Humpback whales on Australia’s east coast have changed their mating habits as competition for females heats up, turning themselves from “lovers” to fighters.
A long-term monitoring project run by University of Queensland researchers has found that male humpback whales used to sing to seek out females, but have increasingly turned to fighting among themselves for the right to breed.
UQ Associate Professor Rebecca Dunlop, who has worked on the project for years, said the change in behaviour over time was attributed to the increase in the humpback population.
“Humpback whales were hunted nearly to extinction. It’s estimated they got down to only around 300 individuals,” she said.
“And then over the years, the population has increased drastically, and that’s going to drastically change the population dynamics.”
Over the course of the study period used for the paper — between 1997 and 2015 — the east coast humpback population grew from 3700 to 27,000 whales.
The researchers said when there were very few whales, it made sense they would have to “sing out” to find mates, but now there were so many, there was more competition for females, and so the males had turned to fighting for mating rights.
Dunlop said it was not clear whether this was a return to “usual” humpback mating behaviour or whether this was a new adaptation.
“The problem is we don’t know what ‘normal’ is for humpbacks because this work wasn’t done before widespread whaling,” she said.