The forthcoming Anabat Chorus - first impressions

Fifteen years ago, if you wanted to do passive monitoring of bats you had three options - the proven and dependable sandwich-box-shrouded Anabat SD1, with it's ZC recording system (seems clunky now, but was heaven-sent in those days of memory-deprivation and snail-like computers) or the Songmeter SM2 from the then new kids on the block, Wildlife Acoustics. Option three was to cobble up some kind of half-baked system with a basic detector plugged into a dictaphone and plenty of us dabbled with that sort of thing! Today  however, the marketplace is full of options and new models keep trickling onto the market.

Wildlife Acoustics recently launched the Songmeter Mini and I'll say more about that in another post, but there is a clear move towards lower-cost passive monitoring machines, possibly in response to the development of the incredibly low-cost Audiomoth. When you can buy a passive detector for thirty quid (extra for the polythene bag to hang it in!) then £1300 or more seems excessive. However, for professional work the Audiomoth seems an uncertain option, with too much geekery involved. Though that will probably change in time, it creates an opening for the manufacturers to slide in new mid-range passive detectors, drawing on their experience and reliability. 

The new Anabat Chorus

Andrew Dobson of Titley Scientific was kind enough to lend me a beta model of their forthcoming new machine, the Anabat Chorus. I've long been quite keen on Anabat equipment - it's not perfect (what is?), but Titley tend to listen carefully to customers and build on what they learn from each model. The Chorus is a good example. At first sight the case looks similar to the Swift and Express models, both of which are a pig to open, as the latches are incredibly tight - a necessity, to seal the case against moisture ingress. The solution is rather elegant - a large lever-type arrangement applies one of those first physics lessons we learned at school and makes opening and sealing the case much easier. There are also pierced flanges top and bottom, increasing the options for attaching the case to a substrate, especially useful for longer-term installations.

Inside the case, at first sight it seems similar to the Swift and has most of the functionality, but instead of the sexy (and costly) touch-screen, the screen is more basic, with up/down/left/right buttons. The battery case takes four AA batteries, but with Eneloops (the rechargeables of the gods), that should give many weeks of recording, in fact Titley claim 40 nights is possible. And they've retained the easily accessible back-up battery, so you can change it yourself when needed. As with most equipment nowadays, GPS is built-in, ensuring that that accurate sunset and sunset times can be depended on. There's also a temperature sensor, though personally, I rarely trust the data from in-built sensors. The detector is not always in the best location to get sensible data, so I tend to use a separate temperature datalogger in a shady spot nearby.

The interior of the machine and the controls - essentially a budget version of the Swift controls, but without losing anything vital that I could find

Rear view, showing the pierced mounting flanges and the lever arrangement, for opening the case with breaking a finger

In use, I found it to function exactly as expected, with similar funtionality to the Swift, using the control panel to select simpler timing options or a new software package to allow custom settings. As with the Swift, you can record ultrasound as .zc or.wav. There was a little distortion in the recordings, though this was probably due to reflections off the case. You can't use an extension lead with the microphone, as with the Swift, but Dean Thompson from Titley advises that there'll be an optional goose-neck extension to move it away from the case and reduce this effect. 

The optional microphone gooseneck

(photo copyright Titley Scientific)

I'm happy to say that they have retained that wonderfully simple crowd-pleaser, the little magnet on a string. This allows you to check the machine is functioning properly once it's in position - rarely essential, but massively reassuring before you walk away, trusting that when you return in three weeks time the detector will have recorded as expected.

Considering that the Chorus will retail at £595 +VAT I was a bit bemused as to where the savings had been made, by comparison to the rather pricey Swift (currently £1194 + VAT from NHBS).  According to Dean, the main differences are:

• You can't use an extension mic lead (the gooseneck will cost extra)
• The machine can only use 4 AA batteries, unlike the choice of 4 or 8 with the Swift.
• It only has one memory card slot, instead of two (but with the massive capacity cards now available, that's hardly a problem).
• You can only record from one microphone at a time.

