Thursday, 15 March 2018

Using acoustics to assess biodiversity in cities

Cities now support over half of the world’s human population. They also support endemic and threatened wildlife. This wildlife provides multiple ecological services to human urban populations, and also provides the daily contact with nature that most of us now experience. However, our understanding of how wildlife persists in urban environments, and how we can design and manage cities to provide the best possible habitat for wildlife is still not very well understood. One reason for this is due to the difficulties of assessing biodiversity, especially in cities. Human surveyors have to consider safety issues, survey equipment is vulnerable to vandalism, theft and destruction, and getting access to private land to conduct surveys can be very bureaucratic. Through my Engineering Doctoral research (EngD) I developed new acoustic tools that can be used to make it easier to assess biodiversity in urban environments. These tools should hopefully be used in the future to better understand the biodiversity supported by cities and to inform the design and management of cities for biodiversity.

Acoustics and biodiversity assessment

Lots of wildlife produce sounds, either by vocalising – think a singing songbird - or through movements of their bodies – think the hum from the rapid wingbeats of a bumblebee. Some species also make sounds that cannot be heard by humans, such as the ultrasonic echolocations of bats.
Ornithologists have used the species-specific calls emitted by birds to identify calling species for centuries. More recently, ultrasonic recorders have been used to record the species-specific echolocation calls of bats which can be used to identify species.
But these examples are very species-specific. There are other species that live in cities such as insects and non-flying land animals like foxes and squirrels that also make sound.
The field of ecoacoustics uses the sounds emitted by all species to get a measure of whole ecological communities, rather than focussing on specific species and species groups. Ecoacoustic theory posits that the soundscape (sounds at a landscape scale) of an environment is composed of biophony (sounds emitted by non-human organisms), anthrophony (sounds associated with human activities) and geophony (abiotic sounds such as wind and rain).
The three elements that compose a soundscape: biophony, anthrophony and geophony. Image credit: Pijanowski et al. (2011) BioScience.

New technology for ecoacoustics

The use of ecoacoustics to monitor biodiversity has really been made possible by the development of passive acoustic recording technology, such as the very popular products from Wildlife Acoustics. These are weather-proof acoustic recorders that can be left outside for long periods of time, recording sound on a user-defined schedule. This technology is making it possible for biodiversity scientists and conservationists to collect vast amounts of acoustic recordings.

An SM2+ SongMeter is an example of a passive acoustic recorder that is commonly used in ecoacoustic research. These devices can be deployed in the environment recording at a pre-defined schedule for days/weeks/months at a time. Image credit:

But what to do with all this acoustic data? It is not practical or efficient to spend days/weeks/years listening to the recordings that have been made.
To overcome this Big Data problem, ecoacousticians have developed algorithms that can measure the biotic sound in acoustic recordings producing a proxy measure of biodiversity. These algorithms are called acoustic indices and can be used to quickly produce measures of the biotic sound in large volumes of acoustic data. They measure a few characteristics of the acoustic data, such as the amount of sound at particular frequencies, to produce a summary measure of biotic sound within an entire sound recording.

Acoustic indices produce measures of the biotic sound in audio recordings. Four commonly used acoustic indices include: A) Acoustic Complexity Index (ACI, Pieretti et al. 2011 Ecol. Indic.), B) Acoustic Diversity Index (ADI, Villanueva-Rivera et al. 2011 Landscape Ecol.), C) Bioacoustic Index (BI, Boelman et al. 2007 Ecol. Appl.) and D) Normalised Difference Soundscape Index (NDSI, Kasten et al. 2012 Ecol. Inform.). The ACI sums the absolute difference in signal power within frequency bins over time using a sliding window and defined temporal steps (indicated by arrow). The ADI is calculated as the Shannon’s diversity index for each recording based on the signal power occupancy of each 1 kHz frequency band. The BI calculates the signal power within 2-8 kHz frequency band of recordings. The NDSI calculates the ratio of signal power in the frequency bands between 1-2 kHz and 2-8 kHz to measure the level of anthropogenic disturbance on the landscape.

