Saturday, 12 December 2009

Bat Parasite Live Action!

Some videos of live bat ectoparasites, recorded through a dissecting microscope at x40...





I used these at a workshop at the National Bat Conference in York earlier this year. It was fun watching people surrepitiously scratching!

My website: http://www.blogger.com/www.plectus.co.uk

Thursday, 3 December 2009

What's in a city?

In modern Britain we live in a man-made landscape. Whether you look at stone walls and sheep folds on a remote hillside in Sutherland, a leafy farmscape in Devon or a built-up part of south east England, man's handiwork is there to be seen, profoundly affecting the habitats available to our wildlife and of course, our bats.


I have always found it interesting to place wildlife within the landscape: where do they live? Where do they forage or hunt? How do they move through the landscape? Where are they present or absent? Where are they threatened by predators and where do they take refuge?
We are fortunate in the 21st century to have easy access to satellite photography free of charge, via websites such as Google Earth and Bing Maps, which allow us to explore this swiftly and with a nice glass of Merlot to hand!


I thought it might be interesting to look at a random square kilometre of a major city and see what habitats useful to bats would be apparent, using one of these websites.


Here is my square kilometre. Two things instantly spring out: this is very obviously a built up area, but there are clearly green places here. Are they just amenity grassland, or more structural habitats which might they offer hunting places for bats. And are they connected, allowing bats to move through the city?


Zooming in makes some of these habitats more apparent. Here, the classic suburban wildlife habitat displays it's strength. These gardens may be individually small, but together they form a block of habitat, with trees and shrubs providing potentially good foraging habitat for generalist species, such as Common Pipistrelle (Pipistrellus pipistrellus) and Soprano Pipistrelle (Pipistrellus pygmaeus). In the south Soprano's tend to have a riparian affinity, but here in Scotland they are more numerous than the Commons and tend to use a wide variety of edge and suburban habitats.

Also in my square kilometre is another classic urban wildlife habitat: a cemetary. I recently carried out some bat surveys close to a large cemetery in East Kilbride and was delighted by the number of Foxes which emerged from it each night, to keep my survey team company. On one memorable evening two of us watched a young Fox edge up to within a few feet, grab a plastic bottle and run to a safe distance with it. Apparently unimpressed it then urinated on the bottle and stalked off!

This cemetery appears to enclose a lot of mature trees. These are likely to harbour plenty of insect prey for bats, especially if some of them are native species. Non-natives tend to be home to generalist invertebrates, but native species are also likely to offer a home to many more native invert species, for whom the tree provides more specialist niches.


Also in the square kilometre is what appears to be a public park, probably offering similar foraging habitat for bats (though not necessarily undisturbed conditions to allow Foxes to successfully breed!) So with a cemetery, a public park and plenty of mature gardens our city bats seem to be quite well-provided with foraging habitat. There are also plenty of houses and industrial buildings which seem likely to provide the potential for roosting Pips and some of the more mature trees could include holes and crevices for roosting bats too. The next question is how do the bats move between all the features? What commuting corridors are available to them?

Often lined with trees and shrubs, urban railways offer excellent wildlife corridors and this square kilometre has several. Here two cross each other and elsewhere a disused railway line has been developed into a cycleway. I'm sorry to revert to a foxy, rather than batty theme, but I was travelling on a train in Ealing which stopped at signals. Right outside the carriage window a vixen relaxed in the sun, whilst her three cubs played, completely unperturbed by the proximity of a trainload of disgruntled commuters!

Even better, within this square kilometre is the mother load: a stretch of canal. With trees, shrubs and hedges providing security for commuting bats and foraging opportunities for Soprano Pips, this is an excellent wildlife corridor. Emergent and submerged vegetation provides homes for plenty of invertebrate prey for Daubenton's Bats (Myotis daubentonii) and the smooth water is perfect for them to hunt over. Smooth water helps echolocating Daubies to pick up emergent insects on or just above the surface.


Canals without vegetation are not necessarily poor foraging places. A few years ago I surveyed the Union Canal with a team of volunteers, attempting to map foraging sites. To my surprise, the most active foraging sites were the ones with little or no vegetation, rather than those with plenty of vegetation and diverse prey species. These concrete-lined canal sections had large numbers of Chironomid midges hatching. They are amongst the first species to occupy stagnant water and the bats demonstrated that, as far as they were concerned, quantity trumped diversity!


