Bats ID looking at spectrograms? (1 Viewer)

[S_Man]

I found these ultrasonic 'traces' while parsing recent night recordings, lowland countryside, West Switzerland/France.

Typ_1 and Typ_2 look more like rodents or insects to me, but they are also very rare occurences and differ from the 4-5 species of grasshopers/crickets that can go on for several hours at a time...

If identification is possible, is it worth recording up to 60 mHz, the upper limit of my microphone in the specs, to catch more species?

 

[pppppvvvv]

Hi
1 and 2 look like insects yes.

No 3 has two calls, one with the main power at 24khz, the other at 22khz, and quite slow repetition. Looks good for Noctule.

No.5 is similar but higher frequency, so either Leisler's or Serotine.

No.4 possibly Serotine.

If your mic is capable of higher frequencies to 60khz, then I'd expect it to be picking up pipistrelle species. Kuhls with a peak at below 40khz, common peaking at 45, Soprano peaking at 55. You may also see the backwards "j" shape of their calls.
A few other species might also crop up like barbastelle, Daubentens, then it hits limitations either due to the mic not going high enough (horseshoe bats), or general difficulties we all have with very similar species (myotis bats)

 

[pppppvvvv]

The maximum power, I'm assuming is the lower point of the signals. Maybe run it in audacity, or another sound analysis tool, and look at the power spectrum of a highlighted call.
4 and 5 would be interesting

 

[S_Man]

The maximum power, I'm assuming is the lower point of the signals. Maybe run it in audacity, or another sound analysis tool, and look at the power spectrum of a highlighted call.
4 and 5 would be interesting

That's a lot of information! I'm using Audacity to find and extract these parts, I'll check that, Analysis > Trace Spectrum to see if I can discriminate between Leisler's and Serotine.

I also found a trace with peaks at 39-40 kHz in other examples, only very few and pale signals, so maybe a Kuhl's pipistrelle!

I was really looking for some mammals and by chance found the signal of the European free-tailed bat in the 12-16 kHz "audible" range (ID'd by comparing with random European bats on Xeno-Canto, luckily this one was in my early selection!), then I recorded at 96 kHz sample rate instead of 48 - which already drains a lot more batteries and SD card space - and found these examples by displaying higher frequencies on the spectrogram...

Thanks a lot!

Edit: corrected mHz to kHz

 

[pppppvvvv]

Yes Kuhl's pipistrelle would be around that peak frequency.
Just be aware that the signals get higher and less easy to identify in cluttered environment.
In open spaces you'll get the classic shapes that are easier to identify

 

[IamFof]

S_Man
Just a comment.
All the frequencies you are quoting, you give as mHz, ie millihertz or thousanths of a Hz. 20mHz = 0.02Hz. This is obviously incorrect
Your sonograms cover 0Hz - 48000Hz = 0Hz - 48kHz (kilohertz) = 0Hz - 0.048MHz (Megahertz)

 

[S_Man]

S_Man
Just a comment.
All the frequencies you are quoting, you give as mHz, ie millihertz or thousanths of a Hz. 20mHz = 0.02Hz. This is obviously incorrect
Your sonograms cover 0Hz - 48000Hz = 0Hz - 48kHz (kilohertz) = 0Hz - 0.048MHz (Megahertz)

Yes, I can't help but write mHz instead of kHz... is it because 1000 is "mille" in French, or I'm just not focusing enough on details... anyway I keep doing this error again and again, it's not the first time, and most likely not the last.

... You may also see the backwards "j" shape of their calls...

Here are also some J shaped signals, near the 20 kHz range, on the right, but too low for Pipistrelles, that lighter trace would be a noctule again?

 

[pppppvvvv]

Yes, I can't help but write mHz instead of kHz... is it because 1000 is "mille" in French, or I'm just not focusing enough on details... anyway I keep doing this error again and again, it's not the first time, and most likely not the last.



Here are also some J shaped signals, near the 20 kHz range, on the right, but too low for Pipistrelles, that lighter trace would be a noctule again?

I'd guess a noctule yes. Based on the frequency.
Maybe feeding or in clutter.
In the open the calls can be much flatter/horizontal

 

[S_Man]

I also got these around 18 mHz but with different shapes... less common in this location, could they be noctules too (3 x same species?), or is that too low? I think it's too high for free-tailed, I believe, peak power is 9.5-13.5 kHz.

Or maybe Myotis sp. ?

I read somewhere that some species have "social" calls, at lower frequencies than echolocation and more sporadic, but these looks like echolocation (at least 3rd image, signals at 17-17.5 kHz, not Blackbirds and other bird species of course in the lower part)

 

[pppppvvvv]

Two of them are likely Noctule. The one with the blackbird(?) Noise, I wouldn't like to say. They seem to have a whole range of frequencies, some looking too low for Noctule.

 

[S_Man]

Lowest single "signals" (1:17:03-04) are at 16.35 KHz, see below how I measured in the middle of the spectrum peak.
Highest single signal is 18.85 KHz, and the whole serie peaks at 17.05 KHz... (main bird noise sounds like Common blackbird alarm call - to my hear).

Maybe a BIG noctule, with a low, deep voice...

 

[pppppvvvv]

The way I remember it, is that if they are in a relaxed flight over open land, then the calls are lowest frequency and the flatter/ horizontal constant frequency elements are present.

Once they hit cluttered environments, or start hunting, then they use a larger frequency range, faster repetition, and the calls move to higher frequency, and appear more vertical on the spectrogram.

So we are more likely to get confused by higher frequency calls in enclosed environments.

So 17khz and 18khz perhaps if it was really gliding over open terrain.

 

[S_Man]

Now you're saying that, I found the following signals in the same recording, 1 minute before the 17 kHz spectrogram... higher frequencies, 20-21 kHz, more vertical traces (as you can see Blackbirds start to call just a few seconds before the ultrasounds are recorded, they must have spotted the bat coming!). it didn't struck me because the frequencies are more usual.

So both spectrograms might be just the same bat/noctule with different behaviour... the area is mixed, with some tall trees, prairie patches, thickets.