Woodland bats research by Aggie Thompson

Aggie Thompson recently completed an MRes in Wildlife Conservation with Marwell Wildlife and the University of Southampton. Her research focused on woodland bats and here she shares her experiences and thoughts with us

What got you interested in Woodland bats?

My interest in bats was sparked during an internship in Southampton, where I researched the impact of artificial lighting solutions on bats in an urban Site of Special Scientific Interest (SSSI). This experience opened my eyes to many of the challenges faced by bats worldwide, driven by urban development and landscape change. Following this internship, I was keen to continue working in this field and so took a post as a seasonal independent bat surveyor for an ecological consultancy. In 2016 I continued my studies and was accepted on the MRes in Wildlife Conservation with Marwell Wildlife and the University of Southampton, which provided me with the opportunity to carry out an 8 month research project from conception to completion. I chose to develop the ideas I had formed during my internship: exploring the impact of human disturbance on bat activity and species abundance. The focus of this study was the landscape complexity within a rural area of Hampshire and how human influences such as woodland management practices and stand structure, land use, and landscape connectivity impact bat populations.

Can you describe the research you carried out during your thesis?
The focus of my research was to assess the impact of both localised woodland features and land use influences on bat populations within a multifunctional landscape. I used two different types of acoustic survey to record bat activity across a complex managed landscape in Hampshire. Firstly, I carried out transect surveys along woodland fringe habitats to assess the impact of woodland management, land use and woodland connectivity on total and species level bat activity. Secondly, I deployed static bat detectors in 21 different locations within woodland stands to evaluate if woodland structural features (understorey height, canopy cover and clutter index), along with woodland management and woodland connectivity were predictors of total and species level bat activity inside woodland.

How can the results from your thesis be interpreted and in your opinion, what are the greatest threats faced by woodland bats?
Some of the biggest threats faced by UK bats are the removal of roosts or potential roost sites, the reduction of certain habitat types required by particular species, and reduced woodland connectivity, leading to isolated woodland patches less accessible to many bat species.  The results from my research highlight the importance of a heterogeneous landscape for supporting fragile populations. Increasing woodland connectivity or the installation of buffer strips would also allow access to currently isolated foraging habitat, and selective woodland management to avoid accidental disturbance or removal of roosts is essential.

Doing this type of study in woodlands is never easy, what were the highs and lows?

The research was very hands on and was quite challenging. It required a great deal of dedication and problem-solving.  Combining both the transect surveys and static detector data collection meant lots of late night surveys followed by full days of setting up static detector equipment, not to mention all of the data analysis!

However, as someone who loves to be outside, this research allowed me to enjoy exploring different habitats in Hampshire. As well as 13 bat species, I was fortunate to spot lots of other wildlife including foxes, badgers, voles and several species of deer. One of the great things about transect surveys is that in the right habitats they are typically high reward, so every night I was seeing and recording my study animals – unusual in wildlife conservation research!





What would your advice be to anyone thinking about doing a woodland bat project as part of their university studies?

Fieldwork can be challenging, requiring technical skills for programming and setting up equipment as well as the time consuming nature of data collection, requiring specialist knowledge of bat call identification. However, bat projects typically offer a combination of rewarding fieldwork as well as interesting data analysis. These projects can also lend themselves to having a wider impact, and given that bats are found worldwide many of the findings are often relevant to populations outside of the UK. Also, given that bats are considered good indicators of habitat quality, this opens up the possibility of drawing comparisons between other species or habitats. Using this comparative approach could help us to pinpoint the real impact of human disturbance on wildlife populations.

Going forward, what do you think are the interesting areas of research in the realm of woodland bats?
It would be of great value to look into practical uses for bats as indicators, in particular as indicators of climate change or to model the impact of future management or agricultural practices. It would also be interesting to establish at what distance certain features impact bat activity, such as the impact an intensively managed piece of woodland has on the use of the surrounding landscape by bats.