The next time you encounter a bat, try using this method to look at the surrounding habitat. You may be surprised how much you can conclude about likely hunting locations, commuting routes and possible roost sites which the bats may use.

Sunday, 19 July 2009

An Intrepid Batling

Baby animals are amazing things: endowed by nature with astonishing resilience, combined with survival instincts.....

Sadly, when the two bats flew I didn't have the camera to hand and it was over very quickly, so you'll just have to take my word for the last part!

My website: http://www.plecotus.co.uk/

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Saturday, 27 June 2009

The Diffusion of Useful Knowledge

Having a first degree in history I have always had an interest in how our understanding of bats has developed down the years (see "An 1892 bat-worker", January 2009). Today's post brought me a copy of "The Penny Magazine of the Society for the diffusion of useful knowledge", published on 7 January 1843.

My first thought was what a wonderful-sounding title and what a sign of the times that there existed a Society for the Diffusion of Useful Knowledge. The Victorian moneyed classes were incredible busy-bodies and loved trying to enhance people's lives, often in rather idiosyncratic ways. (Strangely, paying people enough to live on was rarely considered a way of enhancing lives!)



A regular feature of this paper is a series entitled "Curiosities of British Natural History" and this issue's feature is about bats. Sadly, the author's name is not given but it was either someone who knew the subject or who did a good deal of research as it contains several pages of detailed description of the subject.

Above the start is a gorgeous engraving, showing a Noctule, a Pipistrelle and a Long-eared Bat. The latter has a thoroughly cheesy grin on its face and the Noctule looks too portly to fly, but some of the anatomy is surprisingly detailed: presumably they were engraved from dead specimens.




The article begins with the enticing statement "It may surprise some of our readers to be informed that sixteen or seventeen distinct species of bats are natives of the British Isles". What?! That is our current understanding (depending on whether you include the Greater Mouse-eared or not). In 1843 the two Pipistrelles had not been separated, nor had Brandts and Whiskered Bats. The finding of Nathusius Pipistrelles in Britain was long in the future and, although it had been described elsewhere, I don't think the Grey Long-eared had been discovered in Britain at that time.


So what were the other four species? Unfortunately, the anonymous author doesn't tell us. In fact he only describes eight species, dismissing all the others as "extremely rare and restricted to certain localities". Was he guessing? Was he reading a foreign book and assuming the same species were here? Was he including some long-dismissed sub-species or perhaps bats found in part of the Empire? How frustrating!


The species he describes are: The Common Bat (Pipistrelle); The Great Bat (Noctule); The Long-eared Bat; The Barbastelle; The Reddish-grey Bat (Natterer's); the Whiskered Bat and the Greater and Lesser Horseshoe Bats. The obvious missing species is the Daubenton's, which must surely have been known at that time and would have been relatively easy to distinguish.


As with all writing of the era, wordsmithing was a priority and some of the descriptive text is fantastic: "Often during warm summer evenings have we seen numbers, perhaps several scores, of the Common Bat flitting over pools, in chase of gnats and similar insects, or gambolling with each other in a mazy dance, ever and anon uttering sharp shrill cries of exultation and delight..." The shill calls were presumably social calls, which are sometimes just within the range of human hearing. Incidentally, a score at that time was an innocent number twenty, in case you think the author was using dried bats for questionable purposes.


The piece includes a surprising amount of scientific detail, for example listing the species found to hibernate in caves as Natterer's, Whiskereds, Barbastelles and Long-eareds, though again Daubenton's are conspicuously absent (could it be they confused them with Natterer's at this time?). Given that this was a popular paper, not a scientific journal, there is a remarkable amount of detail: something today's press could learn from.


As with today's press however, the author just can't resist a lurid story and describes bats stealing bacon from chimneys and eating meat in larders. Not perhaps as daft as it sounds, in an era when bacon was hung in chimneys to cure and when meat was kept open in a larder. Houses would have been quite porous to bats at that time and I can imagine a stray Pipistrelle within a house, finding itself next to a joint of raw meat, having a nibble, possibly for the water content.


Something exciting about old texts like this is when they describe the location of bat roosts. The author mentions a Noctule roost under the eaves of Queen's College Cambridge and Greater Horseshoes occupying caves "at Clifton and in Kent's Hole, near Torquay". If anyone reading this lives in those areas, it would be fascinating to know if these sites are still occupied, 166 years later!


