Wednesday, 10 December 2008

Biological Recording & The Scottish Parliament

My recent work on Noctule distribution in south east Scotland (when I get a moment I'll write an update on it) clearly showed how disjointed biological recording is at present. Common understanding of the distribution of this species north of the border turned out to be at odds with reality, once an effort was made to gather records from all possible sources and to address shortfalls. It's relatively easy to do this with a charismatic mammal species, but what about the thousands of other species, for whom we have disjointed and poorly collated distribution information?

BRISC (Biological Recording in Scotland) have placed a petition on the Scottish Parliament website, calling for action to be taken to address this, so that planning and conservation decisions can be made on the basis of full and appropriate information.

Please take a moment to sign the petition. it doesn't matter if you're not resident in Scotland - your opinion still counts.


Tuesday, 25 November 2008

El Duende, Tomb Bats and Handling the Hairy-legged Vampire

With a title like that, perhaps I should have published this at Halloween! But this is the time of year when relatives (or Mr Claus, depending on your age-group) are liable to ask that awful question "What would you like for Christmas?" Having dispensed with the obvious, but hopeless answers of a Jaguar XK120, a Hebridean island and an unlimited research budget (why is it only kids get their heartfelt desires at Christmas?) we then have the nightmare problem of coming up with something we actually want for Christmas that costs under twenty quid. And if we don't come up with something pretty damn fast the result will inevitably be socks, a jumper or one of those naff coffee table wildlife books with lots of pretty pictures and no real content.

Given that last thought, it occurred to me to share my thoughts on three bat books I have come across recently. They are out of the mainstream but they're a good read and are actually in print, unlike some books which should be but aren't (yes, I mean you, Collins New Naturalist - get your fingers out and reprint John Altringham's book.)

The first is the inspiring and impressive "A Bat Man in the Tropics: Chasing El Duende" by Theodore H. Fleming. Fleming has spent his entire adult life studying bats in Central America and Australia. I find it hard to get into books which simply describe impressive wild animals I am unlikely to ever see. Fleming doesn't do that: this is a very readable book which describes his life's work in a very human way. You really feel you're with him, up to your ears in mud and insects, studying pollinating bats. If you want something to immerse yourself in, rather than watch Chitty Chitty Bang Bang on Boxing Day, this is it.

Incidentally, "El Duende" is Spanish for ghost or hobgoblin, which seems quite appropriate, but Fleming uses it as a metaphor for the seach for knowledge about bats, which is deeper but also appropriate.
Next comes a small book called simply "Bats in Roofs". I have to admit I bought this without realising it's provenance. It was published by the Bat Interest Group of Kwazulu-Natal (for those who had the misfortune to be educated instead of going to school, that's in South Africa). This book describes the bat species found in the group's part of Africa, but what fascinates me is the detailed information about bat management techniques used there. They have similar bat-work problems to us in the UK (hence the name of the book), but with interesting twists. For example, the structure of their buildings are very different and their bat species occupy a broader range of niches than ours.

A common problem there is the occupation of verandahs by Epauletted Fruit Bats and Mauritian Tomb Bats (they have great common names for their bats), with the accompanying mess caused by loose droppings. And the solution? A helium balloon tethered on the verandah is apparently an effective deterrent! For anyone involved in practical bat work in the UK, this book offers a new angle on the subject. What is more it's only 44 pages long, so it lies within the pocket of your younger relatives. If they're anything like mine, they'll have found it on-line, ordered it and returned to their Playstations before you've even powered up your laptop.

My final suggestion is "Expedition Field Techniques: Bats". Written by Kate Barlow (now of BCT), this is a practical guide to carrying out field work with bats abroad. It's very comprehensive: for example, I opened it at random and found a picture entitled "Handling a hairy-legged Vampire Bat caught in Columbia". So if you'd like to know how to handle a Hairy-legged Vampire Bat in Columbia, this is the book for you. It is a concisely written manual which is aimed at the professional zoologist and, like the other two books, it throws an intriguing light on the practical study of bat ecology around the world. I find that dipping into it occasionally puts a new angle on British bat work and sometimes puts the difficulties of studying bats in the UK into context.

So, those are my suggestions. If you get a stripey jumper or a pair of furry slippers for Christmas, don't say you weren't warned.
  • "A Bat Man in the Tropics: Chasing El Duende" by Theodore H. Fleming is published by the University of California Press (2003)
  • "Bats in Roofs" by The Bat Interest Group of Kwazulu-Natal is published by Flame Tree Media (2007)
  • "Expedition Field Techniques: Bats" by Kate Barlow is published by the Expedition Advisory Centre of the Royal Georgraphical Society (1999)

My website:

Sunday, 9 November 2008

A Conundrum of Parasites

I was asked to do a talk at the BCT Scottish Bat Conference this year about bat parasites. What follows is a simplified version of my presentation...

When Anne Youngman first asked me to do this presentation I put the phone down and found myself looking at the slides, jars and vials, containing hundreds of specimens of bat parasites, which as you can see take pride of place on my desk. I found myself wondering what the collective noun for a group of parasites might be. You get a herd of cattle, a parliament of owls, a murder of crows and even a boogle of weasels: what about parasites?

My first thought, given the reaction of most people to parasites was a yeeuch of parasites. Then I reflected that that doesn't match my own view: I find these strange creatures quite fascinating. Then I considered an omnibus of parasites, given the number of times I have searched in vain for specimens of a particular species, only to have several come along at once. I finally settled on a conundrum of parasites: there are many gaps in our knowledge and unasnwered questions about the parasites hosted by bats, so conundrum seems an appropriate noun.

What I would like to do today is introduce you to just a few of these conundrums or unaswered questions and hopefully show you how we, as active bat-workers, can make a contribution to answering these condundrums.

First though, for the benefit of those who haven't recently looked at page 54 of "The Bat Worker's Manual", which gives an excellent summary, here's a brief overview of British bat parasites, to put what follows into context.

The basic definition of a parasite is an animal (or plant), which lives on another animal and gains nourishment from the host, without benefitting it or killing it. It is also useful to understand the difference between ectoparasites, which live outside the host's body (e.g. fleas and ticks) and endoparasites, which live within the host's body (e.g. tapeworms or helminths). In this talk I will be concentrating on ectoparasites, and specifically those which are large enough to be found by us when handling live bats.

We should also consider host specificity: some parasites are generalists and may parasitise almost any warm-blooded animal. For example the ticks or hravest mites that pester me are as likely to pester my dog or a passing fox or deer. On the other hand, some parasites are highly host specific and will only parasitise a single species or perhaps a genus or small group of hosts which share a roost. Many bat parasites are highly host specific.

Let's briefly consider parasites taxonomy. British bat ectoparasites fall easily into five convenient groups. The arachnids are closely related to spiders and this is reflected in the fact that adults have 8 legs. These comprise the ticks and mites. Insect parasites of bats comprise fleas, bat bugs and bat flies.

Clockwise from top left - Nycteribia kolenatii (bat fly); Ischnopsyllus octactenus (bat flea); Argas vespertilionis (bat tick); Spinturnix myoti (bat mite). Centre: Cimex lectularius (human bed bug).
These pictures show a Blyborough Tick or Argas vespertilionis, one of just two species of tick wheich exclusively parasitise bats in Britain.
The mites are represented by Spinturnix myoti, one of over 50 mite species recorded on bats in the UK. As well as the largest group they are also the most diverse, occupying many different niches around the body. This species lives exclusively on the wing and tail membranes. This is a female, indicated by the rounded abdomen. This species is viviperous and she is gravid: carrying a larva, to which she will soon give birth as a protonymph. Or that would have happened had she not been pickled in alcohol!
As you can see, bat fleas look superficially like the fleas you may find on your cat or dog: dorsally flattened and with huge legs. Eight flea species have been recorded on bat in Britain.