We always ask this although we know it is not a fair question... do you have a favourite bat species and why?
I think the wonderful thing about bats is the variety of species. There are over 1300 species worldwide, including insectivores, frugivores, nectarivores and hematophages. They are the second most abundant order of mammals and are found almost everywhere in the world. They are a truly diverse taxa and all have their own special qualities. (Have I successfully dodged the question?!)…

Test your mic and avoid a wasted session.

by Peter Flory, Peersonic Limited 

It makes sense to test your bat recorder or bat detector equipment prior to use. Microphones can degrade with time, the main enemy being humidity, or worse still total saturation.

So far, I have found that over a 5 year period I have no customers with failed microphones where they are using handheld equipment. I am sure they are all still working fine, but worry that they might be degrading and the user is unaware.

Static equipment left out in the weather is a different matter. I have observed totally dead mic's, and again more concerning some that have started to lose the top end response after a year or so of use.

So here are some thoughts on how to test your equipment and be sure it is going to be effective, with cost in mind.

Jangling Keys:

If you are a casual user why not just jangle keys. A detector will give you a response, but you just don't know how well it is operating over the frequency range.

Jangling keys is better if you have a recorder, the stimulus can be recorded and the response viewed as a spectrogram.

Here is a spectrogram of key jangling,I tried with different bunches of keys and found that on the whole the stimulus was covering the spectrum well up to about 110 kHz. Although it is not a repeatable signal. 

Fixed Frequency or frequency sweep:

A better test would be to use a definite fixed frequency, generated from a signal generator, a specific sine wave , or series of waves played back through a tweeter can give a measurable stimulus. 

Use a sine wave rather than a square wave as the latter contains many harmonics and it would be nice to observe the response at each frequency step as far as possible.

Signal generators are standard electronic test equipment. They are usually around the £150-£200 area, but there are some lower cost kits too that might be as low as £50.

A low cost China manufactured sig gen at a bit less than £150.

Next you need to select a speaker/ tweeter. These are never designed to cover the full bat spectrum, so some trials and selections are required. However they are not costly. There are voice coil speakers which are fairly level over 20kHz to 90kHz, Or pietzo speakers that will go much higher, both will suffer from features over the band so this needs to be considered. - There is no perfect flat response.

Now it is possible to chose a selection of signals, at predefinied amplitude ( volume ) and set up your own regular test pattern.

Just test and record, and observe and trends in the recordings that suggest deterioration over time.

Monthly perhaps.

Calibration:

Having found that a microphone is deteriorating, typically at the higher frequencies. You might want to calibrate it. You can't.

A mic that is on the way out is best consigned to the dustbin. This should not be confused with the process of matching a mic to a recorder by equalisation. That is fine, but not a great idea if the mic is becoming unreliable.

What to do with a sick mic:

Manufacturers vary, if you are able to replace the internal mic element this should be cheap, if the mic is a unit, you will need complete replacement. So from the lower end ( replacing the insert) to replacing the unit, the cost would be anything from £12.00 to about £300.

Specific bat Ultrasound mic testers:

Rather than go for a test equipment based arrangement, you could do better by obtaining an ultrasonic mic tester as a unit, speaker included or integrated, with features specified in the suppliers data sheet or users manual. Should make life easier.

Some testers emit a spot frequency, 40 kHz, 60 kHz. This will certainly show something, but what about at 125kHz? Or the various points in between? Best thing then is to emit a series of stepped frequencies. Also a chirrup is useful as it gives a fast changing signal and your spectrogram will show up some missing points perhaps.

Stepped frequencies will allow you to check your heterodyne or FD equipment at each point, a full range of patterns is even more revealing for recording FS gear.

At Peersonic I have developed a tester that emits single steps over the range, plus patterns, and for fun some emulated familiar bat sounds.

https://www.peersonic.co.uk/playback

Speaking to my competitors I find there are fixed frequency testers, and I note the Titley "chirp" equipment, which is similar , but moves on to offer a complete test bench that ensures the speaker and receiver are at a fixed distance from each other.

From left to right: a Peersonic multi-mode mic tester, an Elekon dual-mode tester and a Titley Anabat tester 

Test Environment:

If you are expecting to get highly repeatable calibrated measurements you had better hire a sound chamber, and probably some expensive transducer equipment. But, just testing if it's ok is really good enough for most of us. Here is some advice -

Try to keep the following the same each time for best results.

