By Lucien Wilkinson

New Curtin University research has found that Pygmy blue whales visiting an underwater canyon off the Western Australian coast changed their song structure in an effort to stand out among other calling whales.

The research, published in science journal PLOS ONE, examined underwater sound recordings collected between 2003 and 2017 for variations in the South Eastern Indian Ocean pygmy blue whale’s song structure at Perth Canyon, west of Rottnest Island.

Lead author PhD student Capri Jolliffe, from Curtin’s Centre for Marine Science and Technology (CMST), said it was previously assumed that pygmy blue whales called by using the same song but the new research discovered a number of variations in song structure.

“During their visit to the Perth Canyon, the whales’ song structure changes in ways that suggest the animals are adapting to the presence of many other calling whales,” Ms Jolliffe said.

“We found that when the pygmy blue whales became surrounded by other calling whales, they began shortening and breaking up their songs while using higher signal levels.

“We observed that the whales were continuously communicating with varying song structures as if they wanted to identify themselves as being different and stand out from the crowd.

“The variations in the whales’ songs allowed us to better understand how they interact when other calling whales are around them.”

Research co-author Associate Professor Robert McCauley, also from CMST, said the song changes were observed during peak migration season from March to April.

“The song variations occurred at a time when the whales were looking for food sources and there are many other whales around them,” Professor Robert McCauley said.

“We identified three different song types that were used and even hybrid song patterns where the animals combined multiple phrase types into a repeated song.

“We believe that the high level of song variability may be driven by an increasing number of background whale callers creating ‘noise’ and thereby forcing the animals to alter song in order to make themselves distinct from the rest of the crowd.”

The research team comprised of researchers from CMST and the Centre for Whale Research (WA) in Fremantle.

The research paper, ‘Song variation of the South Eastern Indian Ocean pygmy blue whale population in the Perth Canyon, Western Australia’ can be found here.