Bird parents inherit sound of the voice

Researchers discover genetic basis for chirping

Male zebra finches learn their call as well as their vocals from a tutor. © MPI of Ornithology
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People can recognize themselves by the sound of the voice. Birds also know that they are able to identify individually with the song. But how does this voice recognition work? Why are relatives frequently confused? Max Planck scientists have now studied the inheritance of the voice characteristics of individual zebra finches, and found genetic foundations that affect the timbre of the voice.

This is dependent on the morphological nature of the vocal tract, and is inherited, as well as the body size, genetically from the parents, the researchers said in the online edition of the journal "Evolution".

In order to identify people safely in a telephone conversation, the industry has developed computer programs that should enable independent of the spoken text a clear speech recognition based on voice characteristics. This technique makes use of the fact that the tone of our voice is determined by the innate resonance characteristics of the pharynx. With a cold, the stuffy nose changes these resonance characteristics and the software reaches its limits.

Software researches voice characteristics of zebra finches

Such software was first used in a collaboration of geneticists and bioacoustics scientists at the Max Planck Institute for Ornithology to study the voice characteristics of 379 female and 429 male zebra finches.

The vocal repertoire of female zebra finches included only innate calls. So all females chirp the same bit of "text", but this individually very different, one with scratchy, one with nasal, a third with a sonorous voice. "The zebra finches can recognize each other individually based on these sound characteristics", says Wolfgang Forstmeier, the initiator of the study. display

Variety of vocalizations

Male zebra finches, on the other hand, learn both their reputation and their singing from a tutor. This form of cultural transmission has produced a tremendous variety of vocalizations, that is, text. When the scientists isolated the linguistically characteristic properties from the textual mess, interesting patterns could also be identified here.

Surprisingly, regardless of their linguistic education, the females also display the family-specific scratchy, nasal or sonorous voices. According to the researchers, such a hereditary nature of the voice characteristics could be used by the family for the detection of relatives, for example, in the partner choice for inbreeding, or in the care for the detection of cuckoo children. Whether or not they do this will only have to be decided in the future.

Tongue indicates body size

A deep voice, for example, results from a long vocal tract. So it reflects to a certain extent the entire body size of the Lauterzeugers. Especially with birds, where the plumage hides much of the true contours, so the voice can also indicate the size.

According to the scientists, the new study provides an important basis for understanding what birds could signal with their voices. "But if the information inherent in the voice is also used by the birds, the future still has to show, " says S bastien Der gnaucourt, co-author of the study.

(idw - MPG, 27.04.2009 - DLO)