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


Next stop on the World Tour: We’re in Ghana!

Welcome to the second stop on the Bat Detective World Tour! We’ve spent the past few weeks uploading audio data from surveys in the UK, where the Bat Detective team and the Bat Conservation Trust are based. During that time our team of citizen scientists have completed over 7500 classifications, so thank you for your work during the first leg of the world tour. You can learn more about how your input is helping us to improve our automated bat detector softwares at this recent blog post.

Now, just as the UK weather is getting colder, we’ve jetted off to warmer climes. We’ve just arrived in Ghana in tropical West Africa, a country with rich biodiversity and a range of amazing bat species, and an important agricultural producer of crops such as cocoa, sugar cane, rubber, palm oil and bananas. Bats are pollinators for some of these crops, including some mango, cocoa and banana species – one of the many important ‘ecosystem services‘ that they provide for humans.

Starting today, 30th November, over the coming weeks we’re asking our bat detectives to listen through audio recordings of bat surveys around Ghana’s capital city of Accra (shown on the map below), conducted in 2010 by iBats volunteers. Click here to visit the Bat Detective site now to start listening and classifying. As you might expect for a tropical country with high wildlife species diversity and associated acoustic variety within the environment, many of the sounds you’ll encounter in these data are markedly different from the European audio data we’ve previously hosted on Bat Detective. They include different insect species, as well as a variety of bat species with their own fascinating, complex calls.

Accra, where the Ghana world tour audio data were collected

One particular bat species is one of Accra’s most famous urban residents – the straw-coloured fruit bat (Eidolon helvum). Massive gatherings of up to a million individuals of this large species are known for roosting in trees near the centre of the city, before spectacularly taking off at dusk and travelling outward en masse to forage. However, you won’t hear them in our Bat Detective recordings, as they’re part of the fruit bat family Pteropodidae, which do not use true ultrasonic echolocation to communicate and search for food. However, there are a wealth of echolocating bat species in this region of Africa that you might encounter while searching our Ghana data, from the widespread Angolan free-tailed bat and Noack’s roundleaf bat, to the distinctive yellow-winged bat (pictured below) a member of the false vampire bat family.

Although the Ghana recordings are often quite acoustically different to our previous European data, the same general rules for recognising different sounds still apply. Bat calls sound like a chirp, squeak or whistle, and usually show up on the spectrogram as defined pulses of sound, sometimes with additional harmonics at higher frequencies. The following two images are examples of bat calls from the Ghana data.



And the spectrogram below contains two distinct sets of bat calls from two individuals: one series of almost vertical calls at slightly lower frequency; and a separate, very bright horizontal call with two harmonics stacked at higher frequencies.


If you’re lucky you might also come across a ‘feeding buzz’ – a distinctive sequence of call pulses that gradually become closer and closer together as the bat approaches its prey, as shown in the clip below.


Insects often make rhythmic calls which can sound like a serrated rattling, buzzing or hooting. Visually they often look like repeated figures across the spectrogram at lower frequency than bat calls, such as in the following two clips. They can also often sound like car alarms or like distinct pulses within a messy spectrogram.



You might also encounter both insect calls and bat calls in the same clip, such as in the example below, where a bat call is shown in the blue outline, and the insect calls in green. You can usually tell the two apart by listening carefully for the bat’s distinctive chirping or whistling tone.


More detailed information and examples of different sound types are provided in the key at the bottom of the Bat Detective ‘classify’ page.

But if you’re still unsure about whether a sound is a bat or not – or even if you’ve just discovered a particularly strange or interesting clip that you want to draw attention to – just use the Talk function to discuss the call with others in the Bat Detective community and our researchers.

We hope you’ll enjoy searching for bat calls in our Ghana data over the coming few weeks. We’ll be staying in Africa for the next stop on the tour too, so keep an eye on this blog and our Twitter and Facebook pages for future news announcements.

