Read more about how I categorized the unusual social calls of the Nathusius's pipistrelle in this blog post.
A collection of the part A0, D0 and E motifs of the type D social call of the Nathusius' pipistrelle can be found on this page.

Happy to announce that we also recorded the rare hooked / modified echolocation calls this year! Type D social calls including part D, E and trills were also emitted.

Date of recording: 2026-05-27          Recorded by: Boaz van Die          Audio file: 1138132, 1138136, 1138140, 1138142, 1138146, 1138150, 1138152, 1138154, 1138156, 1138158, 1138160

This warble, around 20 kHz, was recorded near a lake where multiple bat species were foraging. The warble is similar in appearance to the trill-like calls of the Leisler's noctule, but echolocation calls of this species was not recorded in the area. Echolocation calls of a Daubenton's bat can be seen in the snippit. Fellow Myotis species such as the whiskered bat and pond bat are also able to produce similar emissions (Middleton et al., 2020: Fig. 8.3.34 & Fig. 8.3.76), but they are not known for M. daubentonii. It took a moment for me to realize that there is another bat species that creates warbles that was recorded at the site during that time: the Nathusius' pipistrelle.

Date of recording: 2026-05-21          Recorded by: Sarah Mahie, Boaz van Die          Audio file: 1138212

Type C social calls (first and second snippit) and type D socials calls including part D motifs (third and fourth snippit).

Date of recording: 2026-06-02          Recorded by: Boaz van Die          Audio file: 1140390, 1140391, 1140393

The first part D and part E motifs of this year were recorded when two Nathusius' pipistrelles were participating in social behaviour, emitting lots of social calls.

Date of recordings: 2026-04-21          Recorded by: Sander Boersma, Boaz van Die          Audio files: 1105972, 1106093 

A type D social call with joined components, forming a trill:

Date of recording: 2026-04-30          Recorded by: Boaz van Die          Audio file: 1133068 

Type D social calls including part E motifs:

Date of recording: 2026-05-20          Recorded by: Boaz van Die          Audio file: 1136570, 1136571

Type D social calls consisting of part B and part D motifs:

Date of recording: 2026-05-26          Recorded by: Sarah Mahie          Audio file: 1137823

Only part D motifs of the type D social call:

Date of recording: 2026-06-05          Recorded by: Boaz van Die          Audio files: 1141946, 1141947

Date of recording: 2026-06-18          Audio file: 1146884

The following recording does not contain social calls, but they are quite oddly-shaped echolocation calls:

Date of recording: 2026-06-14          Recorded by: Sander Boersma          Audio file: 1145391