When a bird tweets an alarm call it鈥檚 not necessarily just its family members who get the message. Some birds respond to an alarm even if it comes from a member of a different bird species 鈥� and now we have a better idea of how they learn to do so.
Robert Magrath at the Australian National University in聽Canberra and his colleagues played a computer-generated 鈥渂uzz鈥� to eight superb fairy-wrens in a nearby botanic gardens. None of the birds flew away and sought cover after hearing the sound.
Next, over the course of two to three days, the researchers replayed the computer buzz between 10 and 12 times 鈥� but as part of a chorus of alarm calls from bird species that live alongside the fairy wrens. Previous studies have shown fairy-wrens will seek cover when they hear alarm calls from the other birds in their environment.
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By the end of this 鈥渢raining鈥� period, Magrath and his colleagues found that about 80% of the birds flew away and hid if they heard the computer buzz on its own. In other words, they had learned that the unfamiliar buzz meant 鈥渄anger鈥� simply by associating it with familiar alarm calls.
Social learning
In a previous experiment, Magrath taught fairy-wrens to recognize unfamiliar sounds as alarm calls by playing the calls while the birds could see images of a predator. This is called 鈥渁social learning鈥� because the fairy-wrens learned from direct experience to associate the unfamiliar sound with the appearance of a predator.
But in the new study the birds came to understand that the computer buzz meant danger through 鈥渟ocial learning鈥�. They couldn鈥檛 actually see a predator, but learned that the buzz meant there was a nearby threat by associating the sound with the alarm calling behaviour of other birds. It鈥檚 a bit like learning the meaning of a word in a foreign language by associating it with a word in your native tongue.
鈥淭he study is the first to show the specific mechanism of social learning through acoustic-acoustic association,鈥� Magrath says.
Because of the low visibility in the forests in which fairy-wrens live, this sort of acoustically driven social learning might be very useful for the birds.
鈥淏irds can rapidly join the local 鈥榥eighbourhood watch鈥� or 鈥榠nformation web鈥�, where many species take advantage of the vigilance of others,鈥� Magrath says. 鈥淪uch information webs occur in many species worldwide.鈥�
Current Biology
