I have often wondered if it’s just my addled brain misinterpreting the auditory sense, or urban birds really do sing at a higher pitch than their country cousins. And now – as reported by Ed Yong in a recent issue of New Scientist magazine – science has come to the rescue with an entirely plausible explanation. I shall certainly sleep better as a result. Well, maybe not.
Research by Richard Fuller of the University of Sheffield, Henrik Brumm at the the Max Planck Institute in Starnberg and Hans Slabbekoorn of Leiden University, among others, has shown that the urban racket can make it extremely difficult for birds to make themselves heard. As a result they have developed the ability to sing louder and at a higher pitch in order to cut through the mainly low-pitched rumble of city life.
Blackbirds, song sparrows, house finches and great tits have all adapted in this way. Some species have adapted by taking to singing at night, which some scientists had interpreted as confusion due to light pollution. Again this fits in with my experience of staying in urban areas largely shielded from bright artificial illumination, but where the local feathered ones chirp away merrily at two in the morning. The bastards.
This evolution of avian singing patterns and behaviour has now reached the stage where we are beginning to see the emergence of distinctively urban species. There is also the possibility that we could observe so-called sympatric speciation, where populations of the same species adopt different strategies to cope with urban noise, leading to splits among communities living in the same neighbourhood.
If you find this difficult to believe, just listen to the blackbirds next time you take a walk in an urban park. And then compare this with the same species lolling about in the countryside, or even in a different part of the city. It is more than a difference in accents or attitude we’re talking about here.