Listening to birdsong is one of life’s great joys, but when researchers heard a particular tune emerging from a tree in a Buenos Aires park, they were especially jubilant. This arrangement was among those chirped by the local rufous-collared sparrows in the 1960s, but had since disappeared from the area. That was until scientists created a computer-generated rendition, curious to find out if birds might consider it realistic enough to imitate.
Less than three months later, a local avian resident began to copy parts of the song. There is a growing recognition of birdsong’s importance to conservation, and of the need to better understand how birds learn to sing. If an individual sings well, and in a familiar “dialect”, they are better placed to find a mate, defend their territory and ultimately survive.
If a species’ population declines, however, there are fewer opportunities for fledglings to become good singers. Birds can begin to tweet abnormally or mistakenly learn the songs of other species, jeopardising their chances of breeding. Male birds are in a better position to attract a mate if they can sing well – which, broadly speaking, means their song is complex, sung consistently and well performed.
But animals’ learned behaviour or culture, such as birdsong, is also an essential part of their population, says Mindlin. The rufous-collared sparrow is not considered vulnerable globally, but researchers hope that synthetic recordings could help teach birdsong to other species whose populations are dwindling, allowing conservationists to tutor individuals where real-life recordings do not exist. About 4,000 of the world’s 10,000 bird species are songbirds (or oscine passerines), such as finches, sparrows and blackbirds, which generally have complex songs that are at least partly learned from other individuals.
Their songs are hugely diverse, though separate research on the wider group of passerine group of birds, which incorporates songbirds, has identified common “motifs” or building blocks: three types of trill, three types of whistle, chaotic notes and harmonic notes. The way that birds use these motifs reflects the environment in which the birds evolved. Flat whistles are more likely to be sung by birds in tropical rainforests where sound must travel through dense vegetation.
Complex motifs, such as ultrafast trills, are more common in temperate regions where birds tend to communicate at closer range. The song studied by Mindlin was recreated based on hand-drawn annotations of rufous-collared sparrow songs that were made in the 1960s. Each song consists of a trill, which is consistent among individuals in the same region, and a theme, which varies.
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