Yellow-winged bat (photo by sandralee, displayed under Creative Commons licensing)

Yellow-winged bat (photo by sandralee, displayed under Creative Commons licensing)

Bat Detective World Tour begins! Welcome to the UK

The Bat Detective World Tour starts today! Over the next few months we’ll be regularly uploading new sets of data to Bat Detective from different countries across the globe – from Europe to Africa, the Americas and Asia – each with its own selection of bat species alongside other acoustic inhabitants. Today we begin our global bat search in the United Kingdom, home of the Bat Detective team and the Bat Conservation Trust (BCT). We’ve just uploaded a brand new set of audio recordings from the UK for our citizen scientists to explore, so to get involved, head across to the Bat Detective site right now.

These recordings are from surveys carried out across Great Britain between 2005 and 2010 – you can see their locations on the map below. The sounds you can expect to hear in these recordings are similar to the earlier Bat Detective data from Eastern Europe, including many of the same bat species, such as pipistrelles, serotines and noctule bats. Found across much of continental Europe, these are also among the UK’s most widespread bats, some of which you’ll probably have seen or heard through a detector if you’ve ever been out for a British bat walk or survey.

They’re also among the main species surveyed in the UK as part of the BCT’s National Bat Monitoring Programme (NBMP), a huge ongoing citizen science project that has been running for over 17 years. Carried out by thousands of volunteers who are trained to recognise different species calls using acoustic bat detectors, it’s a great example of how citizen science can make a real difference to our understanding of the status of wildlife populations.

iBats UK survey locations, which provided data for the UK segment of the Bat Detective World Tour

Survey locations from iBats UK project, which provided audio data for the UK segment of the Bat Detective World Tour.

You can read the most recent results report from the NBMP here. A paper by the NBMP team published in the scientific journal Biological Conservation in early 2015 showed that the long-term data collected by their volunteers could detect changes in bat populations equivalent to a Red Alert (a decline of 50% in 25 years). They also suggested that the current outlook for UK bat populations seems to be relatively positive, with most bat species showing either stable or slightly increasing population trends between 1997 and 2012 – promising initial news after the declines suffered by many species during the 20th century. These results should continue to assist in future monitoring of UK bat populations, and are evidence that citizen monitoring programmes can and do provide scientifically useful data for informing conservation. To find out more about the NBMP and how you can get involved, click here to head to their website.

Our goal with Bat Detective and iBats is to use similar citizen science-led approaches to develop new tools for monitoring bats on a global scale, while taking advantage of new advances in technology. As we’ve explained in previous blog posts, the data collected by iBats volunteers and labelled by Bat Detective users is helping us to develop automated software for reliably detecting and species-identifying surveyed bats. This will allow the analysis of massive amounts of survey data to be standardised across all volunteers and countries, thus increasing the usefulness of the data for drawing scientific conclusions. To read more about why collecting this data is important, read our earlier blog posts, here and here.

As well as some of our better-known bat species, while you’re exploring the UK Bat Detective data, you might also encounter a rather more uncommon visitor – the migratory Nathusius’ pipistrelle (Pipistrellus nathusii), which was named BatLife Europe’s bat of the year in 2014. Much is still unknown about the presence of this tiny traveller in the UK, since it’s rarely encountered here, although some individuals are known to be resident all year round. But researchers are finding increasing evidence to suggest that this species frequently crosses the North Sea between the UK and mainland Europe. In 2013 one individual that had originally been identity ringed near Bristol was found in the Netherlands, a direct distance of nearly 600 kilometres – a colossal trip for an animal that’s only about the size of a human thumb!

BCT are currently running a Nathusius’ pipistrelle project in the UK. Learning more about this amazing species will be important for reducing the potential human hazards it might encounter on its migrations, for example by placing wind turbines away from its main travel routes. So while searching the UK Bat Detective data you might be lucky and hear one too – for information on how to identify Nathusius’ pipistrelle from their calls, visit the BCT site.

Good luck and happy searching during this first leg of the Bat Detective World Tour! If you’re unsure about whether the sounds you’re hearing are bats or not – or just want to highlight something interesting you’ve found – visit the Talk section of the website to discuss your findings with the Bat Detective community.

Nathusius' pipstrelle

Nathusius’ pipistrelle (photo via Wikipedia).

Bat Detective World Tour begins next week!

