Recordings from 2023 to 2025

I am happy to have recorded the echolocation calls together with these interesting type C and type D social calls. The echolocation calls are emitted in their typical click-clock manner with peak frequencies of 29 kHz (clicks) and 24 kHz (clocks).

Date of recordings: 2025-06-27          Recorded by: Sarah Mahie, Boaz van Die          Audio files: 1013600, 1010367, 1010419, 1010420, 1010369, 1010371

These type C.d1 male advertisement social calls were recorded in a residential area surrounded by a wooded area. The calls are suspected to be emitted while in flight. The Leisler's noctule usually emits advertisement calls during a songflight up to 300 meters from the roost (Middleton et al., 2022). In comparison to the common noctule (Nyctalus noctula), the advertisement social calls are shorter in duration and with a descending FM effect.

The white arrows indicate the advertisement calls in the following snippits:

Date of recordings: 2024-09-16          Recorded by: Douwe van der Wijk          Audio files: 935427, 935408 

The following recording is made in a forrest and contains Nyctalus-like type D social calls. Common noctule and Leisler's noctule are both presumed to be present, however the only reference material that shows a similar social call is a recording from a greater noctule (Nyctalus lasiopterus) - recorded by Alex Lefevre, figure 8.22.11 in the book "Bat calls of Britain and Europe" edited by Jon Russ. The latter species would be an extraordinary sighting for the Netherlands, so I am hesitant to identify it as such based on the social calls alone. Due to the present echolocation calls, I currently will name these as from the Leisler's noctule.

Date of recordings: 2025-06-19          Recorded by: Sarah Mahie, Boaz van Die          Audio files: 1008061, 1008063 

Date of recordings: 2023-07-03          Recorded by: Arjan Boonman          Audio files: 822327, 822328, 822329, 822333, 822339, 822412, 822413