The common pipistrelle (Pipistrellus pipistrellus) is the most common bat species in the Netherlands. One would assume that all it's calls would be well documented. But even well-known species have their surprises. This is a collection of the most eyebrow-raising recordings of common pipistrelle calls.
The following recording was made in an area where common pipistrelles were seen foraging in the area for at least 45 minutes. I have considered if the type C social calls belong to the Nathusius' pipistrelle, due to their resemblence of the part D motif of the type D social calls, like some of the components of the part D motif in the recording XC911810. What differs from the part D motif, is that the components in this recording are emitted continuously instead of clustered in groups. The calls also look very similar to the series of type C social calls in the recordings 920862 and 917912 of a common pipistrelle. Since the common pipistrelles seem to be the only present species when looking at the echolocation calls in the recording, the social calls of this recording most likely belongs to a common pipistrelle
Date of recording: 2024-06-08 Recorded by: Simon Boon Audio file: 911624
These type C social call were emitted a whopping 240 times in the short time period of 22,5 seconds. Tessa saw three bats swarming and tapping the gabel of the house, but none of the bats entered the building. After the video was taken, the bats flew away at around 5:00 and they did not return to the location afterwards. This creates the assumtion that their roost was somewhere else. The function of these social calls are uncertain. Since the other bats were common pipistrelles, it is assumed that the social calls were emitted by a common pipistrelle as well. The function of these social calls remain a mystery.
A juvenile bat had fallen out of the maternity roost and was found by the residents of the building. After a little care from a specialist, the juvenile bat was placed on the wall of the building and it climbed its way back to the roost. Around 40 individual common pipistrelles were counted leaving the roost after the juvenile made it save to his roost. Calls of the isolated juvenile (estimated to be around 2 weeks old) were recorded inside of the resident's home, before the bat was directed back to his roost.
In the vicinity of the maternity roost, the same as the previous story after the juvenile made it safely back home, an interesting trill-like call was recorded. This call is shown in the snippit on the left. At first I thought it belonged more into the type D social call category, as one would assume with a true trill. After comparing it to the type A social call of a brown long-eared bat (Plecotus auritus) that also inhibits a trill-like shape, shown in the snippit on the right, I suspect the category of the common pipistrelle call might be type A aswell.
The general type D social call is probably the most commonly known social call of the common pipistrelle, but lesser known is that the first components can be joined. The following two examples are from two different bats, since there is about 155 kilometers as the crow flies between the two recording sites.
More calls with a trill-like nature were recorded near a maternity roost were at least 44 adult common pipistrelles reside. It appears as if these calls first make an upward opening parabola followed by a downward opening parabola. They were emitted numerous times enough to not be a coincidence.
During a survey to check for roosting bats behind wooden window shutters, a common pipistrelle was disturbed by moving the window shutter in combination with the use of a flashlight. During this moment, the bat emitted seven type C social calls in the shape of FM sweeps with a wide withband.
Date of recordings: 2024-09-12 Recorded by: Sarah Mahie Audio files: 933410
Type B social calls might be pretty common in the vicinity of roosts, but I appreciate how clear this recording is. It shows the broad range of vocabulary of this little bat.
Date of recording: 2024-06-07 Recorded by: Manno Kolvoort Audio file: 917123
Type C social calls are also regular to come across, but they come in all shapes and sizes. Hence why a few examples of these calls are a great way to finish this post.
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