Griend is a protected 'bird island' in the Waddensea. The breeding season is at its end. As a warden, I have the privilege to stay here for two weeks. Today I made a walk around the island during low tide. It takes about 1,5 hour. I put my mics on a long stick and made a recording. You hear my footsteps on the beach, birds making mainly alarm calls, some fighter jets passing by, and the wind (3-4 Bft) playing with my amateur boom stick. Overall this setup is to be improved, but I took some of the better pieces for this post.

Zoom F6, 32-bit FP > 16 bit FLAC, 44 kHz, Primo EM272 quasi binaural.

Headphones recommended.

Walk around the Island - 2021/07/08 - Griend

Full spectrum stereo recording of Noctules and Daubenton's bats hunting in a park in the city of Leer. Heterodyned at 20 kHz(Noctules: chip chop) and 33 kHz(Daubenton's: tiktiktik)and remixed using SoX and Audacity.
At ca. 50 sec you hear social calls of the Noctules. Also it can be noticed that the two species interact, getting louder (i.e. closer to the mic) often at the same time, probably trying to catch the same prey. Feeding buzzes are easily recognised.

happy listening, headphones recommended!

Noctules & Daubenton's bats - 2022/05/17 - City of Leer

Green Noise - 22/06/06 - Red Oak (Quercus Rubra)

Two species of pipistrelles were hunting under a cherry tree in a fruit garden in Northern France for about half an hour every evening in early September.  I caught them with my new ultrasonic mics and heterodyned the track at three different frequencies: 20, 42 and 50 kHz for social calls, Pip pip and Pip pyg respectively. You can recognize the Pip pip for its slower pace and the social calls. This is a 3 minute excerpt of the recording.

Headphones recommended.

Tascam DR100 MKIII @192kHz sampling rate. XLR electret ultrasonic mics, stereo AB 15cm. Heterodyned using SoX, mixed in Audacity, upload 16bit/48kHz.

Pipistrelles under a cherry tree - 2022/09/04 - Bayeux, Normandie, France

I made about 50.000 triggered recordings at a maternity roost of Leislers bats during last summer. Many social calls were recorded. 
For the description I use the terminology of Pfalzer (2002) who described Type A–N different calls. This is Type B: a short 'triller' indicating two individuals meeting during flight.
Using: Songmeter Mini Bat & Kaleidoscope Pro (Wildlife Acoustics) and Audacity. Recordings are time expanded (x10) and converted to mp3.

Nyctalus leisleri : Social call Type B - 2022/06/24 - Maternity roost

According to Pfalzer (2002) this is a Type F call - mother to young communication at the maternity roost. Skiba (2009) refers to it as a 'Doppelruf' a double tone/tune. It very much resembles a human whistling to call for attention.

Nyctalus leisleri : Social call Type F -  2022/06/24 - Maternity roost

Less than one minute excerpt out of an hour of bat recording at Zuidlaardermeer near Groningen in the Netherlands. Replayed at 0.14 times the original speed. You hear crickets, they are the rhythm section, geese that sound like elephants or lions and on top of that noctule bats hunting above the mics.
Tascam DR100 MkIII @192kHz 24bit
Self built ultrasonic mics in ORTF
No editing in post except for the speed change.
uploaded as 16 bit 48kHz FLAC

Zuidlaardermeer - 2023/07/28 - from a bat perspective

Since mid July a group of rooks is visiting the trees in our garden every morning. Actually it is a mixed group of rooks and jackdaws. It is a kind of gathering before they leave to the fields for foraging. 
I will try to make best recording as possible. This is a first snap-shot like take. No special effort made, just put my newly made mid-side mic in the garden on a 1.5 m hight tripod.
Things to be improved:
Traffic noise in the background: Repeat on a Sunday morning or with a different wind direction.
Crow voices not as full as I would like: Higher gain setting, try to get closer.
Hiss: All hiss is noise from leaves in the wind. Wait for a quiet wind still morning.
Since I don't want to wait - I will first try to get closer to the birds (to be continued).
Tascam DR05X 24bit 48kHz.
Mid-side mic (self built).
Rycote windjammer WS9 + fur.
MS tot stereo conversion by hand in audacity.
No further editing.

Rook - 2023/07/30 - Take 1: MS

Less birds and no jackdaws today. 
The same MS mic is now on a 6m high pole in the main tree.
The tree itself is at least 2.5 to 3 times higher.
One rook is calling directly from above the mics. Here the voice is with more definition, there was also wing flapping hearable in other parts of the recording.
The other rooks are now further away.
There was more wind and I had to apply a 80Hz High Pass filter.
Very annoying contact noises, probably the pole is waggling in the wind, or small branches hitting the pole.
Still some traffic noise but I could not expect anything else.
Same setup as in Take 1

Rook - 2023/08/02 - Take 2: MS on 6m pole

No wind this morning, so I took the opportunity for a next try.
Mid-side recording from a tripod, mic height ca. 2m.
Left the fur on the windshield.

Rook voices are much better now, much more detail, also other small birds can be heard, as well as wing flapping etc.
Traffic noise is also much clearer, the deep basses of the dredger in the river Ems and the higher tones of the highway A31 about 3 km from here.
Also, this is the first recording with a hiss that, I suspect, comes from the EM283 figure of eight (22 dB of self noise).

