Wednesday, 27 June 2012

Elvis: The Lonely Hunter of Circle Beach

It's not really anything to do with bats, but this short spoof natural history film by Matt Hulse is nothing short of genius!

Sunday, 17 June 2012

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:

Friday, 15 June 2012

The art of radio-tagging a bat

People sometimes ask me when I'm going to write my next blog post. The honest answer is that I'd love to write posts more often, but much of my time is taken up by doing bats surveys, writing reports, analysing bat calls and all the other myriad tasks that keep me busy whenever bats are active!

Here, to keep you going, is an example of what's keeping me from blogging. It's a great set of photos taken by Mike Beard, showing my colleague Rebecca Brassey and I (with help from Isla, Richard and Mike) preparing some Noctule bats for a radio tracking project this spring.

First find your bat. Here it's Rebecca's turn to check a bat box and see if our target Noctules are there. Typically, we found a group of them in the very last box we looked in.

Before attaching the radio tag, biometric data was gathered about each bat. First the bat is sexed, the forearm is measured with a pair of callipers and then the bat is weighed.

Weight is especially important as I need to be sure that the radio tag will weigh less than 5% of the animal's body mass. The ratio between forearm length (which doesn't vary once a bat is adult) and weight is also a useful indicator that the bat is healthy and therefore a suitable candidate for radio-tracking.

Next I wanted to age each bat. This is hard to do with non-juveniles, but with larger bat species it is sometimes possible to get a hint of age by looking at wear on the teeth.

Another feature which can help with understanding the age of a bat is the amount of scarring on its wing membranes, though again this is an imprecise science!

I hadn't examined this colony for ectoparasites previously, so each bat was examined and with Rebecca's help some specimens of Spinturnix acuminatus were taken. This is a species of wing-dwelling mite normally found on Noctules.

The specimens are preserved in a 70% solution of Isopropyl alcohol and labelled in pencil on small slips of paper, which are inserted in the vial with the specimen. This prevents the specimen and label from becoming separated.

Next I check the manufacturer's label on the tag, so that we can check the radio frequency of it's "chirp" transmissions. I am also double-checking the weight of it, to ensure it is below 5% of the bat's weight.

A small patch of fur between the bats shoulder-blades is snipped short. This location is used for the tag, as it is a hard location for a bat to reach to groom the tag off. That won't stop it's roost-mates from having a go.

A thin layer of mastic glue is applied to the trimmed patch of fur and allowed to cure until it is sticky.

A similarly thin layer is applied to the tag....

...and the tag is pushed firmly in place.

Next another layer of glue is painted over the top of the tag...

...and the adjoining fur pulled over it.

In this picture you can see the tag's antenna, the thickness of a human hair, trailing behind it.

Voila, one Noctule bat, with radio tag attached and ready to be released at sunset.

The tags of course do not harm the bat: after a short period the fur will grow and either the tag will fall off naturally or it will be groomed off. But for a few days or weeks the bat will give us a windows into it's life:when and where it hunts, where it roosts, whether it associates with other bats and so on.

My thanks to Rebecca, Isla and the various trainees and volunteers who helped out with this particular project and of course to Mike for the photography.

Please note: all bats are protected from disturbance and harm in the UK and EU. This type of work should only be undertaken by experienced personnel under a specific license, issued by the relevant statutory nature conservation organisation (Scottish Natural heritage, Natural England etc). Attempting to handle bats without an appropriate license is a criminal offence and carries risks. If you are interested in getting involved in working with bats on a voluntary basis contact your local bat group (The Bat Conservation Trust will put you in touch with them).