Ecoacoustics in the city

However, ecoacoustic research and the development of acoustic indices has tended to focus on less disturbed environments than cities, such as temperate woodlands, coastal forests and Mediterranean scrub. The challenge of my EngD research was to see if ecoacoustic could be applied in this new, highly anthropogenically disturbed environment.
I started off by assessing the suitability of a suite of commonly used acoustic indices for use in the urban environment. I collected low (0-12kHz) and high (12-96kHz) frequency audio recordings from 15 churchyard sites across the Greater London area. I was lucky to collaborate with the Diocese of London on this data collection while they conducted a London-wide ecological survey of their churchyards.

Setting up my acoustic sensors

To test exactly what sounds the acoustic indices measured in the acoustic data, I listened to and manually labelled the sounds in a random selection of my recordings. To do this, I co-developed AudioTagger, a bespoke audio analysis software that allows you to quickly listen to and view audio recordings, and draw labelled bounding boxes around sounds on spectrograms (a visual representation of an audio recording).

AudioTagger in action. Sound recordings can be quickly listened to, viewed as spectrograms and annotated by drawing labelled bounding boxes around sounds of interest. Sounds labelled here include birds (blue boxes), electrical buzzes (pink) and road traffic (red).

I identified a very wide range of sounds in my recordings. Anthropogenic sounds dominated the dataset and the variety was much greater than in previous ecoacoustic studies, including sounds such as road traffic, sirens, church bells, footsteps, and applause. Biotic sounds were mainly made by birds and bats, and geophonic sounds were either wind or rain.
Of the four acoustic indices I tested, either the measures of the acoustic indices did not correlate with the amount of biotic sound in recordings, or were biased by non-biotic sounds in recordings (Fairbrass et al.2017).

Therefore, I would not recommend that any of the acoustic indices I tested are used to assess biodiversity in urban environments.

Machine learning as an alternative to acoustic indices

Machine learning algorithms learn to recognise patterns in data based on examples that they’ve seen previously, for example how a spam email application learns to filter emails based on what a user has previously marked as spam (skip to 32:38 for a great introduction to machine learning).
Deep learning algorithms (a type of machine learning) choose by themselves what characteristics define different groups of data, rather than relying on humans to choose. Therefore they can use many more parameters within data to characterise groups than a human ever could, making them extremely powerful.
Machine learning algorithms are potentially much more powerful than acoustic indices, as they do not rely on human defined characteristics of data. What they do rely on is having a large dataset of labelled data with which to learn the characteristics of different groups.
To train a deep learning algorithm that could measure biotic sound in audio recordings from the urban environment without being biased by the non-biotic sounds in the city, I collected audio recordings from 63 sites across the Greater London area.
I used AudioTagger to label all the biotic, anthropogenic and geophonic sounds in a random selection of 45 minutes of recordings from each of the 63 sites. This labelled data was used to train and test a pair of Convolutional Neural Network algorithms, CityNet (Fairbrass Firman et al. in review), which produce a measure of biotic and anthropogenic acoustic activity in noisy acoustic recordings from the urban environment.

Audio data recorded at 63 green infrastructure sites in and around Greater London (A) was used to train (black dots) and test (red dots) the CityNet system. CityNet can be used to summarise the biotic and anthropogenic sounds in large volumes of audio data from noisy urban environments. A week of audio recordings are summarised here to produce daily average patterns of biotic and anthropogenic sound (B and C), which can be interesting to compare between different types of environments, such as sites in the centre (B) and on the outskirts (C) of the city. Image Credit: M. Firman

The algorithms can be used to produce summaries of the biotic and anthropogenic sound in large volumes of audio data from cities – at you can explore the patterns of biotic and anthropogenic sound at my 63 study sites.

Biotic sound as a proxy measure for biodiversity

An open question that remains in ecoacoustics is whether biotic sound is a good proxy measure for biodiversity? And does more biotic sound mean more or better biodiversity? Some have argued that due to the way species avoid calling at the same time and frequency, more sound does correlate with more diversity, but that this relationship only holds in the tropics (Krause & Farina 2016).
To investigate whether biotic sound can be used as a proxy measure of habitats in cities, I conducted habitat surveys at all my study sites and compared local and landscape habitat measures with the biotic and anthropogenic acoustic activity and diversity.
Initial results suggest that there is a relationship between the biotic sound recorded at a site, and the characteristics of the local and landscape habitat. However, this research needs a bit more work before I’m confident in the results, and I will continue to work on this to try and answer the question of whether biotic sound can be used as a proxy measure of habitats in cities.

