Rare Australian bird loses love song repertoire as population dwindles

A female regent honeyeater in Capertee National Park in New South Wales 

Credit: Australian National University

An endangered Australian bird is losing its ability to sing because a decline in numbers means there is a lack of adults to learn from, a scientific study has found.

Male regent honeyeaters, which live in forest and bushland in eastern Australia, are losing their “song culture” as a result of “severe population decline”, researchers from the Australian National University warned.

Fledglings would normally learn songs from adult mentors, just as human babies learn language from their parents.

That link has now been broken and “the complexity of regent honeyeater songs has also declined over recent decades,” the scientists said.

In areas where the bird’s population is particularly sparse, some males “completely failed to sing any species-specific songs and instead sang other species’ songs,” because that was all they were hearing.

They are picking up ersatz versions of mating calls used by species such as black-faced cuckooshrikes and noisy friarbirds.

“This lack of ability to communicate with their own species is unprecedented in a wild animal,” said Dr Dejan Stojanovic, one of the study’s authors.

“We can assume that regent honeyeaters are now so rare that some young males never find an older male teacher.”

Regent honeyeaters were once common across eastern Australia

Credit: Lachlan Hall/AP

Males unable to sing a rich repertoire of mating calls were less likely to find a female mate.

The findings amount to “rare evidence” that a severe decline in population density can result in “the loss of vocal culture in a wild animal.”

That will hasten the species’ extinction, the scientists wrote in a study published in the peer-reviewed journal, Proceedings of the Royal Society B.

The loss of the bird’s ability to produce mating calls was “exacerbating the honeyeater’s population decline, because we know a sexy song increases the odds of reproduction in songbirds,” said Dr Ross Crates, lead author.

“They don’t get the chance to hang around with other honeyeaters and learn what they’re supposed to sound like.”

The regent honeyeater, which once had the rather less elegant name of “warty-faced honeyeater”, used to be common in Queensland, New South Wales and Victoria.

Named for its striking black and yellow plumage, the species is now critically endangered as a result of the widespread clearance of its woodland habitat. It is estimated that the population is now down to just 300-400 individuals.

Scientists now hope to use audio recordings to teach the full medley of songs and mating calls to captive regent honeyeaters, which will then be released into the wild.