In a surprising discovery, wrens teach their young to sing before they hatch – ScienceAlert

In a surprising discovery, wrens teach their young to sing before they hatch – ScienceAlert

Just over a decade ago, researchers in Australia were placing recorders in fairy nests (Maloros is heavenly) when they discovered something completely unexpected.

Female songbirds were singing to their eggs that had not yet hatched.

Even more surprising is that when the chicks finally hatched, experts noticed that all the birds raised in the same nest used a similar tone to beg their mothers and fathers for food.

The chanting and whistle melody they used was strangely reminiscent of part of their mother’s song – RIt is the same song she sang to her offspring while they were still fetuses.

To see if these offspring were learning their mothers’ song from behind the shell, the researchers shuffled the eggs between the nests.

Certainly, the later hatched chicks sang their new nest song, not their actual nest song, suggesting a learned behavior in the egg.

Now, a new study by some of the same researchers has found that this fascinating behavior extends to seven other related species, including the magnificent fairy, the red-backed fairy, the white-winged fairy, the red-winged fairy, and the variegated fairy. The fairy, the purple-crowned fairy, and the thick-billed grass.

In all of these birds, the researchers recorded females singing to their unhatched eggs, usually beginning around day 10 of incubation. There were no other nearby birds visible on the horizon.

The results suggest that this behavior is ubiquitous among Australian wrens, a family known as Maluridae, and may have evolved in their common ancestor millions of years ago.

It is known that almost all birds make instinctive sounds to communicate, but bird song is an acquired trait that many scientists, such as Charles Darwin, have assumed to have evolved almost exclusively among male birds for courtship reasons.

By comparison, songbird vocalizations were historically considered exceptional and meaningless — until a recent study found that more than 70% of female songbirds worldwide also sing. Australia, the home of fairies, is actually where birdsong first evolved about 33 million years ago.

The new discovery among female songbirds of a variety of species adds weight to the idea that female song is not an evolutionary error, but can serve a very real and important purpose in bird life.

But while exposure of eggs to bird calls has been linked to sensory ontogeny and development, how bird songs are learned in the embryo has been largely unexplored. In addition, existing research often uses socially isolated birds.

“In this study, we show maternal behavior that is consistent with pupil-directed vocalization behavior when mothers call their fetuses,” says animal ecologist and lead researcher Diane Colombelli Negril from Flinders University.

In all eight species of the Australian wren family considered, the researchers found that the offspring repeated part of their mother’s call, known as the B element.

After hatching, the chicks sing this song to request food from their parents. Their trying accuracy was improved if their mother had sung the song to them at a slower rate when they were just fetuses, suggesting that the fetuses were really paying attention to the songs.

Of all the parts of fairy song, females sang the B element to their eggs the most, up to 96 percent of the time.

Other elements, such as A, may also have been sung to provide contrast to the fetuses, Maybe it will allow them to break down different melodies when they finally hatch.

As expected, when the researchers played female songs to adorable fairy fetuses, the unhatched offspring showed a stronger heart rate response to the B component than to any other part.

Colombelli Negril and her colleagues don’t know why this early song learning evolved, but they have some ideas.

The sounds in the nest may help fairies avoid fooling the cuckoo, which lays its eggs in the nests of other birds to avoid the demands of raising its own young.

Cuckoo eggs are incubated for only a few days, not long enough to learn the begging song of the Australian wren. When the eggs hatch, the mother wren is unlikely to feed the intruder because she doesn’t have the right “password,” researchers say.

Another possibility relates to sexual selection.

Far from being passive players in courtship, which involves males singing songs to females, it is possible that female wrens, by singing to their young, teach their offspring to prefer certain cultural traits, which will then be passed on to the next generation.

The more scientists learn about the amazing songs made by female birds, the more they begin to realize: Females are not the weaker or more silent sex.

The study was published in American naturalist.

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