David Tomlinson looks at why nightingale number are declining in the British countryside, and finds out where you can listen to them sing.

For more on birds, find out how Cranes have returned to England after centuries of absence, after a remarkable conservation success story.

NIGHTINGALES

Close to my home is an ancient valley fen. As befits a Site of Special Scientific Interest and a local nature reserve, its information board promises a bounty of spring birdsong, from nightingales to reed warblers. The warblers still return every spring but the nightingale’s song is no longer heard. Thirty years ago, there were still several pairs but now they have all gone and it’s unlikely that they will return.

There are several likely reasons for their disappearance. Problems on migration are one, for this is a species whose annual journey involves crossing the Sahara. Degradation of habitat on the wintering grounds in West Africa is another. But though these may be contributory factors, the most probable reason for the lost nightingales is their favoured nesting habitat has been browsed out by deer. The spread of the muntjac in England mirrors the decline of the nightingale and it’s notable that Kent, a county where muntjacs are still scarce, has our biggest surviving nightingale population.

Nightingales have never been numerous in Britain, where they are on the northern edge of their extensive European range. Historically, they have always been restricted to those counties south of an imaginary line drawn between the estuaries of the Humber and the Severn. They have never bred in Scotland or Ireland and it’s 40 years since the last recorded nest in Wales. In recent years, the range has contracted south-east to the core counties of Essex, Kent and Sussex, and the overall population today is probably no more than 4,000 singing males.

English nightingales are usually difficult to see, for they are skulking birds that rarely venture far from cover. The song – usually the only indication of the bird’s presence – is invariably delivered from a hidden perch. The best time to try and see one is in April, when the males are fresh in from Africa and the trees not yet in full leaf.

The celebrated song is much better listened to than described. It may lack the blackbird’s flutey notes, or the sweetness of a skylark’s more delicate refrain, but for sheer force of delivery there’s nothing like it. On a still night, you can hear a singing nightingale a mile away. It is a song that has inspired generations of poets, from Shakespeare to Shelley, Coleridge to Keats. Most make the mistake of suggesting that it’s the female that sings; it is, of course, only the male. The song period is remarkably short, for by the end of May most successfully paired males will be singing intermittently and by mid June they will have stopped altogether. They are competitive singers, best heard where several males hold territories close to each other.

Despite their name and reputation, nightingales sing more during the day than they do at night. According to WH Hudson, writing in British Birds (1918), the nightingale’s music “is more continuous and has a more beautiful effect in the evening. For an hour or two after sunset it is perhaps most perfect.” He goes on to note that, “in the dark, he is silent, but if the moon shines, he will continue singing for hours”. Though difficult to see, singing nightingales are not easily disturbed. There’s a famous BBC recording of a nightingale singing with musician Beatrice Harrison’s cello. Taped in 1924, it was the first wildlife sound broadcast by the BBC. Although it was then generally thought that the nightingale was singing in duet with the cello, it was really singing in competition with it.

Victorian favourite

The Victorians were fascinated by nightingales, and charabanc outings were arranged to take people out to listen to singing birds. However, the identity of the singer wasn’t always established correctly, with blackcaps, garden warblers or other singers masquerading as the real thing. Such was the nightingale’s romantic image that many people were apparently disappointed when they did hear one for the first time, though quite what they were expecting remains a mystery.

The Rev CA Johns, writing in his book British Birds in Their Haunts (1909), describes the nightingale as a fearless bird that is easily snared, with the bird catchers “entrapping them before they have paired when they will bear confinement in a cage”. Those captured once paired would soon pine to death. Many nightingales ended up in cages but few survived more than a few months of captivity, most battering themselves to death against the bars of the cage when overcome by the urge to migrate.

Nightingales make poor cage birds, for their insectivorous diet makes them difficult to feed, while their predominantly brown plumage is hardly eye-catching. For a bird with a such a splendid song, the plumage is remarkably sombre. However, given a reasonable view, there’s not much a nightingale can be mistaken for. The best description is a large robin without a red breast, but with a distinctive russet tail that is frequently cocked. It’s most likely to be seen on or close to the ground and invariably close to cover.

