Their odd behaviour and distinctive call have embedded the cuckoo into our culture and folklores, but they need our help, says Norfolk Wildlife Trust Reserves Officer Robert Morgan.
The cuckoo is one of the heralds of spring and, like the skylark, nightingale and swallow, the muse of erstwhile poets and playwrights. There can be few people - even those never venturing far from the city - that would not recognise the call of the cuckoo. Their wandering voice, carrying across the countryside, is the all too brief sound of the shimmering heat of early summer; plaintive but strangely comforting.
Most would also have heard of their habit of laying eggs in other birds' nests. Known as brood parasitism, a female cuckoo can lay a single egg in up to 20 different nests. An individual female will have a favoured species, commonly either reed warbler, meadow pipit or dunnock, the egg colouration matching that of its chosen host. This evolutionary device to shirk parental responsibility is no lazy way out and, unlike most bird species, it is the female that holds and defends a territory, ideally large enough to contain adequate foster nests.
The male spends little time here in the UK, returning on its journey to Africa as soon as it can, with the female following in early July. This is not before she has worked hard to discover and observe potential nests. Watching from a suitable vantage point, she will scrutinise the movements and activities of possible hosts and, at an appropriate moment, swoop in and remove an egg. She will then lay her own, all within a few seconds. Despite the cuckoo egg being slightly larger, it usually hatches first. The young naked cuckoo chick will instinctively arch its back and, with a herculean struggle, forcibly eject the other eggs or hatchlings from the nest.
Cuckoo chick being fed by dunnock mother by Tim Folkes
Alone, it is fed constantly by its foster parents, quickly growing to several times the size of its dedicated, but unfortunate, surrogates. However, the reason the cuckoo is inclined to lay so many eggs is because the deception is more often than not discovered, with an astute host quickly removing or puncturing the imposter's egg.
Those not familiar with the appearance of the cuckoo are often surprised. It is larger than expected and a blue / grey colour with a black tail and wing tips. It is also barred across the chest similar to a hawk. This characteristic may be an evolutionary trait to alarm small birds into responding in a manner that allows the cuckoo to approach the host's nest. The young are similarly marked, but a rufous brown colour, and very like a female sparrowhawk. This 'camouflage' possibly affords them protection from attack by insightful future victims.
Their odd behaviour and distinctive call have embedded the cuckoo into our culture and folklores. Often associated with madness, foolishness or deception, 'gone cuckoo' or 'living in cloud cuckoo land' are familiar terms. There are stories of medieval villagers building cuckoo pounds to trap and contain a cuckoo so summer would be everlasting. Shakespeare, a great observer of nature, often used metaphors provided by the cuckoo. His King Lear declared: 'The hedge sparrow feds the cuckoo so long, it had its head bit off by its young'. The husband of an unfaithful wife, particularly if a child resulted, was a 'Cuckold' - 'For cuckoo, cuckoo. O word of fear, unpleasing to a married ear'.
Why the cuckoo has developed these habits is unclear, but it is a successful strategy, as the cuckoo has managed to fill numerous habitat types and can be found across Europe and Asia to Japan.
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Cuckoo by Elizabeth Dack
In the UK we have witnessed a sad decline in cuckoo numbers, with its distinctive call becoming less common in our wider countryside. However, the reedbeds of the Norfolk Broads remains a stronghold due to a large healthy population of reed warbler, a bird that is an important host of the cuckoo.
Commons, downs and scrublands, cuckoos' other preferred habitats, have contracted in size and tend to suffer more human (and canine) disturbance now. This has reduced the breeding success of small ground nesting birds such as the meadow pipit, the cuckoo's other principal foster species. Fewer meadow pipits, and other host birds, results in female cuckoos effectively running out of time to find enough suitable nests at the right stage. In addition, the combination of pesticide use and less overgrown areas has reduced its' favoured food - large hairy caterpillars.
Studies, particularly focusing on Norfolk birds, are currently being carried out and involve the tracking of their migration to sub-Saharan Africa. Often a by-catch of illegal mist netting in Southern Europe and North Africa, the cuckoo's journey across long migration routes is becoming increasingly perilous. Shrinking habitats in their wintering grounds and more frequent African droughts due to climate change are placing further pressures on their precarious survival.
Norfolk Wildlife Trust works hard to manage our reserves for all Norfolk's wildlife, including the cuckoo. We manage a number of reedbeds across our nature reserves, and continue to create new reedbeds at sites including
NWT Hickling Broad and Marshes to support our cuckoo population in Norfolk. We also advise other landowners across the wider landscape on how to create the mixture of scrub and open grassland habitat that cuckoos need. This icon of summer needs our help so, as the great bard advised, why not 'consider the cuckoo' and join with us in its protection?
TAKE ACTION
The cuckoo, like all our wildlife, needs both space and a mix of good quality, undisturbed habitats to feed and rest in. By supporting Norfolk Wildlife Trust, you'll be helping to protect the places our cuckoos call home, and helping us to influence decision makers to support wildlife at a local and national level.
Header image: Cuckoo by Elizabeth Dack