Next steps

In this research I have found that existing ecoacoustic tools in the form of acoustic indices are not suitable for use in cities as they either do not measure biotic sound or are biased by non-biotic sounds in recordings (Fairbrasset al. 2017). To overcome the shortcomings of acoustic indices, I have developed deep learning tools, CityNet (Fairbrass Firman et al. in review), which measure the biotic and anthropogenic sound in acoustic recordings made in noisy urban environments. Finally, I have found that biotic sound may be a good proxy for the characteristics of habitats in cities.
Cities are exciting places in which to develop new technologies for assessing biodiversity because the availability of power and Wifi connectivity makes it possible to develop autonomous systems for monitoring wildlife. For example, smart sensors and machine learning algorithms have been used to develop the world’s first end-to-end system for monitoring bat populations in the urban environment ( ). I think it is important that machine learning and sensing technologies continue to be used to improve our understanding of wildlife in cities, enabling us to design and manage better cities for the future.

Monday, 12 February 2018

Daubenton's on ice!

From BCT's Scottish Officer, Liz Ferrell, comes a fascinating story of winter bat behaviour:

Graham White, a nature enthusiast, had never seen a Daubenton’s bat before and certainly not during daylight hours! He therefore felt very lucky to see one (on two separate occasions) over the festive period where he lives in Coldstream, the Scottish Borders. Graham told us he had been walking along a section of the River Tweed on the 4th December. It was south facing and the bank was getting a lot of warmth - even on a very cold day. The old mill weir also meant the river was slow flowing and about a metre deep. The result was like a mirror with not even a ripple on the water. The only movement came from insects which dotted the surface. And then there it was, a Daubenton’s bat flying over the water at one o’clock in the afternoon!
By pure chance, on the 7th January, Graham saw another Daubenton’s. This time 1.5 miles from the River Tweed flying over Hirsel Lake along with the geese, swans and goldeneye he had been watching. The bat flew right next to Graham and for a further two minutes he watched and photographed the bat before it disappeared into the waterside trees. Graham mentions that the most astonishing thing this time around was that the lake was 95% covered in thin ice! The bat of course had found the other 5% unfrozen water (all thanks to some very clumsy geese after they had landed on the lake).
It led Graham to ask what exactly the bats were doing – were they drinking, actively foraging, both, or neither! In truth, it is hard to say. It was certainly a very surprising encounter with this little hunter. I think this story just goes to show that we have so much to learn about bats' activities through the winter and perhaps climate change is also going to have its effects. We all hope that these two bats were able to survive the winter.
Thank you Graham White for sharing your story and photos!

Have any readers seen anything similar? I'd love to hear about it!

Monday, 15 January 2018

Mysteries of the night

Mysteries of the night by Helen Hayes MP (species champion for the common pipistrelle)

Everyone finds different ways of coping with the shorter days and colder winter weather but some British wildlife have come up with enviable methods of getting through the worst of this season. As species champion for the common pipistrelle bat I have been discovering more about how this tiny creature, which weighs less than a pound coin, copes with the harshest of winters. Their tactic is to sleep, or rather hibernate, through the worst of the weather and start afresh when the warm weather returns. I am sure many people would quite like to spend winter that way!

Helen Hayes MP at the start of her bat walk
A lot of my knowledge about this tiny flying mammal comes from a bat walk I took part in last October. The bat walk was in West Norwood Cemetery where I was lucky enough to be accompanied by Jo Ferguson who is the Built Environment Officer for the Bat Conservation Trust (BCT) and Ian Boulton, who is the Environmental Compliance Officer for the London Borough of Lambeth. Both of these ecologists provided me with an array of interesting facts about these fascinating and important animals.  All 18 UK resident bat species eat insects and in winter these are just too scarce to be a reliable source of food so all of our bats spend the winter hibernating. Once the weather warms up enough they awake to restart their nightly chase of flying insects again.

