Table 1. Recording effort of the study.

Only good quality whistles (non-overlapped with the contour clearly visible in the spectrogram) were considered. To avoid pseudo-replication, whistles with identical time-frequency contours were considered only once.

Dolphin group	Date (dd/mm/yyyy)	No recordings	Recording effort (min)	Group size	No whistles
I	18/11/2020	2	20	150	30
II	09/12/2020	2	16	250	14
III	25/04/2021	1	10	300	10
IV	25/04/2021	1	10	80	3
V	07/09/2021	5	38	140	213