Australian humpback whales are singing less and fighting more. Should we be worried?

Eastern Australian humpback whale populations have recovered over the years. New research shows that male whales have adapted their mating strategy in a highly strategic way. I analyzed 123 days of data on Australian humpbacks (Megaptera novaeangleae) collected from 1997 to 2015, and found that as whale populations increase, male humpbacks sing less and fight more.

We think this change in behavior is because male whales do not want their mate to attract another male, we report in research published today in Communications Biology. Rapid evolution, rapid adaptation Humpback populations have grown spectacularly since 1965, when the species became globally protected. Their population on the east coast of Australia was less than 500 in the 1960s and is estimated to be at least 30,000 today. This population has provided experts with a rich dataset.

Male whales in particular have made a big contribution to this because of their catchy vocalizations. Building on work started by Professor Michael Noad of the University of Queensland in the 1990s, we decided to investigate how eastern humpbacks have adapted to increased numbers. The good thing for us was that these whales migrate close to the coast, so we were able to set up a land-based observation station at Peregion Beach, a small coastal town on the Sunshine Coast.

Volunteers on shore helped us track individual whales as they moved further from shore, while an acoustic array recorded the song of offshore whales and tracked singing whales. This method (which was first established by Professor Noad) allowed us to pinpoint the exact location of a particular whale in real time. A trend emerged when our data were combined with the data collected by Professor Noad’s team.

As the population of eastern humpback whales increased, the male whales did not sing as much as they used to. Instead they were increasingly busy silently finding a female to mate with, or fighting off other male competitors. Significantly, the proportion of male whales that sing has decreased from two in ten in 2003–2004 to just one in ten by 2014–2015. Data from 2003-2004 also showed that male whales were less likely to sing on occasions when the proportion of male whales in their social circle was higher.

And it seems that a change in strategy led to a change in results. Males singing in 1997 were about twice as numerous as their counterparts, who appear to associate with and escort a female, possibly in an attempt to mate. But by 2014-2015, whales on non-singing were nearly five times more likely to join a group with a female whale. We cannot say with certainty that joining a group actually results in mating with a female.

In fact this is another piece of the puzzle: how many males (singing or non-singing) that join the group actually mate and then give birth to a brood? In the early years of data collection, when there were fewer whales around, a male could quite comfortably sing to nearby females and convey his message – he didn’t have to worry about crowding out other males Wasn’t Now, with a growing population, that same strategy attracts the risk of being interrupted by other males.

As a male humpback, you spend the breeding season quietly seeking to mate with a female and not attract the attention of other males. Or, if you fancy yourself a Turram Khan, you can battle other males to become the flag bearer of the group. And it relates to one of our working theories as to why singing among eastern humpbacks has decreased over time, and fighting has increased.

Despite what our research has seen, we do not think that whales are in danger of losing their ability to sing. Eastern humpback whales have simply changed their behavior to improve their chances of mating. As researchers work in the field, we still hear whales singing, so we’re not worried.

Disclaimer:IndiaTheNews has not edited this news. This news has been published from PTI-language feed.

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