The common pipistrelle, a species I am very proud to champion, is found right across the UK including in my London constituency of Dulwich and West Norwood. It is by far the most common bat species in the UK although its numbers are thought to have declined dramatically throughout the 20th century. I am happy to report that the work of the National Bat Monitoring Programme run by BCT shows that there are some promising signs of recovery in the common pipistrelle bat and some of the other 10 bat species they are able to monitor. Bats are a great indicator of the quality of our environment, so these signs of improvement should be welcomed by all of us.

Despite being the most common bat species, it remains a mystery as to where most common pipistrelle bats hibernate. This mystery is not restricted to the UK and researchers in the Netherlands were surprised to find that large numbers of pipistrelles were hibernating in the expansion gaps in the balconies of tower blocks.  Could some of Londons pipistrelles be hibernating in tall modern buildings? I am sure with the ongoing dedication of all the passionate volunteers involved in bat conservation we may eventually find out their secret but for now much about their lives remains a mystery.

On my bat walk I learned that there are steps we can all take to make cities more welcoming for bats and other wildlife. There is growing evidence that taking this approach is not just good for them but good for us too. Do take a look at the BCT website ( to find out more about bats and how to get involved in their conservation. There are local bat groups right across the UK including the London Bat Group.

This year I will not only be looking forward to the warmer spring weather but will also be keeping an eye on the night skies so I can spot a different sign of spring, the acrobatic flights of the common pipistrelle bat.

Helen Hayes MP receiving her common pipistrelle poster from Kit Stoner (Joint CEO)

To find out more about the Species Champion Project go to: 

Tuesday, 5 December 2017

Bats about Habitat First Group

Over the last 20 years Lower Mill Estate has concentrated its efforts on providing artificial roosting sites for bats by installing bat boxes on buildings, under bridges and at various locations around the site, as well as converting the roof voids of several bin store buildings on site into bat roosts. With an abundance of foraging habitat and a good population of insect prey, it is no surprise that these artificial roosts are regularly used by species including the Common pipistrelle (Pipistrellus pipistrellus), Soprano pipistrelle (Pipistrellus pygmaeus) and Natterer’s bats (Myotis nattereri).

 Lower Mill Estate by Luxury Marketing House
Excitingly, in recent months the Estate has discovered that the Habitat Houses on site are living up their name and are being regularly used by roosting bats. Bat droppings discovered at specific sites on the outside of the Habitat House were sent to Ecowarwicker Ecological Forensics for DNA analysis to confirm the species. The results of the analysis came back as positive for Natterer’s bat. Known for using small cracks and crevices in buildings and trees for roosting, the species has been using the gaps behind the wooden cladding on the Habitat House for roosting.  It is now intended to carry out bat surveys over the summer months in the villages on the Estate to determine which other species are present and where they may be roosting.

 Lower Mill Estate by Luxury Marketing House
With similar style of housing being built at Habitat First Group’s Silverlake site in Dorset it is hoped that the local bat population there will also benefit from new roosting sites. Meanwhile the bats are already making good use of the bat boxes installed on the boat stores in the villages and the unique bat loft created for Brown long-eared bats (Plecotus auritus) has recently been used by both Brown-long eared bats and Common pipistrelles. Perhaps the only bat loft in the country built from an old quarry sandhopper, this bat loft is a super example of HFGs commitment to sustainability supporting the Reduce, Reuse and Recycle principle.

Habitat First Group has a great reputation for building alongside nature and Lower Mill Estate is thought to support the largest House martin colony in the UK thanks to installing 60 artificial house martin nests 12 years ago. The artificial nests were soon used by the House martins arriving in the summer from Africa and year on year the number of birds has increased until there are now on average of 200 nests annually.  In coming months 150 nest boxes designed to support House sparrows (Passer domesticus) are to be installed around the buildings on the Estate. These birds are now on the Royal Society for Protection of Birds (RSPB) Red-list of birds of conversation concern following a decline of over 65% in their population numbers population over a 30-year period. It is hoped that the new project at Lower Mill Estate will help boost the numbers of these gregarious birds. Silverlake is set to follow suit and be a leader in building alongside nature as it progresses over the coming years.

