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.


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

One thought on “Wildlife Acoustics EM3 – First thoughts.

  1. Tweaking the threshhold on the second run has resulted in an improved 213 wav / 115 zca, we’re getting there but there’s room for more improvement,

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