There are two species of bat fly believed to be present in the UK, usually found on Daubentons and Bechsteins Bats. A third species is believed to be extinct. These animals are highly adapted to life on a bat. Although they are flies, their wings are reduced to simple buds.
Finally, I have shown here a picture of a human bed bug to illustrate the very close similiarities between bed bugs and bat bugs.

A fascinating aspect of this subject for me is the lessons that bat parasites can teach us about their hosts. For example, when sampling mites on Natterer's and Daubenton's Bats in autumn I have often noticed a significantly higher parasite load on females and juveniles than on adult males. This presumably reflects the fact that the females and juveniles have been confined together within the maternity roost for a number of weeks, giving the mites the opportunity to reproduce and spread from host to host. The males on the other hand, will have been in smaller groups and able to move between roost sites much more frequently, reducing the opportunity for the parasites to spread.
With the development of Mitochondrial DNA analysis, there will be many more opportunities to use parasites to learn about bats. A good example is a piece of work recently completed in Switzerland, which studied MtDNA in Greater Mouse-eared Bats, a species of mite which parasitises them and another bat species which also hosts the same parasite. Using their data, the researchers were able to demonstrate that the Greater Mouse-eared, whose distribution is restricted to mainland Europe, was previously present in Corsica.

My first conundrum relates to the Spinturnix family of mites: the Spinturncidae. These are the largest mites found on bats and often the most obvious to the naked eye. They are between 0,5 and 1.5mm long and are only found on the win and tail membranes of the bat, making them easy to see. This slide shows a Daubenton's Bat and you can just make out something within the red circle.

When we zoom in we can clearly see a mite on the wing membrane. This is Spinturnix myoti, a species which parasitises Daubenton's, Natterers and Whiskered Bats.

This brief segment of video shows it's close relative Spinturnix acuminatus. I recently removed this specimen from the wing of a Noctule and here we can see it walking across a microscope slide. You can make out the slightly pointed abdomen, in contrast to the rounded abdomen of the gravid female we saw earlier, indicating that this is a male.

In 2003 Anne Baker of the Natural History Museum and Jenny Craven of Leeds University published a paper which brought together a piece of work funded by the british Ecological Society. They set out to gather all the known records of bat mites in Britain and to examine all available specimens. Their paper set out a checklist of species. This slide summarises their results for the Spinturnix family: eight species, each with the main hosts. However, there are two problems.
Spinturnix Species A has yet to be formally named as a species and may turn out to be a variant of Spinturnix acuminatus. A few female specimens were found on Barbastelles and, until more specimens are founf, the status of these mites will remain uncertain.
Closer to home is the question of Spinturnix mystacinus and Spinturnix myoti. S. myoti is found on Daubenton's, Natterer's and Whiskered Bats. S. mystacinus is found only on Whiskered Bats, the difference between the two being very small. It may be the case that it is in fact a synonym of S. myoti. As you migh expect, a problem with resolving this taxonomic issue is the fact that Whiskered Bats are far from common. More specimens of Spinturnix mites from Whiskered Bats could help in clarifying the status of this species.

Conundrum two concerns the geographic distribution of ectoparasite species. To illustrate this I have chosen to use the Blyborough Tick Argas vespertilionis. This slide shows dorsal and ventral views of an adult. The ruler alongside shows millimetre divisions. I have selected this species because it is easily identified: it is almost entirely round and usually looks like a little 5p coin, either lumbering about the roost as an adult or as a larva, attached to a host, lying vertically within the fur.
The other reason for choosing this species is that it is supported by a professional recording scheme: the Tick Recording Scheme, run by the Health Protection Agency. If any bat parasite species is likely to be well recorded, it is this one.

The main chart here shows the existing distribution records in Scotland: just four records, some of them quite old. Does this indicate that this species is scarce? Or that it is declining, or limited in range to the west?
Probably not: if you look at the inset map, I have added records based on specimens I have found or which have been sent to me over the past two years. As you can see, this has trebled the number of records in Scotland for this species. Bearing in mind that this is probably the best recorded bat parasite species (possibly excluding the fleas, which have a very dedicated national recorder), you can see the problem with distribution data!

Conundrum 3 relates to the so-called Chigger Mites or Trombiculidae. This picture shows the larav of a member of this family. You can make out the mouth-parts to the left, sourrounded by the legs: only six of them as this is a larva. The remainder of it looks pretty much like a little orange jelly-baby.

This slide shows them attached to a host: in this case a Soprano Pipistrelle, with four larvae attached to her ear. They remain attached whilst taking a blood-feed, which provides what they need to metamorphose. After a few days they leave the host and as nymphs and adults they predate on smaller arthropods within the bat roost.
I have seen these larve on Soprano and Common Pipistrelles, Natterer's Bats and Daubenton's Bats. (at this point I asked for a show of hands and over half the audience had also seen Trombiculidae larvae on bats). From that we can see that this is far from an unusual feature.
When Baker and Craven completed their study of British bat mite records in 2003 they had found only four records of Tromiculidae, one of which is questionable. Why should this be? As with the Blyborough Tick, may be partly about a lack of recording effort, but there is another problem with Trombiculidae: identification. There is in fact a published key to thes family. So surely it's just a matter of working through the key until you arrive at the species? The problem is that the key runs to five volumes and the volume which refers to the species found on British bats is 1,100 pages long! So identification of these mites is a real labour of love.

The final conundrum concerns bat bugs. This amazing picture was sent to me recently by Paul Hope and shows a Noctule with two bat bugs attached to it's forearm. My question is: are they Cimex pipistrelli or Cimex dissimilis? There is a long-standing uncertainty about whether both these species are present in the UK or not, fuelled by the fact that the differences are tiny and the taxonomy is the subject of some uncertainty. A DNA study in the Czech Republic aims to resolve these issues and specimens of bat bugs, especially from Pipistrelles, are sought to assist in this.

One of the joys of working with parasites is the occasional opportunity to gross people out. I notice I wasn't scheduled last before lunch, probably for very good reasons...
This slide shows the business end of Cimex pipistrelli. It's a ventral view of the head and I've labelled the forelegs and antenna, to help you get your bearnings. You can just make out the stylet, the organ the bug uses to feed, lying flat against the underside of the head, within it's protective sheath.

This slide shows how the bug uses it's stylet to go about feeding. You'll notice I have coloured the host a fetching pink, to reflect the fact that human bed bugs feed in exactly the same way!
First, the bug pushes it's stylet through the skin of the host...

This is where it gets interesting. The stylet is both flexible and prehensile and it commences probing around the flesh...

...until it finds a capillary and commences feeding. The probing and cutting through the flesh creates a contusion and slight swelling which is occasionally visible on the wing of bat. You may also find it on your own body if your choice of last-minute bargain holiday doesn't wuite work out as you had hoped!

I hope you have found this talk interesting and that one or two of you may still feel like eating your lunch. Hopefully I have also shown what an opportunity there is for us, as active bat workers to make a very real difference to the sum of human knowledge in this area. The four conundrums I have described barely scratch the surface: the simple fact is that any and all parasite records are useful.

