Australia: this endangered bird has become so rare that it forgets how to sing

The Regent Honeyeater, a critically endangered bird native to Australia, has become so rare that youngsters are no longer able to learn their species’ song, a study finds.

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Chirping, whistling, squawking, … Birds have a whole repertoire to express themselves and interact with their congeners. But not all have the same sound language. Each species is distinguished by particular calls and songs which can also vary according to regions and individuals.

Unfortunately for the Regent Honeyeater, a passerine bird native to Australia, this “sound culture” could become history. This is what a published study reveals in the review Proceedings of the Royal Society B by researchers from the Australian National University and the organization BirdLife Australia.

According to these studies, the song specific to the species Anthochaera phrygia would be disappearing. In question: its very small population. The bird would indeed have become so rare that young individuals would no longer be able to learn their characteristic vocalizations.

A critically endangered species

The Regent Honeyeater is a medium-sized passerine, recognizable by its predominantly black plumage dotted with yellow spots and bands. Endemic to Australia, it grows mainly in the eucalyptus forests of the south-east of the continent but it has become considerably rare in recent years.

While the population was previously estimated at 1,500 mature individuals, it now numbers only some 300 birds in the wild, including perhaps 150 males. And the species is listed as Critically Endangered by the International Union for the Conservation of Nature (IUCN).

It was while searching for the regent honeyeater that researchers began to take an interest in its song. “They are so rare and the area they can occupy is so vast – that it was like looking for a needle in a haystack.“, has explained at the BBC lead author of the study, Dr. Ross Crates.

During this research, he found that some birds “sang strange songs“. “It looked nothing like a regent honeyeater. They sounded like different species“, he clarified.

Very different songs

To find out more, scientists collected all observations of the species recorded between July 2015 and December 2019 to assess the distribution and density of wild populations. They then went to the field to record the vocalizations of several dozen males.

At the same time, they also captured the songs of captive specimens and collected old recordings of wild males dating from 1986 to 2011. Verdict: The team found clear differences between the vocalizations of all individuals. In particular in those evolving in the less dense populations.

Where the A. phrygia were relatively numerous, the males uttered rich and complex songs specific to their regions. Some, on the other hand, showed atypical vocalizations, similar but abbreviated. Others emitted completely different songs, imitating those of other species.

“Some were songs one might expect from a droplet meliphage or a shrill polochion“, decrypted Dr. Crates for ABC. “Some were eccentric … The birds sang like an omnicoloured parakeet or a great awakening “. According to the study, 18 males were affected, or 12% of the total population.

Looking at these specimens, the researchers found that all of them were in areas of very low population. For their part, the captive individuals uttered completely different songs from the rest of the subjects studied.

In need of learning

As humans learn to speak, many birds learn to sing through the intervention of older specimens of the same species. However, in young regent honeyeater, this process would be more and more compromised due to the decline of populations.

“When the young birds leave the nest and soar out into the big world, they need to associate with other, older males, so that they can listen to them sing and repeat their song over time.“said Dr. Crates. Except that today, some fail to find congeners to serve as teachers.

“These juveniles then end up learning the songs of other species.“, he continued.”If this species begins to lose its sonic culture, we fear it could be a dangerous red flag that it is literally on the verge of extinction.“, he lamented.

Because it is not a simple question of vocalizations. This disappearance directly influences the behavior and survival of the regent honey-feeds. The results suggested that specimens with songs that were slightly or completely different from the norm were less likely to find a mate and reproduce.

“Many songbirds, including the Regent Honeyeater, use their song to impress females“, recalled the Australian researcher. Except with atypical vocalizations, it would be much more difficult for the males to communicate with their congeners and to attract a possible partner.

Singing lessons in captivity

Scientists fear that this loss of “sound culture” will exacerbate the bird’s decline. According to them, this would be the first time that such an inability to communicate with its own species has been documented in a wild animal. “Our study demonstrates that a significant decline is eroding culture in a wild animal population“, they write in their report.

If the discovery seems alarming, researchers have found a way to help the Australian sparrow. A reintroduction program of captive-born specimens has already been set up at Taronga Zoo in Sydney to boost populations. The idea is to teach the youngsters the song of their species before they are released.

“We use our recordings of correctly singing males that we have found in the wild over the past five years, and play them through loudspeakers to young birds in captivity.“, explained Dr. Crates for ABC. With the hope that they will learn it and then put it to good use.

“We hope that […] if they sing correctly, it will make them more attractive to females when they are released into the wild“, he concluded.

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