What's this I hear you ask? "One of two microphones"? The Chorus has an acoustic microphone as well as an ultrasonic one, giving you the chance to record birds, frogs, crickets or whatever else takes your fancy (for £200 less you;ll be able to get one with just the acoustic mic). It has the same ultrasonic microphone element as the Swift (though they're not interchangeable). 

One concern I have is that the microphones seem quite vulnerable, as they are attached to mouldings on the case. The Swift and Express come with excellent protective carry-cases, but apparently that won't be the case for the Swift, so I think a protective case to store and transport it will be an essential extra.

In this view you can see the two microphones, ultrasonic on the left, acoustic on the right.

Overall I was quite impressed with what we'll get for the price-point. I was also impressed that most of what has been removed to get the price down is unlikely to be missed much and that Titley have taken the opportunity to add some simple enhancements that improve the package. It's disappointing that the gooseneck microphone mount will be an additional cost over the basic price, but they are going to have Wildlife Acoustic's Songmeter Mini to compete with and I reckon that will be a fair fight. 

The machine I was trying out was a beta model, so the final product may be slightly different. And if you want a seriously techie appraisal you'll need to look elsewhere - my musings here are for those of us who want to actually use the machine, rather than devour the specifications! But if that floats your boat you can find the full specification on Titley's website: Anabat Chorus

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PS - the photos above show a foam sock on the ultrasonic mic, but it belongs on the acoustic mic (when I tested it, it was on the correct mic!)

The new generation of unattended bat detectors

It's been a little while since I wrote a blog post, which has irritated me as I have a host of subjects I want to write about, but so little time to do it. However, the inevitable bat worker calendar effect has happened and I am looking out of the window at deep snow and reflecting on the fact that my "to do" list is the shortest it has been for about a year. This wonderful situation won't last long so I'd better get blogging!

Back in 2011 I wrote about the rivalry between Titley Electronics and Wildlife Acoustics, whose Anabat SD1/2 and Songmeter SM2BAT were at that time the only realistic options for unattended monitoring of bat calls. Both machines had strengths and weaknesses, both were (and still are) very widely used by ecologists and bat researchers.

In the past year both companies have launched new unattended bat detectors. In both cases they seem to have listened to customers in an effort to improve on their previous models. It is interesting that the result of their market research has been very different. Wildlife Acoustics moved up-market with a signficantly more expensive machine, the SM3BAT and Titley went for a smaller and cheaper machine, the Anabat Express. I am fortunate enough to have had my hands on both machines for the past year and have had an opportunity to put them through their paces.

Wildlife Acoustics' Songmeter SM2BAT and the slightly improved SM2BAT+ have achieved much popularity in the UK and elsewhere in recent years. Their price tag of around a thousand pounds made them cheaper than the Anabat SD2, though still expensive for non-commercial users. Their ability to record from two microphones at once was attractive, especially for those wanting to record at height and at ground level simultaneously and the fact that they recorded to SD cards, rather than the dated CF cards used by Anabats was also attractive. However they were complex to use, requiring careful setting up and were easy for the inexperienced user to get wrong.

Perhaps Songmeter's most attractive feature compared to the Anabat was that they came in a waterproof case, whereas Anabats needed an additional weatherproof box - Pelicases for the well-heeled, sandwich boxes for others! The  Songmeter's big selling point was that it arrived oven-ready, without the need to fabricate a waterproofing solution. However they suffered from condensation at times and the internal memory card holders were vulnerable to damage when inserting the massive D cells the machines use. Exposing the internal workings of the machine to change batteries or memory cards in inclement weather was hardly ideal, though the SM2BAT+ model had it's internals sprayed with a water-repelling coating to improve this.

Anabat SD1 and SD2 models need additional waterproofing for unattended use. This sandwich box is the low-tech approach!

An SM2BAT mounted at the base of a mast, with one microphone attached and another at the top of the mast, connected by a cable.

Unlike Songmeters, Anabats (this is an SD1) can also be used for transect work.

The Anabat SD2 (and the previous SD1 model) by comparison, though about 35% more expensive was more robustly built (waterproofing aside) and much easier to use, reducing the risk of expensive repeat surveys. They also use standard AA cells, rather than the larger D cells used by Songmeters (though both can also be connected to external 12v batteries for longer term use). They also have the advantage of being excellent for hand-held transect surveys, whereas the Songmeter can only be used passively.

