Scientists have rescued the lost song of the critically endangered regent honeycreeper, one of Australia’s rarest birds.
Regent honeycreepers were once seen in large flocks throughout southeastern Australia, with a distribution ranging from Queensland to Kangaroo Island in southern Australia.
But songbird populations have seen a significant decline in recent decades and are now mostly confined to the Blue Mountains area. As their numbers have decreased (there are fewer than 250 in the wild so far), so has the complexity of the bird’s song.
The typical song of Blue Mountains birds has virtually disappeared from the wild, being replaced by a simpler version containing half as many syllables, with possible impacts on reproductive success.
But a team of researchers has brought the song back from the brink: Using recordings and direct instructions from two wild-born male “song tutors,” they have taught young zoo-bred regent honeyeaters its original wild call.
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A captive breeding program for regent honeycreepers has been underway since 1995 at Taronga Zoo in Sydney. 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.
For the first year, the team played the recorded songs to young regent honeycreepers “every day for about the first six months of their lives,” said the study’s first author, Dr. Daniel Appleby of the Australian National University. That approach was not successful.
In the second year, the team recruited two wild-born males as singing teachers, with greater success. “We took fledgling birds from different parents and bred them to a wild male that sang correctly,” Appleby said.
“We found that if there are too many birds per tutor (i.e. a large class) they don’t learn as effectively,” Appleby added. In the third year of the program, song class sizes were reduced to approximately six young males per adult male tutor.
“The proportion of juveniles that learned the wild song increased from zero to 42% in 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.”
Typical song of the regent honeyeaters of the Blue Mountains
This version has disappeared from the wild.
Previous call of zoo-bred regent honeyeaters
In subsequent years, zoo-bred males who had learned the complete song taught it to the next generation.
Ecologist Dr Joy Tripovich, who studies regent honeycreepers at both the Taronga Conservation Society and the University of New South Wales, said it was “really exciting” to hear the zoo-bred birds sing their restored song for the first time.
Since 2000, Taronga and his partners have released 556 zoo-bred regent honeyeaters in New South Wales and Victoria, Tripovich said. Among the most recent releases are men who have learned their original song.
More research is being done to determine what impact the song tutoring program has on the success of birds returned to the wild, Tripovich said.
“Our goal for the overall project is for the species to become self-sustaining,” he said. “We really want them to increase their numbers on their own so we don’t have to intervene anymore.”
Researchers hope the restored song can improve the reproductive success and overall fitness of zoo-bred birds once they are released into the world. The ultimate goal was “to see how wild and captive birds intersect,” Appleby said. “Historically that wasn’t something we really looked at.”
The research was published in the journal Nature Scientific Reports.
