Social calls of the Nathusius' pipistrelle (Pipistrellus nathusii)

Recordings from 2024 and before, excluding (most of) mating season.

The following recording contains type A, B, C and D social calls. Hence why it is a great example to show as a start on this page. It is presumed that the bats emitted these calls stationairy from within the roost - possibly a mating roost.

Date of recordings: 2024-09-15          Recorded by: Demi Hoeke          Audio files: 934340, 934342 

In the last few snippits, the typical part A of the type D social call appears to merge into a more nasal sound. Another bat doing something similar has been recorded before:

Date of recording: 2024-08-24         Recorded by: Niels Jansen          Audio file: 932560 

The following type B and type D social calls were recorded from a stationary Nathusius' pipistrelle inside a bat box on the gable of a house. 

Date of recordings: 2024-06-10          Recorded by: Kaia Pieters          Audio files: 911981911977, 911980

And these type B social calls (between 6,000s and 6,400s in the first snippit) were within a syntax of otherwise type D social calls of an advertising male:

Date of recording: 2024-08-28         Recorded by: Kaia Pieters          Audio file: 936333 

More similar type D and B were recorded in September, like these:

Date of recording: 2024-08-22          Recorded by: Molito Fego          Audio file: 931602

And these:

Date of recording: 2024-09-16         Recorded by: Isis Knijff          Audio file: 935111 

And these type B and D social calls were emitted by a stationary advertising male:

Date of recording: 2024-09-17         Recorded by: Levi Laluan          Audio file: 935731 

More type B and D social calls emitted by a stationary advertising male:

Date of recording: 2024-08-27         Recorded by: Cas van Joolingen          Audio file: 936337 

And perhaps these social calls, also emitted between type D social calls of an advertising male, could be type B as well. Even though some calls seem to lean towards part D of the type D social calls. After analyzing all the sounds of this year, I am tend to put it in a category that I'll call "tick-tock". Due to the alternating sound of these calls.

Date of recordings: 2024-09-06         Recorded by: Sarah Mahie          Audio files: 932469, 932460, 932461, 932464, 932466, 932467, 932470

Here is another example of what I would call the "tick-tock" sound (between 24,530s and 24,860s):

Date of recording: 2024-09-18         Recorded by: Aielynn Kleian          Audio file: 955833 

And this one might be as well (between 6,380 and 6,540s):

Date of recording: 2024-09-16         Recorded by: Levi Laluan          Audio file: 955941 

The next two examples are the most general variant of the most common type D social call of the Nathusius' pipistrelle. It exists out of three parts, that we will call part A (multi-component), part B (single FM component) and part C (fast trill). Part A can differ in the number of components. Part B and part C are variable in appearance as well and can differ between individuals. There Nathusius' pipistrelle can also shuffle the different parts to create new songs. The sequence and different combinations of parts can convey a more complex message to other bats (Middleton et al., 2020).

Five-component variant of Part A:

Date of recording: 2024-05-18          Recorded by: Niels Jansen          Audio file: 911324 

Seven-component variant of part A:

Date of recording: 2024-05-26          Recorded by: Niels Jansen          Audio file: 911808 

Part A can also contain extra components that go up to 70 - 80 kHz in frequency at the end of part A's regular sequence. In existing literature, the main motif of part A is called A1 and the extra components at the end of the motif are called A2 (Hargreaves et al., 2017).

Date of recording: 2024-06-16          Recorded by: Sander Boersma          Audio file: 913412 

A part A1 can also contain a pre-part that I will call part A0. These are some extra components in front of the main motif (see the two snippits on the right). In the example below, I suspect that this part A0 is used as a stand-alone motif inbetween other parts.

(Left)    Date of recording: 2024-08-15       Recorded by: Nils Reinerie   Audio file: 927475 
(Right) Date of recording: 2024-06-19      Recorded by: Levi Laluan       Audio file: 914575

Date of recording: 2024-06-26          Recorded by: Menno van Berkum          Audio file: 919195 

A Nathusius' pipistrelle emitting only part A more than 20 times. When this happens, confusion with the type D social call of the common pipistrelle may occur.

