11

Nightingales

Thou wast not born for death, Immortal Bird!

No hungry generations tread thee down;

The voice I hear this passing night was heard

In ancient days by emperor and clown.

Keats, ‘Ode to a Nightingale’, 1819

Standing in the Southern Block on a still, late April night, silhouettes of oak trees and shaggy hedges framed against a glittering sky, the outpourings of a nightingale throwing its notes to the heavens are discombobulating. It ‘sends’ you, in the old-fashioned Sam Cooke sense, somewhere beautiful but also distant and unsettling. Thoughts flutter. Longings and misgivings, doubts even, hover in the air. The looming forms around you, the very ground feels unsteady, rocked by the challenge this twenty-gram bird projects into the enormity of space.

The song of a nightingale is not an easy ride. It throws the ear with unexpectedness – phrases fired off, one after the other: florid trills, first rich and liquid, then mockingly guttural and discordant; now a sweet insistence of long, lugubrious piping; then bubbling chuckles and indrawn whistles; and then, suddenly, nothing – a suspended, teasing hiatus before the cascades and crescendos break forth again. The mind tries to anticipate but there is no sense, at least no human sense; no pattern, no repetition. A single nightingale has around 180 ‘riffs’ or song phrases in its repertoire, from a total of 250 for the species, which it sequences differently each time it sings. It is a display of astonishing mastery, heart-rending in its energy and volume – these pulsating strains issuing from tiny vocal cords belting out like organ pipes, throwing the music of the tropics into the English night air. And the performances can be marathon. Though a typical aria lasts thirty minutes, one nightingale has been recorded singing non-stop for twenty-three and a half hours.

Like its fellow African migrant the turtle dove, the nightingale has nested in our culture, become ours. It wings its way through Shakespeare, Milton, Matthew Arnold, Coleridge, Tennyson, Shelley, Keats, John Clare, T. S. Eliot, our greatest poets adding their transports to those of Aesop, Aristophanes and Pliny, the Persian poets and all the minstrels and troubadours down the ages whose imaginations have been teased, provoked and disturbed by the ‘joy that is almost pain’.

But few people in Britain today are familiar with the exquisite unease of a nightingale’s song. Like the turtle dove, it is now almost a miracle to hear one. Between 1967 and 2007 the number of nightingales in the UK fell 91 per cent. For every ten birds that were singing when I was a child, there is now only one. This isn’t supposed to have happened. England, it is true, has always been at the northernmost reach of the nightingale’s range. The breeding capacity of this warm-climate bird is restricted to areas where the temperature in July is between 17 and 30 °C – so, conventionally, nowhere north of Yorkshire, and rarely above an altitude of about 600 feet. But with global warming ornithologists had expected this to change. By now, they had predicted, we should be hearing nightingales in the borders of Scotland and expanding into Wales. Instead, its territory has retracted, shrivelling south and eastwards, with Kent, Sussex and Suffolk the last bastions of its communion with England.

It’s sobering – and surprising – to remember how common they once were. Only a century or two ago nightingales were serenading Londoners. The land on which the royal palace now stands was, when the Duke of Buckingham acquired it in 1703, ‘a little wilderness full of Blackbirds and Nightingales’. The bird that possessed the feverish, tubercular Keats in the spring of 1819 was singing near his house on Hampstead Heath. As the heaths and commons of London contracted or were vigorously tidied up, the Victorians, yearning for its song like the emperor in Hans Christian Andersen’s tale, made pilgrimages to hear nightingales in the countryside and imported them to sing in their parlours and drawing rooms. In the 1830s, a gamekeeper in Middlesex could catch a hundred and eighty nightingales in one season, receiving eighteen shillings a dozen for them in London – a lucrative supplement to his wages. The trade continued towards the turn of the century. According to Richard Jefferies, a naturalist writing in Surrey in 1886, ‘a couple of roughs would come down from town and silence a whole grove.’ A nightingale makes a poor prisoner and the majority battered themselves to death against the bars of their cages. ‘The mortality was pitiable,’ describes Jefferies. ‘Seventy percent of these little creatures that were singing a week before in full-throated ease in the Surrey lanes would be flung into the gutters of Seven Dials or Whitechapel.’

