Zambia. The Pteropodidae, the genus to which fruit bats belong, do not use true ultrasonic echolocation to navigate, communicate and search for food.

However, Kasanka is home to a rich diversity of echolocating bat species, which you might encounter while listening through the data. Among these are two species of horseshoe bat, Lander’s and Hildebrandt’s horseshoe bat, with their distinctive constant-frequency calls; the tiny Schlieffen’s twilight bat (pictured below); and the banana pipistrelle, named for its habit of nesting in the leaves of banana and plantain trees. You might also have encountered some of the more widespread African species, such as the Angolan free-tailed bat, in our Ghana recordings.

Similarly to the Ghana data, the recordings from Zambia are very acoustically diverse – see our Ghana blog post for a guide to some of the sounds you might encounter. Occasionally mechanical noise or insect chirps can prove very challenging to tell apart from bat calls – if you’re unsure if a recording contains a bat call, just use the Talk section to flag it up and discuss with other users and the Bat Detective team. Good luck and happy searching!

Schlieffen's twilight bat

Schlieffen’s twilight bat (photo by Natalie Weber via