The nightingale’s nocturnal song exudes an impressive confidence through a vast range of guttural moans, trills, and light whistles. Its voice will travel across the night-time cold with no interference, being one of the only birds to sing beyond daylight hours. But soon, the nightingale’s song may be absent from the eerie twilight silence after scientists discovered that the bird’s very existence is threatened by the effects of man-made climate change.
The nightingale is a longstanding literary symbol of immortal beauty and fantasy, serving as the subject of Keats’ most famous ode, and can been found across European scrub and forest during the warmer seasons. With a typical adult weighing no more than 20g, the bird has gained a positive reputation for its non-threatening, unobtrusive style of flitting through the night sky and nocturnally warbling to attract nearby mates.
The nightingale is also famed for its impressive annual migration to sub-Saharan Africa, and during the winter months thousands of British birds are thought to make the journey past Southern France and into southern Senegal or Guinea-Bissau.
But researchers at the Complutense University of Madrid have made a worrying discovery. After tracking twenty years’ worth of data on Spanish nightingales making the 3000-mile annual trip south, they found that climate change was interfering with the species’ ‘migratory gene package’ which has resulted in a significant decrease in the size of their wings.
The study, which began work in 1994 and was this year published in ‘Tuesday in The Auk: Ornithological Advances’, also found that nightingale populations are suffering from droughts in their habitats caused by global warming. The rapidly decreasing survival rate of the common nightingale will lead some to question the likelihood of its continued existence in the coming decades, with one contributor to the study, Carolina Remacha, commenting:
There is much evidence that climate change is having an effect on migratory birds, changing their arrival and laying dates and their physical features over the last few decades. If we are to fully understand how bird populations adapt to new environments in order to help them tackle the challenges of a rapidly changing world, it is important to call attention to the potential problems of maladaptive change.
It is the bird’s relatively large wingspan that enables nightingales to migrate so successfully, but as spring arrives earlier due to a warming climate, the birds have been having less time to breed, and this is favouring birds with smaller clutch sizes and shorter wingspans, causing a fall in sufficient migratory abilities. This process of rapid and self-defeating evolution is called maladaptation, and may provide some answers as to why the population of British nightingales has fallen by over 90% in the last half century.