Bird call assimilation found by means of sound science

WASHINGTON — For birds, understanding neighborhood gossip about an approaching hawk or brown snake can mean the difference between life or death.

The fairy wren, a small Australian songbird, is not born knowing the “languages” of other birds. But it can master the meaning of a few key “words,” as scientists explain in a paper published Thursday in the journal Current Biology.

“We knew before that some animals can translate the meanings of other species’ ‘foreign languages,’ but we did not know how that ‘language learning’ came about,” said Andrew Radford, a biologist at the University of Bristol and co-author of the study.

Radford and colleagues at Australia National University wandered around the Australian National Botanic Gardens in Canberra with customized “tweeter speakers” affixed to their waists, looking for solitary fairy wrens. They wanted to be certain that the birds would react only to sounds, not other birds’ behavior.

The scientists first played the birds two unfamiliar recorded sounds. One was the alarm cry of an allopatric chestnut-rumped thornbill, a bird not native to Australia. The other was a computer-generated bird sound dubbed “buzz.”

On first hearing these sounds, the 16 fairy wrens had no particular reaction.

The scientists then trotted around the park and continued to play customized recordings. They attempted to train half the birds to recognize the thornbill’s alarm cry as a warning sound and the other half to recognize the buzz as a distress call. They did that by playing the previously unfamiliar sounds in conjunction with noises that the birds already associated with danger.

After three days, their feathered pupils passed the test.

The two sets of fairy wrens responded to the sound they had been trained on by fleeing for cover but remained indifferent to the other sound.

To put it in human terms, it’s as though a person who speaks only English had learned that “Achtung” means “attention” or “danger” in German simply by listening to people yell phrases with similar meanings in multiple languages at once.

The Associated Press Scientists working with the fairy wren, a small Australian songbird, have discovered that birds can learn to recognize the alarm calls of other species.