As we announced recently, Bat Detective is about to go on a World Tour, and we’re inviting you to join us, starting this coming Monday 2nd November. The iBats monitoring programme, which provides us with our audio data, has now been running for a decade, with our volunteers collecting recordings of bat surveys in locations worldwide. However, to date Bat Detective has made only some of that recorded audio available for our citizen scientists to explore, and that has come mainly from Eastern Europe.

So starting on 2nd November, over the course of the World Tour we’ll be regularly uploading new sets of data to Bat Detective from different countries across the globe. Each country – ranging from Europe to places in Africa, the Americas and Asia – has its own selection of bat species alongside other acoustic inhabitants, so you can expect to encounter a variety of different soundscapes while searching for bat calls worldwide. Your help with classifying bat calls, insect noises and other sounds in these places will be of valuable assistance in our work towards creating automated bat detectors – read more about our research here.

On Monday we’ll begin our trip in the United Kingdom, home of the Bat Detective team and the Bat Conservation Trust. Keep an eye on the Bat Detective blog for a more in-depth post about British bats, citizen science, and what you might hear while exploring our UK data. We hope you’ll enjoy joining us in searching for bats across the globe, so stay tuned and see you next week…

photo via Wikimedia

photo via Wikimedia

The Bat Detective World Tour – join us soon!

Bat Detective has now been running for over three years, and all the input from our community of citizen scientists has been invaluable in helping us to develop machine learning algorithms for detecting bat calls in audio recordings – so thank you! As we explained in our recent post about our current research, adding more annotated data – and from a wider variety of recorded sound environments – will further improve the accuracy and reliability of our bat detector software. This will bring us closer to our goal of creating smart automated tools for monitoring global bat populations, which we hope will in turn help us to learn more about how human activities are affecting the earth’s ecosystems.

So we’re about to take Bat Detective on a World Tour, and we’re asking for your help in searching for bat calls in recordings from across the globe.

Since 2005 the amazing groups of volunteers and researchers on the iBats monitoring programme have been recording audio bat surveys in places ranging from the UK to Japan, North America to sub-Saharan Africa — each with their own distinct environmental soundscapes and unique selection of bat species. So far, however, the audio snapshots we’ve uploaded to Bat Detective have only been those from Eastern Europe. This means we still have lots of new data from all over the world in need of exploring and annotating, all of which will build into improving our automated bat detectors.

All countries where iBats surveys have been carried out to date (data:

All countries where iBats surveys have been carried out to date (data:

So throughout the World Tour we’ll be travelling from country to country, regularly uploading new sets of audio data from a selection of places where iBats volunteers have surveyed. We’ll begin in the UK, where the Bat Detective team are based, before jetting across the globe to search for bats in countries in Africa, North America, Australia and Asia. And as we go we’ll be adding posts to this blog, reporting on where and when the surveys were recorded, and highlighting some of the local bat species (and other curious sonic inhabitants) you can expect to encounter in each location.

Keep an eye on the Bat Detective blog for dates, news and updates as we progress through the tour. And until our travels start in a few weeks’ time, you can still help us track down bats in our current Eastern European data – visit the Bat Detective site to get searching. Thank you for your contributions over the last three years, and we hope you’ll enjoy helping us to search for bats worldwide!

Bat Detective research update – and stay tuned!

This week it’s our birthday! It’s been exactly three years since we first launched the Bat Detective project on 1st October 2012. Since then we’ve had an amazing response from our community of citizen scientist bat detectives, with over 94,000 unique audio snapshots explored by nearly 4,000 volunteers, and more than 11,000 bat calls discovered.

All the hard work you’ve put in so far has been invaluable. Using the data from Bat Detective, we’ve been developing computer algorithms that can automatically search for and detect bat calls in audio recordings with a very good success rate. To do this we’ve taken advantage of recent rapid improvements in machine learning technology for recognising complex patterns within data — such as the distinctive shapes of bat calls.

