• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Mobile batting (2 Viewers)

Don't know.. Another possible gotcha is electrical interference from an alarm system pulsing or similar.. I must admit, much of my recordings are skipped thru until the classic sine wave of a series of definite bat calls is found.
You are right, I should better focus on the real bats, there are enough of them. As you said in an earlier post: "... Lakes or Rivers where you tend you hit hotspots quite frequently.." Pforzheim's rivers were a perfect starting area for me. One of my sonograms had four different bat species. Yesterday I saw three Daubenton's bats at the same time in a calm section of the Enz, in the center of the city. So we definitely have a large bat population here. :t:

Now I believe the "Park Bats" were in fact park rats, or some other rodent. The recordings made on Saturday and Monday gave a hint: these walks of mine had overlapped only in a short segment. By narrowing down the place to a few dozens of metres, it was easy to solve the puzzle. Yes, I had paused there on Saturday, near the river, for some recording. - The closer I was to the shore today, the stronger the whistles. It became clear why some calls had "holes": it is the same phenomenon which can happen with Daubenton's calls: they fly so close to the water that the call is reflected by the surface, and the echoes eradicate parts of the original call. Similar effects could be expected in the case of "water-rats" or other shore-inhabitating rodents.
 
These first steps in unknown territory remind me of my rough start as a birder, two years ago. Armed with a Canon SX50, I even managed to photograph a kinglet. But when I pressed the button, I believed that the bird was a tit! - The return to the whistling place wasn't completely in vain. When I arrived, just after sunset, there were two bats flying over the shore and the river, in large circles. I had the vague feeling that this was not a Common pipistrelle, although it was hard to nail down the difference. In my bird observations I had learned some key rules: try to form an impression, compare them with other birds which you already know. The comparison with the Common pip would have been: similar silhouette, but flight "more powerful". I also noticed that these bats were practically always above me, flying 3 metres or more above me. But that's it, I could never have been sure that this was another species - had I not recorded the ultrasound which the bats reliably delivered.

Thanks to the recordings I now know that it had been two Nathusius' pipistrelles. According to books they are our largest species of pipistrelles. The difference in size is relatively small, but in behind sight it doesn't seem far fetched that the larger build and the more direct flight created my impression of "more powerful" bats. And it is indeed one of their characteristics that Nathusius' pipistrelle prefer to fly 3-10m high. - Whether these hints will suffice to identify another Nathusius' around sunset, I have my doubts. Interestingly, the three British authors Middleton, Froud and French argue that the social call of the Nathusius' could actually help to identify this bat in the field. Quoted from their book Social Calls of the Bats of Britain and Ireland (2014), p. 114: "While listening to these social calls using a heterodyne or frequency division bat detector, it is often possible to hear a di-syllabic (i. e. a double note) effect produced by the two longer parts ('a' and 'c' [...]) of this species' typical call."

While in my recordings the element "a" of the complex Nathusius' social call occurs quite often, I don't see much of the other element "c".

Edit: Sonogram added, showing two species, (a) Noctule and (b) some Myotis bat (whatever it is). Novice question: Is this how a feeding buzz of a Myotis species looks like?
 

Attachments

  • Myotis feeding buzz.jpg
    Myotis feeding buzz.jpg
    250 KB · Views: 238
Last edited:
Edit: Sonogram added, showing two species, (a) Noctule and (b) some Myotis bat (whatever it is). Novice question: Is this how a feeding buzz of a Myotis species looks like?[/QUOTE]

Yes
 
It's definitely a feeding buzz.. the repetition rate goes thru the ceiling. But I wouldn't like to say what species it was. To be honest I couldn't rule out Noctule.
Also the peak frequencies are very low, which confuses me, if I'm reading the scale right.
If you zoom out, can you see the bat echolocations before the feeding buzz kicks in?
It's often easier to identify them with the "relaxed" calls, (even better if they are in the open as opposed to in clutter).
 
Thanks, Harry and Peter!

It's definitely a feeding buzz.. the repetition rate goes thru the ceiling. But I wouldn't like to say what species it was. To be honest I couldn't rule out Noctule.
Also the peak frequencies are very low, which confuses me, if I'm reading the scale right.
If you zoom out, can you see the bat echolocations before the feeding buzz kicks in?
It's often easier to identify them with the "relaxed" calls, (even better if they are in the open as opposed to in clutter).

You are almost certainly right, Peter. The bat emitting the "buzz" is not a Myotis species at all. The wav file attached below "Myotis feeding buzz" may show two or three different bats (I am not sure), but all of them seem to be Noctules. This recording was made only ~30 minutes after sunset, and all the neighbouring files are marked "noc", there are not even pip or nath around.