At the time this paper was produced, people were still grasping to understand how bats found their way in the dark, and, reading the author's description one gets a sense of his frustration: they knew there was something special about it, but couldn't quite put their finger on it:


"There is a singular property with which the bats is endowed, too remarkable and curious to be passed altogether unnoticed. The wings of these creatures consist, as we have seen, of a delicate and nearly naked membrane of vast amplitude considering the size of the body; but besides this, the nose is in some furnished with a membranous foliation, and in others the external membranous ears are enormously developed. Now these membranous tissues have their sensibility so high, that something like a new sense somehow accrues, as if in aid of that of sight. The modified impressions which the air in quiescence, or in motion, however slight, communicates; the tremulous jar of its currents, its temperature, the indescribable condition of such portions of air as are in contact with different bodies, are all apparently appreciated by the bat." So near, yet so far!


My website: http://www.plecotus.co.uk/
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Alana or Envisage?

For years Alana Ecology have been the benchmark supplier for wildlife survey equipment. They were never the cheapest supplier, but their catalogue always drew together kit from a huge range of manufacturers. It always seemed to include the very best equipment and this was coupled with excellent advice: if you called you always found yourself speaking with someone who actually understood what you needed and knew the best solution.

Not surprisingly, for me and for many other people who work with wildlife, both professionally and as a hobby Alana became the standard supplier for everything: a reliable source of advice and good kit.

Over the past couple of years there seems to have been a disappointing deterioration in the standard of service provided by Alana: late and missing deliveries; failure to keep the customer informed, failure to call back etc. After several instances of this kind of poor service I started looking around to see who else is out there and a colleague told me about Envisage Wildcare. Their catalogue isn't quite as comprehensive as Alana's (and irritatingly, you have to download it, you can't simply view it on the web), but most of the key equipment is there.

When I needed a new endoscope I decided to give Envisage Wildcare a try. I phoned at 4pm and spoke to someone who took my order. Pushing my luck, I asked if it would be possible to have it delivered the next day? "Erm, yes, but the van is arriving so I'll need to put the phone down now and run". That is the kind of service that attracts attention and true enough, next morning the endoscope arrived.

Since then, I have heard about several other examples of this kind of thoughtful, professional service, experienced by others. I do think that we would be best served by two good companies in competition: that way they keep each other up to the mark and keep prices low. Having heard a couple of people say recently that had gone elsewhere, I hope that Alana recognise and address their service. They have great expertise and I certainly haven't written them off.

If I were to send messages to both companies it would be this:
Alana - sort out your service, keep your customers informed about their orders and lose the complacency.
Envisage - keep doing what you're doing, but for heaven's sake set up a proper on-line shop, instead of the irritating pdf download.

Take a look and decide for yourself:
http://www.alanaecology.com/
http://www.envisage-wildcare.co.uk/

My website: http://www.plecotus.co.uk/

Sunday, 12 April 2009

Noctules, Boxes and dangling bat-workers

During 2007 and 2008 I spent some time on investigating the distribution of Noctules (Nyctalus noctula) in south-east Scotland, a region where the species was traditionally considered scarce and probably beyond it's natural range. I gathered together incidental records from many bat-workers (thanks!), some focussed car surveys and records from commercial bat surveys carried out by a number of consultants, including me.
The result was a clear indication that Noctules are widespread in the Borders and Lothians regions and probably at a greater density than was previously realised. The results were presented in a poster at the B.C.T. Scottish bat Conference in November 2008. If you're interested you can download a copy as a .PDF file here: http://www.plecotus.net/Noctule-poster.pdf (You are free to distribute this information, in the interests of bat conservation, but please attribute it)

One evening in September I was relaxing in the bar at Preston Montford Field Centre, near Shrewsbury during a training course. My phone made one of the irritating noises that mobiles make, to tell me I had received a text from Carol and Nigel, both active members of Lothians Bat Group. They attached a photo, with the tongue-in-cheek message "do you know what this is?!" You're probably ahead of me here - it was a Noctule, of course. To rub my nose in it, they had found it in a bat box at a country park 2 miles from my home. If I hadn't been on the course I would probably have been there when the boxes were checked. Grumpy wasn't the word for my response....

