Chilean Dolphins ( Cephalorhynchus eutropia ) Produce Both Narrowband High‐Frequency and Broadband Clicks

Most dolphin species produce broadband biosonar clicks for echolocating prey, and whistles and burst‐pulsed calls for communication purposes. Seven dolphin species were previously reported to only produce clicks of a narrowband high‐frequency (NBHF) type, very similar to the clicks produced by porpoises. In this study, we used underwater acoustic recordings of Chilean dolphins ( Cephalorhynchus eutropia ) in southern Chile to show that the click repertoire comprises highly stereotypical NBHF clicks, more variable clicks with lower centroid frequencies and wider bandwidth, and some that are intermediate between these two categories. Both NBHF and broadband clicks were produced in trains, buzzes, and burst‐pulses. Broadband clicks co‐occurred with NBHF clicks in nine out of thirteen Chilean dolphin acoustic encounters, typically during social encounters. We conclude that C. eutropia can relax acoustic crypsis in a similar manner as other members in the Cephalorhynchus genus. Our findings make it likely that other NBHF delphinids have the ability to generate click types with frequencies below the typical NBHF range.