The cuckoo has a regular ‘arms race’

Cuckoo (Cuculus canorus) mobbed by meadow pipit. Picture: Edmund Fellowes/BTO
Cuckoo (Cuculus canorus) mobbed by meadow pipit. Picture: Edmund Fellowes/BTO
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The first cuckoo of spring is on its way. We know this because of the efforts of BTO researchers, who have been studying the movements of these seasonal visitors.

The researchers use tracking tiny devices that utilise the network of satellites orbiting the Earth to show where the cuckoos are at any given time.

The pattern of movements revealed by the work has revolutionised our understanding of cuckoo migration and the risks that these birds face during their travels. We now know that UK cuckoos use two different routes to reach their wintering areas, one through Italy and the other through Spain. The work also shows just how little time a male cuckoo spends in the UK – as little as 15% of the year, with roughly half the year spent in Africa and a third on migration.

An interactive map on the BTO website (www.bto.org/cuckoos) reveals that our tagged cuckoos have already left their winter quarters, located in and around the Congo rainforest, and are now heading North, via West Africa, where they appear to feed up before the long desert crossing that will see them over the Sahara and knocking at Europe’s southern door. The first of the returning birds will reach our shores in the second half of April; by the end of the month many will be back at the sites they visited last summer.

Other researchers, both at the BTO and at universities in different parts of the UK, will spend the summer months studying breeding cuckoos, including those who lay their eggs in the nests of reed warblers and meadow pipits. There is much still to learn about this bird and, in particular, about the ‘arms race’ that exists between the cuckoo and the hosts, whose nests it parasitises with its single egg and resulting chick.

The cuckoo isn’t just of interest to researchers, however; it has strong cultural associations and its call is recognised by a much wider audience. The cuckoo is a special bird for many of us. On 21st April, an event in Cambridge, being held at the new Cambridge Conservation Initiative Campus, will celebrate the cuckoo and explore both the bird’s cultural relevance and the research that is being done to understand why this much-loved species is in decline – cuckoo populations within the UK have declined by 75% since 1967. The event is open to the wider public and also features the storyteller Malcolm Green, who followed UK cuckoos into West Africa, sound recordist Geoff Sample, who has recorded these birds over many years, and journalist Michael McCarthy, whose book ‘Say Goodbye to the Cuckoo’ has highlighted the plight of these fleeting summer visitors.

More details can be found at www.conservation.cam.ac.uk/cuckoo-day, including information on how to book your ticket.