Zooming out doesn't help much, but one weak "relaxed [noctule] pulse" from the bat in question appears to be there, immediately before the buzz starts. Otherwise, only one Noctule is visible throughout the whole recording: the one with the loudest pulses. After the buzz, there could be 2 or 3 Noctules. At the end of the recording, two Noctules are clearly visible. And I guess the successful bat has stopped its echolocation and is busy with his prey, maybe hanging in a tree.
 

Attachments

  • Myotis feeding buzz.wav
    1.3 MB · Views: 231
Daubenton's and (?) Leisler's bat

Re-visiting my recordings taken at the Nagold, the attached file may be the real thing: the feeding buzz of a Daubenton's bat. The river is noisy, but the "buzz" is still audible at the very end of the recording.

Only weeks ago, when I started, I thought that the brackets of data for the various species (frequency, peak, call distance), as they are listed in books or in BatExplorer, are a firm, reliable guide to identify the bats - if we ignore for a moment the overlap, say, for Myotis. But the process of identification is sometimes rather a negotiation with oneself. "So what are the measures for this bat? Lower frequency 24.4 kHz, peak frequency 35 kHz, call distance 64 ms. Ouch, BatExplorer does not accept it as a Daubenton's. So let's change it to 25 kHz, 37 kHz and 65 ms. Phew, what a relief, now it is a Daubenton's."

OK, some data are more relevant than others. The call distance is shorter in a feeding buzz. However, when there seems to be a Leisler's bat in this recording, with two flat signals around 23 kHZ, would it be "legitimate" to "forget" that a call distance of 450 ms between calls is too large for Leisler?

I mean, come on, couldn't the Leisler's have hold its breath for a moment, to get rid of a hiccup?
 

Attachments

  • Daubenton + Leisler.wav
    1.3 MB · Views: 226
  • Daubenton feeding buzz.jpg
    Daubenton feeding buzz.jpg
    254.1 KB · Views: 201
  • Daubenton + Leisler.jpg
    Daubenton + Leisler.jpg
    272.9 KB · Views: 210
Last edited:
Hi, I think the first does show a feeding buzz at the end.

The second, I wouldn't like to say.. I can confidently pick out Noctules and Serotines, but Leisler's falling in between the two always l;eave me in doubt, unless I see the bat, or record it somewhere where Noctule and Serotine don't occur.

If you can discount Serotine, as all the same note, fairly high peak frequency, and irregular, (sounding like a jazz drummer!), then you are left with Noctule and Leisler's:

Noctule is quite easy when it is flying in the open.. very low peak frequency Chip-Chops, at around 22 and 18KHz, BUT..

A Noctule in clutter sounds faster, higher pitched, it loses the chops, and to my ears sounds like a Leisler's. So I think you have hit the buffers in the same way I have at the moment.. However, you have the advantage of the time expansion, and Bat Explorer, to give you more accurate data. That, together with the habitat (open or cluttered) and a glimpse of the bat should get you the results.

I find a lot of contradictory data for what a species sounds like, and the parameters of peak freq., signal length, max and min etc.. I think a lot of it is down to how you configure your equipment, and I think the only sure fire way is to build up a database of known species from your configuration, and don't change anything in your set up!!

See my post here for similar problems..
https://plus.google.com/109037229823351410961/posts/RR9L259coTF

Cheers,
Peter
 
Hi, many thanks for the valuable advice. Actually, I was aware that the odds to meet and identify a Leisler's were small. My local source FF2 claims that Leisler's bat is living in the park, but they are rare, share the place with a much larger number of Noctules, and their echolocation is too similar to be sure - at least for someone with a lack of experience.

After my explorations of the river and the park, for the next days I'll focus on forests and other bat destinations recommended in FF2. Locations known for Myotis myotis, bechsteinii and others.

I think a lot of it is down to how you configure your equipment, and I think the only sure fire way is to build up a database of known species from your configuration, and don't change anything in your set up!!

After reading your link and more information elsewhere, about the difficulties to identify Bechstein's, I have my doubts whether I'd be able to identify this bat, should I meet it tomorrow. Your spectrograms are looking like the best possible evidence - and still the book by Dietz & Kiefer says that there are practically only two ways to identify Bechstein's beyond doubt: (a) sound analysis plus a sighting, or (b) a sound analysis over a longer stretch of time, to be sure that the bat stays inside a narrow band of frequencies. So this may be the wrong species to study with Time Expansion of mere 0.9 seconds.
 
I don't know.. I was hoping you'd come back on here and tell me that the analysis was easy with Time Expansion!
What I should do is run my Frequency division recordings of the probable Bechstein's thru Bat Explorer and see what that makes of the frequencies.