Date of recording: 2024-06-26          Recorded by: Cas van Joolingen          Audio file: 917084 

This example contains a "shuffled" sequence of parts. These three social calls are each made out of part B, part C and part B:

Date of recording: 2024-06-14          Recorded by: Olivier van Aken          Audio file: 913613 

A social call existing out of part B and C:

A social call existing out of part A and B:

Date of recording: 2024-05-27          Recorded by: Hubert Matuszewski          Audio file: 911552 

In this example the bat emitted the motif part B zeven times in a row. Without the presence of other type D motifs, part B is a type C social call on itself.

And in the same recording, the following social call sequence is also present: part A, part B, part C, part B and a new kind of motif that exists out of multiple FM components. In existing literature, this part seems to be adressed as part E (Hargreaves et al., 2017; Jahelková, 2024; Russ and Racey, 2007).

Date of recording: 2024-05-20          Recorded by: Gijs Peters          Audio file: 911550 

An example of a Nathusius' pipistrelle emitting the following sequence of motifs: part B, part B and C, part B and E.

Date of recording: 2024-06-14          Recorded by: Nils Reinerie          Audio file: 913335 

The following snippit contains the motifs: part A+B+E, part B+C and part B+C.

Date of recording: 2024-05-28         Recorded by: Anice Hut          Audio file: 911811 

These social calls of the Nathusius' pipistrelle were recorded near a foraging area. It is most likely agonistic behaviour of the Nathusius' pipistrelle towards the common pipistrelle in "his" foraging area. Among other calls, the recording contains the following sequence of motifs: Part A, B - B, E - B, C.

Date of recording: 2024-07-02          Recorded by: Gijs Peters           Audio file: 918333 

Then you might wonder about the motif part D. While part E is made up out of multiple FM components, part D is made out of multiple downward FM sweeps with a relatively longer qCF ending. There seems to be a slight difference between part D as visualized in the publicaton of Russ and Racey (2017) and from examples in the book of Middleton et al. (2020) with part D as visualized in the publications of Hargreaves et al. (2017) and Jahelková (2011). In the publication of Russ and Racey and in the book of Middleton et al., part D is visualized as components that start as FM sweeps that bend towards qCF endings. The sequence of components create a general concave parabola shape in frequency. The last component of the motif may have more of an overall FM shape. The motif is often made out of four or more components. I will name this variant part D1 for distinction.

The following two recordings are calls from a Nathusius'pipistrelle that was emitting these calls stationery from behind a gutter. The call between 5,900 s and 6,960 s (the first snippit on the right below) is visiually and audibly similar to the faint (or perhaps 'non-joined') slow trill, followed by three FM-qcF components, recorded by Lisa on 2024-06-14 (recording 913306), and is thus suspected to be the same type of call as that one - not a part D1. 

Date of recordings: 2024-05-26          Recorded by: Niels Jansen          Audio files: 911808, 921716 

The other variant of this part D motif were recorded by Niels at the same location, the same evening. In the publications of Hargreaves et al. and Jahelková, the shape of the motif seem to differ from D1 by the sequence not creating a distinct general concave parabola shape in frequency, often being grouped four or less components and the motif lacks the last component with an FM ending. The qCF  'endings' are not necessarily connected to the FM sweeps and the qCF parts alternate between going up and going down in frequency. I will name this variant part D2 for distinction.

In the last snippit of the following three screenshots, two components are visible around 0,600 s and around 1,175 s that are quite clearly FM sweeps with a qCF warble that are not connected. More are present in the recording that are not shown here.

Date of recordings: 2024-05-26          Recorded by: Niels Jansen          Audio files: 911809, 911810 

All previous social calls recorded by Niels were recorded near a roost of Nathusius' pipistrelle where at least ten bats were seen entering the roost. One more oddly shaped call was recorded at this location. It is a call in the shape of a walking stick, present at 23,550 s in the following snippit of the recording. Modified echolocation calls with hooks emitted by Nathusius' pipistrelle were also documented by Jahelková (2011).

