Wildlife Acoustics EM3 – First thoughts.

Wildlife Acoustics EM3 – First thoughts.

EM3 with gps

EM3 with gps

So I’ve had the EM3 for a  couple of survey nights now and had the chance to use it both for static and transect surveys. To start with I’ve used the detector with settings straight out of the box as it’s marketed as being “shipped ready for use” with “settings (which) allow you to begin monitoring bats in minutes”.

Firstky it has to be said that rumours of a flimsy detector seem to be unfounded, it’s not something I’d want to drop onto a hard surface but the EM3 feels sturdy and up to it’s intended use. It fits comfortably in the hand and is light enough not to notice holding it even after a couple of hours use. The self contained nature and lack of faffing with cables is a bonus in this respect.

Plugging in the gps it took about five minutes to obtain a  fix and start displaying lat/long in the status bar of the display which seems reasonable for first use. There isn’t enough leaf canopy coverage to test it’s abilities in woodland at the moment so that’s something for a later test.

Microphone sensitivity seems fine, I’ll be testing it alongside both the D240x and Anabat to get some comparative data, and the default trigger point for recording seems to be a reasonable balance between picking up bats but filtering out car passes and other environmental noise. You will hear fainter bat calls in your headphones that don’t trigger the record setting but it’s down to individual preference or survey aims to decide on where that trigger point should be.

My transect headed out alongside a busy road with several popular Pip feeding spots before dropping into the valley to return alongside a river, pond and sewage farm, usually a guaranteed spot for five species although it’s still quite early in the season so I wasn’t expecting great results. Along the road the detector ignored most passing vehicles but still triggered to record when bats were encountered. All good so far, and the lack of noise files is something that should speed up processing later.

Heading down to the river and away from street lighting I switched the display to white (sonogram) on black (background) from the default black on white to try and keep some night vision but it became noticeably more difficult to pick out the sonogram on the display. This is something I’m going to try to solve next time I’m out by tweaking brightness levels in both settings and seeing which works best. I was happy to leave it because I don’t think there’s much value in trying to identify bats off the small display, I’d rather do that back at home with the recordings on a laptop screen. For me the detector screen seems more suited to monitoring recording state and confirming activity levels.

Back home and it’s time to download the data, which is an easy job of removing the easily accessible SD card and copying files over onto the laptop hard drive. For me the main selling point of the EM3 is it’s ability to record in wav/zca setting which captures both a realtime full spectrum recording and a zero crossing data file. This should allow a quick workflow by use of AnalookW to process the easy species and switching to full spectrum for the Myotis where more songram measurements are useful.

I was a bit surprised to find that although I had 355 full spectrum wav recordings, the detector had only processed 40 zca files. This potentially has a knock on effect for anyone using Batsound for analysis as the time to process 355 calls is considerably longer than 355 data files in AnalookW. It wasn’t partial passes or quiet bats that were missed out on either several busy spots with multiple bat passes had no corresponding zca file. It looks like some tweaking of the zca threshold setting may be needed from default.  I’ll also be comparing recording in wac (Wildlife Acoustics proporietary uncompressed audio) mode then converting the resulting file to zca to see if that gets better results.

Summary?

So far I’ve been really impressed by both the ergonomics and the potential of the EM3. The promise of monitoring straight out of the box is a hard one to live up to but I reckon with a bit of tweaking default settings to get rid of the niggles the detector should be a very useful survey tool.

Next step is to play with settings then a full review review will be published here

Anabat SD1 and SD2

Anabat SD1 (now superceded by SD2)

From: http://www.titley-scientific.com/uk/index.php/anabat-bat-detector

Price: £2062 for SD2 and pda kit

Pro’s: Versatile, small data files.

Cons: microphones sensitive to water damage, cost compared to rivals.

Anabat with pda

Anabat set up with gps and pda

The Anabat is a zero crossing bat detector from Titley Electronics and has long been the workhorse for bat workers needing static longterm monitoring. It’s a versatile bit of kit, capable of either static programmed use or coupled with a pda and gps or just a gps to record transect surveys.

I’ve been using Anabat SD1’s and SD2’s for quite a few years now and up until recently relied on them for most of my survey requirements. The live display of sonograms on the pda is a great tool for instant in the field ID and also invaluable as a teaching tool when running bat detector workshops.

The zero crossing analysis files produced by the Anabat are tiny (think kb’s not mb’s) allowing long term monitoring in busy active sites without the need of purchasing multiple expensive data cards. Coupled with a decent external 12v battery it’s possible to leave the detector running up to a month without filling a 2gb CF card. Workflow using AnalookW to analyse all those collected files is reasonably quick too. Note however this is a very visual system with little useful audio output either in the field or back at the computer.

Hi and Lo MIcs

Ergonomically  and weight wise that Anabat and pda are going to be noticeable if you’re carrying one all night although easy enough to handle in the field.

For european batworkers the two mics of interest are the standard mic and the hi mic, the hi mic is recommended where Horseshoe bats may be encountered or where you’re using an extension cable longer than 1 metre.

For me the weak point of the system is the microphone that needs careful thought to protect it from water contact when deploying it in the field. This is easy on open sites where a cover and 45degree sound deflector can be used to keep the mic sheltered. Underground in typical UK 99% humidity conditions I’ve found condensation eventually builds and takes the mic out. Some users compromise recordings and sensitivity by covering the mic in clingfilm to avoid this.

In use with a pda I’ve also had the system corrupt data files in areas of high multiple bat species feeding activity, a frustrating thing to find at the end of what you think has been a good nights survey. Having started using an EM3 this year, I’ve now gone back to connecting the Anabat to a gps only which when combined with BatNav software is a great reliable tool for simple and quick transect work.

In spite of the above drawbacks I still carry two Anabats in my survey bag because they are just so useful to have and use. The anabat is a great system for long term static surveying with low power use and low data storage requirements but with a few tweaks it could be a lot better. In an time of increased competition I’m looking forward to seeing the next iteration of this detector. If it follows the Anabat Roost Logger I’ll be more than happy

Anabat example sonogram

Anabat example sonogram

Anabat users are advised to keep an eye on Chris Corben’s site for the latest firmware and software.