Australian zebra finches sing a rhythmic high-pitched song while incubating their eggs in a hot environment, which researchers have named a 鈥渉eat call鈥�. Experiments now show that this call influences who the soon-to-be-born chicks choose to learn their own tunes from.
In 2018, , then at Deakin University in Australia, learned that the songbird embryos inside an egg that were exposed to a repeated parental heat call would put more syllables in their song when they matured.
To understand the influence of prenatal sound, Katsis and his colleagues placed two groups of Australian zebra finch (Taeniopygia castanotis) eggs in an incubator. They exposed one group to recorded parental heat calls, while the other group heard non-rhythmic contact calls that the finches use for begging, singing and distance calling. Once the chicks hatched, the researchers returned them to their nest boxes and raised them in an environment with lots of adult zebra finches around.
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Zebra finches learn songs from around the age of 35 to 100 days. After around 170 days post-hatching, the researchers played recordings of the songs of different zebra finches. They found that chicks that had been exposed to parental heat calls as embryos preferred songs from tutors other than their fathers 鈥� they moved closer to the speaker playing these tunes. Embryos exposed to contact calls grew into birds that showed no preference.
Previously, researchers had shown that exposing embryos to parental heat calls slows the growth of the chicks after they hatch, in effect extending the baby phase of the fledglings.聽So those fledglings start begging for food and spending more time around males other than their fathers, hearing more non-paternal calls and building a taste for it, Katsis says.
Songbirds are a good model for showing how an organism can peek into the outside environment even during its embryonic stage to gather cues that reprogram its development, says at the University of Illinois Urbana-Champaign. And that can influence its social behaviour later in life.
Animal Behaviour
