Animals don’t give a fig about international boundaries. Countries are a human invention, drawn on maps rather than etched into the natural world. But take a bunch of sparrows from one place and compare their vocalisations with sparrows from another - how similar or different do they sound?
I’m convinced that the songbirds near me chirp in a Birmingham accent. Listen carefully to their perky tones and I swear they’re saying alright bab! A few hours up the motorway, however, it’s as if they say how do? Not different countries, but different counties. Both populations ‘speak’ sparrow, yet something in their songs sounds different.
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The great man himself, Charles Darwin, made the same observation in 1871, when he noted in his book The Descent of Man, that birds have “provincial dialects.” This was confirmed in the 1950s, when British ornithologist Peter Marler showed that the songs of wild chaffinches in Scotland vary from one region or glen to the next. Researchers went on to show that these differences are not genetically determined but learned. Although chicks hatch with some innate vocalisations, their songs become shaped by the local peers they learn from.
In North America, the song of the Savannah sparrow has a distinct structure. The early part is unique to the individual, the middle part is unique to the population, while the overall ‘theme’ is unique to the species. In other words, the first part reveals the bird’s identity, the middle bit reveals where they are from, while the whole things shouts, I’m a Savannah sparrow.
Songbirds aren’t the only animals with regional differences in their vocalisations. Many social species have their own local variations.
Sperm whales, which live in small tightknit female-led units, communicate with each other via patterns of clicks called codas. Each unit has its own repertoire of codas. Some are shared. Others are more distinctive.
Sperm whales in the Caribbean, for example, use a characteristic ‘1+1+3’ coda. It sounds like a truncated cha-cha-cha and is made only by the units that live in this area – the so-called EC1 vocal clan. Across the Pacific, researchers have identified seven of these vocally defined groups. This means that around a third to a half of the world’s sperm whale population communicates with one of just seven different accents.
So, what’s the point of having these different ways of ‘speaking’? For social animals, sounding like a local may help to reinforce who belongs to the group. Sperm whales preferentially associate with others that share their dialect, suggesting that these vocal traditions help maintain the social bonds that glue their societies together. So, when my local sparrows chirp alright babs, they’re not just flaunting their Brummie accent. They’re reinforcing the bonds that hold their community together.
