Twainspotting: Identity Revealed During a Simple, but Extended Conversation with a Humpback Whale

Abstract

Extended acoustic interactions with a humpback whale (Megaptera novaeangliae) were captured via human-initiated playbacks of the purported humpback "throp" social call and hydrophone recordings of the animals vocalized responses during August 2021 in Frederick Sound, Southeast Alaska. Multivariate statistical analyses performed after the event, that adapted the Wasserstein metric to spectrograms, strongly imply that the played back call was from the same animal, which had been recorded the previous day and initially selected for its clarity. This suggests these interactive playback studies may have formed a probe of time-delayed self-recognition. Fluke photographs taken that previous day and during the interactions revealed that the animal had been identified 38 years earlier, now known as the female humpback named Twain 14 years ago. This exciting and to our knowledge unique series of interactive vocalization events, while hopeful, poses more questions than answers. Most basically, did the half-hour long series of acoustic exchanges constitute an interspecies conversation? We argue that analysis tools available to infer the implied causality of interaction--statistical dependency, multivariate information theory, and machine learning--leave the question open. That said, and perhaps more importantly, the extended interaction broaches questions whose answers bear directly on future interspecies communication and, more generally, the human appreciation of nonhuman intelligence. The reported human-humpback interactions will facilitate exploring these issues at new depths.