To their credit, Carol and Nigel had found the first ever Noctule in a bat box in Scotland and it resulted in some positive press coverage for bat conservation. Fast forward two weeks when I was checking bat boxes at another country park, also in Midlothian and believe it or not, there was another Noctule. Like Nigel and Carol's this was an adult female, squeezed into a slim bat box. She was a delight to handle: very relaxed, even when I placed her on a log to photograph her, before returning her to her box. She was also kind enough to give up some Spinturnix acuminatus mites (well, I was happy about it, even if my companions were a little taken aback).

To put this in context, these two animals were both found in boxes in a county where I can count previous records of Noctules in flight on my fingers. Was it coincidence (or was it the same bat, with a sense of humour?) or does this tie in with our new knowledge of the spread of Noctules? It was certainly a surprise in an area with many bat box schemes and two decades history of only ever finding Pipistrelles in them. By coincidence, in 2007 and 2008 a small colony of Natterer's Bats were found in a West Lothian bat box, so these Noctules seemed too good to be true.


Stuart Smith, chairman of Lothians Bat Group (and one of the grandees of Scottish bat-work), came up with an unusual plan to respond to these new records by installing some new bat boxes, higher than normal, something he had seen at a Vincent Wildlife Trust site in Dorset. Most bat boxes in the Lothians are between 12 and 20 feet (3.7-6.1m ) above ground. Noctules are tree-roosting bats, with a tendency to roost in tree holes, often high up, so higher boxes makes sense. The problem is that 20 feet is the maximum height for access by ladder, without extra safety measures and skills.


The solution? Suspended bat boxes! We used Schwegler woodcrete bat boxes, suspended from pulleys attached to high branches. Wire rope is used to pull the boxes up to full height -around 40-45 feet above ground (12.3-13.8m) - and tied off on bolts mounted on the tree trunk. These are at ladder height, to prevent the local "yoof" from reaching them. When we need to check and clean the boxes we will simply climb a ladder to normal height, unwind the wire rope from the bolts and lower the box to ground level. Once finished, we simply haul the box back to the top of the tree and tie off the wire rope once more. Ingenious!




Now, there is a chicken and egg problem here: how to get 40 feet up to mount the pulley? The Bat Group is lucky to have access to the services of a professional tree-climber, who also has an affinity for bats. George used his skills to climb the trees and install pulleys for us, making it look easy, as tree climbers always do. However, it's very hard work: you need to combine a high level of physical fitness with some somewhat counter-intuitive skills. Come to think of it, strolling about at the top of a tall tree as about as counter-intuitive as it's possible to be!



Watching a bat-box being hauled 40 feet into the top of a tree was quite exciting. Whether they will attract Noctules remains to be seen...


With work over for the day, George offered a couple of group members the opportunity to try out tree climbing techniques (at very low height) and so, trussed up and roped to the tree, we took our turns at making fools of ourselves. I had tried my hand at this in the past, so probably should have known better, but didn't.

An advantage of this being my blog is that you won't get to see my feeble attempt at tree climbing. However, this seems a good moment to wreak revenge on Carol for last year's Noctule text message. You have to hand it to her: she's enjoying herself, even if she isn't making much progress up the tree!

Any comments: blog@plecotus.co.uk

My website: http://plecotus.co.uk/

Saturday, 11 April 2009

The Anabat PDA Bracket

Last year I described a home-constructed bracket for attaching a PDA over the face of an Anabat SD1 bat detector (Ana...nother thing or two about the SD1, November 28 2008)

Although not as strong as the brackets sold by Titley Electronics, my bracket has the advantage that, if dropped during a survey, the bracket is likely to give way and protect the PDA and its precious data. It also cost roughly a 50th of the price of buying theirs, which is handy in the current economic climate.

Several people have contacted me to ask about the design. It's very simple, virtually "Blue Peter" construction, though without the sticky-backed plastic (I could never put that stuff on without bubbles anyway!)

For anyone who wants to try making one, I have put the details onto a .PDF file, accessible here: http://plecotus.net/Anabat-PDA-bracket.pdf

If you make one please let me know how you get on: mailto:blog@plecotus.co.uk

My website: http://www.blogger.com/www.plecotus.co.uk

Friday, 10 April 2009

An early spring...maybe?