For more information on Silverlake, Lower Mill Estate and the Habitat First Group, visit 

Wednesday, 22 November 2017

Papping Bats on Social Media by Liz Vinson

Do you remember the days of taking your precious roll of film to be developed? Did you spend the extra £££ for an hour’s developing or were you able to wait the three days to see what you had captured?

Oh! gone are those days; I remember the thrill of opening the paper wallet in the shop, like Charlie Bucket carefully unwrapping the Wonka Bar – how many photos would be in focus? How many would have been graffitied by the developer with a sticker saying it was over exposed or suchlike? And had you got away with accidentally opening the back of the camera before the film had rewound?

Then there would be the hours spent first showing all your friends and family the photos (“don’t put your fingers on the image, Grandpa, please”) followed by carefully placing your treasured images into an album, editing the best and writing a caption, “If only I had remembered to put the flash on” or “in the distance you can see…”

I remember the first time I saw a digital camera being used, I thought I would never use one because it would spoil the excitement of waiting to see what you had captured! Also, I thought the images would be so grainy they would be like the old Disc Cameras (remember them?!).

My first digital camera was actually a Nokia mobile phone – it boasted a 10 megapixel camera, and I happily filled its memory with random images – none of which, had I taken them with my trusty old point-and-click, would’ve made it past the album cutting-room floor!

After a very short time the novelty of printing out every image petered out, and my albums fell into a dusty retirement.

With the age of the smartphone came social media – somewhere for you to post every image you like for all your friends and complete strangers to look at and critique!

So where do bats come into this do I hear you ask?

“In the United Kingdom it is an offence to intentionally disturb bats or their roosts and this includes any photography without an appropriate license. As a licenced batworker / bat carer I have always exercised extreme caution when photographing bats out on surveys, and have never once used a flash. But then I wonder: should I share the photographs? If I do, who’s to say that unlicenced or untrained people will think it’s ok to start “papping” bats too?

With the ease of snapping just about everything thanks to smartphones, together with the recent flood of social media sites purely for sharing photographs (Instagram, Pinterest, Snapchat, etc.), it is inevitable that unsuspecting members of the public across the world will happily share photos they have taken of bats: bats on walls, bats on the ground, bats in their natural habitat. And who wouldn’t? How many people actually get the chance to get up close and personal with a bat? 

Many of  these images (in the UK and further afield) come from people who have found the bat during the daytime and need some advice or identification, and so have taken to social media for assistance – something the Bat Conservation Trust is excellent at responding to in a timely fashion.

And then there are the sad images I have found whilst searching #bat on sites such as Instagram – most recently a horrific photo from the US of a bat trapped in a toilet bowl, and a vitriolic comment saying they had “flushed the beast back to the depths of hell where it belonged”.

So, for me, there will be no more searching for bat-related images on such sites, as it only makes me cross to see images and statements like that – no matter how ignorant the user.

But as a bat carer I want to spread bat knowledge far and wide, and I do photograph every rescue which comes into my care, although I don’t photograph deceased animals or animals with terminal injuries, as I find them distressing enough to deal with.

Rescued soprano and common pipistrelle (photo by Liz Vinson)
How to transmit these images safely in social media terms?

I am often asked whether bats bite, and I say that we always recommend anyone rescuing a bat wears gloves or at least wraps the animal in a tea towel. If asked, I confirm that I cannot recall ever being bitten by a bat that had come into my care – which is the truth. However, these are wild animals and if they feel threatened they may act like it, hence the necessity for gloves or other protection.

I was trained never to handle without gloves, even if they were long term care bats, and, although it can make things a bit tricky, I manage. I was also told to never publish any photographs of bats in the hand unless I was wearing gloves. 
Rescued brown long-eared bat (Photo by Liz Vinson)

Rescued Common pipistrelle and pup (Photo by Liz Vinson)
Even if the person handling bats in a photo is trained and vaccinated, publishing pictures of them holding bats in un-gloved hands gives members of the public a clouded view of what is safe and recommended. I understand that batworkers wish to show that bats are not threatening, but would simply popping on a pair of gloves really undermine that message?

