22 March 2021
Young male songbirds usually learn their songs from adult songbirds. But when those young birds do not have older ones to teach them, they have less success attracting mates.
For five years, ecologist Ross Crates with Australian National University has studied the singing ability and mating success of birds called regent honeyeaters. These black and yellow birds were once common across Australia. But loss of their living space since the 1950s has decreased their population to only about 300 or 400 wild birds today.
Male birds once formed large groups in the winter. Now they are spread out across the country, so many fly alone. That means fewer honeyeater adults are nearby during the young birds' first year of life.
"Song learning in many birds is a process similar to humans learning languages — they learn by listening to other individuals," said Crates.
"If you can't listen to other individuals, you don't know what you should be learning."
Researchers found that a large number of male birds appear to be learning tunes only used by other species. About 12 percent of male regent honeyeaters end up producing versions of songs usually sung by friarbirds and black-faced cuckooshrikes, among other birds.
The scientists released their research in the publication Proceedings of the Royal Society B. They found that males who sang unusual songs were less successful in attracting mates.
Peter Marra is a conservation biologist at Georgetown University and was not involved in the study. He said, "This research suggests that the loss of a song language once the population reaches a very small size could accelerate their decline."
The exact reason females do not accept the males was not clear.
Scott Ramsay is a behavioral ecologist at Wilfrid Laurier University in Ontario, Canada. He was not involved in the research. He said the songs were like an advertisement: "When male birds sing, it's like putting out an ad saying, ‘I'm over here...and I'm really interested in finding a partner.'"
Ramsay added that female honeyeaters may not even recognize these unusual singers as possible mates, and so do not approach them. Or it could be that they approach, "but then things go wrong if the males" do not behave as expected.
Most male birds spend several months in their first year learning the songs they will sing for the rest of their lives. Some birds learn from their fathers. But regent honeyeaters leave the nest before they learn to sing, so the males need to find other birds to learn from.
Carl Safina is an ecologist at Stony Brook University and also was not involved in the research. He said, "We need to be aware of the importance of preserving song culture in birds...some elements of what these birds need to do to survive isn't instinctive, it has to be learned."
Crates' team has begun putting their findings into action. To help young birds in reproduction programs learn their notes, they have started playing male song recordings. They have also placed skilled male singers next to young learners. The hope is that these experienced birds can pass on their songs to the next generation.
I'm Jonathan Evans.
Christina Larson reported on this story for the Associated Press. Jonathan Evans adapted this story for Learning English. Mario Ritter, Jr. was the editor.
Words in This Story
attract –v. to cause (someone) to like or be interested in something
ecologist –n. a person who studies ecology: the science that deals with the relationships between groups of living things and their environment
tune –n. a series of musical notes that produce a pleasing or recognizable sound
accelerate –v. to move faster; to gain speed
decline –v. to become less in number or lower in amount
nest –n. a place where birds lay their eggs and raise their young
instinctive –adj. relating to or based on behavior that is not based on thinking or learning