Use the same room.

Try to ensure that the furniture is in much the same position each time.

Do not stand next to the speaker, or in front, best to operate from behind the setup..

Avoid wearing wooly pullovers as they are absorbers of sound.

If you can, check that there is no electromagnetic interference, (a desktop PC with the sides off tends to transmit all sorts of rubbish).

Or test outside in an open space.

Conclusion:

Testing your mic is a bit like backing up your computer. Unless you are running a schedule, it really only happens when its too late.

Partnership for Biodiversity in Planning - Wildlife Assessment Check

by Rosalie Callway (BCT's Partnership for Biodiversity in Planning Project Officer)

Since 1970 many UK wildlife species have been in decline, with over 1,200 species now extinct or threatened with extinction (State of nature report, 2016).  One of the factors that has caused this decline is land use changes from urban development.

Smaller developers may be unaware that it is a statutory requirement for UK local planning authorities to consider the ecological impact of developments via planning applications, as well as promote a positive contribution to biodiversity. 

However, some authorities are struggling to find the resources to conduct the necessary checks to see if wildlife may be impacted by a proposed development. Without the right data about the biodiversity impacts, an authority can’t make an informed decision on planning applications – this means that authorities may be granting planning permission to developments that will have negative impacts to wildlife.

The Association of Local Government Ecologists estimates that two-thirds of local authorities do not have an in-house ecologist or ecology team. Restricted local authority budgets and lack of in-house ecological expertise means that biodiversity is given insufficient attention during the planning process. For example, in London, there were over 90,000 planning applications in 2016 but less than one percent (0.86%) of these applications consulted existing biodiversity data records to assess the potential impact of the applications (GIGL, 2017). This is despite the GLA estimating that around a fifth of planning applications (18%) are likely to require background biodiversity checks. In Hampshire, of 10,400 applications in 2017, only 4% (368) were checked by the local environmental records centre. Similar to London, Hampshire-based record centres had flagged a fifth of the applications (2,325) as of potential ecological concern.

The Partnership for Biodiversity in Planning is seeking to increase awareness about the need for background biodiversity checks, by local planning authorities as well as by householders and developers. The partnership, involving 18 organisations, has developed an online tool – the Wildlife Assessment Check – to help indicate when expert ecological input is required as a part of a planning application.

The Wildlife Assessment Check is a free online tool, designed to help householders and smaller developers check whether their proposed site and works are likely to require expert ecological advice before making a planning application. It aims to smooth out the planning application process for applicants by encouraging them to address potential ecological impacts early on, reducing unnecessary delays and costs. It also aims to support local planning authorities who lack in-house ecological capacity by encouraging applicants to take responsibility in addressing ecological considerations. 

The partnership is now rolling out the tool and inviting user feedback over the next few months to ensure that it works well and is straight forward to use.

Twitter: @BiodiversityPs 

Email: pbp@bats.org.uk            

Website: www.biodiversityinplanning.org 

The Pulling Power of Images in Bat Conservation

by Paul Colley

I’m a conservationist by instinct, because I love the natural world. But like many I now worry seriously about climate change, loss of habitat; you know the issues as well as I do.

We can all make a difference. As a photographer I’m naturally interested in the pulling power of good images in conservation. I’m really an underwater photographer by trade and have photographed so many interesting subjects, from trout and grayling in Hampshire chalk streams to blue sharks off the coast of Cornwall and silky sharks in Cuba.

Looking for a new challenge, I saw bats hunting over water whilst photographing trout and thought there was scope to do something different. I could not have found a harder target! The problem rightly started with the bats’ protected status and early in my research I contacted the Bat Conservation Trust and started a helpful dialogue about my project with people there and at Natural England. Although the chosen approach did not require a licence, I inevitably ended up with self-imposed restrictions, principally about levels of artificial light.

