Dolphin Dialogues Update

By Mira Johnson, Field Assistant

You may recollect that the 2024 summer field season began with Lab Manager Jolinde’s blog post introducing us to her research investigating turn-taking behavior in bonobos in the Democratic Republic of Congo. Noticing parallels between great apes and dolphins as a field assistant for the CKDP in 2018, she returned this summer for her PhD to examine communication in bottlenose dolphins. Unlike bonobos, studying dolphins comes with the added challenge of studying animals that live in the water, making observation of gesture-based communicative behaviors difficult. Despite this challenge, we have been able to gather a substantial amount of data using a variety of data collection methods (e.g., hydrophones, drone and Insta360 cameras, photo identification) to help us piece together how not only vocalizations, but also non-vocal communication, are used in dolphin communication. As the field season is nearing its end, I thought I would share with you some of the things we know about dolphin communication, and what we hope to discover with the data we have collected thus far.

How do dolphins communicate?
Dolphins produce a variety of sounds, including clicks, whistles, buzzes, squawks, squeals, and barks (Jones et al., 2020). Of these sounds, whistles are primarily used in social contexts and are used by dolphins to communicate with conspecifics regarding their identity, location, or to engage in cooperation. A signature whistle is a type of whistle that is unique to each individual and has been shown to serve as a contact call. Studies that examine dolphin communication between mother and calves have observed signature whistles to aid in the reunion of separated mother and calves, with the frequency of signature whistles increasing with distance (Kuczaj et al., 2015; Smolker et al., 1993). This suggests that vocalizations are used to reunite mothers with calves, but are vocalizations the only mode of communication at play? Non-vocal communication, like the use of pectoral fin contact with one another for social bonding has been observed in bottlenose dolphins as a way to maintain relationships (Dudzinski and Ribic, 2017). This provides evidence of other modes of communication and reinforces why it is important that we explore not only vocal but non-vocal modes of communication between mothers and calves as well. As we are interested in the turn-taking behavior in dolphins under different contexts, including mother-calf interactions, we have conducted several focal follows on mother-calf pairs this summer. We hope to review the acoustic data soon along with drone footage to see how mothers and calves interact with one another (vocally and non-vocally).

Below are some images of some potential signature whistles of the Cedar Keys population, where we can see how unique each whistle is. The frequency modulation pattern of each individual is distinct, functioning similarly to a name in humans.

​Looking forward
We hope that by using other data collection methods in addition to acoustics, we can get a better idea of how dolphins communicate with one another. By having photo and video recordings, we can see whether dolphins are using other modes of communication besides vocalizations, as well as identify specific individuals to see if and how their whistles change over time or under different contexts.

If you found this blog post about dolphin communication interesting, feel free to read the publications that were referenced in this blog below.

References:
Dudzinski, K. M., and Ribic, C. A. (2017). Pectoral fin contact as a mechanism for social bonding among dolphins. Animal Behavior and Cognition, 4(1), 30-48.

Jones, B., Zapetis, M., Samuelson, M. M., and Ridgway, S. (2020). Sounds produced by bottlenose dolphins (Tursiops): A review of the defining characteristics and acoustic criteria of the dolphin vocal repertoire. Bioacoustics, 29(4), 399-440.

Kuczaj, S., Eskelinen, H., Jones, B., and Borger-Turner, J. (2015). Gotta go, mom’s calling: Dolphin (Tursiops truncatus) Mothers Use Individually Distinctive Acoustic Signals To Call Their Calves. Animal Behavior and Cognition, 2(1):88-95, DOI: 10.12966/abc.02.07.2015

Smolker, R. A., Mann, J., and Smuts, B. B. (1993). Use of signature whistles during separations and reunions by wild bottlenose dolphin mothers and infants. Behavioral Ecology and Sociobiology, 33, 393–402.