Rook - 2023/08/04 - Take 3: MS, No Wind

Sunday morning, no trucks on the highway + slight wind from the east = no traffic noise. MS setup on 5m high pole. Fur. Unfortunately the rooks never turned up. Nevertheless some interesting shots, showing wha this setup can do. The horses for example are about 150 m away (!).

This was an experiment with self built MS mic based on the Primo EM283.

Rook - 2023/08/06 - Take 5: MS, No Traffic, No Rook

For the last nine years I have had recorders in the field almost every winter to detect poaching. Here is a shot taken in early January 2016 shortly after sunset at a protected roosting site for geese and other water birds. At two minutes in the recording, cars arrive at the place where I hid the recorder. You will hear the preparation including the explanation "yesterday I shot so much that I brought the trailer with me today". Then the shooting starts. 62 shots are fired in about 15 minutes. After that the poachers quickly leave the scene.

Primo EM172, Soundblaster Play, Raspberry Pi A+, Sox script, 2 minute triggered recordings @22 kHz.

Poaching - January 2016 - Ostfriesland

During the night all other sounds have disappeared and we hear the mills on their own. As can be seen in the spectrogram, the sound is characterised by high power in the lowest frequencies (infrasound). So, use good headphones when you want to hear it!

300 m from the closest windmill, 2-3 Bft. 
Tascam DR05X, Primo EM172, 48/16 Flac upload, no editing in post.

Nacht im Windpark - 2024/05/03 - Königsmoor

Windpark Königsmoor, 300 m from nearest windmill, 04:00 am. 2 Bft.

Morgenchor im Windpark - 2024/05/03 - Königsmoor

I am still experimenting with infrasound recording and today I had the luck of a thunderstorm passing by. This recording covers the frequencies from 0.5 to 100 Hz. Most of the energy is around 5 Hz and can not be heard. Yet, the lightning rumble and strikes are clearly recognisable.
A nice recording to test the low frequency capacity of your headphones.
Literature: http://www.geo.uu.nl/~paulssen/Publications/assink+evers+holleman+paulssen2008.pdf

Infrasound of Lightning - 2024/08/13 - Version 1

Jedes Jahr überwintern hunderte von Pfeifenten im Westoverledinger Hammrich. Nachts schlafen die auf dem Wallschloot ....naja schlafen kann man das nicht nennen. 

Tascam DR05X, Primo EM272, AB60cm, 48/24 wav converted to 48/16 FLAC, no editing in post.

Für die beste Qualität nutzen Sie bitte einen Kopfhörer. Viel Spass!!

Pfeifenten - 2025/03/06 - Wallschloot

Rook have the strange habit to build colonies directly at motorways. This colony is at a province road. I had the luck of recording ca. one hour during dawn without too many cars passing by. This recording is an eight min excerpt of that. Enjoy!
Tascam DR05X, Primo EM172, 48/24 wav converted to 48/16 flac. No editing in post.

Rook Colony - 2025/04/16 - Grootegaste

I ordered some JLI 140A-HD capsules, cardioids with 80dB SNR, 14dB self noise and a sensitivity of -35dB. First quick and dirty test on a Tascam DR100 MkIII with EIN -124 dBu and 38 dB of gain. Recordings are normalised to -1 dB. The JLIs seem much more noisy than specced. The Primos are at 14 dB self noise. I will have to do some more experiments.

Comparing JLI 140A-HD with Primo EM172

Rietzanger bij ons in de slootkant
Tascam DR05X droprig met Clippies 3,5mm, 48 kHz, 24 bit, 27 dB in post

rietzanger - 2025/05/17 - in de tuin

Dawn chorus at Nienhof Manslagt Region Krummhoern, Ostfriesland, with several bird species a.o. Spotvogel / Gelbspotter / imitating Scholekster / Austernfischer /Oistercatcher. Some morning traffic in the distance and a windmill in the right ear, an old type standing about 500 m away. 
DR05X + Clippies Primo EM272 - uploaded as FLAC 48/16

A quiet monday morning - 2025/05/19 - Nienhof, Manslagt

Een stuk of tien laatvliegers jagen over camping De Korenschoof in Reusel. Het duurt ca. 20 minuten. Hiervan de eerste 10 minuten weergegeven.

Tascam DR100 MkIII 192kHz SR, ultrasonic mics - heterodyned in post and exported as 48/16 Flac

Laatvliegers - 2025/06/04 - De Korenschoof, Reusel

As dusk falls, the first Noctules come hunting. Seven minutes later, they are followed by a large number of Leisleri's and a single Serotine bat. No wind, a perfect night for bats. The hunting goes on for more than an hour. Here are the first twenty minutes. 

Tascam DR100MkIII, self built ultrasonic mics, baffled. 192/48 wav. Band passed from 15-24 kHz and heterodyned to 20kHz (Noctules) and from 24-35 kHz, heterodyned to 27 kHz (Leisleri's and Serotines) - mixed after heterodyning and exported as 48/16 Flac.