The lovely Daubenton's bat (Myotis daubentonii) has that super-cool trick of intercepting an insect just as it hatches at the water’s surface. But I also wanted to show the bat’s hunting flightpath and habitat. The technical challenges soon kicked in. I developed two techniques that were gentle on the bats. Low light (flash guns at minimum power) and infrared (almost invisible to human and bat eyes). Infrared opened up new creative possibilities and I used a constant light, flash guns and cameras all modified to specific infrared wavelengths.

You need millisecond precision to catch the action so I opted for a laser trigger with the beam riding a couple of centimetres above the water. My route to success was littered with a thousand failures, because making this work in the dark was tricky. Not least because I had to power the infrared lights with 240 volts using a 12 volt car battery and inverter, all mounted on tripods over water. It was an interesting risk assessment!

But persistence pays off. I might have given up one night when I stood waist deep in water for almost five hours. The bats were swarming around me chasing a massive hatch of insects. But not a single picture was useable. Utterly dejected, I discovered in the analysis next morning that I had made a silly mathematical error in my trigger calculations.

After fourteen months, over a hundred night field trips and countless other hours modifying the camera trap in my workshop, it came together in a beautiful image. I call it ‘contrails at dawn’ and it won the British Wildlife Photography Awards 2018 (you can see the image here: https://www.bwpawards.org/winners2018). The Bat Conservation Trust is already using it to draw people in to the bat conservation story.

So now I have a request for bat conservationists. Where can I go to document different species and the wider stories behind bat conservation? It must start with powerful imagery of the bats themselves, because that is what will hook people in. I now have an excellent suite of new photography techniques to exploit, but remain open minded about new potential subjects and stories. I’m keen to get involved with people who already hold the appropriate licences. If you would like to work with me in my quest to raise the conservation profile of bats by using powerful imagery, please do get in touch and offer me some suggestions. I cannot promise to work with everyone due to my busy programme. But I’m determined to work with some who might help me create good stories enhanced by the pulling power of new imagery.

Use the contact page at www.mpcolley.com

The MSP’s championing our bats - The Species Champions Initiative 100 day challenge

by Liz Ferrell, BCT's Scottish Officer

I am always a bit apprehensive before bat walks as there is always the weather to contend with in Scotland! But, it has to be said, bats have never disappointed me. They are hardy little mammals and they put on a good display for us as we walked around Holyrood Park in Edinburgh. Perhaps they enjoy the big occasions and Tuesday night was definitely one of those!

Through the Scottish Environment LINK, member organisations (which includes the Bat Conservation Trust (BCT)) were asking over 100 Members of the Scottish Parliament (MSP), who had accepted to become a Species Champion, to participate in a series of actions over a 100 day period (#Species100). We were asking them to help raise awareness about their selected species, the threats to their populations as well as the wider biodiversity concerns in Scotland. 

Taking part in the bat walk as part of this challenge were MSP’s Annie Wells, Finlay Carson and Fulton MacGregor who all attended on what was a wet and windy night at Holyrood. It needed more than rain to dampen their spirits however and it was lovely to chat to them about bats as well as their work as MSP’s. 

All excited to start our bat walk outside the Scottish Parliament 

I am happy to say that their smiles remained there for the remainder of the night! Annie was very pleased to have her species, the common pipistrelle, foraging over her head and we watched as the bat continued to fly back and forth. The poor thing was fighting against the wind and we all agreed that he or she was a determined individual!

Finlay was as keen as ever, even without the opportunity to see or hear his species, the Leisler’s bat. He is very passionate about his chosen species which is found in his constituency of Galloway. He has visited the Wood of Cree where these rare bats are fairly common. Fulton too has still to see his species, the natterer’s bat, and without visiting a roost (which I have promised him) it is a tall order! They are not as easy to find as our pipistrelle species are. But, he knows a lot about his species already and I have run a bat walk for him in his local constituency in August.

