London, Nov 12 : While it has been known that some species of birds use the alarm calls of other bird species to flee danger, how they develop this ability has been unknown. Now, a team of Australian researchers has found that birds develop this multilingual ability by learning the alarm calls of other birds on the job.
In the study, associate Professor Robert Magrath and colleagues of the School of Botany and Zoology at the Australian National University in Canberra found that fairy-wrens have the ability to learn the alarm calls of other species, giving them the edge when it comes to escaping predators.
For the study, the researchers played recordings of calls of different bird species to fairy-wrens (Malurus cyaneus) and monitored their response.
Fairy-wrens living in the Australian National Botanical Gardens and other parks in Canberra fled from the alarm calls of other fairy-wrens and scrubwrens (Sericornis frontalis), but not from the non-alarm call of the galah (Cacatua roseicapilla).
Fairy and scrubwrens have very similar alarm calls - a high-pitched piping noise - so the fairy-wren may have automatically recognised the alarm call of the scrubwren.
However, whereas the two wren species naturally share the same habitat in the Canberra area, only fairy-wrens live in the Macquarie Marshes Nature Reserve in New South Wales, which is outside of the scrubwren range.
When the researchers played the calls here, fairy-wren only fled from the fairy-wren alarm call, and were unperturbed by scrubwren or galah alarm calls.
Magrath said that this suggests, rather than being hard-wired, the fairy-wren needed to have heard the scrubwrens' alarm call, and learnt that it meant danger.
In a second study, the researchers showed that fairy-wrens in Canberra also fled in response to the alarm call of the New Holland honeyeater (Phylidonyris novaehollandiae), with which they share their habitat.
The honeyeater's alarm call is a low-pitched, rapidly descending repetitive tone, quite unlike the alarm cry of the wren.
"It suggests that they can learn about calls that are very different from their own. It's the difference between learning two similar European languages and learning Thai," News Scientist quoted Magrath, as saying.
The researchers also played the honeyeater alarm call backwards to ensure the fairy-wren were not simply fleeing a scary sound.
"To us it sounded machine-gun like, but although they looked up, they didn't flee," Magrath said.
Their findings appear in the latest edition of Proceedings of The Royal Society B.