Sound Activated Recording – Results

Last updated: 2nd March 2017

Here is a selection of some results of my sound activated recording so far, with a brief analysis of results so far shown at the end.

18th April 2016.  Brown long-eared bat social call.

  • Time: 00:54:59. Temperature 1.2°C. Humidity 68%.

The wav file for this recording can be downloaded at the following link.


21st April 2016 – Noctule.

  • Time: 21:37:45. Temperature 10.6°C. Humidity 71%.


22nd April 2016 – Soprano Pipistrelle.

  • Time: 00:55:15. Temperature 10.4°C. Humidity 58%.


1st May 2016 – Noctule or Serotine?

  • Time: 21:41:04. Temperature 10.8°C. Humidity 80%.


1st May 2016 – Noctule.

  • Time: 22:20:20. Temperature 10.7°C. Humidity 80%.


1st May 2016 – Soprano Pipistrelle (with social calls).

  • Time: 22:39:45. Temperature 10.7°C. Humidity 81%.


14th May 2016 – Noctule?

Tine: 21:43:30.  Temperature 12.8°C.  Wind Speed 1.57mph (both now recorded in spectrogram title at time of recording).


2nd June 2016 – Soprano Pipistrelle + Social Calls


22nd August 2016 – Soprano Pipistrelle echolocation and social calls, plus         Rat distress call (Constant frequency calls at around 23kHz)


Log File

When a bat call triggers a recording, I perform a quick analysis to determine the peak frequency in the recording.  If it is above a certain threshold (e.g. 17kHz) then it is likely to be a bat.  I then retrieve some weather data from my personal weather station and log the data.  The recorded .wav file and spectrogram image are uploaded to Dropbox.

A typical log file contains the following data:


10th June 2016 – Soprano Pipistrelle + Social Call.  

  • Frequency plot now created showing all peak frequencies, which are also added to the spectrogram title.

r20160610-232653 r20160610-232653_peaks

Analysis of Results – September 2016.  

The graph below shows the number of bat calls recorded versus average temperature. The larger the bubble, the more calls recorded.  Temperature is on the vertical axis. Results will be updated frequently.

Recording period: 4th April 2016 to 8th October 2016
Minimum number of calls recorded on a single day is 1.
Maximum number of calls recorded on a single day is > 200.
Total number of calls recorded: 4,318

Species Recorded:
Soprano Pipistrelle : 90.0%
Common Pipistrelle : 3.5%
Noctule : 2.6%
Serotine : 2.0%
Brown long-eared bat 0.5%
Other : 1.4%


Bat Calls Recorded 2016 + Max Min Temperatures during recording period