Date of recording: 2024-05-26          Recorded by: Niels Jansen          Audio file: 912056 

More modified echolocation calls were recorded during mating season, together with some unusual social calls. Note the five hooked echolocation calls between 4,600s and 5,200s in the first snippit and one more between 2,750s and 2,800s in the second snippit:

Hooked echolocation calls that are more similar to the walking stick shaped social calls (similar to those of the pond bat and Daubenton's bat) are present in the following snippits. Sometimes it appears to be the arch only or even just the ascending part of the arch.

Date of recording: 2024-08-25         Recorded by: Aielynn Kleian          Audio file: 931845, 931846, 931847 

In my opinion, the modified echolocation calls of the previous recordings also explain the shape of the following calls. Two bats were seen flying through the street. One of the bats tapped a bat box on the wall on its way. The recording starts with type D social calls of the Natusius' pipistrelle. Later in the recording, the echolocation seems to be modified. Even a qCF-FM call is present between 60 and 70 kHz around 19,600s in the recording.

Date of recording: 2024-05-25          Recorded by: Olivier van Aken          Audio file: 911361

Our fieldworker Tessa encountered these social calls that look very similar to the part D2 motifs of the previous recordings by Niels in the vicinity of a Nathusius' pipistrelle roost. However, Tessa saw no behaviour from a bat that would indicate a roost, such as bats entering the building or tapping a possible roost entrance. It is a possibility that the roost's entrance was on the side of the building that was just out of sight.

Date of recordings: 2024-05-27          Recorded by: Tessa van der Eng          Audio files: 911692, 911688, 911690

Some sounds can't be classified to one of the previous described motifs. The recordings of Anice and Lisa are made at the same location, but with almost a month in between.

The first call of the recording of Anice (the snippits on the right) shows a slow trill. The second snippit shows the sequence part B, E and a small 'cheep' at around 37 kHz.

The first call shown in the recording of Lisa (the snippits below) is another slow trill, followed by four components that go up in frequency with each component. Between 8,050 s and 8,110 s (second snippit), there is a faint, or perhaps 'non-joined', slow trill visible.

I will name slow trills part F.

Date of recording: 2024-05-28         Recorded by: Anice Hut          Audio file: 911811 

Date of recording: 2024-06-14         Recorded by: Lisa Vermaning          Audio file: 913306 

What is noteworthy, is that a new type of call was recorded  at the exact same location as the previous two recordings in August (during mating season): a wavy-line call (between 1,850s and 2,000s in the snippit below).

Date of recording: 2024-08-17         Recorded by: Gert-Jan Hendriks          Audio file: 928168 

The wavy-line call is a warbled qCF call. I recorded these calls the first time in May of 2021. The call sequence in the following recording consists out of this wavy-line followed by a part B. The second call sequence consists out of a wavy-line, followed by a small 'cheep' around 15 kHz (at 2,716 s) and finishes the sequence with a part B. Also present in the recording are a part A only call and a part B+C call.

Date of recording: 2021-05-10         Recorded by: Sarah Mahie          Audio file: 911931 (slightly edited the noise out in the snippits for clarity)

I was eagerly waiting for other people to record these wavy-line calls, since we were collecting recordings on such a big scale this year, and I was not dissapointed. Two wavy-line calls after each other (one starting around 17,650 s and the other around 17,900 s in the snippit below), supplemented by a part B+C+B were recording during spring (outside of mating-season) in the beginning of July.

In the same recording, part E was also used in different call sequences:

Date of recording: 2024-07-02         Recorded by: Chris Johan Diepenmaat          Audio file: 918721 

This recording was made near an area where a common pipistrelle and a Nathusius' pipistrelle were foraging, as seen from the feeding buzz in the beginning of the recording (not shown). The Nathusius' pipistrelle emits multiple part B calls. It is suspected that these FM calls are agonistic in nature, since the majority of the recordings where this motif is used as a type C social call, is when a foraging Nathusius' pipistrelle is in the vicinity of other species of (foraging) bats - for example in recording 911550 and 912750. In this particular recording, an interesting type D part D2 call is present after one of the FM calls.