Mercifully, the market for caged birds fell away in the twentieth century and there were still nightingales left to sing in the countryside through the Second World War. The voice of a nightingale can reach 95 decibels, way above the levels requiring industrial workers to wear ear defenders. Technically, it can be classed as noise pollution. On a night in May 1942 a BBC sound engineer accidentally made what has become a famous recording: a nightingale in a Surrey back garden poignantly raising its love-song against the approaching thrum of the engines of war – Wellington and Lancaster bombers on their way to bomb Cologne. The live broadcast was suddenly terminated when the BBC realized they could be alerting the Germans to the raid.

By the Second World War the possibility of hearing a nightingale in the capital was no more than a dreamy illusion, though romance had it otherwise. There is something in a nightingale’s song that seems to strain for the sublime, as though it might lift the world away from the pains of reality.

That certain night, the night we met,

There was magic abroad in the air.

There were angels dining at the Ritz

And a nightingale sang in Berkeley Square.

Somehow, these lyrics of 1939, recorded by Vera Lynn, Glenn Miller, Frank Sinatra, Nat King Cole and a host of others down the decades (including, more surprisingly, Rod Stewart and Manhattan Transfer), have developed a life of their own, as if wishful thinking has made the fantasy, fact – that nightingales really did sing their hearts out to lovers in Mayfair during the Blitz.

Berkeley Square, though, is not, and never has been – at least not since the seventeenth century – nightingale habitat. The British Trust for Ornithology describes the nightingale as a woodland species – shy, reclusive, hiding deep within thickets in the understorey of woods. Its decline is linked, once again, with the decline of coppice. The proliferation of nightingales at Knepp on open, formerly arable land has therefore been something of an ornithological thunderclap, as surprising as the purple emperor’s appearance here to lepidopterists. Knepp is only the second place in England – after Lodge Hill in Medway in Kent, owned by the Ministry of Defence and where plans for the development of 5,000 houses have, for the moment at least, been suspended – where the numbers of nightingales have been rising. Their rapid colonization of Knepp has shaken up what we thought we knew about this bird and, like the purple emperor, thrown up wider questions about where conservation has been going wrong.

In 1999 a national nightingale survey carried out by the British Trust for Ornithology recorded nine territories on Knepp. But Charlie and I can only remember hearing them here once in the 1990s, one memorable year when, standing at midnight on the dam wall at the end of Knepp lake, we heard three singing in concert, two from the heronry on one side and one from the rookery on the other. It is possible they had been displaced by the harvesting, that year, of large areas of coppice over at Arundel – one of the few significant areas of coppice left in the county. Our delight at the manifestation of their pure, penetrating song, amplified over the Mill Pond under a full May moon, was dampened by the notion that these tiny birds had flown across two continents to find their habitat demolished. The farmland of Knepp was clearly no substitute. We went down to listen to them the following night but they had moved on.

By 2001, the year we started rewilding, nightingales seemed to have disappeared from the estate altogether, in line with the national decline of 53 per cent between 1995 and 2008. The suspected causes of the nightingale crisis were the usual: declining availability of food resources due to widespread use of pesticides and livestock wormers, housing development on habitual nesting grounds, loss of coppicing, changes to nightingale wintering grounds in Africa and climate change affecting the migration route.

So it was a surprise, seven or eight years later, suddenly to be hearing nightingales again at Knepp – and this time in numbers. In the Southern Block we could hear three, four, sometimes five competing with each other. Anticipating their arrival in late April we began to have nightingale dinners, taking groups of friends out after supper to listen. Most had never heard one before. Contrary to poetic convention, only a male nightingale sings. He sings both night and day whilst he is trying to attract a mate, but it is at night that his arias, disentangled from the racket of diurnal birdsong, burst forth with such clarity and conviction upon the human ear.

Conservationists began to show an interest and in 2012, the year of another national nightingale survey conducted by the BTO, the biology department at Imperial College London was sufficiently intrigued to send one of their MA students, Olivia Hicks, under the auspices of her tutor, Alex Lord, to investigate. Olivia stayed with us for two weeks in May, keeping nightingale hours, often returning to bed just as we were getting up for breakfast. Her goal was to identify nightingale territories and the type of habitat they had chosen at Knepp, and then to work out if the males had successfully paired, to give an indication of breeding rates. For this, she returned for another bout of insomnia in the last week of May and first week of June.

