Cuckoo’s clocks are going cuckoo – because of climate change, experts warn
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Cuckoo clocks go cuckoo – due to climate change: Experts warn their internal body cycles haven’t adapted to spring arriving earlier
- Researchers argue that cuckoos cannot adapt to earlier spring seasons
- The birds reach their breeding grounds out of sync with their primary food
- This phenomenon could have implications for the bird’s survival, experts warn
Cuckoo clocks can’t keep up with climate change, new research warns.
The birds spend the winter in Central Africa, before traveling north to Western Europe to herald the arrival of spring.
But researchers believe their internal body cycles — which determine when they set off on their epic journey — can’t adjust to spring getting earlier and earlier.
It means they reach their European breeding grounds out of sync with the peak availability of hairy caterpillars, their primary food.
Lead author Dr. Chris Hewson, from the British Trust for Ornithology (BTO), said: ‘Many other species are thought to be able to advance their arrival by adjusting their internal clocks to leave their wintering grounds earlier – but this does not appear to be a option for the UK Cuckoo population.’
Experts argue that cuckoos cannot adapt to an earlier spring amid climate change
The phenomenon may have implications for the bird’s survival.
Most species that breed in Europe but winter in sub-Saharan Africa have made the necessary adjustments and arrived earlier on their breeding grounds to adapt to climate change.
Previous research has shown a link between migratory birds unable to change their arrival dates and severe population declines.
Now Dr. Hewson and colleagues used data from the long-running BTO Cuckoo tracking project to reveal why cuckoos are so vulnerable.
The study, published in the journal Proceedings of the Royal Society B, also shows the potential impact on the struggling British population.
Cuckoos migrating to the UK leave their wintering grounds in the rainforests of Central Africa in late February.
They spend a month or so fattening in West Africa prior to their grueling non-stop traverse across the Sahara.
Information gathered on 87 cuckoos tagged since 2011 shows that the birds must wait for the explosion of invertebrate prey brought on by the monsoon each year.
The birds now reach their breeding grounds out of sync with their primary food
While the timing of that annual event remains unchanged, spring comes earlier in Europe.
It has led to a discrepancy between the arrival of the cuckoos, the peak availability of the caterpillars they rely on for food, and the reproductive cycles of the host species they parasitize.
Species that cannot shift the time of their arrival at their breeding grounds are known to decline more quickly than those that can.
Results suggest that cuckoos are exposed to a greater risk of death if they race to get back to their breeding grounds in time.
Dr. Hewson said: ‘Migratory birds are generally returning to their breeding grounds earlier to adapt to the changing climate. However, some are not and their population trends are less favorable than those that are.
“We’re also finding evidence that trying to keep up with the demands of earlier springs on the breeding grounds results in costly compromises, increasing the mortality rate in early migratory birds.”