The music was still ringing in my ears after a night on the beers at The Whaler in Salamanca, listening to the trio playing there, Les Coqs Incroyables. I’d also been listening to the spring-time dawn chorus in Britain, relayed to me by a friend dangling with his mobile phone out of his bedroom window at six in the morning. I suspect he had also been on the beers.
“All the birds go tweet-tweet-tweet when my sugar walks down the street” ran the lyrics of the song played by the trio, stuck in my head. Now I had the sweet melody of a blackbird to contend with. I couldn’t work out if it was for real, or part of the chorus of garden birds relayed to me from Wimbledon, in south-west London.
International Dawn Chorus Day has just been celebrated in Europe, hence my friend hanging his phone out of the window. The dawn chorus only happens in full volume in spring, and so we are out of tune in Australia. But birds sing at sunrise whatever the time of year. It’s only more intense in spring when males declare breeding territories and broadcast for mates. The blackbirds introduced from Britain make a point of singing loudly all year, giving us a musical, living link to a land on the other side of the world.
There is no single dawn chorus, but the harmonies of hundreds of bird voices at first light change from place to place in a huge wave that surfs around the world as the planet rotates.
The dawn chorus is part of a wider soundscape – the interaction between natural sounds and human generated noise like traffic. It is often the most prominent component of the soundscape at sunrise, but it never exists in isolation.
Scientists believe that birds structure their early morning singing in a way that prevents overlap, using different pitches to share the acoustic space. In open landscapes birds use shorter, scratchier songs, while birds in woodlands use longer whistling notes – each evolved to allow the best transmission of their song in their own habitat. Birdsong is filtered by trees, grasses, across water and through urban areas, to create the soundscape phenomenon that differs from region to region.
In cities, birds have to sing louder to overcome the noises made by people and their machines. An urban landscape of concrete and glass also creates echoes, sounds are not absorbed by the bark and leaves of trees.
More worrying, researchers in Europe and the United States are finding the spring soundscapes are becoming quieter, because of the decline in bird communities, linked to a warming climate, pollution and habitat loss.
As for Dawn Chorus Day, perhaps we should think of a similar celebration for the southern hemisphere when spring comes around in September and we can join the birds in a “tweet-tweet-tweet” duet.