Tuning in to birds migrating at night

First Spring

The software is slow to update the sonogram – watching the screen is like watching a photograph develop in the darkroom. It’s low resolution at first, blocky rather than blurry; then, at last, the trace becomes clear. Now a call stands out – sparkling and lovely. 

My wrist on the computer mouse is getting tired from scrolling through so much noise and then this shines out bright and pure – a short phrase, just over half a second long – with a rich, vibrant timbre. I listen through the headphones over and over again – I must have listened to that one hundred times by now. It captivates me. But I cannot recognise the bird.

I post on the Facebook group and replies soon come back – ‘Skylark’! – so I search on-line, on xeno-canto, for their nocturnal calls; I download samples and compare the sonogram shape to my bird. I examine the familiar Skylark song – cutting out a scrap of its heartpourings and comparing with my recording. Finally, I am convinced – yes, this was a Skylark flying over my house, calling, on that starry spring night.

I remember as a boy wandering the North Devon sea-cliffs – in summer there were always Skylarks, suspended – impossibly high, singing non-stop.  They were the sound of summer, like the blue of the sky, the warmth of the sun and the sound of the waves crashing and grinding pebbles at the base of the cliffs.  A sound so commonplace that it almost wasn’t noticed, would come and go out of focus. I would lie on my back on the sheep-cropped grass at the cliff edge, surrounded by sea pinks, and take in that song.  

Back then time didn’t exist, and now time is everywhere; short scale, I’m thinking I should be doing something else right now, and long scale, I am looking at graphs showing the population of Skylarks in England reduce by over sixty percent in fifty years. Yes, I do still hear them on the moors around here in summer, but now when I listen, as beautiful as it is, I cannot hear it in the same way as then. This is not, anymore, an untroubled, careless yet wondrous, listening. The fact that they are disappearing gives an urgency to the listening and I start to think of a purpose to the listening. Do I need to record it and report it, so that surveys can be made?  Would that help to halt the decline? Maybe I have some responsibility? 

It was early in 2021 that I first read about nocmig: a rather clumsy term for the practice of leaving a microphone running overnight, pointed at the sky, and listening out for the calls of nocturnally migrating birds. I found it difficult to believe that birds flew and called at night on migration, or that I would be able to capture these calls, but I thought I would try. My initial recordings were brief, mainly to test the equipment, and later I extended recording to run continuously from sunset to sunrise. 

12th April 2021

There is a light wind from the west, and it is cold for the time of year – minus two degrees with a little light snow falling; sunset was at 20:05. Between 22:00 and 23:00, above the noise I hear series of simple soft and rhythmical whistles – pyu – pyu – pyupyu with individual members of the flock audible at different times and at slightly varying frequencies. So, although the calls themselves are minimal, mesmerising cross rhythms occur.

I have recorded three flocks of Common Scoter. One hundred thousand of these all-dark sea ducks spend winter off British coasts. As I am thirty miles inland, I know these are on migration, heading from the Solway Firth, crossing the country through the Tyne Gap to the Northumberland coast and onwards out over the North Sea in darkness. 

I am hooked on nocmig from that first night. For over a year I continue to record from my garden , listening to the sounds of the night, tuning in to birds calling out on their hidden journeys.

At this time of year, as winter visitors leave, summer visitors arrive.


Curlews are the most pressing bird conservation priority in Britain; they are on the UK red list and globally ‘near threatened’.  A quarter of the worldwide population breeds in the UK and their numbers have declined steeply by over 40% from 1995 to 2008. Two related species, the Eskimo Curlew and the Slender-billed Curlew (which were once widespread) are now thought to be extinct. 

These graceful long-legged birds with long curved bills spend winter around the coast of the British Isles and breed on northern uplands. They are the emblem of the Northumberland National Park.

In spring, I always see and hear them when I walk up across a couple of fields from home and out along the Racecourse Road that follows a low ridge above the Tyne valley. At night from early April, I have recorded them many times returning to their breeding sites. They have a call like their name – a far-carrying, rising, fluty, melancholy whistle, ‘cour-lii cour-lii’. 