So given all these pro's and cons I was intrigued to see what the two new machines are like and how the two manufacturers have responded to the feedback of their customers.

The Songmeter SM3BAT was the first of the new machines to reach me. One of the criticisms of its predecessors was that they were a bit "plasticky" and some parts were easy to damage. My first impression of the SM3BAT was that it had been cast in a furnace, rather than built! It's taller than the old machine and the case appears to be capable of withstanding having cattle tap-dance on it (a more common issue with this type of equipment than you might think), though I wouldn't recommend experimenting with that. It's also heavy at 2.5Kg without batteries. The solid metal casing includes holes for securing the machine, either by bolting it to a wall or by attaching it to something solid with a bicycle-lock style cable.

The SM3BAT in use. The microphone is at the end of the cable on the right, allowing the machine to be put out of sight if necessary.

The controls and screen are now on the outside of the machine, with robust plastic to protect them. Battery compartments and memory card compartments are accessed by removing waterproof plugs on the side, so that there is no longer any reason (or indeed any ability) to access the interior of the case. Thus several criticisms of the SM2BAT are removed - the new machine feels solid and robust, it gives confidence that it can cope with whatever is flung at it.

In use the SM3BAT is similar to the SM2BAT. It can record in ZCA (Analook) format, or in WAC or WAV formats. As before there are four memory card slots to allow you to provide the machine with plenty of space for the latter two memory-hungry modes. Wildlife Acoustics are proud of the fact that it is compatible with the latest generation of 256GB SD cards, providing potentially a Terrabyte of memory. A big criticism of the SM2BAT was the memory-hungry nature of Wildlife Acoustics' preferred WAC format. With advances in computer technology the ability to store and process large amounts of data has become steadily easier since then, though that burden should still not be underestimated if you plan to use these modes.

The SM3BAT comes with an upgraded microphone, which like the SM2BAT one is omnidirectional (a key difference to the Anabat SD1/2 microphones, which are unidirectional). However it is significantly bigger and can no longer be plugged directly into the side of the casing. Wildlife Acoustics advise it is more sensitive than their previous microphone.

Titley Electronics' new machine is the Anabat Express. They have chosen to produce something much more compact and with less visual impact than their competitors machine. The Express is a similar size to the old Anabat SD1/2 but is now in a camouflaged waterproof case. The case, though made of plastic is strongly made and similar to those used for camera traps. It now has an omnidirectional microphone, which is stored safely in a slot within the case and then screwed into the exterior for use. Unlike the SM3BAT the Express has a built-in GPS, which it uses to calculate sunset times (the Songmeters need to be programmed with their location to calculate this). This is a big step forward for Anabat. Titley's previous models could only be programmed to start and end recordings at fixed times, with no allowance for day-by-day changes in sunset and dawn times. Songmeters have the useful facility to start and finish at a set time in relation to sunset or dawn. Now the Express can do this, with the added bonus that it doesn't need to have latitude and longitude pre-programmed, as with Songmeters.

The diminutive Anabat Express, with a £2 coin for comparison.

The interior of the Anabat Express, including built-in instructions.

In use the Express is virtually idiot-proof (believe me, I'm an excellent measure of this). When we're out in the field, setting up equipment and it's cold or wet and we've been working all day even the best ecologist or bat-worker is liable to do something daft - we're only human after all! The Express even has step-by-step instructions pasted to the inside of the lid. All you have to do is connect the microphone to the outside, switch it on and wait for the GPS to get a signal. Then you cycle through three options for recording time (continuous, sunset to dawn or pre-programmed), close the case and you're ready for action. A cord attached to the case ends in a magnet, which can be used to check the machine is functioning correctly. A friendly blue light winks to confirm all is well when the magnet is placed in the right position on the case.

The Express uses standard SD cards, with no prior set-up, so formatting CF cards is a thing of the past. Of course, unlike the Anabat SD1/SD2 this machine isn't suitable for transect or other hand-held work - it's only effective as an unattended detector. It only records in ZCA format, so if you prefer to use audio recordings for analysis this is something to think about. Personally I prefer ZCA for most purposes. I'm not thrilled about the fact that you have to open it up to operate it - that was one of my criticisms of the Songmeter SM2BAT. However, the interior of this machine is far more robust than the SM2BAT and, like the SM2BAT+ the interior has been sprayed with a water-repelling coating.