Last night I took a group of ecology undergraduates to a 200 year-old kirk (that's church to those without a Scottish education) in East Lothian, to watch for bats. I had my fingers firmly crossed on the way there: although I know the church and churchyard to have plenty of summer bat activity it is still very early in the season for bats to be at all dependable.

In the summer the kirk has a Soprano Pipistrelle (Pipistrellus pygmaeus) maternity roost within the roof structure and also has Brown Long-eared Bats (Plecotus auritus) inside the kirk itself - during the summer there is usually a light scattering of droppings over the pews. Last year I watched one flying up and down inside the kirk, warming up before going out to forage.

The most I could really hope for was that there might be one or two individual Pipistrelles foraging around the kirkyard - it's in a secluded, tree-lined valley, alongside a burn (or stream if you prefer), so it's good foraging habitat, even this early in the season.


When we arrived and walked round there were no droppings inside the kirk, althought there were some on the exterior, making me hope that at least a few of the Pipistrelles may be present.

At sunset a few Soprano Pips overflew the kirk at first, commuting from other locations in the valley. Then there came an excited squawk over the radio, announcing that someone had seen a bat emerge from the edge of the kirk roof and we watched about 30 Sopranos emerge from the same spot where I watched several times that number come out in the autumn last year.



I am sure that there will be many more than 30 bats in that roost in mid summer, when Soprano Pipistrelle females gather in large numbers to rear their young - these are probably the first arrivals. Interestingly, we also heard a male Soprano in songflight, the string of mating calls designed to attract mates. This is primarily an autumn activity, but seems to occur a little in spring as well.

It's not hard to see why the bats are active so early in April. The chart below shows night-time temperatures at the Met Office's Gogarbank station, near Edinburgh. There have been two weeks of fairly consistent temperatures around 7 to 8 degrees, which seems to be the level at which bat activity in this area picks up. As a happy coincidence, last night was also the warmest night of the year so far.



However, this might not be the end of the story. It's still very early in the year and weather is never as reliable as we would like. As you can see below, last year April started off warm like this and then went into a cold period for a couple of weeks, causing bat activity to fall away until nearly the end of the month. Only time will tell what will happen this year.



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Saturday, 28 February 2009

A Most Peculiar Hibernaculum

Bats are very good at doing what they shouldn't do: ignoring the books and turning up in the wrong habitat or behaving in an unexpected way. That's part of the charm of working with them. There's a constant chess game in which we try to stay one step ahead.

Usually these unexpected things turn up one at a time and mercifully they are outnumbered by "correct" behaviour. Recently however, I have done some hibernation surveys at a site where the bats seem to specialise in intriguing behaviour.

The site is a tunnel about 500m long, accessed via a small hole, high in the hills of southern Scotland. The tunnel was hewn by hand from the solid rock, in order to carry water from one valley to the next, for industrial use. On end has long since collapsed, but the other is still accessible to those who know where it is. Despite it being far from habitat likely to be used by foraging bats, it seems to be well-known to bats and is regularly used by Daubenton's Bats (Myotis daubentonii) and Natterer's Bats (Myotis nattereri).




The tunnel is small, mostly just high enough for me to stand up in (I'm just over 6 feet tall) and between one and two metres wide. As there are few crevices, the bats tend to tuck themselves into angles in the rock, meaning that it possible to be fairly confident that the majority of bats will be seen during a methodical survey. This is a rare luxury: in many hibernation sites it can usually be assumed that, for every bat seen, there are likely to be more out of sight.




Because of this, I thought it would be interesting to place some temperature dataloggers within the tunnel, to measure the temperature variation at different depths. The dataloggers were in place for four weeks, during which there was a warm spell, followed by several days of very cold weather, accompanied by snowfalls. Despite this, a datalogger just 7m from the entrance (C on the chart) showed a temperature variation of less than one degree either side of 4.5 degrees. A second logger 100m from the entrance (B on the chart) showed a steady temperature of 6 degrees, never varying more than a tenth of a degree. A third logger another 100m in (A on the chart) showed similar consistency around 7 degrees. Hardly surprising then that the tunnel suits the bats well.








Water runs along the floor of tunnel throughout, but never more than a few centimetres deep and I can be quite confident that it rarely rises above that height. Why? because last week I saw a Daubenton's bat tucked into an angle in the rock less than 30cm from the floor. I have rarely seen bats low on the walls of other hibernacula, but here they have been seen doing this several times.