One other option you might want to try is to go out before dawn, and hopefully stumble on a roost with bats swarming round the area.. This way you'd potentially get better views as it gets lighter, plus you'd potentially identify a valuable roost location for conservation. However, we might be too late in the year for this, and it's not particularly easy to find a roost.. requires lots of luck.
 
I don't know.. I was hoping you'd come back on here and tell me that the analysis was easy with Time Expansion!
I like the Time Expansion feature. It is great to see so much detail in the calls of a Nathusius' pipistrelle, how it varies its calls a lot more than a Common pipistrelle. Two examples below. - A large part of the fun is the BatExplorer, it is phantastic - and free. It just works, and I can focus on studying bat calls.

Since the micro trio is my first detector, I have no comparison. But it may be a major bug that the device mirrors signals along a virtual 60 kHz line. Thus a strong 40 kHz call also appears as a "ghost call" at 80 kHz. I've googled for it, finding a hint that an older detector, the "Bridge Box" (Laar) was similar, yet it mirrored along a 100 kHz line. Plus the comment that the ghosts usually did no harm, only you had to be aware of the problem. If a Greater Horseshoe emits its 81 kHz call, I guess I'll see the signal repeated around 40 kHz.

The more expensive, professional devices from Elekon, Pettersson or the new generation of tablet-based microphones could prove their superiority when it comes to harmonics or other sound details. Dietz & Kiefer (2014) say that "good recording levels often show a weak second harmonic" for Bechstein's.
 

Attachments

  • Nathusius' call.jpg
    Nathusius' call.jpg
    109.8 KB · Views: 212
  • Nathusius' call 2.jpg
    Nathusius' call 2.jpg
    82.1 KB · Views: 248
The weather is getting colder, and the forecasts predict rain. In the last nights, bat activity was low - except the occasional visits of Nathusius' pipistrelles. My autumn experiment comes to an end, but in late August 2015 I'll search for the forest bats which I have missed.

There are some recordings left which I'll eventually check, but I don't expect any surprises. Except one bat species echolocating at 34 kHz, a last intriguing bat puzzle which I hope to solve in the next few days.
 
Last edited:
I won't say what I think the 34KHz bat is.. and keep the detector handy, you never know if we have a mild spell one or two may emerge.. Otherwise, we can start again next spring!
 
I did receive my new micro trio a week ago and guess what. It sounded exactly the same as my old one. So it looks like I have a special ear that makes the hiss very annoying while using HD or TE.
Anyway, the device works fine for bat detecting and identifying and when recording to the MP330 the noise is eliminated somehow. Only when I make direct recordings from the Micro Trio to the computer the background hiss is recorded (Don´t ask me why). But this can be eliminated using Audacity.
Regarding the MP330 settings (Quality level and volume) I made quite a few test and I did see no major impact on the recordings except when using low level sampling rate (8.000 Hz) that end up with a non useful sonogram. The difference with you Stefan, is that I open the files with audacity directly from the MP330 (instead of importing) and I don’t have to choose the sampling rate, as Audacity get the info from the file itself (32,000 Hz in high level recordings). I guess it is no sense to force it to 44.100 Hz as the recording of the MP330 is made at 32.000 Hz.
Anyway, all my recordings either from the MP330 or direct recordings to the PC, seem good for identifying bats and I am having a lot of fun in doing so.
Some other technical issues are:
- Mirror sonogram at 60 KHz. I also get a mirror image above the 60 KHz line but no problem with that.
- Most my sonograms include the y-axis up to 200 KHz or more. Is there any way to reduce it to a practical 60-80 KHz?
- I am getting some harmonics but not all correspond to half the frequency of the main call, so in that case they are not harmonics. What are they? Is there any other mirror effect in the micro trio?
- While listening in HD to common pips at 45 KHz I turned the dial to 100 KHz and I did also hear the bats (Not at 70 KHz though). What could that possible be? In the TE recordings I see nothing special, as the micro trio only records up to 60 Khz. What will happen when making a TE recording of a high frequency bat like the Rhinolophus? Will something appear in the sonogram?
And this is it regarding the technical issues. In the next post I will upload the recordings and sonograms of the species I have detected so far. It is also raining heavily in Spain, so no bats in the past days. But warm weather will come before winter so more chances to detect more bats in the future.
 
The difference with you Stefan, is that I open the files with audacity directly from the MP330 (instead of importing) and I don’t have to choose the sampling rate, as Audacity get the info from the file itself (32,000 Hz in high level recordings). I guess it is no sense to force it to 44.100 Hz as the recording of the MP330 is made at 32.000 Hz.
Audacity uses 32.000 as the default setting for importing files, which isn't far away from 48.000. I have nevertheless changed Audacity's setting to 48.000 (in the second menu, last point) as the MP330 manual says it is recording "medium quality" with a sample rate of 48.000.