So Titley have chosen to go for a low-profile, simple-to-use machine, whereas Wildlife Acoustics have gone for a big, solid, bomb-proof detector. Which would I buy? As ever it's a case of horses for courses. The SM3BAT suffers from high visibility but balances it by being massively robust. It would be hard to install it in a situation where theft or vandalism is a concern. Not only is it big and obvious it looks expensive. Your average thieving ned couldn't help but wonder what it will fetch on eBay. Although it can be securely attached to something, that wouldn't protect the controls or the battery and SD card compartments from interference. At over 2.5Kg before you put batteries in, you wouldn't want to carry a rucksack of these machines around a site for temporary installation. However you might choose it as the ideal machine for long-term installation on a met mast, or somewhere where unauthorised interference can be prevented.

The Anabat Express on the other hand doesn't suffer from these security issues. It's small and camouflaged and therefore suitable for installation with low visual impact, perhaps in places with regular visitors. It comes in a protective zip-up case and you could happily carry a dozen of them with you all day. So for short-term, high risk installation it couldn't be better and I like many others already have several of them for that purpose. If you do want to install one in a higher-risk situation Titley sell a steel case and steel python cable, allowing you to attach it securely to something solid. The Express is also very easy to set up in the field, so the risk of mistakes is low. Unlike the older Anabats you don't need to worry about where the microphone is pointing and it lends itself to attachment to a tree trunk or similar.

An Anabat Express in use with Titley's optional security system

There are a couple of other issues to consider in comparing the two machines. One is power consumption, Wildlife Acoustics claim that the SM3BAT is less power-hungry than the SM2 models were and claim up to 20 nights on a set of four Alkaline D cells. It can also be used with an external 12 volt battery or power supply. The Express can last for up to 30 nights if you use Lithium AA batteries (high capacity Lithium batteries are not an option for D cells, so far as I know). you cannot connect an external 12v battery to the Express, so it's not a machine for long-term use, though 30 nights is a long monitoring period!

The other thing to consider is price. Wildlife Acoustics have abandoned their £1000 price point with the SM3BAT, which sells for over £1400. This compares with £660 for the Anabat Express. In other words you can have two Expresses for the cost of an SM3BAT and still have money left over. I supsect this is the clincher. Both are good machines, both appear to work extremely well and I have had no problems with reliability of either machine. But two machines for the price of one is hard to ignore, especially when the Express is also less likely to be stolen or vandalised and easier to deploy in numbers across a site. For bat groups and those working on a budget the decision seems like a no-brainer. But if you want a long-term installation or if you want something with a well-engineered and professional appearance perhaps the SM3BAT has something to offer.

It's particularly interesting that Wildlife Acoustics have now launched a smaller, lower-cost, ZCA mode only model called the SMZC. From the little I have seen it seems extraordinarily like an attempt to emulate the Anabat Express, though it still has the look of something made in a foundry and weighs 1Kg (the Express weighs 385g). It also lacks the GPS functionality of the Express, but is priced about 10% cheaper, so it may turn out to have something to offer.

Please note that all prices quoted include VAT and appear to be correct at the time of writing. All weights exclude batteries. 

See our website: David Dodds Associates Ltd

Two steps up for bat monitoring?

I've written before about my hope that the rescue and revitalisation of Titley Electronics (makers of Anabat) would result in a shake-up of the market for unattended monitoring equipment. With Titley and Wildlife Acoustics (makers of the Songmeter) battling for the marketplace the winners will be those of us who use their equipment. With remarkable symmetry both companies have looked at their existing offer, listened to customer feedback and both are launching ground-breaking new machines. Interestingly they are also swapping places in the cost stakes.

Wildlife Acoustics appear to have addressed a lot of the issues with their SM2BAT with their new SM3BAT. With a die-cast aluminium case it will be more robust than the previous machine. They have also addressed problems with cumbersome access and risk of letting water inside the unit. The control and screen are now on the outside of the case, making them more accessible and the batteries now slide into slots in the side of the machine. 