In January this year I walked through the tunnel, noting the various Myotid bats. almost 250m from the entrance was an especially small bat. I had to look at it for a few moments before the evidence of my own eyes registered: it was a Pipistrelle. Why on earth a Pipistrelle had chosen to hibernate so deep in an upland underground site is beyond me! Normally Pipistrelles hibernate in conditions with far less consistent temperature and humidity. I would love to have known which Pipistrelle species it was, but without handling it, it was impossible to tell.


Undoubtedly my favourite oddity at this site was a Natterer's, which had found itself a small crevice. Perhaps the bat would prefer it if the site had more crevices for them to crawl into, as at other hibernacula, because this bat seems to have decided it wanted to be in the crevice come hell or high water. It had managed to get it's head in and no more and there it had settled down to hibernate. It had it's backside stuck in the air and it's wings akimbo, looking for all the world as though someone had hammered it in with a mallet...



Regular reader of this blog will have heard this many times by now, but please be aware that it is usually a criminal offence to enter a bat hibernaculum in the UK without a licence issued by one of the statutory nature conservation organisations (NE, SNH, CCW etc). It is also extremely dangerous to venture underground without training. Blundering about below ground in winter is a great way to harm both yourself and hibernating bats. Sorry, but my sympathies are with the latter! If you want to take part in these activities, join your local bat group. What are you waiting for?

My website: plecotus.co.uk
Contact me: mailto:blog@plecotus.co.uk

Tuesday, 27 January 2009

Winter Bat Activity

We tend to think of winter as a time when bats hibernate and won't be seen again until spring. In fact hibernation is not as simple as that: bats do awaken at times and move around. Indeed, they are sometimes seen flying in the midst of winter.

This afternoon whilst walking the dogs I spotted a Pipistrelle foraging over the River Esk. It was flying round in circles in the clockwork flight pattern typical of the genus and occasionally dropping down to catch an insect. A feature of winter bat activity is that it happens in daytime, as the higher ambient temperature means there is a greater likelihood of catching enough insect prey to offset the energy costs involved in coming out of hibernation.

I tried unsuccessfully to interest the dogs in the bat, as I have an idea it could be rather useful to have a dog trained to listen for bat calls and alert me when there's a bat nearby. Unfortunately, my pair of canine delinquents find the command "sit" quite challenging, so they aren't likely to succeed in training as bat-dogs.


When I passed by later on at dusk the bat was still hard at work hunting and seemed to be having some success, despite the ambient temperature being only 3 or 4 degrees. I have heard several suggestions as to why bats occasionally feed during the winter. It may be that individuals have been forced out of hibernation because they have failed to build sufficient fat reserves to see them through the winter, but it seems more likely that fluctuations in temperature may cause individuals to take advantage of the opportunity to forage on insects which have become active.

Different bat species have differing requirements for hibernation. Here in Scotland Myotis species, such as Daubenton's (Myotis daubentonii) or Natterer's Bats (M. nattereri) seem to be particularly exacting, hibernating below ground in caves and mines which feature a steady, low temperature, low airflow and high humidity. They usually hibernate in crevices or ledges where the microclimate may be particularly stable.

Brown Long-eared Bats (Plecotus auritus) are less exacting. When found underground they tend to hibernate on walls or hanging from the roof and are often closer to mine entrances than the Myotids.

The least exacting bats are the Pipistrelles, which are rarely found underground, instead selecting relatively exposed holes and crevices, which are more likely to be influenced by changes in the weather. Whether there are differences between the two Pipistrelles is difficult to judge. As they are impossible to differentiate without handling, they tend to be lumped together in hibernation surveys.

Last winter I wrote about a castle where a group of Pipistrelles and a Brown Long-eared were hibernating in crevices within a cellar (See "Hibernating Pipistrelles", February 2008). The castle sits atop a hill and there is a constant breeze blowing through the cellar. Unsurprisingly, no Myotids were found hibernating there.


A hibernating Pipistrelle

Carol and Nigel Terry, our local bat carers noted that a casualty Pipistrelle kept through the winter in a cold room tended to wake up and feed every 10-14 days. It may be that Pipistrelle autecology makes use of winter foraging opportunities and that they choose hibernation sites which better allow them to respond to these opportunities.

