Echolocation

Most bats use echolocation to hunt their prey.  British bats are insectivorous and all use it to a greater or lesser degree.  Brown and Grey Long-eared bats have such well developed hearing that they rely less on echolocation than other insectivorous bats but nevertheless they still use it.

We have dozens of hours of recordings in Jersey and although 90% of these are the Common Pipistrelle, we are gradually discovering new species.  For example a Geoffroy’s Bat was discovered through DNA analysis of its droppings in 2013.  We have many recordings of the Serotine from St Mary’s village and St Peter’s Valley.  We regularly record Soprano Pipistrelles and occasionally Nathusius or Kuhl Pipistrelles.

Henry recorded a Natterer’s in St Catherines Woods in 2014 and Miranda a possible Leisler’s later in the year.  No doubt David will have interesting recordings from his IBats surveys.

In early August 2015 Miranda saw and recorded a Myotis hunting low over one of the island’s small reservoirs.  As there are so few European bats that hunt in this manner it most likely was a Daubenton’s.

This page is for members to contribute spectograms.  If the bat is unknown then other members can help to identify it or at least eliminate some species.  If you have trouble inserting the image please send it to me and I will try to do it.

Serotine at St Mary July 2013

10X00010 Here is the .wav file so you can listen to the Serotine.  It is rather long but you can clearly hear the call at 24seconds and at 101seconds.

Below is the spectogram.  It is fairly typical of a Serotine emerging from its roost but has a slightly higher peak frequency than the books say.  I have recorded this Serotine on many occasions and generally, for reasons of geographical differentiation or other reasons it peaks higher than normal.

Here are the parameters:

Shape: Steep FM (Frequency modulated).  When hunting this species produces pulses of FMqCF

FMaxE = 33.4kHz,   Duration = 8ms     IPI = 127ms (averaged over 6 pulses),    Start fr.= 62kHz, end fr: = 25.1kHz

Note the harmonics slightly to the right and above the main pulse.  These pulses resemble those of a Common Pip but are of a lower frequency.

 

Spectogram of Serotine
Spectogram of Serotine

 

Kuhl’s or Nathusius at Val de la Mare May 2014

10X00028  Here is the sound file containing the Kuhl’s/Nathusius.  These two bats are so similar in their calls that it is very difficult to differentiate between them.  It starts with weak Common Pip then leads to a strong Soprano Pip and at 34 seconds leads into a long recording of Kuhl’s/Nathusius.

Below is the spectogram of the Kuhl’s/Nathusius.

The parameters shown below are as follows:

Shape steep FM (the shape can sometimes be FMqCF), 

FMaxE  = 39.3kHz, Duration = 6ms,  IPI = 92ms, start fr = 76kHz, end fr = 32.8kHz

If I had to take a guess I would say this is more likely to be a Kuhl’s as the IPI is quite short and it has a long FM sweep.

Kuhl's or Nathusius spectogram
Spectogram of Kuhl’s or Nathusius

 

 

 

Leave a Reply

Your email address will not be published.

Jersey's dedicated Bat Conservationists