Cuckoos can’t adjust migratory patterns, study shows
Cuckoos are unable to adapt their migration patterns.
A new study has discovered that cuckoos are unable to adapt to changes caused by climate change, which could threaten their survival.
The study, from British Trust for Ornithology (BTO), showed that cuckoos are unable to adapt their migration patterns in line with the earlier arrival of spring in Europe, which has left the cuckoo out of sync with the peak availability of their invertebrate prey and the breeding ecology of their host species.
While most other species of bird that spend the winter in sub-Saharan Africa but breed in Europe have adjusted migratory patterns for the earlier arrival of spring, it has previously been unclear why cuckoos have been not adapted their migration in the same way.
However the latest data, collected from 87 cuckoos that have been tagged since 2011, shows that cuckoos must wait for the arrival of west African spring rains, the annual timing of which has remained constant, before they can cross the Saharan desert to reach Europe.
The west African rainfall is vital to the cuckoos migration, attracting enough invertebrate prey for the cuckoos to fatten up before they begin their long journey across the Sahara.
Now the earlier arrival of spring is exposing cuckoos to a greater risk of death, as they race to return to their breeding grounds in time.
Scientists believe that providing habitats at strategic locations along the migration route might help the birds complete the journey in a more timely and energy efficient way.
Dr Chris Hewson, BTO Cuckoo Tracking Project lead scientist, said: “It’s fantastic to have this new insight into what determines the spring arrival of our cuckoos, 12 years after the tracking project first allowed us to follow their return from central Africa. Many other species are thought to be able to bring forward their arrival by adjusting their internal clocks to leave their wintering grounds sooner – but this doesn’t appear to be an option for the UK cuckoo population.
"Understanding why these are not arriving back earlier – and the possible costs that individual cuckoos pay for trying to do so – will help us to best direct efforts of flyway restoration that may allow them to make their migrations in a more timely and successful fashion.”
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