My website: David Dodds Ecology

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Sunday, 25 January 2009

Bat-workers & golf carts: be very afraid!

At this time of year there seems little for a bat-worker to do. Hibernaculum surveys are strictly limited, to avoid the risk of disturbance and there are only so many site visits one can do before running out of enthusiasm for assessing bat potential! These are the days when the mind wanders back to highlights of "real" bat work, before the onset of winter.

One such highlight last year was an autumn visit to a well-known golf and country club in the Borders to check and clean the bat boxes. A large group of bat-workers from Lothians and Borders Bat Groups assembled to go round the boxes, checking them for bats and recording the amount of droppings (an indication of how well each box has been used during the year).


I'm not entirely sure whether it shows trust or naivete, but we were allowed the use of a small fleet of golf carts in order to get round the course with our ladders. If you have never seen a conga line of golf carts, full of bat workers and equipment snaking across the landscape you have never known fear!


Fortunately we were accompanied by the course green keeper and one of his team, which probably helped curb the temptation to descend to the level of "Wacky Races". More importantly, it allowed them to see for themselves the great work they have done, making and erecting bat boxes around the course.

Annual bat box checks have several practical purposes. Firstly, the boxes can be cleaned out in readiness for the next year and any damage identified for fixing. Secondly, we have the opportunity to assess the extent to which each box has been used, providing data which shows the progress of the individual bat box scheme and, when combined with other schemes, a rough measure of how bat populations are doing locally. Thirdly and perhaps most importantly, less experienced bat group members get an opportunity to get close to live bats. Many very active bat workers (including me) started off with bats, with the thrill of seeing a Pipistrelle in a bat box.


In South East Scotland it is extremely rare to find anything other than Pipistrelles in bat boxes (with some intriguing exceptions in recent months) and this site was true to that experience. In autumn boxes tend to be used by male Pipistrelles as the base for a mating territory and it is usual to find boxes occupied by either an individual male or by a male and a harem of females. Where boxes are grouped together it is unusual to find more than one occupied, as they would lie within the same territory. The droppings however, often reveal that other boxes have been used, either earlier in the year or in differing conditions, with bats moving between boxes to find optimum temperate conditions.

The course is home to some remarkable buildings and is known to be home to roosts of Brown long-eared Bats (Plecotus auritus), Common Pipistrelles (Pipistrellus pipistrellus) and Soprano Pipistrelles (Pipistrellus pygmaeus). Best of all is a large maternity colony of Daubenton's Bats Myotis daubentonii). Although the roost was breaking up at the time of our visit, we were still able to glimpse a group of around 20 bats clustered together. I took the photograph below earlier in the year, when there were over 50 bats present, with a cluster of Nycteribia kolenatii bat-fly pupae clustered around (you can see them better in the lower picture).


It was a very successful day in terms of finding bats, recording useful data and giving people the chance to get close to bats. Best of all it was that very rare thing: a chance for bat-workers to get together in daylight!

Please note: handling or disturbing bats is a criminal offence without an appropriate licence issued by a statutory nature conservation organisation (Scottish Natural Heritage, Natural England, Countryside Council for Wales, Northern Ireland Environment Agency).

Most bat groups welcome new members and give them the opportunity to take part in events like this. To find your local bat group contact the Bat Conservation Trust

My website: David Dodds Ecology

Thursday, 8 January 2009

An 1892 Bat-worker

As an ecologist whose first degree was in history, I have always had an interest in the development of natural history. I would love to have been one of those wealthy edwardian or victorian country parsons whose lives were devoted to natural history (whilst presumably paying a curate to take care of the religious stuff!)

Last year I heard a talk about the use the Botanical Society of the British Isles makes of historical records in order to understand changes in the distribution of vascular plants. Some of their impressive database comes from the notebooks of victorian botanists and the voucher specimens they made, which are often still to be seen in herbaria. Other records are found by trawling old natural history books and drawing out biological records from descriptions of species and their distribution. Inspired by this I resolved to seek out any such data I could regarding bats in my part of Scotland.

