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Friday, 22 November 2013

Bats and Breathable Roof Membrane what’s all the Fuss?

As bat Ecologists we are often told/asked by Architects that they will/would like to use a Breathable Roof Membranes (BRM) in there development project, however we advise that they are not used when bats are encountered. Why?

Background: -

BRM’s are increasing used in modern buildings due to their energy efficient nature, current insulation standards and their ability to allow water vapour (but not liquid to enter) to exit the roof void. Formerly traditional materials such as felt and air-bricks were used to prevent water vapour build up.

BRM’s are produced using layers of non-woven materials that are then bonded through pressure and heat. A long polypropylene fibre is used to produce the outer layer and it is this that has caused concern amongst bat workers.

Although common, most people don’t realize that some bats (due to habitat loss) now rely on man-made structures for shelter and security, often this is a dwelling or similar. This is where problems arise and these often go unnoticed due to the bats habits.

What are the issues?

There are three main issues with BRM’s and bats: -

1.    Entanglement or trapping

2.    Microclimate

3.    Membrane longevity


For Ecologists this is by far the most concerning aspect of BRM’s and bat interactions. Although not scientifically proven (to date) anecdotal evidence strongly suggests that bats are getting trapped in the fibres of the BRM. Stacey Waring is currently undertaking a research project on this very subject and the evidence gained strongly suggests bats do get entangled, check out her Blog


A traditional felt lined roof will have very different thermal properties to a BRM (Waring, S. et al 2013). However the research here is lacking and other than the obvious there is no way of knowing the effect that BRM’s may have on a long term roost.

Further research in roosts that have been changed from a traditional felt to BRM needs to be undertaken. It is however likely that temperature and humidity will be affected (Waring, S. 2013)

Membrane Longevity

Again research is lacking but anecdotal evidence suggests that damage to the membrane can occur from when the bats claws become entangled. This causes something called ‘fluffing’. This is where the fibres of the BRM fluff up to form a cotton wool like structure on the surface of the BRM.

Other concerns are the oil in bats fur, urine and droppings causing the BRM to lose its water vapour/proofing properties.

This in turn could cause damage to the BRM installed and the water vapour and water tight properties of the BRM to become reduced or useless (Waring, S. et al,2013).

So, which BRM’s are suitable to use when bats are present?

Well the simple answer is, none!

Current advice is not to use a BRM in a roof where bats are going to be encountered. Traditional bitumen felt (although having its own issues) has been used for over 100yrs, with only a minor number of reports of bats being entangled.

Put simply, if bats are going to be present in a roof following re-roofing or a new build following demolition of an older building a traditional felt should be used. Although there is an increase in the use of the BRM current Building Regs allow the use of a traditional felt, normally known as a ventilated roof system.

References: -
Waring, S. 2013,, assessed on 25/11/2013
Waring, S. et al, 2013, Double Jeopardy: The Potential for Problems when Bats Interact with Breathable Roof Membranes in the UK.

Monday, 7 October 2013

The Last Bat Group Survey of the Season

As the bat survey season winds down and planning surveys can no longer be undertaken, it gives us consultants a chance to put some time back by volunteering for bats.

At this time of year bats are preoccupied with mating and checking out hibernation sites ready for winter.

Last night I organised an autumn swarming survey (this is different to dawn swarming, in that it occurs over hours rather than 15/20minutes and goes late into the night).

A site we have had access to for several years now just outside of Luton already has one autumn swarming site confirmed, however we wanted to check another area that was a former Bothy (semi-underground, gardeners den (for want of a better description).

So last night (06/10/2013) 8 of the bat group keen to get in one last survey headed off to try some harp trapping and mist netting.

We walked down to the site and proceeded to set up just after dusk. Following the set-up we all settled down to wait.

Nets and the trap were checked regularly, but other than the odd Pipistrelle (common and soprano)call nothing was heard.