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Ana...nother thing or two about the SD1

Earlier in the year I described my impressions and opinions about the Anabat SD1, describing it as "God's own bat detector" (August 2008). Since then I have had many more opportunities to use the machines in a wide variety of situations and discussed them with a number of people, including those who were kind enough to reply to my post with advice and information (thanks!).

One thing I commented on then was the option to pay nearly £450 extra for a PDA (hand-held computer) mounted on a bracket on the front of an Anabat. This delivers the opportunity to view live sonograms as bats fly past. Although a great teaching tool and potentially quite useful in the field I had strong doubts about whether this was a realistic option as it is a lot of cash to lay out on something which would be vulnerable to damage in the field, unlike the Anabat on it's own, which is quite robust.

After receiving some intriguing emails I decided to look for an alternative way of achieving the same end. I spend quite a bit of time training bat-workers and a way of displaying live sonograms without touting a lap-top around could be very handy.
The finished SD1 + PDA + GPS in use

Chris Corben, who designed the Anabat, has an excellent website, full of practical suggestions, based on his own experience of using Anabats (see below). This includes a step-by-step idiot's guide to setting up a PDA to work with an Anabat and even some advice on PDA models known to work. A look on eBay revealed that some of these are out-dated for more advance puposes and are therefore available cheaply second-hand. A few days later I had an HP Ipaq HX2190 in my hands for the princely sum of £38.25. It came with the cables and cradle to charge it and link it my home PC. Following Chris's notes it was remarkably easy to install Anapocket (the PDA version of the Anabat software - it comes free with the Anabat) onto the PDA and I was quickly able to view sonograms I had recorded previously.

Next I needed to connect the PDA to one of my Anabats. The cable used for this is the same as those used for synchronising a PDA with a PC - I just needed to find one with a serial plug rather than the more usual (nowadays) USB plug. Once again eBay came up trumps (£3.85). Hey presto! Live sonograms - it really was that easy.
The next thing I needed was a bracket to attach the PDA to the Anabat, so I could walk around with it. There are three threaded holes on the SD1 case, designed to take bolts on the standard bracket. These are simply M3 machine screw holes (the bolts are readily available from DIY shops). I considered making a bracket out of some aluminium or brass sheet, with two folds to make the required U shape. I remain concerned about the vulnerability of the whole set-up and decided instead to make a bracket out of 7 mm foam board - a lightweight yet strong material used in building exhibition displays etc and available from large stationers.

A little experimentation showed the best size and shape for three pieces to create the bracket (email me if you'd like a copy of this). A little Araldite and spray paint (the latter more cosmetic than anything else) and I had a strong, yet light bracket. I attached the PDA to the bracket using stick-on velcro strips. In the event of the unit being dropped or bashed against something the foam board is likely to break before the PDA, so my small investment will be safe. More importantly, so will any survey data on the PDA.

To make the most of this new set-up in the field I needed two more things: a spare battery for the PDA and a CF GPS unit to plug into the top of it. It is possible to use a Bluetooth GPS with the PDA (if, like my one it is Bluetooth enabled, though I think most are), but Chris mentions experiencing problems with the GPS and PDA losing contact from time to time. I also think that, when using an automated GPS in the field, there is a danger of the GPS losing the satellites and the user being unaware of it. Having the GPS plugged into the top of the PDA means it will always be held upwards, unshielded and in the best possible position to retain a view of the GPS satellites.

In my earlier piece about Anabats I bemoaned the fact that, when using an Anabat with a GPS, it was necessary to manually cross-reference bat passes against a GPS file to get a grid reference for each bat. Using a PDA with GPS resolves this problem and now all my bat passes are automatically grid referenced by the PDA. I also questionedthe problem of losing night vision by looking at a PDA screen in the dark. Even turning down the PDA brightness to minimum may leave it too bright. I had heard a Titley employee describing keeping the PDA facing away when not looking at it, which seemed rather self-defeating. I have resolved this by changing the colours on the screen, so that the background is black and the sonogram traces and Anapocket menus are the only things in a bright colour.

The PDA screen, with the Anapocket background set to black, to reduce glare.

So now I have a great teaching tool, a really good toy and a solution to the problem of GPS-referencing bat passes. Compared to the £450 it could have cost I actually paid a total of £61.63 (plus a bit for postage and packaging). I still think it's a Heath Robinson approach and vulnerable to damage, but I don't mind that so much when I've saved £387. After several decades of living in Scotland, something seems to have rubbed off....

Chris Corben's Anabat website:

Anabats in the UK are sold by Alana Ecology, who are usually knowledgeable and helpful:

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Wednesday, 1 October 2008

A Result of Careless Angling

We often hear about the terrible effects that abandoned fishing line and hooks can have on swans, but it isn't so often we hear how it also affects bats. Hear in Scotland the main form of recreational angling is fly-fishing and a fly designed to be attractive to a trout can have just the same attraction for a bat.

One recent Sunday morning I was hoisted from my slothful lie-in by a call from the Pentland Hills Ranger Service. A member of the public had spotted a bat suspended from a telegraph wire alongside a loch used as a fishery and Victor (one of the Rangers) was hoping I could help. The Pentland Hills are close to my home and half an hour later I was standing beside him, looking at the bat, suspended above our heads. It was showing no signs of life.

The first problem was working out what the set of wires carried, as I had no desire to get mixed up with high voltages. Fortunately the bat was dangling from telephone wires. The next problem was how to reach it, 6 metres above the ground. I had brought a telescoping ladder and we tried lashing this to the side of the Ranger Service Landrover. Not only was climbing it not an experience I would repeat in a hurry (awfully wobbly!), it didn't get me high enough to reach the bat.

Enter the owner of the fishery, stage left, with a knife lashed to the end of a long pole (which shows how often this particular problem occurs) With a bit of work the bat was cut free and fortunately had a soft landing. It was a juvenile male Soprano Pipistrelle (Pipistrellus pygmaeus), tangled up in a length of fishing line with two hooked flies. It seemed barely alive, though that may have been partly due to the amount of line tangled round it.

It transpired that the bat had a fly caught in it's mouth, presumably because it had seen what looked like a tasty meal swaying in the wind and attempted to catch it. In the warmth of the vistor centre it started to move about more. I couldn't see the tip of the hook and, as it was quite deep in his mouth, I couldn't be sure if it was caught in his throat. Luckily he was able to drink and later, at home took some minced up cat food (sorry Haggis, but the bat's need was greater than yours!), suggesting he wasn't too badly hooked.

The next morning I contacted the Dick Vet Small Animal Hospital, part of Edinburgh University. Kevin Eatwell, one of the specialist wildlife vets there anesthetised the bat and removed the hook. He seemed none the worse for wear and that evening I took him back to a spot close to where he was found and released him.

On the 300m length of telegraph wire which runs parallel to the loch I could see seven other lengths of fishing line caught around the wire, at least one of which carried a hook. Not only is this the result of bad casting, leaving it without bothering to tell anyone is nothing short of criminal, especially as the fishery owner is equipped to remove it. After all, there has been considerable publicity about the dangers posed to wildife by abandoned fishing tackle causes.

My web-site:

The Dick Vet Small Animal Hospital:

The Pentland Hills Ranger Service:

Sunday, 31 August 2008

Last Bat of Morning

I came across this wonderful piece of writing by Verlyn Klinkenborg, originally published in the New York Times. It really captures the essence of dawn and dusk outside a bat roost.

