Answer: Superb Fairywrens

Some human parents play classical music to their babies in the womb in a bid to make them more cerebral when they finally emerge (a trend of dubious efficacy and mostly beneficial to companies selling headphones for pregnant tummies), but that’s nothing compared to the trick superb fairywrens pull. The wrens, found in southeastern Australia, teach their babies a secret vocalisation pattern that their lives depend on.

In an incredibly clever bid to protect their offspring from parasitic bird species that would dump their young on superb fairywrens and flee, the wrens consistently use special vocalisations while the young wrens are still inside their eggs. Before parasitic birds like the Horsfield’s bronze-cuckoo can drop their eggs off in the nest, the wren’s own babies already know the secret vocalisation pattern by heart.

When all the eggs hatch, the wren chicks incorporate the secret vocalisation pattern into their begging for food and the mother provides the chicks that produce the vocalisation pattern the most accurately with the most food. The parasite’s chicks, on the other hand, don’t know the vocalisation pattern and the mother wren neglects them.

Photo by JJ Harrison/Wikimedia.