Some time later at approx. 21.00 the harp trap was checked, not expecting anything to be in the trap, a quick glance suddenly showed a bat. This turned out to be a male Daubentons bat, most probably a juvenile.

This was the first of several more bats caught, with a total of  six Natterer's again all male and last but not least a male Barbestelle

                                          Photo: - Barbestelle in the hand (Martin O'Connor)

This Barbestelle is a new species for the site and is the first to be caught this far south in the county, it could well be a cross border bat, given that Hertfordshire is only a stones throw from the site, but nevertheless it was caught in Bedfordshire.

All the bats caught were male and the site is now confirmed as the second autumn swarming site within the grounds of the estate.

This was my first opportunity to handle a Barbestelle, having only seen them 'up close' in hibernation or missed them on previous netting sessions due to having to leave early for work the following morning.

So in total nine bats were caught, six Natterers, one Daubenton, one brown long eared and one Barbestelle.

This goes down as the best night at this site and confirms the estate as probably the best bat site in the south of the county and by far in Luton.

                                          Photo: - Daubentons being weighed (Martin O'Connor)

Photo Bob Cornes
Photo:- Natterers bat with hair loss (Bob Cornes)

Monday, 16 September 2013

Sad News


I write this with a heavy heart, having set-up this Blog to inform you all of the progress of the Noctule that was brought into captivity some 3 and a bit years ago. Then she give birth and the saga of the release of the pup followed.

Over the last three and a bit years this bat has worked for the bat group as an educational bat and has reached many 1000's of people. Helping to dispel myths and fears of these wonderful creatures.

She has been to schools, WI meetings, events and many other functions. She was much loved by the group and it is sad news for the bat group and those that have meet her over the years.

Unfortunately over the weekend (13/09/2013) she died whilst being looked after by one of the bat care team (I was away for the weekend).

She had been displaying some symptoms of being ill, such as being bunged up and going off her food. And although we did everything to help her the efforts were in vane.

This blog will continue in her memory and hopefully bring better news in the future.

Wednesday, 4 September 2013

Wildlife Acoustics EM3

This March I was told by my MD (I am a bat consultant) that he was upgrading all of our equipment, so after much looking around, I came across the Wildlife Acoustic EM3 handheld detector. I had been aware of it, but hadn't given it much thought due to the price.

I had been using a Petterrson D240X with recorder for much of my work and although it is an excellent detector it can be cumbersome due to all the wires running to and from the detector.

The EM3 seem to fit the bill for what we wanted e.g. handheld, built in recorder (with several formats, I use WAV) and it had a screen which allows the sonogram to be displayed.

I have now had an EM3 for the whole of a bat season and have come to grips with using it. Hence this little review.

On first thoughts I didn't really like it to much!

It was quite large in the hand (although I have fairly large hands), it was complicated and not intuitive and it ate batteries (even though these are re-chargeable). The real time expansion (RTE) sounded odd compared to the D240X and the heterodyne mode although good was difficult to scan though the frequencies.

The build quality looked poor and it lacked a lanyard to secure it, when fumbling around in the dark, so it could be dropped.

However: -

I have come to love using this detector and really would be lost without it!

The sonogram screen although small is just excellent, allowing almost instant confirmation of the species your listening to (assuming it is not Myotis or other difficult species) and you can zoom into the call if you if you need to. You can toggle between a white background and dark background to save your night vision. Recorded without the need for other devices and loads of wires everywhere and instantly check the call on the screen .

Having now learnt how to set it up to my needs (check the Wildlife Acoustics website for tutorials) the detector has taken on a life of its own. I now listen in RTE as standard so that I don't miss any bat passes and don't have to fumble around with buttons on the wrong side of the detector. I have changed the trigger level of the detector so unwanted noise is not recorded and it saves the files in small snippets making sound analysis fast.

There are still problems with this detector, for instance changing the buttons to the left side would be a great help as I am right-handed, adding a lanyard to the case to prevent dropping it in the dark and installing a more sensitive microphone would all be good additions.

However with all that said, I really couldn't do without this bit of kit anymore!