The new Songmeter SM3BAT from Wildlife Acoustics

(Photo copyright Wildlife Acoustics)

The Wildlife Acoustics approach of recording in ZCA (Analook) format as well as in compressed WAV (audio) format is strengthened by a massive increase in memory to a Terrabyte, allowing those large files plenty of room for a change. Another problem with the old SM2BAT was the vulnerability of the microphones and W.A. have a new and more robust microphone for the SM3BAT. They also claim an improvement in power consumption and there is no longer a need for an adaptor to use an external battery.

It all sounds very promising. The downside is that they have abandoned the £1000 including VAT price point to pay for the improvements and I understand the SM3BAT will market at £1500. The new microphones are also double the cost of the old ones at £200 each. A big increase, but maybe worth it?

Titley are countering by moving downmarket with their new Anabat Express. At just £500 each you could buy three of these machines for one SM3BAT (though the SM3BAT can record from two microphones concurrently, if required). 

The new Anabat Express

(Photo copyright Titley Electronics)

Compared with the older SD1 and SD2 Anabats the Express is very different and, like W.A. Titley have listened carefully to customer feedback. A key reason why people started buying SM2BATs in preference to Anabats was the the Anabat's lack of integral weatherproofing. The Express is built into a stout weatherproof case, screen-printed with camouflage. The case is little bigger than the original Anabat machines, making it rather smaller and neater than the SM3BAT. The older chunky Anabat microphones have given way to a new and smaller mic. Happily Titley have finally given up on CF memory cards, moving to the ubiquitous and smaller SD card (in fairness they had already done this with the Roostlogger).

Titley also claim a significant improvement on power consumption and the Express uses 4 AA batteries. Oddly in the SM3BAT W.A. have chosen to carry on using 4 large and heavy D cells.

This interior view of the Anabat Express, with AA batteries in place shows how small this low-cost machine is. 

(Photo copyright Titley Electronics)

The Express also has built in GPS for the first time. It's not really a hand-held unit, so the purpose of the GPS receiver is to allow the machine to calculate sunset and dawn times, making it possible to programme the machine to start and stop recording at times relative to these, rather than fixed times. This was always a strength of the SM2BAT, compared to the older Anabats, which require regular reprogramming through the season.

It's great to see both companies listening and innovating and it will be interesting to see what these two new machines are like in practice. W.A. have a habit of making equipment complex to use in the field, which is fine if you're a bit of a techno-geek, but more of a problem if you're just an average bat worker. Titley's previous machines have always been relatively user-friendly, though the manuals for their previous models have been unintelligible! Whether all these innovations deliver the goods remains to be seen. Happily both manufacturers have been kind enough to offer me machines to try out.

On paper it looks like W.A. are aiming for the gold standard with the SM3BAT, though it's costly and more visible, therefore potentially vulnerable when left in the field. The Anabat Express, with its low price-point could be bought in quantity and its small size and camouflaged appearance makes it potentially less vulnerable. If both machines live up to their promise it could be a case of "horses for courses". For long-term placement on a wind farm Met mast the SM3BAT could be ideal. For large scale deployment over a site the Anabat Express could fit the bill. Time will tell...

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The Echometer EM3: The machine I love to hate

Ever since I got my hands briefly on a pre-production example of Wildlife Acoustics Echometer 3 (EM3) late last year I have been looking forward to trying one out in the field. This machine has been much discussed by professional bat-workers: a detector with heterodyne, time expansion and frequency division functionality, SD card recording and the ability to display live sonograms on a built-in screen represents a  step forward in bat survey technology. Now that I have had a few months to try one out for real I have two things to say about it:

1. Do I like it? No, I don't.

2. Would I buy one? Hell, yes.

At first sight that doesn't appear to make much sense, so perhaps I should explain...

The Echometer EM3

(Photo copyright, Wildlife Acoustics Inc)

I don't intend to recite the capabilities of the EM3. You can look that up for yourself on the Wildlife Acoustics website and in any case it would take too long. This machine is packed with functionality, and it's packed into a surprisingly small box. So I shall leave you to do your own research and tell you what I think matters.

