The social calls of the common noctule are the most variable among all Palaeartctic bat species (Weid, 1994).

Click on the following buttons to see all relevant recordings of that specific year:

Type A

Used aggressively while individual bats are in dispute with each other within the roost (Middleton et al., 2020).
Recorded in the vicinity of a roost. Example: 910857 

Type B

Variant 1: an agonistic call. Often a longer sequence of FM components. No example.
Variant 2: roosting sounds. Examples: 930849, 930845, 930850, 934501 

Type B.2:

Type C

Variant 1: an FM call; also often used in a "false-feedingbuzz" motif. Examples: Examples: 910871, 913398, 911495, 924811 
Variant 2: an FM-qCF call. Often used in groups of three or more calls and supplemented by a type D2 call. Examples: 910858, 910862, 913398 
Variant 3: low-frequency stretched-s-shaped calls. Often repeated numerous times. Examples: 911207, 910947, 910942 
Variant 4: a qCF call with a sharply, in frequency, ascending tail at the end of the call. Examples: 920702, 914235, 910936, 920702
Variant 5: a qCF call with harmonics. The motif often seems to be emitted twice. Examples: 917065, 910936, 911495, 930851 

I am unsure if the components of "the stairs" motif need their own category. Part A of this motif consists out of three small qCF notes. Part B consists out of three small FM notes. Example: 914235 

Modified echolocation: an FM sweep with a hook at the start of the call. Examples: 930845, 930849, 930846, 930844, 930842, 930850, 930847, 930848 

False feeding buzz motif, consisting out of multiple type C1 calls:

Type D

The common noctules produces two variants of trills as their type D social calls (Pfalzer and Kusch, 2003; Barros et al., 2014; Middleton et al., 2022). Both variants can differ greatly in their number of components, overall shape and frequency.

Variant 1: Slow trill motifs, consists out of V-shaped and FM components. Examples: 910862, 910936, 913398, 917065
Variant 2: Fast trills, with or without harmonics. Examples: 910871, 912136, 910942, 910936

Songs

The common noctule often uses a mixture of type C and type D calls and motifs in their songs. The sequence of these motifs can vary a lot. There might be a few more regular used sequences.

For instance, a group of type C2 calls are very likely to be followed by a type D2 call (the "count-down" sequence, example: 910858) and the "false feedingbuzz" motif, consisiting out of multiple type C1 calls, often takes place ater a type D1 social call (example: 917065).

The following sequence could be considered a general sequence for a song of the common noctule:
D1 - multiple C2 - D1 - multiple C2 - D1 - multiple C1 - D1 - multiple C2 - D1 - D2

When type C3 calls are present, the frequency of all social calls often tend to stay on the lower frequencies - not surpassing the 40 kHz. 

The "count-down" sequence:

The "false feeding buzz" sequence:

All images on this page are licensed under the following Creative Commons Attribution-NonCommercial-NoDerivs 4.0 license and in courtesy of Sarah Mahie. 

Literature list:

- G. Pfalzer & J. Kusch (2003). Structure and variability of bat social calls: implications for specificity and individual recognition. Journal of Zoology, London. 261: 21–33. https://doi.org/10.1017/S0952836903003935

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

- Paulo Alexandre Rodrigues Barros, Luís Pires Braz, Hélia Vale-Gonçalves and João Alexandre Cabral (2014). First records of Nyctalus noctula social calls in Portugal. Vespertilio. 17: 37-44.

- R. Weid (1994): Sozialrufe männlicher Abendsegler (Nyctalus noctula). Bonner Zoologische Beitrträge. 45: 33–38.