Swineshead Re-Visited

Swineshead revisited

Last week the guys headed back to Swineshead wood with the aim of catching and perhaps tagging one of the Myotis bats we heard earlier in the year.

We were joined by Daniel Hargreaves who stopped off on his way to Luton Airport for a flight at silly o’clock this morning.We set up two harp traps and lures and settled down to wait. We didn’t have to wait long before not one but three bats entered the first harp trap.

We caught a male Natterer’s and the first of four barbastelles in beautiful condition
But the third bag was the most exciting and indeed the most satisfactory in purely dramatic terms, for therein rested a male Nathusius. This is the first Nathusius we have had in the hand for twenty years. The only previous sighting was a single male who was found grounded and died soon after.
Nathusius pipistrelle Photo Jude Hirstwood
Nathusius pipistrelle Photo Jude Hirstwood
This bat had very large buccal glands as you can see in this photo and was in full breeding condition .
Nathusius pipistrelle. Photo Bob Cornes
Nathusius pipistrelle. Photo Bob Cornes
Nathusius pipistrelle with prominent buccal gland. Photo Bob Cornes
Nathusius pipistrelle with prominent buccal gland. Photo Bob Cornes

Swineshead is quite a way from the nearest large water bodies.Perhaps he was migrating in a quest for females.

One thing is sure, this really is an exceptional wood!.

Nathusius males sit in a suitable spot and call, often all night in the hope of attracting a female. You can see Daniel Hargreaves’ video of an advertising Nathusius  on You Tue

Sunday, 18 August 2013

First Natterer's in bat boxes


weighing bat
Aidan processes a bat Photo Bob Cornes

Yesterday we did another check of the King’s Wood boxes and found rather more bats.

Natterer's bat
Juvenile Natterer’s Bat Photo Bob Cornes

The highlight of the day as finding our first Natterer’s  – a group of 6 juveniles, four males and two females in a box which has previously occupied first by pips and then by Brown long eared bats.

Photo Chantelle Kerr
Photo Chantelle Kerr

Tickilsh? Photo Bob Cornes
Ticklish or smug to have escaped first time?  Photo Bob Cornes
Photo Chantelle Kerr
Photo Chantelle Kerr

Another box had 36 Brown long eared in it – 36 in all 14 adult females, 12 of which were lactating) and 10 juvenile males and 7 juvenile females. Another four managed to sneak off when the box was opened. We found four more brown eared bats in nearby boxes  2 juvenile females and 2 adults which might have been these Houdinis. A lot of these juveniles were very young , in contrast with the Natterer’s who were late juveniles.

We also found a male Noctule in what is euphemistically called “full breeding condition”He was not an exhibitionist ( unlike some bat group members) and was not prepared to flash his genitals for the camera.
Photo Chantelle Kerr
Photo Chantelle Kerr

We also found one male soprano pipistrele, similarly well endowed. Last year we found many pipistrelles and it is interesting that we have found so few this year.
With the delay in the renewal of Bob’s Licence, we were unable to get the rings we wanted  ( you have to have a current licence to ring bats) and so will have to delay ringing till nest time .

Friday, 9 August 2013

Bedfordshire Serotine Roost

The bat group were really sorry to learn that the owner of the serotine roost died last year.
Audrey loved hosting the bats and made us very welcome whenever we went round.
The serotine roost was used in a PhD research project which involved ringing the bats. We have been returning every year since to try to catch the bats and check the ring numbers.
Photo Hedj Dollman
Photo Hedj Dollman

Audrey was very clear that she wanted us to continue to monitor the roost and Tony went round to see the new occupants who did not realise they shared their house with bats. They were happy to let us check the roost. The bats were as sneaky as usual and of the 6 bats that emerged we only managed to catch two of them using our patent bat catcher- which Iain described last year as “A zimmer frame wearing a nappy”,
Photo Jude Hirstwood
Photo Jude Hirstwood

One of the bats was  a female ringed three years ago and not caught since, she hadn’t had a baby this year and the other was  a male juvenile ( our first ever captured male). Numbers were lower this year but we know that serotine colonies use several roosts.

