What is the purpose of this song-laden warning? According to New Scientist magazine, the song is intended to keep the chicks from growing too large after they hatch if the weather conditions are too warm.
The behavior has been noted with zebra finches and the finches sing a different intonation of song to the unborn chicks. Zebra finches inhabit a wide range of grasslands and forests, usually close to water. The birds are loud and boisterous singers; however, their song varies between a loud beep, meep, oi! or a-ha!
With the observed effect, the finches change their song when singing to their unborn young. When timed right, to avoid the excessive heat, the young bird, on hatching, are born well developed and they appear to recognize their parents by their voices.
To show this, scientists from Deakin University in Victoria, Australia studied a number of finch nests and placed special microphones close by. A series of observations and recordings were made. The special song was noted and it was found that this particular song was only sung when the weather was warm.
To test out the reactions of the unborn chicks, studies were replicated in a laboratory where various recordings were played to unborn chicks. The song of interest and the one observed in the wild triggered the chicks to hatch from the eggs.
More details about thew song are shown in the following video:
The study is published in the journal Science, the research is headed: “Prenatal acoustic communication programs offspring for high post-hatching temperatures in a songbird.”