Use headphones and enjoy!


Noctules, Leisleri's and Serotines - 2025/06/10 - Witrijt

De zomereik (Quercus robur) herbergt meer dan 400 soorten organismen waaronder veel insekten. Al onze inheemse soorten vleermuizen zijn insekteneters en weten de zomereik goed te vinden. Hier hoor je een paar dozijn bosvleermuizen (Nyctalus leisleri) jagen rond twee grote zomereiken op een windstille zomeravond. Af en toe landen ze op een blad, vermoedelijk om iets te pakken, en daarna gelijk weer verder te vliegen.

The common oak (Quercus robur) is home to over 400 organisms, including many insects. All our native bat species are insectivores and know how to find the common oak. Here you can hear a few dozen Leisler’s bats (Nyctalus leisleri) hunting around two large common oaks on a windless summer evening. Every now and then they land on a leaf, presumably to grab something, and then fly on again.

Tascam DR100MkIII, self built ultrasonic mics, improved baffle, 192/48 .wav bandpass 24-35 Hz, heterodyned to 27 kHz and exported as 48/16 Flac.

Bosvleermuizen - 2025/06/11 - Zomereik

Young people may hear noctules that call around 20 kHz. Like most older people, I cannot. We need a transformation of the sound. The two most used transformations are heterodyning and time expansion. In both cases some of the original experience is lost. With heterodyning some of the tonal quality is lost, but the rhythm in time is conserved - you can hear the activity in real time. With time expansion much more of the tonal quality is preserved, but the time is slowed down (in this case by 90%) - as a result the rhythm, the intensity of the activity is lost. I prefer heterodyning for that matter. For those, who like to listen noctules in time expansion: here it is. this is a 75 seconds excerpt of the same recording (Noctules, Leisler's and Serotines - 2025/06/10 - Witrijt) slowed down to 10% of the original speed.

Noctules, Time expansion - 2025/06/10 - Witrijt

This is a 75 seconds excerpt of the 'bosvleermuizen' recording transformed through time expansion (compared to heterodyning). In the heterodyne presentation I removed the Noctules by a bandpass filter. Here they are included. The Noctules are hunting at greater distance in open air, whereas the Leisler's are concentrated in narrow space around the oak trees and were the main subject of my recording.

Bosvleermuizen, Time expansion - 2025/06/11 - Zomereik

Hunting noctules over Leda-Altarm, Landkreis Leer, Germany.
Tascam DR100 MkIII @192kHz.
Stereo mic Panasonic WM-61A.
Time expansion (10% of normal speed) using SoX.
Uploaded as mp3 at 128 kbps.
These are the first 18 seconds (x10 = 180 seconds) of the previous recording (soundscape with bats) processed in a different way, i.e. time expansion vs. heterodyne.

Hunting noctules (TE) - 2019/05/07 - Leda Altarm

An exercise in wind shielding and rain protection. Mics are standing in the open field. Wind shield OK, Rain protection to be improved. Yet I am optimistic, it can be done.
Tascam DR100 MkIII @44.1 kHz and 20 dB preamp(can't go lower!), Primo EM172, stereo AB 40cm.
Uploaded as mp3 @128 kbps.

Rain & Thunder - 2019/05/19 - Muhder Hammrich

I came home early from a night of bat detecting. Sparrows were chatting in the morning sun. They breed under our roof. I put the recorder outside and searched for my bed.

Stereo AB 50 cm. Use headphones.

Sparrows in the morning sun - 2019/05/24 - Kloster Muhde

Bats hunting over a pond in Hollen, Ostfriesland. Mainly three species: Pipistrelles (pipistrellus & nathusii) and Daubenton's bats.
Tascam DR100 @ 192 kHz, Panasonic WM-61A, Stereo AB 4 cm, baffled.
Hypass filter 20 kHz and heterodyned @41 kHz using SoX and Audacity.

Hear what you can not hear otherwise....have fun!

Hunting bats - 2019/05/27 - Hollen Ostfriesland

The lament of an old milking machine in a mild winter storm.

Pseudo-binaural: headphones will give you the best experience.

DR100MkIII, Primos, 48/24 FLAC, no editing in post

Old milking machine's lament - 2019/12/20 - Am Schöpfwerk

Second track of the wind blowing ahead of the 'Dennis' storm forecasted for tomorrow. This particular tree was hit by 'Ciara' (UK,NL) alias 'Sabine' (GER) and landed in his neighbour. The sound is different from that of the dead tree. In the third minute a Bussard flies over crying loudly. The stronger wind sounds are from a Douglas fir wood some 100 meters away.

Headphones recommended.

Tascam DR100 MkIII, Primo EM172 Phantom powered, 48/24 FLAC

Wind & Wood - 2020/02/15 - Oldehave, Ostfriesland

After a very mild winter bats are active again. This recording was made at the churchyard in Leer. It is a heterodyne translation of the ultrasonic echolocation calls. You hear serotines and pipistrelles.

Headphones recommended.

Elekon Batscanner Stereo, automaticly heterodyning. Line out. Olympus LS 11 48/24 Line in.

Gerwin Meijer

Pinned to spotlight

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