It's 6 a.m., a dark, gray morning in late August, the dim light a reminder how far we've gone on the downhill side of summer. Ethel, a border terrier, and I are behind the house investigating a woodchuck scent. There is a dark smudge in the mist above us, and then another. The bats are returning to their bat house, a thin, slatted box, high up under the eaves. Each bat comes in over the roof, makes a dive for the ground and then swoops upward toward the narrow entrance of the bat house. Some slip inside on the first try, some fall back and try again. After a few minutes, the air is still, the last bat home. Ethel and I turn toward breakfast.

I have seen the bats come out at evening again and again. It is one of the joys of living here, watching them drop one by one into the night. But I've only seen them coming home a few times. The bats of evening are the last flutter in a world that is growing still. The bats of early morning have already been engulfed by birdsong, rooster-crow, the stirring of nearly every creature on this place. Their flight is less erratic just before roosting, no longer distracted by an insect in the air. It's as though each bat brings a scrap of night's darkness home with it, leaving the sky pale and brightening. It's as though night itself were being stored in the bat house till dusk.

When the last bat had vanished, I felt almost absurdly alone, strangely vacant in that thin slice of morning. It reminded me of a feeling from the city a long time ago - that moment, after staying up all night, when you can feel the world gathering pace and energy just as you're beginning to fade. Watching those dawn bats, I imagined them punching out of their night's work as they settled, and I felt as if I'd somehow clocked into their schedule. And it seemed that the best use of a dark, gray morning with mist in the air was to go back to bed, only a few feet, and a couple of walls, away from where the bats are sleeping.

(Normally I have a thing about horrible US English spelling, but writing this good deserves to be left as the author intended!)

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Wednesday, 20 August 2008

God's Own Bat Detector

Ok, that's maybe overdoing it a bit, but I have recently become a fan of the Anabat SD1. For some time now the SD1, and it's more cumbersome predecessor the Anabat II (with ZCAIM recorder) has been the industry standard equipment world-wide for passive monitoring, and rightly too, but having spoken to several people who rated it highly as a detector for use on transect surveys I though I'd better try it out.

There are several reasons the Anabat is so good for passive recording. Alternative methods of recording bat calls use audio formats such as .WAV or .MP3, which quickly gobble up available memory in just a few hours. The Anabat records each bat pass as a series of co-ordinates, plotting the loudest frequency every few milliseconds, creating miniscule data files, allowing many thousands of bat passes to be squeezed onto a single 1Gb CF memory card.

The fact that the memory card is held within the detector is a further advantage, but the biggest advantage lies in the way the detector ignores the spaces between bat passes and simply records each bat pass (or other ultrasonic noise) as a new file. The Analook software which comes with the machine allows you to very quickly scroll from bat call to bat call, identifying each pass and creating a spreasheet showing each one, with date, time and species. The time saving, compared with using other software analysis systems, such as Batsound or Batscan is huge.

So the Anabat is great as a passive detector - why is it good for transect work? The designer, Chris Corben, has built in an interface which allows a GPS receiver to be plugged into the detector. Every two seconds the Anabat asks the GPS where it is and records that data on the CF card, alongside all the bat passes it records as you walk along. This means that for each bat you encounter you have a sonogram of it's call, the date, the time and an accurate grid reference.

Anabat SD1 with Etrex GPS velcroed to it and connected.

What more could you ask for?

Well, I've made it sound great, and it is, but there are plenty of problems too (though apparently Titley Electronics, who make the machine have recognised that there is a huge market for the machine and are working hard at improving it):

1. The GPS data isn't attached to the sonogram: you have to transfer it manually.
2. Even with the GPS and Anabat both set to the correct time, an error of one hour creeps in, though it's easily edited out.
3. Becasue the machine is built in Australia, the GPS data is recorded as Latitude and Longitude, using the WGS84 datum, instead of the British OS datum. This means you have to use a utility programme to convert the data to British National Grid and remember to convert the datum, otherwise you can end up with proper-looking grid references, which are simply wrong.
4. The standard Anabat microphone is not as sensitive as it could be. I set the Anabat's sensitivity control as high as it could take and used it alongside a Bat Box Duet. The Duet was clearly more sensitive, which was disappointing, given the Anabat's £1,400 price tag.

Despite all the above, Anabat plus GPS is still streets ahead of anything else currently available. When used together with the GPSU GPS utility programme and the superlative DMAPW mapping programme, bat data can be identified and transferred to a map with incredible ease and efficiency. Unlike Victor wotsit, the chap who was so impressed with a shaver he bought the company, I didn't go that far, but three weeks after buying an Anabat for passive monitoring I'd bought another for transect surveys, despite the high price.

It's worth mentioning that you can buy an SD1 with a PDA mounted on the front and a GPS plugged into the hand-held computer. This allows you to see sonograms live and also tags the GPS data onto each bat pass as it records it, which is a fabulous toy, but of questionable value.

I was on the receiving end of a hard sell for this system at the Welsh Bat Conference and failed to understand why I would want to pay an extra £400+ for this. Titley admit that the PDA screen will cause you to lose your night vision and advise that you should carry it, pointed away from your eyes! The bracket looks utterly Heath Robinson and vulnerable. When I pointed this out I was told that the bit which would break if you tripped whilst carrying it would be the bracket, the cheapest £100!

In fairness to Titley and to Chris Corben, this is an excellent idea and has immense potential. Why plug your bat survey data into a computer when you can take the computer to the bats, but there's a lot of work to be done yet. Meanwhile, like many others, I am waiting with baited breath for the new Batbox Griffin to be launched. It just might beat Anabat at their own game.

Chris Corben's Anabat website:
Batbox, makers of the new Griffin:
GPS Utility:
Alan Morton's DMAP mapping programme:

And of course, my website:

Happy Harp Trapping!

A couple of times this year I have described my Tuttle (or harp) trap, built with the intention of creating an effective trap for harmlessly catching live bats, but smaller and more versatile than the commercially-available traps. Cheaper too! (see The Kitchen Table Harp Trap, February 2008).

Back in May I described the trap's first outing, when it was unfortunately placed over a roost entrance which wasn't in use. (See A Bat in the Hand, May 2008). As the bat maternity season started soon after that I had to wait with gritted teeth for the breeding season to end, so I could find out whether the trap worked or not.

A couple of weeks ago Lothians Bat Group had a trip to a site in the Borders and I set the harp trap up at the entrance to a Daubenton's Bat (Myotis daubentonii) roost and waited with baited breath. With 8 or 10 people waiting to get a close-up view of the bats, I couldn't help dwelling on the fact that the wretched gadget had yet to catch a bat - talk about pressure!

The first 2 or 3 bats flew past the trap, finding ways around it or even through it, causing a sweaty brow on my part. However, this is always a problem with harp trapping at a roost, so after a little work closing the gaps with coats, twigs and anything else that came to hand my fingers were re-crossed.

I got involved in a conversation and missed seeing the first bat to be caught, but yes, a bat was actually caught. My week's hard work back in the winter wasn't in vain after all! It quickly became apparent that the plastic lining of the catching bag was too long, which slowed the bat in moving into the sides of the bag, where it could not get out. In all, twelve Daubies were caught and I was able to check several of them for parasites, watched by some Group members. At the same time, other members of the Group were able to gain some valuable bat handling training.