We’ve had great results so far, thanks to all the audio data the bat detective community has searched through, and all the calls you’ve identified. The majority of those have been searching calls (over 7,000), but you’ve also labelled over 2,000 each of the more rarely recorded social and feeding calls. We’ve used this annotated data to train our machine learning algorithms, by showing them thousands of examples of what bat calls look and sound like. This enables them to better tell apart the sounds we’re interested in from other background sound, such as insect calls and mechanical noise.

We’re now at the stage where we can use these algorithms to detect bat calls throughout the millions of recordings collected through the iBats monitoring project. What this means is that we’re a key step closer to developing automated software for accurately detecting and species-identifying bat calls from recorded audio — a vital move towards a global monitoring programme for bat populations. To read more in-depth summaries of the work our team members have been doing towards that goal, see our recent blog post for Methods In Ecology & Evolution.

This graph shows how well our algorithms are currently performing at finding known bat calls within a large set of audio data that we’ve already annotated. The closer the curve reaches to the top right of the graph, the better the results we’re getting — this means we’re maximising the proportion of the bat calls detected within the audio (increasing the recall) while minimising the number of non-bat sounds that are incorrectly classified as bat calls (improving the precision). When we use four times as much data from Bat Detective to train the algorithms (shown as a green line), we get a large improvement in performance compared to when we use much smaller amounts of data (shown as the blue and purple lines).


So the more data we can use to train our algorithms, the more accurate and reliable they will be. This will allow them to more successfully detect even calls recorded in challenging acoustic conditions, when there’s lots of background noise or the bats are far away from the detector — those trickier cases where they’re failing now. That’s why the ongoing help from the bat detective community is so valuable for our research. So later this month we’ll be announcing some new developments in the Bat Detective project, where you can help us search for bat calls in recordings from all around the globe — stay tuned for more information very soon!

Bat Appreciation Day

Today is Bat Appreciation Day!

To celebrate we have written a blog post for Methods in Ecology and Evolution. We mention the great work that has already been performed by the Bat Detectives and give a round-up of the latest methodological advances in bat monitoring and what we hope to see in the next few years.

The post can be found here:

The Funnel-eared bat (Natalus stramineus) – © Veronica Zamora-Gutierrez

The Funnel-eared bat (Natalus stramineus) – © Veronica Zamora-Gutierrez

Progress to Date and New Data

The bat detective project has been running for over a year and a half and we have had a fantastic response from our community of detectives. In this blog post we are going to give a short summary of all the hard work that has been performed by the community to date.

As of this month we have had over 310,000 classifications on the site. Close to  2,400 registered users have viewed and listen to over 70,000 unique audio snapshots. Of the 70,000, 8,350 were labelled as containing bat calls and 35,000 as having insects. Our top two most prolific detectives have viewed over 40,000 snapshots each!

With over half a million recordings in total, there is still a long way to go. In a future blog post we will talk about our current research into building computer algorithms which will help us find bat calls automatically. These algorithms rely on being shown many examples of what a bat call sounds like so they can try and learn what makes them different from all the other sounds we capture. That is why the continued help from the community is so invaluable.

We have just uploaded some new data to the site. So best of luck!

bat Detective

Do you enjoy being a part of Bat Detective?

UCLIC Would you be willing to talk about your experience as part of a Skype or phone interview? At the UCL Interaction Centre, Dr Charlene Jennett and Zoya Ajani are hoping to understand more about the experiences of Bat Detective volunteers – how did you find out about the project and what motivates you to take part? By understanding your experience at Bat Detective, Charlene and Zoya are hoping to gain valuable insights into ways to improve online citizen science projects in the future.

CyberlabThis work is being conducted as part of the Citizen Cyberlab project, a three-year EU project that aims to study and enhance the opportunities for learning and creativity available to participants in online citizen science projects.

CharleneZoyaInterviews are between 30 mins to 1 hour, and participants will be rewarded with an Amazon gift voucher. If you think you would like to be interviewed, please email Charlene for more information.

Hang out with the Bat Detective team


Hopefully the link above should take you to the Youtube page for the first ever Bat Detective hangout, which will start just after 7pm GMT. Once we’re done, that should magically transform into a link so you can catch up with the Bat Detective team again and again and again.