While I am lying on the grass
Thy twofold shout I hear;
From hill to hill it seems to pass,
At once far off, and near.
In the rainforest of the Congo the cuckoos are now stirring, contemplating their long journey to their breeding grounds in Europe. They fly by night. Depending on the wind and the weather, the voyage to Britain takes about six weeks, their ‘cuckoo’ call on landing being a traditional signal of spring. People once wrote excitedly to The Times to proclaim the news of the first cuckoo, and farm workers would have the day off and retire to the woods with a keg of beer; it was not so long ago that the birds sang the seasons into being, the landscape into life. Of interest still for its date of arrival, the cuckoo is an absolute fascination for its habits, particularly the objectionable depositing of its eggs in the nest of another bird. And the yet more objectionable, even downright homicidal, habit of the young cuckoo of ejecting from the nest every occupant except itself. Such 'unnatural' behaviour, one of the strangest tales of the countryside, suggested that the cuckoo was either mad or bad.
In more than one Northern English and Scottish dialect the noun for cuckoo and fool is the synonymous 'Gowk', from the Old English géac, cognate with Old Norse gaukr. Down South, the cuckoo became ‘Gawk’, leading to gawky (as in teenager), and even by a stretch of the etymological imagination, geeky. On arrival in Britain, the cuckoos line their stomach with insects, principally moth larvae and beetles, and then their fancy turns to continuation of the species. The male cuckoo booms out the distinctive 'cuckoo' audio-lure to the female from a song post, majestically high in a tree, in a tail-raised, wings-dropped posture. Nature takes its reproductive course and the female’s maternal work begins.
In the jargon of ornithology, the common cuckoo is an ‘interspecific brood parasite’, meaning it lays its eggs in the nests of species other than its own, leaving the host to raise the cuckoo young, the original ‘cuckoo in the nest'. During May and June the female cuckoo lays her eggs, between twelve and twenty five, all in different nests across the selected locality. The eggs are fabricated in the colour and the pattern of the eggs of the selected host; if the female cuckoo fails to find a clutch of her favoured host, she may, as a last resort, lay in the nest of another host species. This egg, however, is more likely to be rejected, as it will not be a decent facsimile of the host egg. The female cuckoo’s internal egg-colouring system, akin to the spray-painting of a car on a manufacturing line, cannot facsimile at will; it is pre-programmed to reproduce the egg pattern of a particular species. There are cuckoos who manufacture eggs to copy those of dunnock, there are cuckoos who copy the eggs of bearded tits. Cuckoos are dependent on the species they adopt.
Cuckoo eggs in all their various colours.
So when meadow pipits disappear, so do their dependent cuckoos. When Dunnocks disappear, so do their dependent cuckoos. And so on, and so forth. Across Europe, 145 bird species act as host to the cuckoo. The major cuckoo fosterers in England are meadow pipits, reed warblers, pied wagtails, and dunnocks.
The entire egg-laying raid, undertaken when the host bird has nipped off for a meal, takes just 8 seconds on average. As the female cuckoo departs the scene, she often gives a chuckle call, as if in triumph for her foul deed done. The cuckoo chick, like its mother, has a ruse or two to ensure the promulgation of the species, aside from the fratricide. In 1743, a book was published whose German title is translated as Winged Theology: an attempt to inspire humankind to admiration, love and reverence for their creator by a close consideration of birds. The author, JH Zorn, wrote:
The young cuckoo cries as loud as a whole brood of host nestlings. The reason is to enhance the feeding by the foster parents.
Alone in the nest, the cuckoo has the sole attention of its foster parents, who will dart around the whole day long to feed it. They will have no time to breed again for the entire season. The cuckoo chick lives like a dauphin, a spoilt brat. The infant cuckoo utilises another wile while in the nest, as well as brood-impersonation, but this time to ward off predators. As Edward Jenner, ornithologist as well as physician, observed in a 1788 scientific paper:
Long before it leaves the nest, it frequently, when irritated, assumes the manner of a bird of prey, looks ferocious, throws itself back, and pecks at any thing presented to it with great vehemence.
