Configuration for pipistrelle bats

For a study on alpine bats at high altitude, in Italy, we used the settings in the attached file. On a 128 GB SanDisk Extreme card and Duracell Optimum batteries we always manage to record 5 nights. Best regards Paolo

When I started using AudioMoths, I knew next to nothing about bats and probably still don't know much :)

I use the following settings

Sample Rate set to 192, in order to be able to include the whole range of Pipistrelle Sounds.

Gain slightly enhanced

Sleep Duration set to 5 secs - because Audiomoth seems to need that, regardless of how long the recording period is.

Recording Duration set to 25 (or fifteen) so that I get 2 or 3 files per minute of recording time. I know that 5 secs is generally thought to be sufficient, but I like to be able to see visually the entire call sequence in a sound editor (I use Audacity)

I like to record a period that extends a little outside normal dusk and dawn. THis is what I have set currently.

I'm using Energizer recargeable batteries which seem to last about 3 days (4 max), so I regularly change the batteries and the exact times used for recording.

For the purposes of saving space on the memory card, I use the Amplitude Trigger, I use a Minimum Trigger duration of 1 second, which I have found works best for me. I record in my garden and if I set a longer trigger, I don't capture much activity. I set the Amplitude Threshold to 5% - this is the change in volume that triggers the start of the recording. You will have to experiment with these two settings to optimise your own disk usage. I use 64GB and 128Gb cards and find that with these settings and replaceing the batteries every few days, I don't run out of space.

I sometimes play about with this filter settings. For example you could use the band filter to set limits for the lower and upper ends of the frequency range that you are interested in. I am also interested in recording Birds, Mammals and any Bat species, so I tend to have the Audiomoth record across the entire range.

Using the whole range maybe overkill for your needs, thats a decision that you need to make. Remember, the Sample rate on the first tab, determines the frequency range that is available. Eg setting the sample rate to 250, increases the upper limit to 125KHz. Decreasing the sample rate to 96, reduces the upper limit to 48KHz.

Another key consideration in using Triggers is that, when enabled, the AudioMoth generates T.WAV files rather than just .WAV. These are more compact on the microSD card, enabling you to record more data but should be 'expanded' before use., once you have transferred them to your PC . It might be worthwhile buying a large portable hard drive (5TB or so) as you will generate a lot of data and if you want to retain all your data collected, you will need a lot of disk space.

I always tick the box 'Use daily folder for generated WAV files', so that the files for each day are collected together in separate folders on the microSD card. I also enable the energy saver, though I haven't noticed much benefot from using it.

With these settings I regularly pick up 3 pipistrelle species, Noctule etc.

I use BatClassify to scan the generated files, then take the files with the best scores (i.e. greater than 75% accuracy) and upload them to the BTO Acoustic Pipeline website for analysis.

I find that the results generated for the Pipistrelle and Noctule species are pretty accurate. I've not had enough experience recording the other Bat species in the UK, to get a real feel for the accuracy of the analysis for those species.

[If I have posted any misleading nonsense above, I'm happy to be corrected. I'm learning all the time]