The householders have said we can go back next year and continue monitoring the roost – the only known serotine in Bedfordshire.

We are very happy to do this and honour Audrey’s request.

Tuesday, 6 August 2013

Noctule Mum Released

Way back in the winter we brought a very  underweight noctule into care.  She gave birth earlier this year and Simon has been caring for both of them. Mum got very podgy and was not keen to fly. So she was put through an intensive training course and her mealworm intake was reduced still further. Junior has still to get the hang of flying and is not that keen on exercise either, but he will see the light in time!

The Noctule prior to departure. Photo Jude Hirstwood
The Noctule prior to departure. Photo Jude Hirstwood

Yesterday we went back to the spot where the Noctule was found. We were a bit concerned when it began to rain early in the evening, but that cleared when we made our way out from the car. Simon and his family had got quite attached to the bat during her time in residence. Simon’s daughter insisted he dad give the bat a final cuddle before she was released. This was duly done.
Simon says goodbye to the Noctule
Simon says goodbye to the Noctule

To begin with the bat was perfectly happy to stay nestled in his hand, but when he held her out to the elements her curiousity peaked. She crawled onto the edge of his glove and then stretched her wings. We held our breath and then she opened her wings fully and launched herself off into the night- too fast for me to get a photo We listened to her on a bat detector as we watched her fly away. She did several large circles, presumably orienting herself to her home environment and flew off strongly.
The moment of release Photo Jude Hirstwood
The moment of release Photo Jude Hirstwood
It was a wonderful moment to see her fly free. Bat care is time consuming and often the outcome is not successful but this makes up for everything.
Now Simon is going to concentrate on getting junior flight ready. Thanks to Simon for all his hard work.

Wednesday, 31 July 2013

Another Barbastelle

We have been monitoring Stockgrove Country Park regularly for the past twenty five years. In recent years we have heard occasional barbastelles, but on Monday night we tried harp trapping there and found ourselves in the middle of  a high level of barbastelle activity, and much to our delight one, a  non breeding female, graced the harp trap with her presence.
Barbastelle, Photo by Bob Cornes
Barbastelle, Photo by Bob Cornes
Some people think these are ugly bats as there eyes are difficult to spot but we have a soft spot for them.
barbastelle fur One of their nicest features is silver tipped fur

Saturday, 27 July 2013

New Project

Phil Brown (University of Bristol) is carrying out two surveys in Bedfordshire

This is part of his university project looking at Whiskered/Alcathoe/Brandt's (WAB)

Further details to follow once the surveys have been completed.

Bat Box Project updated

When fixing dates for the monthly box surveys we deliberately put the June check early in the month and the July one later.

We found nothing but birds on the June one and had heard that people were finding new born Brown long eared bats in boxes in other counties recently.

It was decided to go ahead with the check but not to disturb any boxes that held brown long eared bats.

Almost the first box that was checked appeared empty,  but on being opened had a very young juvenile in it.

There was no sign of its mother. The box was closed immediately and for the rest of the check, boxes containing Brown Long Eared bats were not opened.(Their long ears are, fortunately, pretty visible.)
Brown long eared bat Bob Cornes
Brown long eared bat Bob Cornes (photo taken last year)

This meant that the check was quite speedy as no boxes contained anything other than brown long eared bats. The questions has to be – where were the pipistrelles.

Further Woodland Surveys

With the good weather the bat group has been able to go out a lot.

On Tuesday Aidan, Bob and Dave headed to Kings Wood Heath and Reach and tried netting in a woodland block.
Griffins were set up at high and low level.

There were no echolocation calls but we picked up some interesting social calls. Alarmingly Jude failed to provide any cake.

This alarming event caused great concern so on Friday when we went to resurvey a wood we had visited with Lia Gilmour last year, everybody brought cake, so that some came home at the end of the evening.