First of all, the facility to view live sonograms (and oscillograms) is incredibly useful, allowing faster and more conclusive species identification in the field. I have long been a convert to this, having been using an Anabat-PDA combo in the field for several years. However, this has always been a large, cumbersome set-up and one that is clearly a bit of a bodge-up. It's also a bodge-up that costs an outrageous amount of money (but that's the Titley Electronics way of doing business: marry up minimum product to maximum price and factor in poor quality control for good measure!). So having the screen in a more convenient and much cheaper box should appeal to me, right? Actually, in use I found the EM3's display clarity disappointingly poor, compared to the lovely clear picture you get on a PDA screen.

In terms of functionality, the EM3 allows you to record in WAV (normal audio), WAC (Wildlife Acoustics own compressed WAV format) and also ZCA (Anabat) format. Including ZCA is great, as it means that you can use Analook to analyse calls far faster and easier than is possible using any other software. It also means that you can choose to record in a more high-fidelity mode whenever you choose to.

One of the great things about an Anabat is it's flexibility: you can use it as a handheld detector for transect work or as a passive (unattended) monitoring machine. I was expecting the same to be possible with the EM3. It is, but for some unaccountable reason you can only record in ZCA format if you also record in WAV format simultaneously. The inevitable result is that the SD card rapidly fills up with unwanted WAV files, limiting the machine's potential as a passive monitor, as it can only be used for short periods.

Wildlife Acoustics appear to have listened carefully to their customers: the machine has a number of handy and innovative gadgets. For example the ability to tag calls with a site name and user-specified labels. An interesting function is what Wildlife Acoustics have termed "Real Time Expansion" or RTE. Effectively this provides you with a Time Expansion Detector, but without the traditional problem of TE detectors: you listen to what just happened, rather than what is currently happening (TE detectors normally work by recording bat calls and replaying them to you, at around 10 times slower, thus reducing the call frequency so that you can hear it). RTE digitally reduces the gaps between the calls. so that you get the TE functionality with the advantage of continuous monitoring. Clever, though a bit weird in use.

So, why don't I like it? Well, we live in an age when electronic equipment packs more and more into the same box: many mobile phones can do a phenomenal range of tasks. Wildlife Acoustics have tried to do something similar here. But with a bat detector, it's not just about functionality - it's about the human being using it. Picture the scene: it's late at night in the middle of the bat survey season. You're tired, possibly cold and wet and you're doing your fifth survey of the week. You also face the prospect of 3 hours sleep, followed by a dawn survey. In that situation what you need is a simple-to-use and reliable detector: something that will prevent you from accidentally doing something silly and ruining your survey results. For all its cleverness, the EM3 is not as intuitive to use as I would like it to be and 5am in the morning is not time to be digging out the manual.

Now let's consider ergonomics. This may be unfair, given that the EM3's nearest competitor is an Anabat with a PDA clipped to the front, but if you're going to carry a machine in your hand for many hours you want it to FIT in your hand....comfortably. And you want all the controls to be in the right places. With all it's cleverness, the EM3 misses the boat here. It's uncomfortable to hold and awkward to use. Wildlife Acoustics would be well-advised to look at the Bat Box Duet. It's amuch simpler machine, but it's curved to fit the hand, with the frequency wheel placed exactly where your thumb sits and it's built into a solid case that you could probably play football with and still find it fully functional.

Whilst on the subject of ergonomics, the EM3's loudspeaker is poor. It's buried somewhere inside and squirts the sound away from you, instead of towards you, where you need it. With any amount of background noise it can be a struggle to listen to it. Purists will say that you should use headphones with a bat detector, as it allows you to hear and understand a bat call more easily. They're right, but when you're working alone and don't know who else might be walking about, remaining aware of surrounding noise is an important safety factor. Also, our commercial survey team use radios to keep in touch during a survey, which really wouldn't work with headphones.

To tell the truth, I don't really like the EM3: it's uncomfortable to use and hard to listen to; it feels quite cheaply made and potentially vulnerable to damage and it's just a bit too complex to be sure that a dopey, sleep-deprived mind will remember to do everything correctly.