Date of recording: 2024-06-26         Recorded by: Sanna Gerdes          Audio file: 916811 

It is thought that bats that emit part D motifs are stationary (Middleton et al., 2020; Russ, 2021), but the recordings of Olivier - where the regular echolocation calls seems to pause when type D social calls including part D2 motifs are emitted - seems to show otherwise. Even though the last four snippits look like they contain wavy-lines, I believe these are faint part D2 motifs aswell, since vertical lines are still faintly visible. About five minutes after these two recordings, a serotine bat flew by emitting multiple agonistic calls (914886). The Nathusius' pipistrelles had their roost nearby.

Date of recordings: 2024-06-19         Recorded by: Olivier van Aken          Audio files: 914884, 914885  

The following recording is made in the same village as the previous recordings, near a foraging area and next to a row of trees that might function as a flying route. The motifs part A, B, C, D1, D2, E and F can be recognized. There seems to be a few extra notes that are occasionally emitted before the main part A1, a pre-part that I have decided to call part A0. There appears to be a new sounds present aswell: a fast trill.

The calls between 14,750 s and 15,400 s (first snippit below) are hard to distinguish, since at least two bats are emitting calls at the same time. A single bat could not produce a part B and a part A(0) motif at the same time (14,790 s). Since the main part A motifs are fairly different, I suspect these belong to different individuals. There are four part B motifs present at two different frequencies, two around 19, 5 kHz (bat A) and two around 33,5 kHz (bat B). Since bat A emits a part B motif during the first part A(0) motif, the part A must be emitted by bat B. Since the second part B motif of bat B overlaps with the only present part C motif, we can conclude that the part C motif is emitted by bat A. This leaves us with the following two sequences that, I believe, bat B emitted: a "Part A0 and A1 + part B" and a "fast trill + part B". The second snippet shows a fast trill without a part A. I consider it a possibility that this fast trill is the beginning of part A, but with the components connected, just like the example of the 'joint up' soprano pipistrelle social call in a recording of F. Gargill (Middleton et al., 2020). The similarity of the fast trill and the part A motif in the third and sixth snippit (both emitted by bat B) are striking. In the beginning and end of the second snippit, slow trills are also visible, altough very faint.

Date of recording: 2024-06-19         Recorded by: Levi Laluan, Louis Nijholt          Audio file: 914575, 914893 

A slightly different low-frequency fast trill. It was recorded in an area where common pipistrelle, Nathusius' pipistrelle and serotine bat were foraging. Unsure what species emitted this social call, but it shows most similarity to previous calls recorded of the Nathusius' pipistrelle.

Date of recording: 2024-06-28         Recorded by: Hubert Matuszewski          Audio file: 917429 

Another possible low-frequency fast trill that looks very much like the one in the previous recording (between 2,550 s and 2,600 s in the first snippit, between 8,800s and 8,850 s in the second snippit). It was recorded on two locations about 90 meters apart. Both snippits are the same calls from the two different locations. There is another small trill / wavy-line present aswell (between 3,170 s and 3,250 s in the first snippit, between 9,420 s and 9,500 s in the second snippit). Recorded in the area where the slow trills of recording 911811 on 2024-05-28 and 913306 on 2024-06-14 were recorded aswell.

Date of recordings: 2024-07-11         Recorded by: Job Hoven, Sam Harbers          Audio files: 920400920326  

I might reevaluated the three previously mentioned fast trills due to the following recording made during mating season. The call between 8,525s and 18,700s shows a lot of similarity to the fast trill structure, but I wouldn't exclude it for a wavy-line call. Perhaps I need to rethink the parameters to categorize them.

In the same recording, there is some proof that the trills originate from 'joined' part A motifs as theorized:

Altough, still not all of the trills can be explained that way:

I would consider the call between 23,700s and 23,850s to be a 'true' wavy-line call:

Date of recording: 2024-08-19         Recorded by: Declan Frerichs          Audio files: 929731 

A Nathusius' pipistrelle was emitting a series of social calls and tapping the entrance of a bat box on the wall of a buiding before entering the bat box. The type D social calls in the following recording are mainly part A only. Between 1,300 s and 1,900 s and between 3,400s and 4,100 s in te recording there are also some unusual tunes present.

In the recording directly after this, the social calls consisted mainly out of part A and B. In the recording after that one, the social calls consisted out of of part A, B and C.