When we were there last year the temperature was 4 degrees centigrade. It was very different last night. A juvenile noctule, several Daubenton’s and a soprano pipistrelle were caught, but there were still no Natterer’s.

A Response to the Westminster Hall Bats and Churchs Debate


Photo Jon Dawson
Photo Jon Dawson

There has continued to be lots of comments about Sir Tim Baldry’s  recent speech at Westminster Hall.  .

Dr Kirsty Park of Stirling University has just posted a comment on her blog . (Kirsty’s PhD was bat related and she knows of what she speaks).

I should point out to those of a nervous disposition that these are not real bats  and that the bats living in our churches are not this size.

They are made by greensmith (someone who works with copper). I stole this photo from

Barbastelle tracking

No posts for a while and you may have thought we had gone into torpor!!

Far from it, we have had a radio tag on a non pregnant female (obviously) barbastelle and have so  far found 5 roost trees, and got some good film footage. Once the tag  stops working I will try to update what has been happening. If interested , in the meantime have a look at our facebook page where Jude has been posting regular updates.

Quick update – found a 6th roost. Tag must be nearing end of its life soon – then we can catch up on (a) sleep and (b) this blog. She escaped vigilant eyes again last night Think we may rename her “Stealth”

The tag lasted fourteen days and has now expired. This means some of us are busy catching up on sleep but we will have more to say about this.

 Right until the end our little lady continued to guide us to new roosts. We found 7 in total.

Barbastelle in hibernation, normally this is as close as we get!!

Thursday, 9 May 2013

Driven up the pole by bats

The bat group has recently bought another Griffin from Batbox using the proceeds from data searches. The fine weather on Monday night was too good not to exploit and Bob headed off to the home of our main bat box project to try it out.

We noticed that last season that bat detectors placed at 8.5 m ( atop a window cleaners pole and a de-bristled brush) gave us very different results from what we heard at ground level, but as we only had one Griffin we could not record at two levels at the same time with a time expansion detector)( We used . batbox Duets instead which , not being time expansion detectors, can’t give such high definition recordings)

The first Griffin was mounted on the lower part of the window cleaner’s pole. Photo Bob Cornes

Using a Petterson time expansion detector which was handheld, Bob only reported a few common pips, , the Griffin placed on the pole low down picked up a Noctule pass, while the Griffin at canopy height picked up both common and soprano pips, a serotine, a barbastelle, and what was possibly a Leisler’s (though it might just have been a Noctule playing silly devils.

The dpuble Griffin se4t up. Youcan just about see the 2nd Griffin at canopy height right at the top of the photo. The object ion the tre trunk is a bat box (unoccupied) Photo Bob Cornes
The double Griffin se4t up. You can just about see the 2nd Griffin at canopy height right at the top of the photo. The object ion the tree trunk is a bat box (unoccupied) Photo Bob Cornes
The plan is to repeat this methodology at a number of sites this season, and to return here later in the yer when the canopy is denser.

Saturday, 20 April 2013

Baby Noctule update

The juvenile noctule continues to come on in leaps and bounds.

He is now eating mealworms and soon we shall have to get him some flight cage practice.

Photo Simon Pidgeon

Infra-Red Camera Set- up

Following a workshop at the National Bat Conference on Infra-Red (IR) filming of bats, I decided to set-up my own system. A quick trip to ebay and a little research later I came up with the below.

Most of the set-ups I have seen to date have relied on external battery packs and lots of connecting leads. Although the footage was excellent and the systems seemed fairly simple to set – up, I was looking for something that would be self-contained.

I found IR lights called ‘bullets’ on an ebay shop, produced by SpectIR components, these seemed ideal as they take batteries. The added bonus was that they were cheap, being £30 for both lights. Each light takes four ‘AA’ batteries to the rear. These are expected to last at least 2- 3hrs of continuous use. The two lights can light an area of approx. 15- 20m. This is generally good enough for most roosts that I have tested the system on.