I find that white cotton gloves, which are available from most good pharmacies, are ideal a. for handling the smaller species and b. for photography purposes. (Although having said that, I have usually just been feeding the bat when I take a photo, and nine times out of ten I have the remnants of their supper somewhere visible on my gloves.) I also like to wrap bats in a soft cloth as it makes them more secure and less wriggly – something every bat carer dreads whilst trying to hand-feed the insides of mealworms to a tiny pipistrelle!

For larger species, such as serotines, I would not recommend anything thinner than a good gardening glove! Cumbersome as they are, I would not want to run the risk of having the bat’s jaw clamped onto my little finger, all for the sake of a good photo!

The pen is mightier than the sword

Almost more important than the image (of a bat in a gloved hand) which you post are the words that you choose.

Put a little statement about the bat, what species, why you have it and what people can do to help if they find a grounded bat.

Choose your #’s wisely!

If they’re not already there, consider adding the hashtags #licencedbatworker and/or #trainedbatcarer to your bio on social media sites. Other useful hashtags are #batsneedfriends, #batconservation, #batcare, #notapet and #protectedspecies.

Tag your local bat group and BCT so that they can like and share your image, helping to spread bat awareness.

And finally try to respond to any comments you may receive, especially those that ask if the bat is a pet!! – I have seen many comments on bat images on social media like “oh I want one” “I need a pet bat” “where can I get one?” and the original poster hasn’t replied at all.

So we can all do our bit for bat conservation awareness on social media, in a manner which should be the norm. It would be extremely detrimental to bat conservation if a member of the public picked up a bat, was bitten and tragically contracted rabies, and then pointed the finger at a bat carer who shared lots of images of bats in un-gloved hands. Food for thought…

Finally, returning to where I started – film canisters – now there was a useful piece of equipment to take on a roost survey for bat poo sample collection!

Gone are the days….

Liz Vinson
VBRV and registered Bat Carer
Self-employed marketing and social media manager

For more information about how to get involved with Bat Rehabilitation:

For more information about the importance of wearing gloves when handling bats see:

Thursday, 26 October 2017

Twilight Bat Walks at Mid-Essex Hospital Services NHS Trust – A summary of 2017

by David Jackson

Now that the autumn season is upon us, it provides a great opportunity for the Mid-Essex Hospital Services NHS Trust (MEHT for short) to reflect on another hugely successful Bat Walk Programme.
All bat species in the UK are endangered, with populations declining over the past decades; these fascinating mammals are protected by law.  Bats are also a biological indicator species, meaning their presence illustrates high ecosystem functionality and good environmental management.  At the MEHT, we are proud to have high bat activity around the Broomfield Hospital site, with a bat roost of soprano pipistrelles known within our Estates building.  Both soprano & common pipistrelles have been found foraging within our natural areas, feeding on insects during their summer months and highlighting our effective natural management.
Bat walks offer a unique educational opportunity to experience these intriguing creatures, and in 2016 we launched an inaugural Twilight Bat Walk Programme, led by a local bat enthusiast.  The walks proved to be a huge success, providing education in an endangered species whilst promoting healthy walking alternatives within Broomfield Hospital.  Following on from these walks, a larger Twilight Programme was produced for the summer of 2017.

A staggering 400% increase in participation occurred, with over 100 individuals expressing interest, comprising of staff, patients and members of our local community.
Marium, a former Trust Doctor stated ‘I and my three friends thoroughly enjoyed the bat walk, the guide was incredibly knowledgeable.  We heard about the opportunity after a friend was enthusiastically posting about it on Facebook after attending a previous walk!’
Carol, a member in the local community quoted ‘It was a fascinating evening using the monitoring equipment and identifying the sounds.  It's excellent that the hospital invites the public and hosts community events.  The guide’s enthusiasm and passion for bats was lovely to see and it's great to be able to share knowledge’
David Jackson, the bat enthusiast, and now the Trust’s Sustainability Project Coordinator said ‘It’s been great to see the walk participation increase so quickly…educating those in our community about endangered species is hugely valuable to their future conservation, whilst achieving it through the promotions of an active lifestyle.’
Bats are now moving to their hibernation roosts, but keep a look out for promotional materials when the Twilight Bat Walk Programme returns next year.

