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There are bat detectors...and there's the SSF Bat2
For some time I have been wondering what the next steps in bat detector technology would be. For a while it looked as though it would be the long-awaited Bat Box Griffin: heterodyne, frequency division and time expansion in one unit, with in-built recording. That may well prove to be a world-beating piece of equipment, but it's launch has seen many delays (though in the 21st century it's nice to see a manufacturer which respects its customers enough to perfect a product before launching it...Microsoft Vista comes to mind).
Last year the Italian Dodoultra promised digital processing and many clever features. Possibly they were delivered but it really didn't matter as the detector was woefully poorly designed in terms of ergonomics and usability in the field. The Dodoultra's manufacturer ignored two simple facts of bat detector design: bats move around fast and they do it in the dark. Detectors need to be easy to use and swift to change function. The Dodo delivered neither and followed it's namesake.
So when I heard of a new detector from SSF in Germany with clever functionality I was cynical, to say the least. However I am a sucker for new toys and so 160 Euros was spent on a shiny new SSF Bat2. Note that price: 160 Euros, delivered from Germany is good value for a decent quality heterodyne detector. But the SSF2 isn't just a decent quality heterodyne detector, it turned out to be rather more than that.
If I were to ask what are the major drawbacks of using a heterodyne detector, compared to say and £1800 Anabat+PDA you might say these: 1. The hassle of tuning up and down in order to find bat calls. 2. The difficulty of identifying the peak frequency of a brief bat pass. 3. The risk of missing a bat because you're on the wrong frequency.
The Bat2 display shows the frequency the detector is tuned to, as you might expect. But it has three other displays. Firstly, there is a second frequency display, which shows the peak frequency of the bat call you are listening to. Hit one of the four buttons on the front of the detector and the detector jumps to that frequency (and unlike the Dodoultra, which also included this function, it works properly. The Dodo had a tendency to latch onto harmonics, instead of the main call). Pipistrelles and other frequency-critical calls can be swiftly tuned to peak, even during a brief pass.
All heterodyne detectors have the problem that they only receive a limited range of call frequencies at one time. How broad a range depends on the individual detector, but between 5 and 20 kHz is usual. Of course this means that, if you are tuned to 20kHz, listening to a Noctule and Greater Horseshoe flies past you are going to miss it. The Bat2 includes a small graph on it's display, showing the frequency range of the received call. In theory this means that you can see that Greater Horseshoe, though you would have to be walking about staring at the display, which means you're not going to see any bat behaviour and will probably trip over a tree root. Nonetheless it's a handy function.
The Bat2's tuning is controlled by up and down buttons on the front. If. like me, you like the thumbwheel tuning on the current generation of Bat Box detectors you may view this with the same suspicion that I did. It turned out to be surprisingly usable, even one-handed (as every chiropterologist knows, bat surveys require at least three hands). Cleverly, the detector has four user pre-set frequencies which can be jumped to by pressing a button, thus removing the tedious need to c=tune from one end of spectrum to the other.
All good stuff so far, so what's are the downsides? Well, apart from it only being a heterodyne detector (and surely that graph indicates that this machine must be processing frequency division internally? Couldn't it have an FD recording output?) the only complaints I have are very minor. The battery compartment is held shut with a small Phillips screw. Nice and secure, but hardly the game you want to be playing in the dark at 2am when the batteries run out.
My other niggle also relates to the batteries. It uses 4 AA batteries, which makes it a little heavier than other detectors which use 9volt PP3 batteries, but not enough to be a problem. I found that the battery indicator read low as soon as I inserted a fresh set of batteries. It took me a while to realise that rechargeable batteries only deliver 1.2volts, compared to the 1.5volts of a dry cell. Thus, the Bat2, when presented with rechargeable batteries registers low battery, regardless of the state of charge.
All in all I am delighted with my Bat2 and for the time being it is my detector of choice for watching bats, though for anything where I may need to review calls later I'll still use an Anabat+PDA or a Bat Box Duet and digital recorder. Please SSF...bring out a frequency division version...oh, and a handbook in English would be nice.
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WW2 Bunker to Bat Hibernaculum
Several winters ago a couple of good friends and I were searching structures I had trawled from an archeaeological database, in the hope of finding previously unrecorded bat hibernaculum. A group of massive World War 2 structures had caught my eye on a satellite photograph. These turned out to be former RAF bomb stores - useless for hibernating bats, but now handy cattle sheds for a farmer.
Nearby a small square of concrete on a small hillock within a pasture field caught our eye. Taking a closer look, we found a small hole in the ground alongside the concrete square. When we crawled through the hole we found a hidden world. A group of brick-walled underground rooms formed an airfield defence bunker. The concrete square was a pill-box, allowing the commander a 360 degree view of the surrounding RAF airfield, now long gone.
 The bunker was humid and seemed to have the sort of steady low temperature suitable for hibernating Myotis and Brown Long-eared Bats. Whilst it was full of historical interest, including an iron bedstead and a utility WC, sadly there were no crevices in the masonry which could be used by hibernating bats. Nonetheless, I couldn't help thinking it had potential and that fact was filed away in the tardis-like bucket of trivia which masquerades as my brain.
 Fast forward two years to a conversation with Stuart McPherson of East Lothian Council and my randomly-wandering brain spat forth the news of this potential bat hibernaculum on his patch. We arranged to look at the site with the landowner and a plan was hatched. With a generous grant from Scottish Natural Heritage we would dig out the entrance to the bunker, to give bats easier access and to help them to find it. Inside we would install crevice boxes to facilitate hibernation and a hedge would be planted, linking the bunker to nearby woodland and hedgerows.
The difficult part was going to be the clearance of several tonnes of soil and rubble. "No problem" I blithely said, promising that Lothians Bat group would be able to produce a team of volunteers to take the work on (and provide funding in kind to balance the SNH grant). With my fingers firmly crossed I wondered how long it would take to do it on my own.... 
I needn't have worried. One August weekend found a team of 7 intrepid bat workers, equipped with spades, shovels, picks and buckets, together with a tractor and trailer provided by the landowner. I am here to tell you it is simply astonishing what a group of bat-centric conservationists can achieve when two and a half tonnes of spoil needs digging out and moving. As well as making the bunker far more accessible for both bat workers and bats we discovered all sorts of reminders of our 1940's forebears. The star find, considering this was an RAF base was an empty brylcreem bottle!
As ever, Nigel Terry went above and beyond the call of duty, splitting his trousers as he toiled and sweated. This blog can exclusively reveal the highly appropriate nature of what was revealed.... Words fail me!
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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
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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.
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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/ Contact me: http://www.blogger.com/blog@plecotus.co.uk
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Bat Blogs around the world 
