Decoding the secret language of birds — new film Birdsong is endearing and enlightening

Seán Ronayne who grew up in Cobh, County Cork, went on a mission to record the vocalisations of every bird species in Ireland

Birdsong: For birdwatchers, the ability to identify the calls of various species, to ‘decode’ the secret language of birds, is key to identifying species and understanding behaviour

Evolution is a mysterious thing. Their oldest known bird fossil is 150 million years old, and their various shapes and forms have gone through a mammoth amount of fine-tuning since then. From the fossil record, ornithologists have a reasonable understanding of how they evolved, beginning as dinosaurs, developing the ability for flight, a full covering of feathers, specialist bills, and a syrinx — the apparatus that enables them to sing so spectacularly. Gradually, birds have become the tuneful, feathered beings we so love, with an estimated 10,000 species in existence around the globe — each specialised to occupy a specific ecological niche.

But the evolution of their voices is something altogether more difficult to trace back in time. While scientists have discovered a great deal about the evolution of wings in birds, for example, very little is understood about the origin of what is perhaps one of the most conspicuous characteristics of living birds — their songs. Bird calls and songs leave no material trace in the fossil record, though the evolution of the syrinx, the organ through which their complex vocalisations are made, is being studied.