Reflecting back on this 100 day challenge, I have to say it has been great. It was such a pleasure to see how genuinely enthusiastic our MSP’s all are about their species and to see that they know so much already about bats! It has certainly kick started my engagement with them and I am really looking forward to working with them all going forward as we organize some more batty evenings. I hope I will have further news to share with you on this initiative soon…

LINK’s award-winning initiative “Species Champions” pairs MSPs with species that are under threat in Scotland. With almost 1 in 10 species in Scotland at risk of extinction, political support for protecting our precious natural environment has never been more critical. To find out more about this initiative check the Scottish Environment LINK’s website here. 

‘Testing Times Ahead – A Cosmic Bat Adventure’

Beverley Clarke, of the Loch Lomond Bat Group (LLBG), explains about a big leap the small group have made this year. 

So, what did you do on the very hot and sunny May Bank Holiday Weekend? (Apologies to those of you in England who were subject to flash flooding). Well, here in Scotland, where summer conditions are a rarity to be savoured, most Scots were making the most of the tropical like conditions - having a barbecue or garden party, going for a picnic, visit to the beach or camping. However, for some Loch

Lomond Bat Group members it was to be a hot and sticky venture into their first BCT/Forest Research ‘Putting UK Woodland Bats on the Map’ survey (PUKWBotM). Loch Lomond Bat Group are a very small hardy bunch of bat enthusiasts.  We have a core membership of just five or six people at any given point, who start each survey season with the hope that they will at least make it through our NBMP surveys and public events programme.  Every year we endeavour to recruit some more hardy souls to join us, but usually by the time we get to Field Survey time, we are back to the Famous Five!

Liz Ferrell helps with set up of SM2

So, it was quite a leap into the unknown for our wee bunch to take something of the magnitude of PUKWBotM.  For context, we have likened it to a classroom full of kids making water bottle rockets in one week and sending one of their pupils to the moon on another week!! Maybe a slight over exaggeration, but when the Scottish Bat Officer Liz Ferrell organised the first training night to help familiarise us with the equipment we would using in the survey, that is what the learning curve felt like.

In brief, for those that may not be aware, the survey involves the of testing three types of bat field monitoring equipment – standard SM2 detectors, low cost acoustic sensors called Audio Moths, and Pettersson Ultrasound Microphones (which connect to tablets).  As well as setting out the static recording points, there is also a walking transect. The final aim is to gather data that can be used to calculate representative detection probabilities for different bat species in woodland, to inform the design of future woodland monitoring schemes.

Adam and Gavin trying to set up an SM2

The two members who gleefully signed us up for the project last year, had to design the transect themselves in two types of woodland; broadleaf and plantation. This they dutifully did last year, and this year were sent through all the gadgets and gizmos, with our key member, Adam, signing his life away to a few thousand pounds worth of BCT equipment.

We now had our ‘rockets’ to play with but had little idea how to launch them despite the extensive manuals and ‘idiot guides’ sent through by the Woodland Officer, Sonia Reveley from London. This is where the amazing Liz Ferrell, the new Scottish Bat Officer stepped in. Through her experience, knowledge, sheer will, enthusiasm, Doodle Polls and some backside kicking, she helped those that signed up to get trained, set up the first dates for the surveys and helped us set up the equipment for the first survey on a sticky midge filled Saturday night in a broadleaf woodland in the Trossachs, after having driven directly from Wick from her holiday! By the Monday night for the plantation survey, we were on our own!  The mission to the moon had begun!

With the first month’s surveys done, we have another four to go. We have already hit a couple of meteorite-like snags on our mission, but we are still learning.  Maybe by the 3rd or 4th survey, we might make it all the way there!

We are very proud, if a little foolish, to be the only bat group in Scotland attempting this survey, but if we can pull it off, it may seem like a small step for those bat conservationists out there, who do this on a regular basis, but for us it will be a great leap for little group of enthusiasts.
Finally, a huge thank you to Liz for her help, support and dedication to our group and for getting us to the launch pad in time….to infinity and…. right enough of that!!

Liz Ferrel and Suzie the guinea pig with trainees

An interview with a Helpline Out of Hours Volunteer

Rachael Varney is a Bat Helpline Out of Hours (OOH) volunteer, a service where volunteers answer emergency calls from the public who have found a bat in need of help. The OOH Bat Helpline is active in the evenings (5:30PM - 10:30PM) and on weekends and bank holidays (9AM - 10:30PM). 