The trap in place at the Natterer's roost (the roost is in a crevice in the wall behind)

Now that I knew the bat worked I followed up with an evening at a newly-discovered Natterer's Bat (Myotis nattereri) roost in the wall of an old farm steading, where I needed to confirm how the roost was being used. Again, the trap did it's thing and I was able to catch five bats (although a sixth was caught as I was taking the trap down). With three adult females, a juvenile male and a juvenile female, I was able to conclude that this had been a maternity colony, with the young bats now flying and the trap had earned it's place.

A juvenile Natterer's Bat

Before I next use the trap I'll trim back the plastic lining. The only other problem that has come to light is that the legs are a bit spindly and wobbly. The trap is light in weight, so the legs don't need to be too strong, so I'll delay making any changes to that for now. But at last, eight months after building it, I know the trap is fully functional and effective.

Please note, everything described above was carried out under appropriate S.N.H. licences. Trapping and handling bats can be harmful to them if not done with the correct equipment and skills. To do so without a licence is a criminal offence.

Thursday, 31 July 2008

Bat Bugs and Bed Bugs

I thought I would take the opportunity to share some pictures of a little friend of mine, with a little friend of her own. She's a non-breeding female Soprano Pipistrelle (Pipistrellus pygmaeus), with a low body-weight and in fairly poor condition. When this photo was taken I had just hand-netted her as she emerged from a roost. You can just make out a reddish blob on her wing, which caught my interest. It's a species of bat bug which is widespread in the British Isles, Cimex pipistrelli.

Bat bugs are interesting creatures: members of the family Cimicidae, which also includes human bed bugs, amongst other delightful creatures. The odd thing about this one is it's presence on a bat in flight. They are temporary parasites and are normally found in cracks and crevices in the roost of the host species. They are not equipped to stay attached to a bat in flight and usually leave the host's body as soon as they finish feeding. I can only assume that this one got caught out!

Like all true bugs (bat bugs are Hemiptera, the same order as such familiar sucking insects as Shield Bugs), bat bugs suck their food via tubular mouth-parts. They use this structure, correctly called a rostrum, by inserting it into their host like a hypodermic needle to ingest body fluids. The close-up below shows the rostrum at rest, lying in a groove below the head and prothorax.

It's interesting to note that human bed bugs are thought to be descended from bat bugs, from the days when bats and humans were more closely associated than today. I can imagine Bronze Age or Neolithic people living in huts, with perhaps Brown Long-eared Bats roosting in the rafters and bat bugs gradually adapting to this larger and less difficult host.

If the pictures haven't given you the creeps, then this will: it's an article from the Lancet, which describes a house in Scotland, where a student was being bitten by what were initially thought to be human bed bugs. They turned out to be bat bugs, wandering from a roost above his bedroom. Fortunately for bat conservation, this seems to have been an isolated situation!

My website:

Saturday, 19 July 2008

Peat Bogs, Rape Fields & Other Nasty Places at Night

I've just returned from a week-long soiree in the northern half of Scotland. Not a holiday, I'm sorry to say, but a surveying trip, working at some wind-farm sites.

Surveying wind farms is different from most bat survey work, for two reasons. Firstly, the focus is on finding commuting and foraging bats in the vicinity of proposed turbines, rather than the usual roost-finding focus of most commercial surveys. Secondly, proposed wind farms tend to be in places where no sane bat might be expected to go: exposed, windy places and bats don't usually go together.

The difficulty faced by developers (and their consultant ecologists) is that we don't know enough about how bats commute and migrate around the UK. We know that much migration takes place in continental climates, such as in mainland Europe and North America. We also know that in these places badly sited wind farms can kill many bats. So, until we understand what our own bats in the UK are doing, we do intensive surveys of wind farm sites.

Thus I came to be trekking around various nasty places in the middle of the night, carrying out 5 minute activity surveys at 100m intervals, along transects which took 4 or 5 hours to complete. Fair enough, but when the first site was a called ***** Moss I realised things could get interesting. First came the midges - hordes of the little swine, but I was ready for them with my midge hood. I amused myself squirting them with Jungle Formula and watching them zoom back for second helpings, fangs dripping with my blood (it doesn't matter how much anti-midge gear you wear - they always find a way through).

The next piece of fun was the gradual fading out of the track I was following across the site. Having got lost twice in the dark and had to GPS may way back to a known point on the transect, my sense of humour was beginning to fail me. A quick look at the site plan revealed I needed to follow a fence line for the next part of the transect. I'm not entirely sure why the soggy peat that surrounded that fence didn't suck it down, but it made up for it with me. I consider myself a patient man, but I do recall howling into the wind, as I pulled myself out of my third bog hole, holding the precious Anabat over my head "Wind farm? As far as I'm concerned, they can TARMAC the bas***ding place !!!!".

The next site seemed more civilised, at least from a survey point of view, if not an ecological one. A prairie-sized arable farm, with hardly a hedgerow to be seen and every crop planted close up to the field boundaries. It looked easy enough to traverse, until I met the delights of mature Oilseed Rape. This stuff stood higher than me, stank like Satan's bottom and did it's best to trip me up with it's stout stems as I tried to navigate the eighteen-inch gap between the crop and the barbed-wire fence. But the real problem was the Cleavers. You know, Cleavers, Galium aparine a.k.a. Sticky-weed, Goose Grass etc? Harmless, amiable stuff? Not when it grows in great swathes, fed with nitrogen by the Rape. It grew taller than me, with stems as thick as my little finger, twisting round itself to create a miniature jungle of impenetrability, constantly tripping me up in the dark as I tried to force a way through.

A bat surveyor's lot is not a happy one etc. etc.

Oh, and bats? Surprise, surprise, there were very few and mostly in the obvious places round the edges of the sites.

I said "mostly" and what was interesting was that both sites produced snippets of bat behaviour that went against the books and perhaps justifies some of the survey effort expended at these sites. First, I watched a Common Pipistrelle (Pipistrellus pipistrellus) patrolling up and down a track, feeding on midges. The odd thing was this track was in the middle of a wind-swept moss, without hedgerow, fence or any kind of above-ground feature.

The second interesting thing was a small colony of Common Pipistrelles dispersing from their roost across arable land. Some were following field boundaries, as you might expect, one followed the route of a former field boundary (working from memory?) and I watched another set a course across open arable fields.

We still have a lot to learn about these animals...

My website:

Sunday, 29 June 2008

Swarming Pipistrelle Video


A few weeks ago I included a brief snippet of video, showing a colony of Soprano Pipistrelles (Pipistrellus pygmaeus) swarming at dawn, before entering their roost. I have now had opportunity to film a longer video with a larger colony.

The video was recorded between about 04.10 and 05.00 on a morning when dawn was around 04.30. A colony count the evening before showed that 383 bats left the roost. I hand-netted two of them and both were lactating females, indicating that this is a maternity colony. When I filmed them it was too early in the maternity season for the young to be flying, but in just a few weeks there will probably be double this number of bats, as each young bat starts to follow it's mother out to feed at night.

The video shows up to fifty bats at a time swarming and there are close-ups of one of the roost entrances, showing how the bats "touch and go" at the entrance, without actually entering. At times, so many bats were attempting to do so that there was an aerial queue and the clattering on the wooden barge-board as they touched and pushed off again was audible some distance away.


