Ethics
This study was approved by the University of St Andrews School of Biology Ethics Committee. Song recording in French Polynesia was conducted under permits issued to M.M.P. by the Ministry of the Environment, French Polynesia. Song recording in Ecuador was conducted under permits issued to J.D. by the Environmental Ministry, Ecuador.
Data accessibility
The dataset supporting this article (comprising raw song transcripts) has been uploaded as part of the electronic supplementary material (electronic supplementary material, S2) [101]. Song strings per singer are provided in table 1 and unit sequences for all phrase type set medians are provided in electronic supplementary material, table S1.
Authors' contributions
J.N.S.: formal analysis, investigation, writing—original draft, writing—review and editing; J.D.: conceptualization, data curation, funding acquisition, writing—review and editing; J.O.: conceptualization, data curation, funding acquisition, writing—review and editing; M.M.P.: conceptualization, data curation, resources, writing—review and editing; E.C.G.: conceptualization, data curation, funding acquisition, investigation, methodology, project administration, software, supervision, writing—review and editing.
All authors gave final approval for publication and agreed to be held accountable for the work performed therein.
Conflict of interest declaration
We declare we have no competing interests.
Funding
The NERC Sea Mammal Research Unit made a contribution towards the write-up of this study (NE/R015007/1). E.C.G. is currently funded by a Royal Society University Research Fellowship (UF160081). Fieldwork in French Polynesia was funded by a Royal Society Newton International Fellowship (NF140667) and National Geographic Society/Waitt grant (no. W396-15) to E.C.G. Funding in Ecuador was provided to J.D. by COCIBA grants of USFQ in 2016, 2017 and 2018 and Rufford Foundation grants to J.O. as well as volunteer contributions of Project CETACEA Ecuador.
Acknowledgements
We thank Vincent Janik and Peter Tyack for comments that improved a previous version of the manuscript. We are grateful to our numerous volunteers, students, and boat captains during the fieldwork seasons from 2016 to 2018. In French Polynesia, Nicolas Buray and Arii Richmond assisted fieldwork, while Dolphin and Whale Watching Expeditions provided logistical support.
Footnotes
Electronic supplementary material is available online at https://doi.org/10.6084/m9.figshare.c.6125250.