In recent years, there’s been a distinct change in the nightingale’s preferred habitat, which might be a reaction to deer browsing or simply adaptation to a changing countryside. Woodland is being abandoned; instead, scrub has become increasingly important. There has been a similar trend on the near continent, too, with marshland forest and dune scrub now supporting increasing numbers of breeding pairs. However, despite this unexpected adaptability, numbers are thought to have declined in England by at least 50% since 1995. In 2015, it became a red-listed species for the first time, making it a bird of conservation concern in the UK, and one of 16 woodland species on the red list.

In a bid to halt the nightingale’s decline, considerable research has been undertaken to discover more about the bird and its requirements. In 2009, the British Trust for Ornithology (BTO) started a project attaching geolocators to nightingales. These tiny devices, weighing less than a gramme, contain a clock and a light sensor, sufficient to let scientists track an individual bird’s migration. One bird, tagged on its breeding grounds at Methwold Hythe, in Norfolk, on 2 May, started its migration south on 25 July. It passed west of the Pyrenees on 4 August, continuing towards Madrid before heading west towards Lisbon, where it remained until mid September. It then resumed its migration south, spending a month in Senegambia until reaching its final destination in Guinea in mid December.

Frustratingly, the geolocator then stopped recording, but the bird made it back successfully to Methwold Hythe the following spring, and was recaptured within 50 metres of where it was originally trapped. The recovered locator then revealed the secrets of the bird’s southerly migration. What is interesting is that this particular nightingale spent just 30% of its year in England, a reminder that the conservation of migratory birds is more than just looking after them on their breeding grounds.

However, the breeding season is clearly much the most important part of the nightingale’s year, and we now know a great deal about how to create and manage ideal conditions for nesting birds. They like coppiced woodland, but as the trees get older they shade out plants such as the brambles beneath, leaving the ground layer too open. Thus, maintaining our current nightingale populations is a matter of getting the woodland management right, with a variety of trees of different ages and, ideally, a mixture of coppice and scrub. The birds favour a damp microhabitat, with bare ground for feeding and thick vegetation for nesting. The nests are invariably built close to the ground. Lastly, but perhaps most important, fencing out deer is also vital.

Where the habitat isn’t managed, even strong populations will soon decline. Paxton Pits, a Cambridgeshire nature reserve close to the A1, had 25 singing males as recently as 2009, but now it has none. It is thought that tree cover became too dense, leading to little or no ground cover for the nightingales to nest in. While the nightingales were doing well there was no site management; now they have been lost, an attempt is being made to restore the woodland and, hopefully, attract the birds again.

In theory, our warming climate should suit nightingales, but there has been no sign of our birds extending their range north. Encouragingly, despite the decline of our population, the situation across Europe is largely stable and in many areas this stunning singer isn’t just common but abundant. In several Mediterranean countries, numbers reach an astonishing density of up to 100,000 pairs per 50sq km. The other remarkable thing about Mediterranean nightingales is that they are much easier to see than our birds, but that may be because there are so many more of them.

It’s not unusual to hear Mediterranean nightingales singing throughout June and even into July, long after our birds have stopped. This is because these birds are double brooded, so the males hold territories much longer than our single-brooded birds. I have fond memories of Mediterranean nights, when the hot air has pulsated with a chorus of nightingales: it’s something I’ve experienced in Spain, Italy, Greece and Bulgaria. Last year, for the first time for decades, the pandemic denied me this simple pleasure. There are many things I have missed in the past 12 months but the song of the nightingale comes close to the top of the list.

Where to listen to nightingales

• Woodlands in east Kent: Blean Woods near Canterbury and Ham Street Woods near Ashford are particularly rewarding.
  Northward Hill, Kent: an RSPB reserve with several pairs, as well as the UK’s largest heronry.
• Fingringhoe Wick in Essex: with around 25 singing males, this Essex Wildlife Trust reserve is one of the best places to listen to nightingales in England.
• Pulborough Brooks: this West Sussex RSPB reserve is a reliable site for hedgerow-nesting nightingales; they have a reputation for being easy to see.
• Knepp Castle estate, West Sussex: one of the few sites to record increasing numbers in recent years.
• The Chiddingfold Forest complex in Surrey: the best spots vary from year to year depending on habitat management.
• Minsmere RSPB, Suffolk: despite numerous muntjac, Minsmere still has around 10 singing males; it once had many more.
• Highnam Woods RSPB, Gloucestershire: the most reliable westerly breeding nightingales in England.
  Almost any Mediterranean or Balkan country: both France and Spain have at least one million pairs, with Italy not far behind.