Sonogram ID (1 Viewer)

I am a beginner when it comes to sonogram creation and this is my first year of bat detecting! I can only assume looking at the peak frequency this is a noctule bat? There are very few sites I can find which show sonograms for ID using a FD detector. This has a decending three sweep pattern (I'm sure thats not how one should describe it! I'm unsure of the technical jargon for the pattern) Can anyone confirm if the sonogram pattern matches the Noctule bat?
Many thanks for your time and help
Kim

Try the Northern Ireland Bat Group - they have sonagrams which may be able to help.

Hi Kim, I don't know much about this but check
http://www.somersetbirder.fsnet.co.uk/page15.html
http://www.batdetective.com/sonograms.htm
Nothing there on Noctule. Maybe the Natural History Museum or the British Wildlife Sound people would know.
Regards, DT

Hi Kim,
The lowest line of signals at approx.20KHz looks good for Noctule in terms of the peak frequency. Difficult to say for sure without hearing the file, but if it had the "Chip-Chop-Chip-Chop" sound then probably was a Noctule. Did you see it in flight? They tend to be very high, fast and straight, with a wedge shaped tail.

I think the higher signals are harmonics of the 20KHz so can be ignored.

Also looks like a Soprano Pipistrelle at 55KHz on your sonogram just to confuse matters! Don't know enough about Pipistrelles to rule out a Pipistrelle's "social call" which might be at 20KHz? If you could post the wav/mp3 file that would be interesting.

Thanks for your help Peter I'm fairly certain it was a noctule it was high and large but flew fairly slowly. I know now to look at the tail shape! My duet was tuned at 45khz
I will post the clip but need to know do I post the a) the stereo sound? or b)the FD left channel or c) the right hetrodyne channel?
Regards Kim

Hello, if you saw it up high and it was large, then it is definitely a Noctule. Was just a bit suspicioous of the Pipistrelle at the same time.. obviously a good place for bats!
The stereo file might be interesting to listen to.

Hi Peter I have attatched the sound clip -stereo version un-processed (ie both channels FD & Hetrodyne) recorded on a Batbox duo set at 45 frequency. I think the small bats along the river which roost under the bridge where this was recorded are Daubentons?
Regards Kim p.s hope the sound clip works!

Hello,
yes that sounds like a Noctule (slow "Chip-chop"), and lots of Daubentens (rapid clicking) in the background. Can't make out the Pipistrelle that was in your Spectogram. Sounds like you are getting good results with your set up.

Cheers,
Peter

Thanks Peter
It has been a steep learning curve! I like to get things confirmed as I am so new to this.
Thanks for your time and help
Regards Kim

You are right ,a few chip chop Noctule and lots of Daubenton's. The Daubenton's have such a flat regular tone. Worth remembering the narrow wings of Noctule, they belt about shouting loudly at 20khz over open country often high, as one of the largest species they are very distinctive and often out before dark. Serotines are broader winged and often fly along tree lines. If you set your detector to 20Khz when noctules are around the chip chop sound is really clear. Their chestnut colour is great if the light is good enough.

I have no experience using FD detectors for sonograms, I use a TE detector the following link has some information on the limitations of FD detectors http://www.batsound.com/psonfaq1.html I think you may have some problems with analysis due to this limitation in harmonic analysis. A noctule sonogram using a TE detector has maximum power output at 20khz and the sonogram would not show the other pulses at that power level if it showed them at all, http://www.batcon.org/batsmag/v19n4-06.html shows this. The problem as far as I can understand your sonogram is the 3 pulses presumably caused by the Noctule all show similar power amplitudes so selecting the 20khz level is based on the supposed id of Noctule and knowing that is the "right" frequency. In this case listing to the sound file its clear this is correct. The 3 pulses probably are an artefact of FD detectors as they do not appear on a TE sonogram; the Daubenton's seem to be clearly represented, but not showing the same shape as in the TE sonogram link .

Its easy sometimes to miss the other species on a sonogram and getting used to dark bush crickets where they are common. Is this problem with the noctule a result of the fundamental frequency problem mentioned on the batsound website. Perhaps they would respond to an email, I've found them helpful in the past. Otherwise try Bristol university or some other such source. The best solution is to use TE, the cost is higher, but TE is going to give you a picture of real sound with less artefact risk. Not that sonograms are quite what you at first hope, not certain id for everything, but they are a big aid. I recommend Frank Greenways course at Juniper hall if its still running. Seeing bats attracted into mist nets by pre recorded sound is incredible, especially when you are dealing with Bechstein's. The bat conference often have sonogram workshops as well.

Thanks Phil, for helping out, some really useful information. I was confused thinking it was a distictive pattern of the sound! I get so excited when I pick up the calls I forget to fiddle and change the frequency! Practice and patience!
Thanks again. Regards Kim

Its amazing how things go wrong; I'm all set up and then pull out a lead or some such thing, and the spring brings on the inevitable I knew how to use this last year, but its lots of fun, just wish there was more time.

here are some sonograms online

http://www.londonbats.org.uk/batdets.htm
http://www.batdetective.com/sonograms.htm

I've recently had it beaten into me that its not safe to ID Noctule on the chip/chop on a heterodyne detector alone. Unless you see it, Leisler's Bat is highly confusable.

Hi Jane, it does seem the identification for a few similar UK species are being developed all the time. I guess the extremely low 18KHz Noctule calls are fairly safe.. But I have had ones calling in the mid 20's that sound nothing like Noctule, but don't really fit Leisler's either (or Serotine).
Given your coastal location, do you pick up many bat calls from your house? Migration is also fairly poorly understood, so you could get some very interesting records from your home, which might prompt the rest of us to take the bat detector on some evening seawatches!
Given that Leisler's bat is common in Ireland, I reckon you might have a better chance than most of us of picking one up.

Leisler's are about 25kz and are quite good on a sonogram. I have found them rather rare in East Dorset where I have mainly bat detected. If its totally dark you could have some problems. The big advantage of both species being rather open country animals and out early? is you can see them. I have not seen leisler's "hunting" high up over grassland like noctule in the period since I did my bat license training with Bob Stebbings in 1989, despite working outdoors and therefore being in the field a fair bit, the only ones I have found were following hedge lines in open fields surrounded by large woodland areas. They were a couple metres or so above high hedges and following features in open country. Once found they were rather predictable in their pattern of activity. Its tempting to consider that they have some sort of niche selection to avoid competition with the commoner noctule which presumably in Ireland is removed due to noctule absence. Not a species that I have had much chance to be familiar with, the pro's armed with radio tracking devices can reveal such incredible detail now of the habits of species which were total mystery a few years ago. I feel inspired to look out some papers on leisler. I did almost mention them in my earlier posting, but getting used to commoner species is not a bad way to get started.

I have a huge Noctule colony nearby!

Phil: I have no experience with TE recorders, but have a question..
From Wikipaedia for Time Expansion detectors:
"While the recorded sample is being played back slowly, nothing is being recorded, so the bat calls are being sampled intermittantly. For intance, when a 1 second call is being played back at 1/32 rate, 32 seconds of bat calls are not being recorded."

Does this mean that you are missing large chunks of the evening? e.g. only grabbing 1 second in every 30 seconds? Never understood how surveying works using this technology.

Is anyone able to explain the above query?