The critically endangered regent honeyeater is losing its "song culture" due to the bird's rapidly declining population, according to new research from The Australian National University (ANU).
Just like humans learning to speak, many birds learn to sing by associating with older birds of the same species. They risk losing this skill if adults become too rare. And if they don't learn to sing a sexy enough song, their chances of mating are reduced.
"If endangered birds are unable to learn how to sing correctly, it seriously impacts their ability to communicate," lead author Dr Ross Crates said.
"It could also be exacerbating the honeyeater's population decline, because we know a sexy song increases the odds of reproduction in songbirds. Females will avoid males that sing unusual songs."
The study found that in places where there were still reasonable numbers of regent honeyeaters, males sang rich and complex songs. Where the birds were rare, males sang simplified or "totally incorrect" songs.
"For example, 18 male regent honeyeaters - or around 12 per cent of the total population - were only able to copy the songs of other bird species," study co-author Dr Dejan Stojanovic said.
"This lack of ability to communicate with their own species is unprecedented in a wild animal. We can assume that regent honeyeaters are now so rare that some young males never find an older male teacher."
The study also showed regent honeyeaters born in captivity have totally different songs to wild birds.
The research team believe this could prove crucial when it comes to conservation.
"The unusual songs of captive-bred birds could reduce their attractiveness to wild birds when they are eventually released," Dr Crates said.
"So we've devised a new strategy to teach young captive regent honeyeaters to sing the same song as the wild birds by playing them audio recordings.
"Loss of song culture is a major warning sign the regent honeyeater is on the brink of extinction and we still have a lot to learn about how to help them."
The study is published in the journal Proceedings of the Royal Society B.