My web-site

Thursday, 26 June 2008

Welsh Bats and Scottish Bat-workers

Last weekend I made the long trek to Aberystwyth - a 7 hour drive each way - for the B.C.T. Welsh Bat Conference. Organised by Tom McOwat and hosted by Aberystwyth University, this was an excellent conference at a reasonable charge (even for us consultants, who usually pay extra). A pleasant surprise was the discovery that no less than nine of us were travelling down from Scotland, so with a bit of hectic organisation everyone squeezed into two cars and we did our small bit to save the planet and avoid having to remortgage the house to buy a tank of petrol.

There were a number of good talks. It would be remiss of me not to mention the two Scots: John Haddow describing tips for identifying bats in the hand and Kirsty Park on bats in man-made habitats.
Another highlight for me was Helen Miller describing BCT's new survey programme for the rare Bechstein's bat. This rare woodland bat is extremely hard to survey for: they fly fast and cover large distances, so the survey method employs an actic technique: using ultrasonic lures to attract Bechsteins into harp traps by broadcasting their social calls. Very clever, and with a strict methodology that minimises disruption to the bats.

Another fascinating talk was by Chris Corben, the innovative Australian who designed the Anabat system, which is revolutionising professional bat-work. The Anabat SD1 is a frequency division detector which saves data direct to a CF memory card. It allows effective long-term monitoring of bats and is increasingly finding a place in transect work too. With the associated Analook software, which is designed to work with frequency division data (unlike Batsound etc, which use audio files) it is astonishingly easy to analyse large numbers of bat passes swiftly and efficiently.

A very clever idea incorporated into the conference was the usual evening bat-walk. Except it wasn't the usual one. Instead, all the delegates were divided into teams and spread out over twelve woodland sites around Ceredigion. The result: a far greater survey effort in one night than most bat groups could manage in a year. And to validate the results, the Sunday morning session comprised analysis workshops for the various software programmes.

Naturally, the Scottish bat hooligan squad had to push things to the limit. Not satisified with six bat species in our patch of woodland (including a possible Nathusius' Pipistrelle - a very rare species), we wanted more. We set out to look for Lesser Horseshoes, which we were told had been recorded at a road widening scheme a few miles from Aberystwyth. Imagine the scene: a car bursting with wild bat enthusiasts and literally bristling with bat detectors, careering down a Welsh country road in the middle of the night. We had three Bat-box Duets poking out of the sun-roof (set to 20, 50 and 120 kHz), an Anabat SD1 poking out of the side window and one intrepid bat-worker (who shall remain nameless) hunched in the passenger seat, monitoring the frequency division output of one of the Duets, just in case a bat escaped all the other detectors.

So, did we get any Horseshoes? Did we heck. But at least we have an excuse to go back to Wales...if they'll have us!

My website:

More on the Bechstein's Project:

Chris Corben and Anabat:

Tuesday, 24 June 2008

A Rant About Planning

Early in 2007 the Scottish Government (or was it still the Scottish Executive then?) wrote to all local authorities in Scotland, clearly setting out their responsibilities in relation to European Protected Species (which include all UK bat species) and the planning process. What they said includes some very simple guidance: " is clearly essential that planning permission is not granted without the planning authority having satisfied itself that the proposed development either will not impact adversely on any European protected species on the site or that, in its opinion, all three tests necessary for the eventual grant of a Regulation 44 licence are likely to be satisfied." Surely that isn't hard to understand?

Why then, are some local authorities still granting planning permission for developments without giving the slightest consideration to protected species? Edinburgh are the worst offenders I know of, but I'm sure there are others. I have recently seen a development involving the direct destruction of a known roost. I was called in by the owner to give advice on how to proceed and was appalled to discover that planning permission had already been granted.

On the other hand, some local authorities are diligent: the planners at Scottish Borders Council not only make it clear to applicants what species need to be surveyed for, they provide succinct guidance, written by the county ecologist and clearly focused on the individual development.

This process is the safety net through which pointless destruction of bat roosts can be prevented: ensuring developers and others face their responsibilities towards protected species and helping them understand what they need to do and when. It's basic and essential conservation law.

My other frustration is the local authorities who approach their Habitats Directive responsibilities with a "one size fits all" approach. One west of Scotland local authority responds to planning applications by setting out what programme of surveys must be carried out, without knowledge of the characteristics of the site or it's bat potential. Yet the BCT Bat Survey Guidelines are clear: "It is worth noting that the type of survey to be undertaken and amount of effort expended can often only be fully determined after visiting the site at least once." I recently completed a pointless set of sunset surveys at a modern city centre building with very low bat potential, no nearby or connected habitat and no records of bat activity in the area. The local authority's ecologist insisted on his standard litany of "two to three emergence surveys", with no mention of an initial inspection survey. After I carried one out it was abundantly clear that no further survey was necessary, but was obliged to do so anyway. As a result, the developers have been delayed, have paid over the odds and are disillusioned with the whole process. In other words, conservation has been discredited by thoughtless actions.

For all I know, their next development could be a steading conversion surrounded by prime habitat: a building with high bat potential. After their bad experience at this site, they could be tempted to turn a blind eye to protected species. If the local authority is one of those which does the same, the result could easily be the destruction of an ecologically sensitive roost.

Rant over (climbs down from soapbox).

Tuesday, 10 June 2008

Pipistrelle Roosts: from Intermediate to Maternity

The roosting cycle of the commoner UK bat species is reasonably well understood: hibernaculum in winter, then move to an intermediate roost in spring. In the breeding season, the females move into maternity roosts and in most species the males use other sites. Once the young are flying in late summer, intermediate roosts become important again, with mating roosts used in some species, then it's back to hibernacula. More often than not, we only see little snippets of this and have to work hard to interpret what we see. I've been lucky enough to see a slightly bigger piece of the picture with two Soprano Pipistrelle (Pipistrellus pygmaeus) roosts I've been working with recently.

The first is the site at which I videoed swarming bats in May ("Dawn Swarming", 15 May). On that occasion I saw around 70 bats swarming, 30 of which entered the roost, the remainder flying off to the north-east. We know of another roost about 500m away in that direction, so clearly there was likey to be a link. Last week I returned at sunset to do a colony count and volunteers from Lothians Bat Group went to the other roost site to the same thing simultaneously. 48 bats had been counted at the other site a week previously, so I was intrigued to see which roost would be used for breeding.

Unexpectedly, only three bats emerged from "my" roost. I hand-netted one of them, which turned out to be a very small non-breeding female. She was in poor condition and was carrying an enormous (by Pipistrelle standards) Cimex bat-bug (a close relative of the human bed bug) on one wing and huge numbers of Macronyssidae (a family of tiny mites).

Incidentally, it's quite unusual to see a bat-bug attached to a bat outside of the roost. They are not really equipped to grip on to a rapidly moving wing for long and normally feed from bats within the roost, dropping off before the bats emerge, so it looks like this one got caught out! It's probably Cimex pipistrelli, but there are records of another, rarer Cimex species on bats and I'll reserve judgment until I have it under the microscope.

Here you can clearly see the Bat-bug (Cimex sp.) on the bat's wing

And the other site? Only thirty bats emerged, suggesting that the maternity roost is probably somewhere else entirely. What we now need is someone mad enough to prowl the streets of Edinburgh at dawn for a few days, looking for a swarm of bats, to tell us where the maternity roost is! It's not that we really need to know, but it would be nice to find the missing jigsaw piece.