Equipment –

1.    Sony Handycam DCR-SR35 HDD ‘Nightshot’ (already owned and more importantly has the night shot facility).

2.    Camera Tripod (I opted for a small tripod that could be used internally in barns and small loft spaces).

3.    2 x Infra-Red (IR) lights, Bullets (produced by SpectIR Components).

Figure 1: IR set-up

Figure 2: IR set-up

Figure 3: IR set-up

Now I have had a chance to test the system and the results can be seen here:

This piece of footage was taken from a known roost in Bedfordshire.

Tuesday, 19 March 2013

Noctule update

Noctule and newborn Photo Simon  Pidgeon
Noctule and newborn Photo Simon Pidgeon

A new born bat is not by any stretch of the imagination a thing of great beauty it has to be said but watch this space. As he grows he will become much more pleasing on the eye!!
Photo Simon Pidgeon
Photo Simon Pidgeon

A week after being born and he weighs 5 grams
week old noctule. Photo Simon Pidgeon
week old noctule. Photo Simon Pidgeon

Last time round we couldn’t release mum back into the wild, but this time we should be able to. Meanwhile mother and baby are doing well. We will keep you updated.

Monday, 11 March 2013

Another Noctule, Another Pup

Hi All,

Well back in 2010 this blog was set-up to document the development of a noctule pup that was born in captivity.

On Friday of last week I had a panicked call from Simon (the main bat carer for Beds).

He had been over-wintering a female noctule that was found in a tree, in all likelihood she was going to be pregnant, however the hope was that she would be fit enough for release before this occurred.

Well it turns out that this is not the case and she gave birth to a male pup on Friday, below is the email that has been sent to the group:

Dear all,
A little bit of news for you (being the bat care team and all that). Most of you are aware of the captive Noctule we have which is overwintering until the weather cheers up. This young lady was found in a tree that had come down in December.. When found, she was only half the weight she should be and Jan Ragg/Colin Edwards were straight on the case of feeding her up. She would have almost certainly died if the tree had NOT come down! She was passed to me shortly afterwards (as she was from Millbrook).
Fairly quickly, she put on weight and seemed quite content (though grumpy for a Noctule).
I’ll get to the point….Last Friday (8th March) I got her out in the afternoon to give her a feed before work. To my complete shock, when I looked in I was met with a bat much smaller than our female. Yes, she had given birth. I knew the likelihood was that she would be pregnant, but a baby in early March…..slightly concerning (not to mention ‘dejavu’ for the Beds bat group for out last captive Noctule). When I first saw the pup (a male), he was on his own on one side of the inside towel and mum was the other end on the opposite side. Thankfully, after a good feed and a massive drink, mum soon got baby to attach and so far…both appear to be doing fine.
As soon as I get a chance, when mum kicks baby (now named ‘bobby’ by my daughter) off for a while I’ll weigh them both. I have had a clear view of the Pup’s abdomen and I can see milk patches so at the moment, I’m happy he is feeding. They will both need close monitoring but as a group, we need to work out how/where they are going to be released. It’s a long way off at the moment but unlike our last mum and pup, mum can be released too.
Will keep you updated with some proper pics/weights etc. I thought the birth of my son last month was going to be the last baby we had in the house!
So this means that this year there is likely to be the storey of Bedfordshires second noctule born in captivity.
So far the pup is doing well and mum is doing a fine job of feeding and looking after him.
As and when there is more news I will get an update on here.

Tuesday, 12 February 2013

Hibernation surveys Jan and Feb

Thanks to everybody who helped with the hibernation surveys. There were 161 bats in January and 154 in February.

Natterer's numbers were good  with 91 in Jan and 87 in Feb, Daub's 41 in Jan and 31 in Feb, 7 Barbs in January and 12 in Feb, BLE 18 and 21 = not to mention 54 Herald Moths at one of the sites (thanks to Phil who found a stash of 30 of them).

Another year of high numbers. Now all we have to do is wait until they wake up.