They sing a very long, haunting, bubbling song as they gently glide down to the ground, described in the Collins Bird Guide as:

starting with drawling notes, merging into a distinctive rhythmic, rippling trill:

‘oo-ot, oo-ot, oo-eet trru-ee trru-eel, trrru-eel trrru-eel trrru-uhl’.


Several Redshank flew over in late April and early May. I played the recordings back many times to be reminded of the evocative and melancholy calls: teu-huhu teu-huhu. 

Is it just evocative and melancholy for me – or do others who have never heard the call before think of it in the same way?

The estuary

He walks out on a low embankment that extends from the disused railway line over the salt marsh to the mudflats. He is trespassing; many years later this area will be full of cyclists, joggers, and walkers – but now, he is alone. This is the place where there will be a high-level road bridge across the width of the estuary, bypassing the white town and the old bridge. Today, the slow river, mud, and sky merge in luminous pale morning mists.

Idly he gazes out over the flats – glistening like the back of a horse in the rain; grey – but lively, with hints of greens and yellows – thick and oozy. When he reaches the high-water mark, his nostrils are filled with the stench of rotting seaweed. Now, the tide is starting to turn – not a smooth encroachment, but a searching of fingers, feeling their way up the creeks and inlets in the vast tracts of sludge. As the water rises, wading birds are agitated and fly off calling – tyu-lu-lu       tyu-lu-lu           tu-tu    –   slipping from sight over the silent landscape – but persisting.


25th September 2021

During the day I heard geese overhead, heading south from the breeding quarters before the ice closes over, flying to their wintering grounds – places of sanctuary, food, and shelter. I wonder how much they know about their future. I can’t help but be interested in them, and I search out the direction of the sound; pause, figure out where they might be heading, listening to them call. Individual notes counter-play against the notes in a series, and against calls of the other members of the flock.  The music comes suddenly into my consciousness and now fades away, and there comes a point when they are no longer part of my perception but continue in my thoughts.

And now, listening through headphones to the sound recorded last night, I can clearly understand it as a flock moving overhead. I can picture in my mind’s eye the flock moving through the darkness against the stars and the moon and clouds, over the chimneys and the roofs. I wonder what view they have; I wonder what they are thinking and what purpose they think they have. What do they think of themselves and of the birds next to them and the flock as a whole? How are they sensing their direction and feeling the purpose of that direction? How is that magnetic sense felt, how does it look and feel to them?

I hear yelps, bark, squeaks, and grunts, and every so often, the characteristic high-pitched wink wink, wink wink wink. These are Icelandic Pink-footed Geese – or ‘pink-feet’.


I wonder if some of my recorded calls belong to birds that died in storms crossing the sea or struck a wind turbine or met their end at a lighthouse window.

Using my datastore and database I can reanimate any call at any time. 

18th February 2022

Storm Eunice followed Storm Dudley. Overnight snow.

24th February 2022

Bright between snow showers; cold blustery wind. Walking along the lane with the dog, two Oystercatchers dart overhead, k-peep k-peep. Then a different cry – and I stop, stand motionless, turning towards the sound, focussing completely on that call, searching for the bird – cour-lii … lii-lii … cour-lii

The Curlews have returned!

Second Spring

26th February 2022

What is this I hear now? – a high pitched meeo-meeoo-meeeoo – some sort of gull? – maybe a Mew Gull? – I have heard this before, in fact, now I think about it, I hear it often around this time. Ah! The neighbour is calling their cat! Now I realise that quite a few of my unidentified birdcall recordings are, in fact, people whistling for their dogs. I hear this at almost any time of night, depending on the owner’s working hours. And I realise that I have several recordings of my own dog whistles, calling her back after she had slinked off as I put the mic out. 

I have three basic whistles. The low, gentle, whistled version of her name ‘Myrtle’ – eeeooo – this is used when she is nearby or repeatedly as a contact call when we run through the woods together. Then there is the more insistent, four equal, high-pitched, piping notes – I use this to tell her to come, and then for when she is far away out of sight, potentially lost, the loud continuous whistle with two fingers from each hand pushing my tongue back as I squeeze my lips around them and blow hard. She doesn’t comprehend my lack of smell-sense when I use this slightly panicky ‘where the hell are you?’ call, while all along she was next to me, hidden in a bush – she appears, and makes eye contact, quizzically. 