The other site is the one I mentioned in February ("Two Roosts for the Price of One", 6 February), with droppings of two species in the attics. As yet the Brown Long-eareds (if my dropping analysis is correct) haven't put in an appearance. At dawn one morning in May, I watched 7-10 Soprano Pipistrelles swarming around the gable end of the "wrong roof", i.e. the attic which did not have Pipistrelle droppings in it in February. Did I have it all wrong? Was the maternity roost actually here?

(Above) The roost entrance identified in May - the bats swarmed in front of this gable end and entered via the gap visible below one of the roof tiles

(Below) Droppings stuck to the timber facing below it, 3 weeks later

When I returned with a team of helpers at sunset last week, there were many droppings stuck to the wall around the access hole the bats had been using on the previous visit, indicating it had seen some use. However, at sunset no bats emerged from there. Instead, 118 bats emerged from two holes in the gable end of the main attic, right where I originally found piles of droppings within the attic. So, not only were we able to confirm the location of the maternity roost, the May visit enabled the identification of an intermediate roost, which wasn't apparent from signs within the attic.

Bats are always enigmatic and rarely give up their secrets easily. It's nice when, once in a while, we can see tiny bit more of their lives than the usual tiny snap-shots...

My website:

Thursday, 22 May 2008

Ten Things Every Duet Owner Should Know

Last night I was surveying for emerging bats that didn't emerge, so I had plenty of time to think about life, the bats and everything. It occurred to me that the detector I was using, a Bat Box Duet is of the most popular detectors on the market, and rightly so. It's sensitive, selective, ergonomic, robust and sensibly priced.

As with any piece of equipment, there are hints and tips that help the user, some of which I've picked up from other users and some I've worked out myself. So here are my ten top tips for using a Bat Box Duet:

1. Try plugging your headphones into the tape socket, instead of the headphones socket. You will hear the heterodyne detector in your right ear and the frequency division one in your left. Whatever frequency the detector is set to, you will still be aware of bats on other frequencies. The audio level is fixed, so the volume control has no effect: if you're beside a road or river you may struggle to hear over the background noise.

2. If you want to try this technique somewhere where there is some background noise, try plugging the detector into a minidisc machine and plugging your headphones into the minidisc. You should hear the audio from the bat detector and the minidisc volume control will allow you to hear it louder. This is good practice when recording, as it allows you to be confident that the detector output is being recorded properly. It's very frustrating to get to the end of a survey and find you've recorded nothing because you accidentally knocked the stop button or a plug has come out.

3. When the low battery BAT warning appears on the display, don't panic if you haven't brought a spare battery: the detector will continue to function for a short while. Eventually the frequency indication will go haywire and then the detector will switch off the display to save power, but the detector will still operate for a little while longer.

4. Even in that situation you can by without the frequency display. Although you don't know what frequency you're tuned to, if you rub your fingers together, this sound will be loudest at 40kHz, giving you a very rough frequency indication. Of course, its a lot easier just to carry a spare battery!

5. Have you ever wondered why a seemingly random digit appears when you first switch the detector on? This is the software version.

6. If you have a childish sense of humour (like me) you can convince gullible people you have a very clever detector. Using a worn battery, turn the volume high, without headphones. The loudspeaker is the most power-hungry part of the detector so, when a bat is picked up, the extra current consumption will cause the word BAT to appear. When the call ends, the word disappears again. Fun for all the family!

7. Fed up tuning up and down, to ensure you don't miss any bats? Try tuning to 42kHz. You'll hear Myotis calls as a regular machine-gun type call, Common Pipistrelles as an irregular, thudding and Sopranos as an irregular squeaky sound. Noctules can be hear when close, as this frequency is close to the first harmonic of their call. For heaven's sake don't try this for anything important: you will lose a lot of sensitivity, and you may miss something important (especially Horseshoe bats) but it's handy if you just want a general idea of what's happening. I sometimes do this when I set up a Duet on a tripod to record the frequency division output. In that situation I know everything is being safely recorded, so missing the odd call is less important.

8. Did you know there have been some subtle changes in the design of the Duet since it first came out? Earlier versions had a less sensitive microphone, which looks like a small black plastic grille. the later, more sensitive microphone looks like a tiny metal disc, surrounded by a rubber grommet.

9. Another change is the function of the REF button. In earlier versions this produced a steady reference tone. With more recent Duets, this button shunts the microphone to normal audio. This is handy for taking field notes, as anything you say into the detector will be picked up on the left-hand stereo track and recorded (assuming you are recording the survey). Be sparing in it's use: whilst you are talking the frequency division detector is inactive.

10. I only had nine things, so for number ten I'll mention that the Bat Box III has now been revamped into the same style of case as the Duet. I have yet to get my hands on one, but I suspect it will be a very good heterodyne detector. The original Bat Box III was excellent, but it's only weaknesses were poor ergonomics and difficult frequency indication. The new version (Bat Box IIID) fixes both of those issues and will probably be a really good little brother for the Duet.
The Stag Electronics (Bat-box) website:

My website:

Wednesday, 21 May 2008

A Bat in the Hand....

...takes a great deal of work to achieve!

In company with a small group of people from Lothians and Scottish Borders bat groups I attempted to try out my new harp trap last night (see "The Kitchen Table Harp Trap", under February 2008).

The site was a ruined castle, set in a secluded valley in the Scottish Borders. "Ruin" is probably the wrong word, as the seventeenth century noble who set about building it never completed the job but, with massive stone walls up to 50 feet high, it really looks the part. Barrel-vaulted cellars with plenty of deep gaps and cracks in the stonework provide good roosting opportunities for bats. There are woods and a river close at hand, providing foraging opportunities for several bat speices and in the past we have trapped Natterer's Bats (Plecotus nattereri), Daubenton's (Myotis daubentonii) and Brown Long-eareds (Plecotus auritus).

Trapping bats is enjoyable, but there needs to be a valid scientific reason to interrupt the bats in their normal activity. On this occasion bats were to be rung as part of a long-running study of bats using sites of this type in the Scottish Borders. In addition, I was planning to remove parasite specimens as part of my studies into their distribution and host associations.

Two harp traps were put in place: mine and a slightly larger one, each covering the entrance to one of the cellars. There is an art to siting a harp trap: it needs to cover as much of the entrance as possible and gaps need to be filled as far as possible, to prevent bats flying round the trap. A tarpaulin, some leafy twigs and an old coat were pressed into service around my trap:

It was quite cold, dipping as low as 5 degrees centigrade after sunset and bat activity wasn't high, apart from the large numbers of Soprano Pipistrelles (Pipistrellus pygmaeus) dispersing from their roost in a nearby farmhouse. Nonetheless, we caught four male Daubenton's, all of which emerged from one of the cellars. Frustratingly, it wasn't the cellar which had my trap at the entrance!

Two of the bats were recaptures and had been rung on previous visits to the site, but the other two were new and, as well as being weighed and having their forearm length measured, each had a tiny numbered aluminium ring slid onto it's forearm.

None of the bats had many parasites. This is often the case in spring, especially with adult males, which usually carry a lower parasite burden than females and juveniles. They are able to move between roosts to avoid parasite accumulation, whereas the females and juveniles are together in the maternity roost for several weeks each year, often with many other bats. I like to think that juvenile bats may also have similar personal hygiene issues to many human teenagers!