Nightingales are notoriously difficult to spot. An unassuming LBJ (‘little brown job’, in twitching terminology), they melt into their cover. Nests are even harder to find. But their song is a giveaway, and the fact that they are deeply territorial, rarely straying from their chosen nesting site, makes them relatively easy to count. The male nightingales arrive in England in an advance cohort in early to mid-April, having flown from wintering grounds in equatorial Senegal, Guinea-Bissau and Gambia, to take possession of a suitable nesting site. Not all nightingales leave Africa to breed. But millions do take on the Herculean challenge of the 3,000-mile migration for the chance to raise chicks in Europe where there are far fewer predators (even insects eat fledglings in Africa) and less intra-species competition for territory and food. The female follows a week or so later, flying at night to escape avian predation. In the inky vastness she catches the notes of males singing below. She’ll drop down to join one, attracted, recent research suggests, by the virtuosity of his performance – volume and complexity being an indication of physical strength and maturity: signs of a good father. In daylight she’ll inspect his choice of breeding spot. If she doesn’t approve, she’ll fly on in search of a more discerning mate.

Nest-building is done exclusively by her, while her mate continues to sing. After pairing, though, his song is territorial, conducted only during the day, and without the depth and urgency of his earlier broadcasts. As soon as the young are hatched – about thirteen days after the eggs are laid – he joins in feeding them and virtually ceases to sing altogether. This is key to estimating breeding success. By June the only nightingales left singing are bachelors – lonely hearts, failed homemakers, vainly hoping to attract a straggling female.

Olivia’s findings were astonishing. She found thirty-four nightingale territories on Knepp. From having no nightingales at all, we were now, after just nine years, hosting between 0.5 and 0.9 per cent of the UK population. Of these thirty-four territories, twenty-seven of them were paired – a 79 per cent success rate compared with the European average of 50 per cent. Two of our neighbours allowed Olivia to use their land – an area totalling 1,040 hectares (2,600 acres) of intensive arable farmland – to use as a comparison. Here she found nine territories (significantly higher than the 1999 BTO survey) but with only two of them (18 per cent) paired. Her findings showed that Knepp had not only become a breeding hotspot for nightingales. It also suggested that males, perhaps juveniles or late arrivals, were spilling over onto neighbouring land once the prime territories at Knepp had been taken.

Deep inside the exploding skirts of an overgrown hedge, a nightingale’s nest – a tangle of twigs and moss, a few feathers and dry oak leaves, just a foot above the ground – identifies why the nightingales are attracted to Knepp. The majority (86 per cent) of the birds had taken up sites in overgrown hedgerows, twenty-five to forty-five feet deep, where there is around 60 per cent blackthorn with thorny cover extending right to the ground (no browse-line from deer or rabbits), fringed with brambles, nettles and long grasses, and where the cavernous, cathedral-like structure of the thicket’s interior offers a safe haven for adults and their fledgling chicks to peck about for insects in the leaf-litter.

So a nightingale – Knepp reveals – is not a woodland bird. Trees need not play a part in the picture at all. But what does this mean? Are nightingales changing their habits? Is Knepp a truer picture of their ideal habitat? Or is it just an improvement on conventional woodland? Is this information really new to science? In Knepp’s library, looking back through the giant illustrated folios of The Birds of Great Britain by my old friend, subject of my very first book, the Victorian ornithologist John Gould, the nightingale nest is described in simple terms as ‘generally placed on the side of a bank, and occasionally in a shrub or bush’. In our well-thumbed volumes of Birds of Sussex published in 1938, nearly a hundred years later, the Sussex ornithologist John Walpole-Bond, son of a vicar of Horsham, describes how the ‘favourite breeding-haunts . . . are supplied by woods, particularly their outskirts; spinneys; shaws; thickets on down; common and waste ground generally, even expanses of shingle like the Crumbles; and certain sorts of hedgerows, double hedgerows especially’. Their nests, he says, are ‘usually in wild sloes, brambles, heaps of debris, even on ivied walls’. Nightingales were all over the place.

