Bottlenose dolphins can use learned vocal labels to address each other

Abstract

In animal communication research, vocal labeling refers to incidents in which an animal consistently uses a specific acoustic signal when presented with a specific object or class of objects. Labeling with learned signals is a foundation of human language but is notably rare in nonhuman communication systems. In natural animal systems, labeling often occurs with signals that are not influenced by learning, such as in alarm and food calling. There is a suggestion, however, that some species use learned signals to label conspecific individuals in their own communication system when mimicking individually distinctive calls. Bottlenose dolphins ( Tursiops truncatus ) are a promising animal for exploration in this area because they are capable of vocal production learning and can learn to use arbitrary signals to report the presence or absence of objects. Bottlenose dolphins develop their own unique identity signal, the signature whistle. This whistle encodes individual identity independently of voice features. The copying of signature whistles may therefore allow animals to label or address one another. Here, we show that wild bottlenose dolphins respond to hearing a copy of their own signature whistle by calling back. Animals did not respond to whistles that were not their own signature. This study provides compelling evidence that a dolphin’s learned identity signal is used as a label when addressing conspecifics. Bottlenose dolphins therefore appear to be unique as nonhuman mammals to use learned signals as individually specific labels for different social companions in their own natural communication system.

The acoustic repertoire of wild common bottlenose dolphins (Tursiops truncatus) in Walvis Bay, Namibia

“…A more detailed analysis of behavioural context using simultaneous underwater video and acoustic recording equipment (Dudzinski et al 1995;Herzing 1996) could shed light on the functionality of the sound types described, although the application of this method in Walvis Bay may be hampered by poor underwater visibility. Alternatively, playback experiments provide a powerful tool for investigating functionality of call types in dolphin communication systems (Sayigh et al 1999;King and Janik 2013).…”

Interfaces and Keyboards For Human-Dolphin Communication: What Have We Learned?

“…In addition, the system can play specific signature whistles created for each of the researchers, along with actual signature whistles of prime dolphin candidates who work with the system on a regular basis. This allows the system to function like dolphins do (e.g., to greet each other with their signature whistles -see King & Janik, 2013), at least to some degree. The system has all the advantages of a computer; it is fast, data is fully recorded, and programming changes can be made in the field if needed.…”

Vocal matching: the what, the why and the how

“…However, with regard to dolphins, because signature whistle copying only occurs between social companions [13], it is perhaps unlikely that strangers would be matched. Instead signature whistle matching appears to be used by animals to strengthen social relationships [13] or to facilitate the localization of specific individuals in large social networks [11,29,43]. So, although dolphins may learn the signature whistles of individuals within their wider social network, only the signature whistles of close social affiliates are routinely copied.…”