“That is the voice of …” As is well known, we can recognize many of our fellow human beings by their individual sound signature. This talent apparently connects us with a prominent bird: zebra finches can recognize more than 40 conspecifics by their chirping, shows an experimental study. Apparently, they memorize the sound characteristics very quickly and then keep them in mind for a long time. The ability to capture familiar chirps is believed to play a role in the cohesion of groups of zebra finches in the wild, the researchers explain.
There is singing, croaking, twittering and beeping: you cannot fail to hear that many bird species have developed complex systems of sound communication. Many studies have already looked at the many aspects of this subject. It seems clear that many species also have a pronounced acoustic learning ability. For example, you can learn the meaning of alarm calls from other animal species, or even imitate the strange sounds. The ability to recognize certain individuals has also already been documented: some birds can distinguish their partners or parents from others on the basis of certain sound characteristics. These observations are already based in part on studies on zebra finches (Taeniopygia guttata), because these easy-to-keep songbirds are typical feathered experimental animals in behavioral research.
You know each other
In their Australian homeland, the zebra finches live in groups that often contain more than 50 animals and maintain a very solid bond with one another. The scientists working with Frederic Theunissen from the University of California at Berkeley therefore asked themselves to what extent these birds’ ability to recognize individual voices goes beyond their closest partners. One thing is clear: the birds are quite chatty: They make contact calls as well as a kind of twittering. “These birds own what we call a fusion-splitting society,” said Theunissen. “The animals always separate and then come back together with their acquaintances”. It is possible that the animals’ characteristic vocalizations convey to distant group members: “Come to us, we are here!” Explains the scientist.
In order to sound out the vocal memory abilities of zebra finches, the researchers trained 19 test animals to “carefully” operate a play button that triggers the playback of different twittering recordings. When a known bird sounded, the animals were asked to listen to the entire file – afterwards they would receive a reward. If, on the other hand, you heard an unknown chirping, you should press the button again to go to the next sound example. In order to receive a reward, the test animals had to click their way through the database until they came across a known utterance. The birds understood this principle very quickly and so the researchers were able to add more and more sound examples. In order to confirm that the animals oriented themselves to individual sonic characteristics and not just to the structure of the recordings, the researchers also changed the versions of the recordings of the known birds.
Detected: the chirping of 42 little birds
It turned out that the test animals of both sexes managed to recognize an average of up to 42 individual vocalizations of conspecifics in the end. In order to memorize them, they only had to hear them five times before, the researchers report. As the repetition of the experiments after a month showed, the memories were also anchored in the long-term memory of the birds: The performance in the tests had hardly decreased. “These results surprised us. The astonishing auditory memory of the zebra finches shows that the brains of these birds are to a high degree adapted to demanding social communication, ”summarizes Theunissen.
In conclusion, the researchers write in their publication: “These voice recognition and perception capabilities can now be added to the long list of amazing cognitive capabilities in birds,” said Theunissen and his colleagues.
Source: University of California, Article: Science Advances, doi: 10.1126 / sciadv.abe0440