STUDY: Birds all over the world use the same sound to warn of threats

The study suggests that over 20 species of birds from all around the world that are separated by over 50 million years of evolution use the same call when they see their respective brood parasite species. However, past work has shown that birds that have never seen a cuckoo do not produce this call, but they do after watching others produce it when there is a cuckoo nearby. In other words, while the response to the call is instinctive, producing the call itself is learned.

Language enables us to connect with each other and coordinate to achieve incredible feats. Our ability to communicate abstract concepts is often seen as a defining feature of our species, and one that separates us from the rest of life on Earth.

This is because while the ability to pair an arbitrary sound with a specific meaning is widespread in human language, it is rarely seen in other animal communication systems. Several recent studies have shown that birds, chimpanzees, dolphins, and elephants also do it. But how such a capacity emerges remains a mystery…

While language is characterised by the widespread use of sounds that have a learned association with the item they refer to, humans and animals also produce instinctive sounds. For example, a scream made in response to pain… A new study, published in Nature Ecology and Evolution, describe the first example of an animal vocalisation that contains both instinctive and learned features…

Birds have a variety of enemies, but brood parasites are unique. Brood parasites, such as cuckoos, are birds that reproduce by laying their egg in the nest of another species and manipulating the unsuspecting host to incubate their egg and raise their offspring. The first thing a baby cuckoo does after it hatches is heave the other baby birds out of the nest, claiming the effort of its unsuspecting foster parents all to itself.

During these earlier experiments, we couldn’t help but notice other species were responding to this call and making a very similar call themselves. What’s more, discussions with collaborators who were working in countries as far away as China, India and Sweden suggested the birds there were also making a very similar call – and also only towards cuckoos…

If this call is something like a “universal word” for a brood parasite across birds, we should expect different species to respond equally to hearing it – even when it is produced by a species they have never seen before. We found exactly this: when we played calls from Australia to birds in China (and vice-versa) they responded the same. This suggests different species from all around the world use this call because it provides specific information about the presence of a brood parasite…

The study suggests that over 20 species of birds from all around the world that are separated by over 50 million years of evolution use the same call when they see their respective brood parasite species… But while these birds know how to respond to the call, past work has shown that birds that have never seen a cuckoo do not produce this call, but they do after watching others produce it when there is a cuckoo nearby. In other words, while the response to the call is instinctive, producing the call itself is learned. WILLIAM FEENEY

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