Date of recording: 2024-06-28         Recorded by: Kaz Veldtrom          Audio file: 917393          Video footage by: Kaz Veldtrom

Sometimes, social calls can be very misleading. The following calls took me quite some time to identify. The recording 912750 (not shown) was made around 15 minutes later than the following two recordings and cracked the case for me; a Nathusius' pipistrelle was emitting part B as type C social calls in that recording. Could that mean that these were from the Nathusius' pipistrelle as well? I was a little thrown off by the shape, but the type C social calls in a recording of C. Nason (Middleton et al., 2020) would suggest that type C social calls of the Nathusius' pipistrelle can take on this form aswell.

Date of recordings: 2024-06-12          Recorded by: Sarah Mahie, Declan Frerichs          Audio files: 912757, 912759 

For about 10 minutes, a Nathusius' pipistrelle and common pipistrelle were seen foraging. Feeding buzzes of both species were witnessed. Type C and type D social calls, including a part D2 motif, are emitted by a Nathusius' pipistrelle. I do not exclude the possibility that some of the type C social calls are from common pipistrelle.

Date of recordings: 2024-07-01          Recorded by: Jasper Geukemeijer           Audio files: 917980, 917979 

Two Nathusius' pipistrelles are present in the following snippit. One of the two bats emits a series of high frequency social calls.

Date of recording: 2024-06-14          Recorded by: Nils Reinerie          Audio file: 913335 

More type C social calls, high-frequency as well as low-frequency:

Date of recording: 2024-09-14          Recorded by: Hubert Matuszewski          Audio file: 947652 

Two Nathusius' pipistrelles were seen flying close to each other. The ecolocation of both bats can be heard up until around 21,300 s in the following recording. Suddenly, it looked like one of the bats (or maybe both attached on each other?) fell down.

There could be two faint calls present at 21,830 s and 22,175 s, but they are to faint to hear. Between 22,200 s and 22,450 s there is noise. Directly after at around 22,560 s there is a clear bat call (FM) present with it's peak at 19 kHz. The next call (FM) is at 22,780 s, with it's peak around 36 kHz. From that moment on, from 22,830 s, it looks like it's trying to stabilize it's calls to more regular echolocation with the first 'normal-looking' call at 23,095 s and 42,5 kHz. From 23,970 s on, echolocation of the second bat is visible too again.

Date of recording: 2024-06-23          Recorded by: Thomas Kooiman, Sarah Mahie          Audio file: 915774 


All recordings are licensed under the following Creative Commons Attribution-NonCommercial-NoDerivs 4.0 license and in courtesy of Sarah Mahie.
All the original video footage can be found on our Youtube channel: United by Ecology
All sonograms are screenshots of the recordings imported in the ultrasound analysis software BatExplorer 2.2 (Elekon, Switzerland). 

 

Literature list:
- Daniel Hargreaves, Helena Jahelkova, Oliver Lindecke and Guido Reiter (2017). Bat Species of the Year 2015: Nathusius’ pipistrelle (Pipistrellus nathusii). Facts compiled for BatLife Europe.

- Helena Jahelková (2011). Unusual social calls of Nathusius' pipistrelle (Vespertilionidae, Chiroptera) recorded outside the mating season. Institute of Vertebrate Biology, Czech Academy of Sciences. Folia Zoologica, 60(1): 25-30. https://doi.org/10.25225/fozo.v60.i1.a4.2011

- Jon Russ and Paul Racey (2007). Species-specificity and individual variation in the song of male Nathusius’ pipistrelles (Pipistrellus nathusii). Behavioral Ecology and Sociobiology, 61(5): 669-677. DOI:10.1007/s00265-006-0295-9

- Jon Russ (2021). Bat Calls of Britain and Europe: a Guide to Species Identification. Pelagic Publishing. 

- Niel Middleton (2020). Is That a Bat? A guide to non-bat sounds encountered during bat surveys. Pelagic Publishing.

- Neil Middleton, Andrew Froud and Keith French (2022). Social Calls of the Bats of Britain and Ireland (second edition). Pelagic Publishing.

- Stuart Newson, Neil Middleton and Huma Pearce (2020). The acoustic identification of small terrestrial mammals in Britain. British Wildlife. 32(3).