Of course, I know she doesn’t need my calls. One day I decided to leave her at home and three miles into my run I heard a familiar panting and pattering behind me – she had broken out of the house, squeezed under three gates and negotiated two road crossings before joining me. 

When it snowed, I saw her tracing the tracks of field mice at a steady trot, nose scrapping the white. If she had needed to look or listen, she would have held her head up, but she didn’t.

Still, I can’t resist whistling to her – bird-like. 

18th March 2022

In the morning I hear the first overseas summer visitors: tiny, non-descript, green-brown leaf warblers, weighing less than ten grams. These had migrated overnight from wintering sites in southern Europe or North Africa. The male birds sing their name – chiff-chaff – loudly from the treetops as soon as they arrive, staking a claim for their one hundred square feet of territory. 

21st March 2022

Sunset 18:21. At the end of civil twilight – 18:58 – I set the mic up and sit near it.

Glass of whisky. 

Even the string-like terminal branches on the tall aspen are still. In the treetop opposite, a Robin sings – plaintive. A soft distant roar reaches me from the dual carriageway. I have my big coat and hat on. Another Robin sings – this one down the bridleway that leads to the reservoir. I should do this more – just sit and listen.

The sky above just holds some of the day’s blue. This imperceptibly grades to grey on the northern horizon and towards the west there is just a hint of warmth. I hear caw caw caw far-off. It is spring but you wouldn’t know it; trees are still bare silhouettes against the remains of the light. Cloud has been creeping from the west and now above are some sketchy white-grey shapes. Again, a crow caws at the limit of my hearing, then the day-birds fall silent, and the road noise intrudes. 

A Waitrose van passes with provisions for Number 7.

Half the sky is covered.

19:24 – First Tawny Owl call.

Feet are cold.

The sky is now like the skin of a toad.

Eight redwings fly over on migration – Zzeer, Zzeeer, Zeer Zzzeeeer, Zzeeerr, Zer, Zzeeer, Zzeieerip.

24th March 2022

No recording last night.

This morning I walk across two fields. Mist blunts the low sun to a pale disc. On a bare hedge sycamore, on the last bud of the last twig of the last branch:

siff saff siff siff siff saff dut dut dut

He flits and flicks and sings – then stops, head cocked, listening as a chiff chaff chiff chaff chaff chaff chiff is returned, attenuated, from the woods below. A brief pause before he sings again – and listens again, before dipping and bouncing to the next tree and repeating. 

28th March 2022

I am getting tired of hearing so much noise. On my recordings there are many distracting sounds – sheep, cows, horses, foxes, badgers, cats and dogs and so much human sound – odd shouts, calls, and whistles at all times of the night. And the sound of the police cars and ambulance sirens and vehicle reversing warnings, trains, planes, motorbikes, cars, church bells and an ever-present low frequency rumble… maybe it is a mix of all the sounds leaking out from the houses in the town below or maybe it is emanating from the chipboard factory over two miles away. There seems more noise than there was this time last year. Maybe because we are no longer in lockdown.

Below in the town, over the last year, on the site of a previous nuclear bunker, a Travel Lodge, Lidl Supermarket and MacDonald’s have been built and there are two new housing estates on the east side. The dual-carriageway junction has been upgraded, so that now through traffic doesn’t need to slow down. 

Every now and then there is a magical moment of hearing a bird call – clear and beautiful above all this noise.

Meet the Author!

Jim Lloyd is a winner in the Rialto ‘Nature and Place’ poetry competition. His poems have appeared in The Rialto, Stand, bind, Green Ink Poetry, One Hand Clapping Online, Presence Haiku Journal, and Wales Haiku Journal. He is studying for an arts practice-based PhD at Newcastle University, considering representations of avian perception. He lives in Northumberland, UK.