Scientists have rescued the lost song of the critically endangered regent honeyeater – one of Australia’s rarest birds.
Regent honeyeaters were once seen in vast flocks across south-eastern Australia, with a distribution that ranged from Queensland to Kangaroo Island in South Australia.
But the songbirds have experienced significant population decline in recent decades and are now mostly confined to the Blue Mountains area. As its numbers have diminished – to now fewer than 250 in the wild – so has the complexity of the bird’s song.
The typical song for the Blue Mountains birds has virtually disappeared from the wild, replaced by a simpler version containing half the number of syllables – with potential impacts on reproductive success.
But a team of researchers have now saved the song from the brink: using recordings and direct instruction from two wild-born male “song tutors”, they have taught young zoo-bred regent honeyeaters their original wild call.
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A captive breeding program for regent honeyeaters has been under way at Taronga Zoo in Sydney since 1995. Over a three-year period beginning with the 2020-21 breeding season, scientists set out to teach young males their full song, which plays a key role in attracting mates and establishing territory.
In the first year, the team played the recorded songs to young regent honeyeaters “every day for about the first six months of their life”, said the study’s first author, Dr Daniel Appleby of the Australian National University. That approach was unsuccessful.
In the second year, the team recruited two wild-born males as singing teachers, with greater success. “We took fledgling birds from all different parents, and we creched them with a wild male who sang correctly,” Appleby said.
“We realised that if you have too many birds to one tutor – so a big class size – they don’t learn as effectively,” Appleby added. In the third year of the program, song class sizes were reduced to about six juvenile males per adult male tutor.
“The proportion of juveniles that learned the wild song increased from zero to 42% within three years,” the study found. “The full version of the wild song taught to zoo-bred males disappeared from the wild during the study, making the zoo population the only remaining source of traditional song culture.”
In the years that followed, zoo-bred males that had learned the complete song subsequently taught it to the next generation.
Ecologist Dr Joy Tripovich, who studies regent honeyeaters at both the Taronga Conservation Society and the University of New South Wales, said it was “really exciting” hearing the zoo-bred birds sing their restored song for the first time.
Since 2000, Taronga and its partners have released 556 zoo-bred regent honeyeaters into New South Wales and Victoria, Tripovich said. Among the more recent releases are males who have learned their original song.
More research was under way to determine what impact the song tutoring program has on the success of the birds released back into the wild, Tripovich said.
“Our aim for the overall project is to have species become self-sustaining,” she said. “We really want them to grow their numbers on their own so that we don’t need to intervene any more.”
The researchers hope the restored song could improve breeding success and overall fitness of zoo-bred birds once they are released into the world. The end goal was to “see wild and captive birds interbreeding”, Appleby said. “Historically that wasn’t something we ever really observed.”
The research was published in the journal Nature Scientific Reports.
Disclaimer : This story is auto aggregated by a computer programme and has not been created or edited by DOWNTHENEWS. Publisher: theguardian.com