More effective still an anti-predator device, the cuckoo in the nest emits foul smelling liquid brown faeces when touched. Clever birds cuckoos. Neither mad nor bad, the cuckoo is one of the more curious examples of Darwin’s survival of the fittest. With no more new host clutches to parasitise, their summer’s job done, the adult cuckoos set off on their long journey south to Africa, to join the gorillas of the Congo. The parent cuckoos never see their own offspring. Juvenile cuckoos follow on a few weeks later, all alone. Nowadays, across swathes of Britain, any cuckoo arriving, let alone the first, is an event worthy of record. According to the latest assessment from conservation groups, the number of cuckoos has declined by more than 65% since the 1980s. Today, the cuckoo is red-listed by the IUCN, the International Union for the Conservation of Nature.
The fall of Cuculus canorus is undemocratically uneven. Indeed, contra the national picture, the Scottish population of the cuckoo has risen by 30%, and the Welsh population remains stable. At the micro level, within the squares of Ordnance Survey maps of England, it is clear that cuckoos are faring much better in heathland and hill than in farmed lowland.
Heathland, where the cuckoo still thrives.
The first culprit in the murder of the cuckoo?
Intensive agriculture. With its hedge-ripping and hedge-clipping, with its monotone multi-cut grassland, intensive agriculture has reduced the necessary habit for the cuckoo - and its preferred host species, the meadow pipit and the Dunnock. No traditional old hay meadows, no rambly hedges with trees (which are needed, not least, by female cuckoos as look-out posts ) means no meadow pipits, no Dunnocks, which equals, by the law of Nature, no cuckoos. The 'icides' of conventional farming, the pesticides, herbicides, the molluscicides, and fungicides, have further reduced the food supply for the cuckoo (as well as its host birds.)
Since 1968, the Rothamsted Insect Survey has monitored annual populations of large moths across England, Wales and Scotland, with a network of about 100 light traps. In the 35 years to 2003, the annual total number of moths caught diminished by 31%, with the greatest decrease in the southern half of the United Kingdom. The moth effect is particularly pronounced on cuckoos because the hairy, toxic and aposematic moths favoured by the bird - and avoided by most other avia - are highly sensitive to agricultural intensification. These moths, especially those in the families Lasiocampidae, Sphingidae, Notodontidae and Erebidae have suffered declines of over 90% in highly managed grassland and arable areas. In Devon, for instance, the cuckoo was widespread in the 1980s; it is now confined to the edges of Dartmoor and Exmoor. In other similarly agri-industrial counties, the cuckoo has gone up hill to the high country. The cuckoo is becoming a moorland bird.
Culprit number two in the murder of the cuckoo is migration. British birds use two distinct routes during outbound migration: they either head Southwest (the West route) via the Iberian peninsula or Southeast (the East route) via Italy, Greece and the Balkans. Most English cuckoos go southwest through Spain, but only half of the tracked birds survive the desert aerial trek. By contrast, most Scottish and Welsh cuckoos take a different autumnal route, south-east through Italy. More than 95% of these tracked cuckoos make it safely to winter quarters. In other words, the birds taking the more deadly West route are from the already struggling English population.
The unforgiving terrain of the West route.
What explains the excess mortality on the West route? Increasing droughts and wildfires in South West Europe, together with habitat change, has made it hard for cuckoos using the route to maintain sufficient fat reserves for the long southing. All in all, in England at least, the cuckoo may not be here for much longer.
The cuckoo is indeed a curious bird, and one of its prime curiosities is this:
In the Congo, where it spends some seven months of the year, it has never been heard to sing.
Two Cuckoos have been recorded as laying 25 eggs, and one of those through human intervention. They rarely even lay 12. One dominant female, with a following wind, might get 10-12 eggs away but the window of opportunity is short. Most miss the first clutches of the meadow pipit due to their late arrival, so either wait for the second clutches or maybe try their luck into Dunnocks or Robins nests. Ground nesting hosts face a battle with predators, corvids, rats, weasels and stoats are just a few who help themselves and with the young cuckoo being in the nest for 25-30 days, the risk is higher. Not many get away
This was wonderful, thank you John. I was unaware of just how many eggs a cuckoo can lay, nor that a female is specific to her host. That makes some sense of the tragic declines as concomitant declines have been affecting Meadow pipit etc.
I will be recommending your Substack far and wide!