Tuesday, 10 October 2017

Bat House extraordinaire!

Darren Henwood contacted the National Bat Helpline recently with a desire to find out more about creating an ideal residence for bats. Darren has now created an extraordinary bat house which he is hoping will be appreciated and used by bats in the area of Essex where he lives. We decided to do an interview with him for this blog to find out more.
Darren Henwood with his 7.5m wide bat house in the background. 

Darren created roughly 21 square meters of accommodation for bats!
1. Can you remember seeing your first bat?
Yes, I saw my first bat when night fishing with my dad when I was about 5-6, made me jump at first but he said to relax and keep and eye around the bushes hanging over the waters edge, my first bat was part of a considerably large amount of bats! :) Looking back there must have been hundreds that night...

2. When did you first contact Bat Conservation Trust and why?
I had recently built a wooden garage at our home, and as we were keen to expand from the chickens we had to more livestock and some conservation factors too, we decided to build a bat roost/home on the flank end, also we had become privy to knowledge that a derelict, old, old pub on the corner of our road (the only other building on it in fact) was due for demolition, so this inspired me to "go big" and try to encourage any residents there to re-home here, I suspected there may have been horseshoe bats and pipistrelles as the roof damage looked promising for both to be there, from what research I had done anyway :) I wanted to basically re-iterate these findings and researched info with a nexus of the right info, so the BCT seemed a logical choice, and Grace was fantastic help sending info to answer all my questions and with some varied plans, so I used this information with that I had researched to try and couple all the elements into what you have called the BHE (which we love here btw!)

Darren is looking forward to the bats moving in
The design is based on the Kent Bat Box

3. What inspired you to create this magnificent bat box/house?
Most of what I said in question 2 is covered for this question, however I also have a keen technology mindset and wanted to be able to get cameras and bat listening devices set up in the BHE so that when (hopefully) it is occupied and I can no longer "intervene" things would be in place to enable the family and I to observe from the house, phone or even at school/college... :) Also once this is in place, if there is any data or information that would be of use to the BCT or other people keen to home bats, then that would be equally fantastic!

4. Do you have a favourite UK bat species? 
I have no favourite species, although my first memories are that of what I now know to be Pipistrelle bats, so would be keen to see them again, and have built a fair %age of the BHE for them to hopefully enjoy, also the lesser horseshoe bat has been accommodated for with plans from both the BCT and other online shares by enthusiasts, I kept the options lower for them as I believe there is a less habiat for the pipistrelle around us, but with all the essex clad barns etc, I think the horseshoes have a good shout in our area.. but then I'm only a few months into checking this all out, so.........
That said, any species would be welcomed as there is the added bonus that we can spend more time outside at night with less chance of being munched on by annoying biting insects :D

5. Any weird/wonderful bat facts or bat experience that you want to share with us?
Nothing that's going to turn heads sadly, but have previously had a bat fly into my landing net when it was set up to dry in the breeze at dusk, I now leave my nets on the ground till daylight/bat free hours :D

6. Why do you think bats are misunderstood or undervalued by so many people?
Late 50's horror films, old wives tales and Christopher Nolan. I would say they are undervalued by people as I feel there is very little useful information generally available, people have to actively seek information, and I suspect many people don't understand or know half of the species (all animals) in this country that could really do with a little help from us Humans... If you asked 100 people if they would have bats roosting in their eves or an eves/wall box they would probably shun them thinking they are blood sucking dirty monsters,,,

7. In your opinion, what is the biggest threat faced by bats?
Ignorance to their need for safe, undisturbed habitat/s and destruction without thought of existing habitat, as we think happened just up from us here.

8. Huge thank you for what you are doing. What advice would you give others who might consider following your example.
Ask questions, no matter how stupid you think they are to recognised bodies such as yourselves at the BCT, I had no practical/useful knowledge of bats so I immediately searched for a good, reliable source of information, as I said earlier Grace was very helpful and I would say anyone wanting to help maintain and help with propagation of bats should ask first, asking isn't a silly thing to do!