MIGRATORY BIRDS
The chestnut-crowned babbler birds were able to tell the meaning of soundsREUTERS

New research suggests that communication through "meaningless" sounds to produce a message is not limited to human communication as it has also been discovered in some birds.

Researchers from the Universities of Exeter and Zurich found that Australia's chestnut-crowned babbler is able to rearrange sounds in its calls and produce new messages when doing so. The experts believe that it may be a crucial early step in the emergence of the highly complex language systems that humans use.

Lead author Sabrina Engesser from the University of Zurich said: "Although previous studies indicate that animals, particularly birds, are capable of stringing different sounds together as part of a complex song, these songs generally lack a specific meaning and changing the arrangement of sounds within a song does not seem to alter its overall message.

"In contrast to most songbirds, chestnut-crowned babblers do not sing. Instead its extensive vocal repertoire is characterised by discrete calls made up of smaller acoustically distinct individual sounds."

Co-author Professor Andy Russell from the University of Exeter added: "We think that babbler birds may choose to rearrange sounds to code new meaning because doing so through combining two existing sounds is quicker than evolving a new sound altogether."

The researchers recorded two sounds from the birds – dubbed sound 'A' and 'B' – which the animal was able to rearrange depending on the message they hoped to convey. For example, when flying the birds would chirp AB, but feeding chicks brought the call BAB.

The team played the sounds back to the listening chestnut-crowned babblers who were able to differentiate between the flight call –when they heard it they would look out for incoming birds – and the feeding call – for which they would look at their nest. They were also able to tell the difference when the researchers switched elements between the two calls, according to the findings published in PLOS Biology.

Co-author Dr Simon Townsend from the University of Zurich said: "This is the first time that the capacity to generate new meaning from rearranging meaningless elements has been shown to exist outside of humans.

"Although the two babbler bird calls are structurally very similar, they are produced in totally different behavioural contexts and listening birds are capable of picking up on this."