It took a while to find a suitable source of data: bats were not recorded anything like as much as vascular plants were, botany being a "suitable" occupation for those few victorians and edwardians who had time to spare. However, I recently came across a copy of "The Mammalian Fauna of the Edinburgh District", written by William Evans in 1892. In it, Evans set out to record the distribution of mammals in Eastern Scotland between the Tay and the Tweed (a rather broad definition of "Edinburgh distict" by today's standards). He particularly wanted to record the distribution of bats and small mammals, as these were felt to be under-recorded at the time. Arguably then, Mr Evans was one of the first ever bat-workers in Scotland.

There are some fascinating distinctions between the work of this dedicated natural historian and modern bat-work, but some remarkable parallels too.

Not surprisingly, the methods used are utterly different and at times seem a little barbaric to a modern reader. In a day when bat detectors were still 6 or 7 decades away, the art of finding bats was focussed on roosts and upon seeing and catching bats in flight. Whereas today we consider it appropriate to make biological records based on seeing (or hearing) a bat and recording the salient characteristics, in an age when conservation was unheard of and probably unnecessary, the true scientist's voucher specimen was a dead animal. Evans described removing bats from roosts, catching them in flight using butterfly and fishing nets, plus some less savoury approaches. The Daubenton's Bat (then Vespertilio daubentoni, now Myotis daubentonii) seems to have come in for more of it's fair share of hasrh treatment: "During the summer of 1869 I observed a number of bats flitting above a still reach of the Esk above Penicuik, and one which I succeeded in striking down with a walking stick proved to be of this species."

Three other specimens of this species were sent to him from the Dunbar area by a contact who, rather than battering them to death with a walking stick, chose the gentlemanly approach....and shot them!

In another section Evans describes how impressed he was with the nimble flight of a Pipistrelle he watched, though his methods of evaluating this were a little rough by today's standards: "In June last I watched one for fully a quarter of an hour flying in the bright sunshine at Broomhall, near Dunfermline and was much struck with its activity and the facility with which it evaded stones and other missiles thrown at it."

Lest you think too poorly of Evans, he also described caring for live bats (probably captures, rather than the sick and injured bats the modern bat-worker might deal with), in particular a Brown Long-eared Bat given to him by the gamekeeper at Dalkeith Country Park (where there is still a Brown Long-eared roost): "It delights in scrambling about the pictures, the window-blinds and even the chairs; and often settles on the floor, where it moves with considerable rapidity (indeed, it may almost be said to run), keeping the body practically clear of the ground. A more knowing little creature I have seldom seen; and, having discovered that there is sufficient space below the room-door for it to creep through, it's endeavours to overcome obstacles placed in the way of it's escape are most persistent and amusing."

Aside from the very limited equipment Evans had available by modern standards, the victorian understanding of bat taxonomy was rather different. He describes there being 12 species of bat nationwide, whereas today we accept there are 16 or 17 (depending on your views about the Greater Mouse-eared bat's status in the British Isles). The most obvious difference is the Pipistrelle. We now know that there are three Pipistrelle species in the UK, whereas in Evan's day only one was known, the splitting of Common and Soprano Pipistrelles being still a century away.

The most surprising thing about Evan's work and the thing for which he deserves to be remembered is the fact that, despite limited taxonomic understanding and huge limitations in method and equipment, compared with today, his description of the bat fauna of the area is remarkably in tune with what we know today. He described Brown Long-eareds as "by no means rare", Daubenton's Bats as "...locally at least, not uncommon" and Pipistrelles as "undoubtedly by far the most abundant and generally distributed." Ignoring the split of the Pipistrelle species, these three are the most abundant bat species in the region today.

More impressive still is that he was remarkably accurate about the rarer species too. He described a record of Natterer's Bats from near Dalkeith (the two known roosts of that species in the Lothians today are in the Dalkeith area) and goes on to hypothesise that Whiskered Bats are likely to be present in the region too. They are, but there are only three modern records of them in the Lothians. In fact, his only shortfall was his failure to mention the Noctule, which we now know to be present in the Lothians. Whether they were present 117 years ago is a moot point, but it's only in the past decade that they have been identified in south east Scotland. Were they here in Evan's time? We'll never know.

If you're interested in helping to put historical biological records to work, try visiting http://herbariaunited.org/atHome/ This project uses on-line volunteers to transfer information from thousands of old herbarium sheets onto a modern database. It's easy to do and rather addictive!

My website: http://www.blogger.com/www.plecotus.co.uk