Yet, despite that I keep finding myself taking it out on surveys. That fantastic functionality is addictive and the live sonograms are great. Okay, the screen is naff compared to an Anabat and PDA, but it fits in your pocket and no Anabat is ever going to do that, even before you erect the scaffolding to support the PDA. The bottom line is that Wildlife Acoustics have raised the bar by developing the EM3. And let's not forget that they did it for less than a grand, which is great price for a professional bat detector.

The EM3 is far from perfect and there are many things that niggle me every time I use it, but it's still impressive. Somehow it's wriggled it's way into being an essential part of my bat survey kit and if I'm honest, I'm not sure that I would part with it willingly, though I wouldn't want it to be my only choice of detector.

Wildlife Acoustics: www.wildlifeacoustics.com

Anabats and Songmeters

I have written before about my good opinion of the Anabat SD1 (now replaced by the SD2, with some minor upgrades), a machine which offered huge advances in passive monitoring of bats (i.e. leaving a machine on site to continuously record bat calls), in use with a GPS receiver for walked and car transects (where a route is followed, recording bat calls and their locations) and for use as a training aid when connected to a PDA personal computer, to display live sonograms of bat calls. Prior to the arrival of the Anabat the only way of doing these surveys was with a Frequency Division bat detector, recording WAV (or poorer MP3) audio files: a massively time-consuming and data intensive process, so the Anabat was a big step forward.

Like all good things, the Anabat had some downsides: reliability has never been as good as it might be, technical support is patchy and confusing and the price (around £1400) is prohibitive for many users. So the arrival of the rival Songmeter SM2 on the UK market last year generated a lot of interest. At around £800 it is clearly cheaper and many bat workers and ecologists were excited to try out the latest generation of bat detector. Personally, I was quite cynical and, having had the chance to use several Songmeters this year, my reservations may have been justified. Let me clear though: I am not saying that the SM2 is not a good piece of equipment: it has a lot going for it. What I am saying is that, just like the Anabat, it has strengths and weaknesses and to claim as some have, that it is a technical advance on the Anabat is simply nonsense!

The two importers of the Songmeter, Alana Ecology and Envisage Wildcare have marketed the Songmeter powerfully in the U.K. and it's arrival on the market suggested that it was a new and exciting development. In fact the Songmeter had been on the market in the U.S., alongside the Anabat for quite some time. Anabat had been successfully sold in the U.K. by both companies for several years and both provided excellent technical support. In early 2010 Titley Electronics (who make the Anabat) suddenly withdrew the product from them and set up a European sales office in the U.K. Deprived of a key part of their product ranges, both companies looked around for a replacement product and settled on the Songmeter. So it's arrival here was a result of commercial necessity, rather than technical development and the flurry of interest in it is primarily a result of marketing hype. So I was interested to get my hands on some Songmeters this year and find out how they match up to the hype.

An Anabat SD1. The later SD2 version has a USB socket on the right-hand side, rather than a serial port. The velcro on the left was stuck on to allow a GPS receiver to be attached for transect work.

A key advantage of the Anabat is the fact that it converts bat call audio to a digital format, so that each bat pass generates a tiny file of around 2-5KB. Thus a 2GB memory card can last weeks or even months, without needing to be replaced. The SM2 records WAV high quality audio, compressed to form WAC files. Theoretically, this allows the creation of better quality sonograms for analysis. Unfortunately, the compression results in very large files, compared to Anabat. My experience of using SM2 has been of long hours spent downloading, copying and converting many tens of Gigabytes of data. The Songscope software supplied by Wildlife Acoustics (the makers of Songmeter) is expensive and unpopular, so that most people use Analook (the Anabat software) to analyse Songmeter data. Wildlife Acoustics supply a free program (WAC2WAV) which converts WAC files to ZCA format, so they can be analysed using Analook. However, running WAC2WAV on large amounts of data (and most passive monitoring produces large amounts of data) is slow and tiresome.