The picture above shows the fouth bat to be caught, who caught my interest as he had a tromiculid mite larva in his ear. The Trombiculidae are a large family of mites, including members of the genus Leptotrombidia, which parasitise bats for part of their life-cycle. Their larvae hatch within a bat roost, climb onto a bat and attach themselves, often in the bat's ear or on the forearm. There they take a meal, before dropping off the bat to become predators of other small arthropods within the roost during their nymph and adult phases.

I was particularly interested, as there are very few records of these parasites on British bats, partly because records of any bat parasites are rare and partially because they can be difficult to remove. Fortunately, this bat was quite placid and, with Carol-Ann (the "bat whisperer") holding him, I was able to paint the mite with a little isopropyl alcohol using a very fine brush, to make it release it's grip, and then remove it with fine soft forceps.

Once home I checked and have been unable to find any records of a trombiculid mite on a Daubenton's bat in the UK (unless anyone reading this knows better?), although that doesn't necessarily make it a rare species: probably just an under-recorded one. It will probably be a while before I am able to positively identify it to species: there are no field guides!

I haven't mounted the mite yet, but here's a rough and ready picture taken at x120. The larvae are usually a distinctive orange colour when seen on a bat. With their mouthparts buried in the bat, they look like tiny orange jelly beans.

As for the harp trap, it is still waiting to be christened with it's first bat. Watch this space...

Please note, trapping and handling bats without proper equipment, training and experience can be very harmful. Furthermore, in the UK it is illegal to do so without appropriate licences from Scottish Natural Heritage, Natural England, the Countryside Council for Wales or the Environment and Hritage Service in Northern Ireland.

If you're interested in getting involved in working with bats, the best starting point is your local bat group:

A checklist of mites found on British bats can be downloaded here:

My website:

Thursday, 15 May 2008

What is it About Bat Surveys...?

Maybe it's the peculiar hours that bat-workers keep, or maybe it's the association with unusual animals, but there's a definite tendency for odd occurances and very odd characters to be encountered whilst doing bat survey work.

The people we meet range from the scarily enthusiastic, through the utterly barking and the dangerously misinformed to the simply peculiar. On one survey for Daubenton's Bats alongside a canal a bewhiskered Wing Commander type approached me and barked an enquiry as to what we were doing. When I told him he replied "That's alright then: I thought you might be looking for otters." I should probably have extricated myself there and then, but my curiosity got the better of me and I asked why he might ask that. In return I was treated to an extensive diatribe on the evils of the poor otter: how it kills lambs, despoils the countryside, wrecks fishing and probably bears off virgin maidens, causes global warming and harbours Osama bin Laden in it's holt. Where he had got all this rubbish from wasn't clear but it was obvious from the gleam in his eye that his opinions weren't open for discussion and I beat a hasty retreat.

On another occasion I was carrying out a dawn survey in a small park in Livingston, not a town noted for it's ethnic diversity. Just before dawn an enormous black gentleman jogged purposefully towards me, wearing colourful, flowing West African robes and fez hat and carrying a huge carved staff. He padded past me on bare feet without a sideways glance. Ten minutes later he returned in the opposite direction, still with the same purposeful, steady gait and again he acted as though I wasn't there, leaving me wondering if I was dreaming (at 4.30 in the morning that's entirely possible!).

In a town noted for it's UFO sightings I had to attend to a remote bat detector with odd noises emerging from it's radio receiver. When I reached it, I found two men with the case of the detector open, staring at the electronic gadgetry inside. I introduced myself and asked what they were doing. Their candid reply was that they though it might be a bomb, so they had opened it to see. What degree of utter stupidity led them to decide that it was a good idea to open a suspected bomb? Then again, perhaps they had a point: an Anabat detector belonging to the Highways Agency was recently destroyed by the Bomb Squad in a controlled explosion after it was found attached to a motorway bridge.

It's sometimes hard to understand chiropterophobia (or fear of bats), but for those it affects it is a very real problem. Last year I was checking a heated bat box on Ministry of Defence property. The sergeant on duty was built like the proverbial brick sh**-house: his muscles probably had muscles and I had no doubt that he could probably kill me with his little finger, whilst drinking a mug of NAAFI tea with the other hand. Nonetheless, it seemed a good opportunity to attempt some bat PR, so I explained what we had found and tried to show him a photograph on my camera. In a trice he was on his feet, backing away and shaking. I swear, if I hadn't calmed him down he would have reversed straight though the wall.

I was recently asked to look over some derelict council flats for any signs of roosting bats: a long day of methodically working through attic after attic. I expected them to be empty, as the occupants had long gone, but almost every attic was a treasure trove of the weird. One contained a knitting machine and enough wool to keep a knitware factory supplied for months. Another contained most of the body panels for a Ford Escort. Even odder was the attic in which several hundredweight of soil was lying in heaps, reminiscent of the PoW hut roofs in The Great Escape. Why? How? Your guess is as good as mine.

In case anyone reading this is feeling put off bat work I should stress that the odd situations and people are outweighed many times over by enormous numbers of warm-hearted, helpful and interested members of the public.... but the other sort are far more entertaining!

Please remember that some of the bat work described here requires a licence, issued by one of the four statutory nature conservation organisations. It is an offence to disturb bats or their roosts without one.

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Dawn Swarming

Someone once said that bats are hard to study "...because you can't see them and you can't hear them." It's certainly true that they don't give away their secrets easily, though bat detectors have allowed us to start the long hard job of understanding them.

A behaviour exhibited by most British bats which tips the balance a little on our side is dawn swarming, in whcih bats returning to a roost fly around the roost entrance for a period of time at dawn, often making false landings at the roost entrance. In doing so they give away the roost location. This is in stark contrast to evening emergence, when they dive out of the roost, flying hell for leather to avoid any possible predators, making it hard to spot where they have emerged from!

Of course the downside is that dawn is a horribly antisocial time of day to be about, something I was reminded of when my alarm clock went off at 2.45 am this morning. With dawn in Edinburgh at 5 am I wanted to be alongside a roost site at a suburban house well beforehand, to watch swarming develop. It wasn't just for fun: I had a suite of things I needed to know about these bats. All I knew was where the roost entrance was: at the end of a flat roof bargeboard, giving access to a hollow wall; and that they were Pipistrelles. I needed to find out which species they were, whether they were roosting in any other parts of the building and approximately how may bats roosted there.

For the first half hour there were steady comings and goings, with Soprano Pipistrelles (Pipistrellus pygmaeus) entering and leaving the roost in small groups and occasional bats flying close to the entrance in twos and threes. At 4.25 am swarming started, with numbers gradually building up to a peak five minutes before dawn, with around 60-70 bats zooming round the adjacent garden. You can see a brief snippet of the action here:


Soon after this bats started to enter the roost. Up until this point, everything was as I expected: no other part of the house roof was involved, I knew the species of bat and could see an approximate number. All I had to do was count them as they entered the roost, giving an accurate count and the job was done...or was it?

Only 30 bats actually entered the roost. The remainder gradually gained height until they were around 5-10m higher then the house, then one by one they flew off to the north-east. I have never heard of this behaviour before and was quite astonished to see it. Stuart Smith, of Lothians Bat group was later able to tell me of another roost site about half a kilometre away in that direction, so perhaps that is where they were heading. It is quite common for a colony to move around between several roost sites, but I have never before heard of them swarming at one site and then splitting up, to roost in mor than one location.

Whatever the cause, it was worth being up early to see the spectacle: the video doesn't really do it justice!

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