Critically endangered Regent honeyeater songbirds are learning the tunes of other birds, which is causing them to be spurned by potential mates, a new study finds. The bird is losing its 'song culture' due to a rapidly declining population, according to new research from The Australian National University (ANU). Males of the species have been passing on their mating song for thousands of years, but the declining population has meant the song is dying out along with the birds. Younger males are learning 'mating songs' from other bird species by mistake as there aren't enough adults to teach them, explained lead author Dr Ross Crates.