Marine Mammal Foundation
Marine Mammal Foundation

Finding the voice of a critically endangered Australian dolphin

Embargoed until: Publicly released:
Peer-reviewed: This work was reviewed and scrutinised by relevant independent experts.

Australian researchers have been gathering data on the ways a critically endangered Australian dolphin species communicates. The Burrunan dolphin was only recently described as a distinct species, with only two known resident populations documented. To learn more about this species, researchers collected sound recordings from both populations - in Port Phillip Bay and the Gippsland Lakes - to look at how this species communicates and how it differs from other dolphins. The researchers have described several types of whistle, a bark, a squeak, a creak and a moan, and they say the two populations make similar vocalisations. They say the more we know about these dolphins, the easier it will be to identify them, and the more we can do to help conserve the species.

Journal/conference: Royal Society Open Science

Research: Paper

Organisation/s: Curtin University, Marine Mammal Foundation, Australia

Funder: This work was supported by the Victoria State Government via the Port Phillip Bay Fund, the Lord Mayor’s Charitable Fund and the Victoria State Government for the Gippsland Lakes.

Media release

From: The Royal Society

Burrunan Babble: Acoustic characterisation of the whistles and burst-pulse sounds of a critically endangered dolphin

Royal Society Open Science

Understanding the vocal repertoire of delphinid species is essential for effective long-term studies. In this research, we present the first quantitative analysis of whistle and burst-pulse sound characteristics for the critically endangered Burrunan dolphin (*Tursiops australis*). Acoustic data were collected from the two known resident populations in Port Phillip Bay (PPB) and the Gippsland Lakes (GL), Victoria, Australia, between 2016 and 2023.

Our analysis encompassed 12,973 signals, including 3,401 whistles and 9,572 burst-pulse sounds, drawn from nearly 21 hours of recordings. We classified whistles into six contour classes, with upsweep (41.46%) and convex contours (24.64%) being the most prevalent. The fundamental frequency of whistles varied from 0.49 to 42.50 kHz, with durations ranging from 0.02 to 1.86 s. Burst-pulse sounds were categorized into four classes, with barks (71.74%) being the most common, displaying peak frequencies from 0.09 to 47.81 kHz and durations of 0.01 – 5.29 s. Significant variation in vocalisation characteristics were observed between the two resident Burrunan dolphin populations, with PPB repertoire more restricted than GL.

Variation in whistle repertoire composition between Burrunan and other Tursiops spp. was also found. This study provides crucial insights into the vocal characteristics of the Burrunan dolphin, which will inform conservation efforts.

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