Male humpback whales are singing songs over many hours as part of a complex courtship to woo potential partners.
University of Queensland (UQ) researchers have discovered singing males spend more quality time with females who may be using the male’s song as the basis for mate choice.
The researchers, UQ PhD student Joshua Smith, his supervisor, whale expert Dr Michael Noad from UQ’s School of Veterinary Science, and volunteers have tracked whales off Peregian Beach, on Queensland’s Sunshine Coast.
The UQ team has been observing and tracking the whales for the last three years as the whales migrate south from their breeding inside the Great Barrier Reef.
During September and October each year, they recorded whale behaviours, interactions, took genetic samples and used hydrophones (underwater microphones) to record male singers round-the-clock.
Scientists had suspected that whale songs were used for female attraction and male repulsion, but the UQ team was the first to provide a range of evidence that linked to courtship.
“Songs appear to be directed more towards females possibly as a courtship and mating display than a signal to warn off or repel rival males,” Mr Smith said.
“Singers are joining females with calves more often and singing for a much longer duration with them than any other social group.
“The characteristics of the song are possibly being used by the female to assess these males.
“The way they structure the songs, perhaps using particular elements like higher or lower frequencies and how well they do that could reflect attributes of that male such as his fitness, maybe his age.”
Mr Smith said male whales sang mostly in the presence of females but the songs also attracted other males too.
He said the songs were repetitive but structured, made up of chirps, moans and barks that could last for 10 minutes up to 23 hours.
“Their songs are basically broadcast signals that other whales and hydrophones can detect from at least fifteen or twenty kilometres away.”
The 27-year-old from Highgate Hill said he couldn’t say the male songs were necessarily attracting females but the songs still helped sexual interaction.
Dr Noad has also disproved a theory that whale songs regulated spacing between singing males.
Since 2002, the UQ Team has recorded more than a thousand hours of whales’ songs. This is stored as 400GB of data — enough to fill about five computer hard drives.
Mr Smith and Dr Noad’s research has been part of an international project called the Humpback Acoustic Research Collaboration (HARC).
It’s a joint project for American and Australian scientists primarily funded by the United States Office of Naval Research but also by the Australian Defence Science and Technology Organisation.
Other contributors are the Woods Hole Oceanographic Institution, the Scripps Institution of Oceanography, the University of St Andrews and the University of Newcastle.
Mr Smith said he hoped to work in marine animal acoustics or with the Australian Antarctic Division when he finished his PhD in six months.
His PhD is also supervised by Associate Professor Anne Goldizen, an ecology expert from UQ’s School of Integrative Biology.
Listen to this whalesong recorded in 2003: http://omc.uq.edu.au/audio/news/whalesong.mp3
Media: Mr Smith (0404 802 278, 07 3365 2506, jsmith@zen.uq.edu.au) or Miguel Holland at UQ Communications (07 3365 2619, m.holland@uq.edu.au)