Using Anabats for passive monitoring has always created the problem of waterproofing, leading to many imaginative ways of keeping Anabats dry and free from condensation when used in the field. Unfortunately, long-term use in our wet Scottish climate has always been a problem, with inevitable condensation build-up leading to failure if the machines aren't occasionally taken somwhere warm, to dry out for a few days. The SM2 case is waterproof in itself and needs no further protection. It also addresses the Anabat problems by including "Humisorb" pouches inside the units and having a valve to equalise air pressure inside with that outside. That sounds ideal and would be...if it worked. At present several of the SM2s I am using have proved unequal to the challenge of a cold, wet upland site, with quantities of condensation present inside the machines. In fairness, none has yet stopped working and the manufacturers have proved keen to find a solution. Only time will tell if they are successful.

There is a clear cost benefit in buying an SM2, rather than an Anabat, but there are also hidden costs. A 2GB CF card for an Anabat costs around £15, but a set of four 32GB SD cards for an SM2 could set you back several hundred pounds (how many you need will depend on how often you download data). SM2s have internal capacity for a set of outdated D size batteries. The machines reportedly do not respond well to the lower voltage produced by rechargeable batteries. Happily the machine, like the Anabat, will work with an external Sealed Lead Acid Battery. Unlike the Anabat, you will have to pay around £100 for an external voltage regualator. Oh, and if you want the software designed to be used with the Songmeter, that will be another £500.

Probably my biggest beef with Songmeter is its lack of flexibility. It is a passive monitoring machine. Full stop. Anabat has a range of potential uses, as I described above. The SM2 does have some interesting potential though. For example, it comes with an in-built temperature recording unit. It also has the ability to work with two separate microphones concurrently. Potentially, this allows some interesting studies to be carried out, using extension microphone cables. For example, recording the direction of bat movement along a linear feature such as a hedgerow or comparative studies of bat activity at ground level and at height.

A Songmeter SM2 in position, attached to a post. This unit is being operated with two microphones simultaneously.

Another intersting feature of the Songmeter is it's omnidirectional microphones, which pick up bats in all directions. This is potentially a useful feature in a passive monitoring machine. When a detector is used in the hand we tend to point it at bats we hear, getting the clearest possible calls. When a detector is used passively the directionality of the microphone works against us, so an omnidirectional microphone seems a good idea. However, it has drawbacks too. A microphone which picks up bat calls in all directions also picks up background noise from all directions too, reducing the gap between noise and bat calls. This could easily reduce the clarity of a recording and increase the number of non-bat ultrasound recordings.

My biggest beef with the Anabat has always been it's limited ability to keep accurate time. Over a period of weeks they are fine, but over protracted periods of use the internal clocks tend to lose or gain time. So far the SM2s I have been using have been reliable in that respect. They also have a useful ability to be set to start and stop recording at specified periods before sunset/after dawn, rather than specified start/finish times, as with the Anabat. This saves having to reprogram them through the year, to reflect changing dawn and sunset times.

One colleague I spoke to this year was hopeful that using SM2s intead of Anabats might reduce the number of equipment failures. Sadly that hasn't been my experience. It's easy to think that, when you buy a machine with a high price tag you are getting high quality electronics, but electronic development doesn't really work that way. The major cost in producing any electronic equipment is the initial development cost. If you are developing a new iPod, confidently expecting to sell millions of units, you can afford to invest millions of pounds in perfecting the design. If you are developing a bat detector, with an expected sale of a few thousand units then the development budget is inevitably much smaller. In this respect both machines are in the same boat and they appear to have an equal propensity to fail.

So what would I spend my cash on? Well, the SM2 is an interesting piece of equipment, with some useful features. It had the potential to knock the Anabat for six on waterproofing and reliability, but so far it has proved no better on either score. It lacks the Anabat's flexibility and it's memory-hungry format is time-consuming to manage. So, unless I was involved in a project which could benefit from the specific extra capabilities of the Songmeter I would spend my hard-earned cash on an Anabat.

Wildlife Acoustics (maker of the Songmeter) www.wildlifeacoustics.com

Titley Electronics (maker of the Anabat)

www.titley-scientific.com

Wildcare & Alana (the UK Songmeter importers) http://www.wildcareshop.com
http://www.alanaecology.com


My website: www.plecotus.co.uk