Yet these observations, made by punctilious field naturalists only a century or so ago, are rarely consulted by modern science. In academic papers the onus is on referencing contemporary research. Another example of shifting-baseline syndrome. The nightingale – like the purple emperor – has been labelled a woodland species today, because that is where we see it. We study it there, make all our calculations of its behaviour there. Woodland coppice has become, to our minds, perfect nightingale territory because, in the absence of open-grown thorny scrub, thickly vegetated banks and double hedgerows replete with insects, that is all we have been offering the birds. And where – does anyone consider? – would nightingales have nested before wood coppice came along? Our baselines are entrenched in a landscape of human activity. We talk of ‘woodland’, ‘wetland’, ‘heathland’, ‘moorland’ and even ‘farmland’ birds. But their true context, before man began parcelling up the landscape and assigning bio-geographical and ‘habitat’ categories for species, may be much more complex and amorphous, as denizens of the shifting margins where one habitat blends into another.

Our views in the UK are constrained, too, by insularity. On the Continent, in places where nightingales are still plentiful, they quite obviously appear to favour the habitats described by Gould and Walpole-Bond. I’ve heard them singing in scrub on the salt pans of the Camargue; even seen them, bold as brass, on shrubs around orchards in Bulgaria. A German research paper of 1973 describes them, categorically, as a bird that disdains closed-canopy woods. Yet, somehow, in Britain we seem to regard our islands as an exception to the rule, as if species change their preferences halfway across the Channel. Had we set out with the intention of attracting nightingales to Knepp we would almost certainly have been encouraged by British conservationists to create woodland coppice – and most likely been disappointed with the results.

The following year another Imperial MA student, Izzy Donovan, continued Olivia’s work on nightingales at Knepp. She added to her study another six birds of European conservation concern: two of them – the green woodpecker and whitethroat – amber-listed; four of them – cuckoo, linnet, song thrush and yellowhammer – red-listed. Calculating densities of birds per ten hectares she compared numbers at Knepp with densities given in the Atlas of European Breeding Birds, and on the site of a neighbouring intensive farmer. The results, once again, were astonishing. Knepp performed at least as well as, if not better than, what are considered good habitats elsewhere:

Species	Densities in good habitats	Knepp density estimates	Local farm (control) estimates
Linnet	5.5–9.2	8	1.3–2.2
Yellowhammer	4.7	4.5–7.5	3.6– 6.1
Song thrush	15	3.5–5.8	None
Green woodpecker	0.3	3.8– 6.38	1–1.6
Whitethroat	10	8.5–14.2	2.6–4.4
Cuckoo	0.3	3.5	None observed
Nightingale	2	7–11	1.3–2.2

The only, as yet unexplained, anomaly was the song thrush, numbers of which, according to our 2016 survey, are now conspicuously high.

The findings about the nightingale’s habitat were so exciting that on 1 May 2014 we held a Nightingale Workshop at Knepp, attended by several of the top brass from Natural England, as well as representatives from the National Trust, Wildlife Trusts, Country Landowners’ Association, National Farmers’ Union, the British Trust for Ornithology, the RSPB and a number of interested landowners. We hoped Natural England – whose response so far had been extremely positive – would be able to feed this new information into their grant system, to incentivize farmers and landowners in areas where nightingale populations were still clinging on, into growing out their hedgerows to the prescribed twenty-five feet or more to provide extra habitat. To us it seemed a relatively simple step that could halt the decline of one of our loveliest birds and benefit a host of umbrella species.

But the reality in conservation is never that simple. Shortly after the meeting one of the landowners, who had several nightingales on his farmland in Suffolk (one of the most northerly sites for the species), applied for a grant to allow some of his hedgerows to scrub up. His local Natural England office turned him down, arguing that the lack of nightingales for five miles around his land would make it a bad use of their funds. Despite encouraging signs at first, the nightingale hedgerow initiative failed to gain traction at Natural England. Enthusiasm for the project amongst all those sitting around our table gradually fizzled out. And sadly, it seems, without incentives and direction from above, most landowners, even those who are conservation-minded, rarely have the time, drive or resources to devote to conservation measures – even when they are as simple and rewarding as this.