- Most my sonograms include the y-axis up to 200 KHz or more. Is there any way to reduce it to a practical 60-80 KHz?
- I am getting some harmonics but not all correspond to half the frequency of the main call, so in that case they are not harmonics. What are they? Is there any other mirror effect in the micro trio?

From memory, I remember that I had this 200 kHz y-axis in BatExplorer come up when I used "high quality" in the MP330 settings. I'd simply guess "high quality" catches more sound than "medium", and some sound bites in higher frequencies are the reason why Audacity's logic does not erase/simplify/compress the sound file as much as it does with the medium quality. - If I choose "medium" and "3" for volume in the MP330 settings, BatExplorer will usually open the resulting files with the y-axis limited to 80 kHz.

Harmonics are multiples of the original signal, so a 25 kHz bat call that shows harmonics (which isn't always the case) can be visible also around 50 kHz (= 2nd harmonic) and even around 75 kHz (3rd harmonic). Not to be confused with the possible "ghosts" at 95 kHz produced for strong signals by the mirror effect of the micro trio. Harmonics don't change their orientation, while the mirrored ghosts do... I've read that heterodyne or FD recordings don't retain the harmonics of the original calls emitted by the bats. For some bats harmonics can be a help to identify a bat correctly. TE recordings, at least in theory, allow to study the harmonics.
 
Audacity uses 32.000 as the default setting for importing files, which isn't far away from 48.000. I have nevertheless changed Audacity's setting to 48.000 (in the second menu, last point) as the MP330 manual says it is recording "medium quality" with a sample rate of 48.000.
I think you have some units mistake in your post. MP330 has a medium quality recording of 48 Kbps, not KHz.

My manual says Low=8KHz, Medium=16KHz and high=32 KHz. But I found a different manual on the internet that says Low=32Kbps, Medium=48kbps and high=64 Kbps.

It should be easy to find the conversion between KHz and Kbps, but do not ask me how.

I start a new thread with my recordings in a different post not to steal your thread...

http://www.birdforum.net/showthread.php?p=3091618#post3091618
 
Last edited:
I start a new thread with my recordings in a different post not to steal your thread... http://www.birdforum.net/showthread.php?p=3091618#post3091618

You are always welcome in "my" thread! - The separate thread on Spanish bats may be a good idea, considering how many different species the Iberian peninsula has. A discussion of the settings or technical problems can perhaps continue here, as a public service for other novices. o:D

I think you have some units mistake in your post. MP330 has a medium quality recording of 48 Kbps, not KHz.

My manual says Low=8KHz, Medium=16KHz and high=32 KHz. But I found a different manual on the internet that says Low=32Kbps, Medium=48kbps and high=64 Kbps.

You are right, I had confused sampling and compression rate. Moreover, the "48 kbps" for medium and "64 kbps" for high were replaced in the new/recent model of the MP330 to better compression rates between 32 and 320 kbps. In the future I'll just use the import default settings of Audacity, 44.1 kHz is clearly sufficient.
 
I have some wav files which I have been trying to ID in Bat Scan 9
is it possible to import these into bat explorer as I cannot seem to do this.

I am clearly missing something


Any advice appreciated

Thanks

Mark
 
Hi Mark,

I am not familiar with BatScan, but it seems that it is specialized on analysis of FD recordings. I have opened FD recordings from the micro trio in BatExplorer (by typing 10 and 0 in the entry dialogue), but the result wasn't useful. BatExplorer works with Time Expansion recordings.

Stefan

Edit: What you can do: measure the frequencies, length of the call, call distance in BatScan, then start BatExplorer and open another TE recording (e.g. one from this thread). Replace the measures for the opened file with your data, and you can try and identify the bat with BatExplorer. Not an ideal use of the software, it is practically diminished to an excel archive holding the data of the European bats. But it does support the identification, and you can see sample files of the species you are interested in.
 
Last edited:
I have some wav files which I have been trying to ID in Bat Scan 9
is it possible to import these into bat explorer as I cannot seem to do this.

I am clearly missing something


Any advice appreciated

Thanks

Mark

In my case, I can not open with Batexplorer the .wav files that I get from my transcend MP330 recorder. But if I open them with audacity and then save them again as .wav then I can open them with Batexplorer. So I do suggest you to use Audacity before, which is a free software.
 
Warning! This thread is more than 9 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Users who are viewing this thread

Back
Top