The nightingale’s wings – famous for its beautiful birdsong – are shrinking in response to climate change, a study finds.
This change will make long migrations to Africa more difficult and threaten its survival, scientists have warned.
Male nightingales in particular are known to sing for hours every night during the breeding season.
However, this song may be harder to hear, as nightingale numbers have fallen dramatically in recent decades, largely due to global warming.
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The nightingale’s wings – famous for its beautiful birdsong – are shrinking in response to climate change, a study finds. This change will make long migrations to Africa more difficult and threaten its survival, scientists have warned
The nightingale breeds in Europe and parts of Asia and migrates to Sub-Saharan Africa every winter.
In the UK alone, the population of nightingales has fallen by 90 percent in the past 50 years – the number of singing men has now fallen to only around 5,000.
Several factors are responsible for the decline, including browsing deer that they eat ‘from home and house’ and the development of the birds’ former breeding grounds.
Other reasons include less coppice – cutting down trees to encourage growth – and changes in wintering areas of the nightingale.
Now, a study has found that warmer temperatures have made their wings smaller – a trend seen in other bird species as well.
“There is a lot of evidence that climate change is affecting migratory birds, which has altered their arrival and laying dates and their physical characteristics in recent decades,” said zoologist Carolina Remacha of Complutense University of Madrid.
From an analysis of twenty years of data on the birds, her team found that the natural selection caused by climate change causes the nightingale to develop shorter wings, making them less likely to survive their annual migration.
A comparison of wing shape variation and survival in two populations of nightingales from central Spain showed that the bird’s average wing length has decreased with respect to its body size.
Birds with shorter wings did not return to their breeding grounds as quickly after their first round trip to Africa.
Male nightingales in particular are known to sing for hours every night during the breeding season. However, this song may be more difficult to hear, as the number of nightingales has fallen dramatically in recent decades, largely due to global warming
The researchers linked changes in wing length and reduced survival to a phenomenon known as the ‘migrating gene package’.
This predicts adaptations related to migration – including a long wingspan, higher resting metabolism, greater coupling size, and shorter lifespan.
These are driven by a series of linked genes, so selective pressure on one trait affects the other.
In recent decades, the timing of spring in central Spain has shifted and the summer drought has become longer and more intense.
This leaves nightingales with a shorter window to raise their young.
This means that the most successful birds are those that lay smaller eggs, which means they have fewer chicks to care for.
If natural selection prefers smaller claws, it can simultaneously push nightingales away from all linked traits in the ‘migrating gene package’.
Evolving smaller clutch sizes and inadvertently also getting shorter wings and therefore a reduced chance of survival is an example of what experts call ‘maladaptive’
Evolving smaller clutch sizes and inadvertently also getting shorter wings and therefore a reduced chance of survival is an example of what experts call “maladaptive”.
This is where organisms’ responses to changing conditions are ultimately harmful rather than beneficial.
“To fully understand how bird populations are adapting to new environments to help them meet the challenges of a fast-changing world, it is important to highlight the potential problems of inappropriate change,” said Dr. Remacha.
Scientists have long known that individuals of a particular animal species are smaller in warmer parts of their habitat.
However, it was only recently determined that climate change also led to smaller body lengths, with an American team reporting in December that migratory birds in North America have shrunk over the past 40 years.
The discovery was based on an analysis of more than 70,000 migratory songbirds collected after deadly construction strikes in Chicago and Michigan.
Slightly larger than a robin, nightingales were first spotted in Anglo-Saxon times, although fossilized remains date back as far as 100,000 years ago.
The full findings of the study are published in the journal The Auk: Ornithological Advances.
WILL GLOBAL SPECIES REDUCE SPECIES?
A recent study in Canada found that the region’s beetles have shrunk over the past century.
By looking at eight types of beetles and measuring the animals of the past and present, they discovered that some beetles adapted to a smaller body size.
The data also showed that the larger beetles shrink, but the smaller ones do not.
About 50 million years ago, Earth warms by three degrees Celsius (5.4 ° F), and as a result, animal species shrank by 14 percent at the time.
Another warming event about 55 million years ago – called the Paleocene-Eocene Thermal Maximum (PETM) – warmed Earth to eight degrees Celsius (14.4 ° F).
In this case, the animal species shrunk by a third at that time.
Woolly mammoths were victims of the warming climate, shrinking habitat and increased hunting of a growing early human population that drove them to extinction – along with many large animals
Decreasing body size is evidenced by various events in global warming.
As global temperatures continue to rise, the average size of most animals is expected to decrease.
In addition to global warming, the world has seen a dramatic decline in the number of large animals.
So-called ‘megafauna’ are large animals that become extinct. With a long lifespan and relatively small population, they are less likely to adapt to rapid changes as smaller animals reproduce more often.
Often hunted for trophies or food, large animals such as the mastadon, mammoths and the western black rhino, which was declared extinct in 2011, have been hunted to extinction.