What inspired you to volunteer on the national bat helpline out of hours service (OOH)?

I used to work as a veterinary receptionist and when injured or grounded bats were brought in to the surgery I would always have a quick peek at them in the box! Nobody seemed to know much about how to care for them, but luckily, we had a very knowledgeable bat carer who we would call upon to take them off our hands. When I saw the volunteer opportunity for OOH, I thought it would be great to learn more about bats, and hopefully do a little to help them too.

There are lots of wildlife you could have given your time to, why bats?

I think bats are misunderstood and somewhat shrouded in mystery, and many people dislike or even fear them. As well as wanting to learn more about bats myself, I hope I can educate people whilst doing the OOH call taking to realise what interesting creatures they really are.

What do you enjoy about volunteering on OOH?

I enjoy talking to different people from all over the UK – you never know who will be on the other end of the phone, or what situation the bat is in. Most people who have taken the time to call OOH, have a genuine desire to help the bat, even if they have a fear or are unsure of what to do. It’s great to be able to give people advice and the confidence to be able to help the bat – there’s a real feel-good factor involved. I enjoy learning about ways we can lessen our impact on the natural world and regularly get involved with online petitions on social media, but I sometimes feel overwhelmed by all the negativity. OOH has shown me that there are some really kind people who are willing to go out of their way to help, and that’s quite uplifting.

What’s your at-home set up like for OOH?

I make sure I have everything to hand -  some snacks, a couple of cold drinks, a notepad and pen, and my OOH folder given to me during training. I’m quite lucky to have a spare bedroom that acts as a little office, so I can concentrate on OOH without too many distractions, although I do sometimes end up with the cat sat on my knee!

Do you have a favourite or most satisfying call that you can share with us?

I think my favourite call so far was from a gentleman who had been out walking his dog on a park and had seen a bat trapped behind the mesh of a large disused speaker. Before calling OOH he had already contacted the places I was going to recommend – the RSPCA, the local council to see who the speakers belonged to, a security firm connected to the park. I was at a loss as to what to suggest, but put him in touch with a bat carer local to him, in the hope they might have come across a similar situation before and had some more ideas. I was hopeful, but really worried it would not be a happy ending for the bat.

After my Bat Watch, I spoke to my allocated Back up Staff (during Bat Watches,  volunteers always have a phone number available for a member of staff from the Bat Conservation Trust to provide advice or assistance, which is really reassuring). I decided to call the gentleman back just to double check we had discussed every possible avenue of people or places to call upon for help in trying to rescue the bat. I’m so glad I made that call as what he told me made my weekend! The RSPCA had managed to send out an inspector, and the bat carer who I put him in touch with had attended to help, along with the local fire brigade! They managed to saw through the speaker so that the bat carer was able to get close enough to get hold of the bat and safely contain him. It was a fantastic team effort from everyone involved to rescue this little pipistrelle bat, fondly named Boris by the man who spotted him. I have since heard that Boris had a little rest and recuperation that evening with the bat carer and was fit enough to be released the following evening.

How about your most challenging call so far?

So far, I’ve been quite lucky, and I’d say my most challenging call was from a lady who was struggling to hear me over the excited chattering of her young children who had just found a bat! I think it’s important that children take an interest in nature and advised the caller that the Bat Conservation Trust would happily send out some children’s activity packs, so they could learn more about bats.

What advice would you offer to anyone else considering taking up OOH volunteering next year?

Go for it! Although I come from an ‘animal background’ having worked in a veterinary practice, I knew hardly anything about bats.  The Bat Conservation Trust provide a day’s training which covers everything you need to know to get started on OOH call taking and offer great support for volunteers along the way. OOH volunteers are usually the first port of call for members of the public who have found a bat and are usually the ones who ‘get the ball rolling’ for a rescue / rehabilitation attempt. It feels great to be part of something so beneficial for British wildlife.   

We have to ask… favourite bat and why?

I’ve not seen one in real life (yet!), but it has to be the long-eared bat. Those ears are just too cute!