Esther Woolfson on the habits of starlings in an extract from her new book

They look as if they’re in conversation, like two nuns, their feathers like wimples blowing white in the wind, treading piously on their big, light feet.

In Marischal Street, the town’s pigeons are beginning their roost, edging the Georgian roofs with a frill of tail and feather. It is a steep street, sloping down to the harbour and seems to have ships docking at its foot, all masts, reflections of water and moving lights. It’s a street of 18th-century town houses with an air of the past that seems alive as I walk this ancient route from the Castlegate to the harbour.

From the short brilliance of Solstice Day, the day has expanded to eight hours and fourteen minutes on the steady minute-by-minute progression towards summer and its eighteen hours of daylight. It’s twilight. There seems to be so much of everything here. There are different kinds of wind, different kinds of snow, different kinds of twilight.

Even now the harbour’s busy, lit and bustling, vessels getting ready to sail out to rigs at sea, the huge Northern Isles ferries preparing to head out north to Orkney and Shetland.

On the way home, I pass one of the busiest crossroads in the city, where people used to stand to wait for the daily preparation of the starlings for their evening roost and the sky would be scattered from every direction with dark ingatherings of tiny, darting urban commuters making their way across the city to their meeting point above the bridge where they’d huddle together for warmth and the noisy, structured companionship of avian societies. Flying in their busy, purposeful parties, they’d join in a vast and gorgeous display, a sweep and flight that transformed the sky, the city, the lives of the observers with the inexplicable mystery of their precision and grace, with the sight of this moving grey wave, this cloud of birds closing and spreading, dipping and soaring, thousands of Sturnus vulgaris, those quick and lively birds, those beautiful creatures of oiled, shimmering gold and green.

I’d stand, breath held, sharing in the birds’ joyous flight, in their song, their exuberance and energy until the moment when, as one, they’d turn, their undulating tissue of bird-cloud folding, narrowing into a streamer of molten darkness to disappear under the parapets of Union Bridge.

As I walk back, it’s through the noise of traffic alone. The dusk air’s emptier now. The song of winter evenings has been diminished. A few years ago, someone at the council decided that starlings were damaging the paintwork of the bridge, that their excrement was blocking land drains, that they were a nuisance and had to be removed. “Control” methods were implemented and netting installed under the bridge to prevent the starlings from settling.

It’s almost always hygiene that leads to these extirpations. Birds excrete, and their excreta collects. It can damage stonework and metal but can also be removed and cleared away. The threat of zoonotic diseases is often used too as a reason to remove the habitats of gulls, starlings and pigeons but it is a threat that is vastly exaggerated. (Diseases! Spores! Bacteria! All carried by every darn thing that moves or breathes.) The incidence of histoplasmosis, which people can catch from starling faeces, is extremely rare. It is a disease caught mainly by people working in areas where droppings have accumulated, and is easily prevented by the wearing of appropriate facemasks. (You might get it more readily if you go caving, or live in the Ohio River Valley.) Zoonotic diseases do occur and many can be dangerous but, in this case, protection of the populace from the unmeasurably small chance of contracting the disease doesn’t seem to justify what’s been done.

I look up as I walk. A few starlings fly above the bridge in groups of ten or twelve. They look lost, disembodied, as if they’ve been broken off something larger, something whole.

Even if I hadn’t known one personally, I’d have a special fondness for starlings. They were the first birds I knew, the first birds to make their vibrant, noisy existence known to me in my childhood, ubiquitous in the city, in crowd and chorus, their singing lighting the darkness of the Glasgow dusk. The starling I knew personally was Max, a bird found and reared by an American family who couldn’t take him home with them when they went back. (The United States doesn’t know what to do with the many millions of introduced starlings they already have.) We took him. I think of the years he lived with us, of his excitements and his irritations, his swearing (of the serious but not entirely discernible sort), his sotto voce mutterings, the instant connection he brought to me with a long-ago past. I think of the nature of his character, the exquisite sweetness of his evening solos as well as the extraordinary beauty of the bird, the gilded feathers, the neatness of wing as he flew around the house. After I got to know him, I’d look anew each evening at the cloud of swirling starlings, understanding that each one of them was as Max was. Knowing increased my amazement at their individuality, at the magical coordination of their movement, the singular, transcendent beauty of this turning, sweeping cloud of birds. I used to wonder if they looked down from their elevated high-flying towards those of us watching from the pavement, and see only undifferentiated members of another species.

When I get home, I look out the poem The Starlings in George Square in which the late Edwin Morgan, Makar of Scotland and a fellow Glaswegian, writes of the council that complains of the noise and the mess starlings make, and employs the “bird-men” to remove them; of the amusement of people who watch the birds trying to land on the plastic rollers they’ve installed: “The Lord Provost sings in her marble hacienda ... Sir Walter’s vexed that his column’s deserted.”

Starlings, despite congregations of large numbers, are critically endangered in Britain. Their numbers have declined by over 65 per cent in the past 30 years (as with other birds whose numbers have similarly declined, no one quite knows why) and now their habitat, the foundation for one of the marvels of the natural world, has been destroyed, probably for ever, and I wonder how future generations will learn about the value of the life around them, of birds such as starlings. How will they know what they’ve lost or are losing? Who will teach our children what starlings were?

When Edwin Morgan asks if we really deserved the starlings, it is a question I ask too, knowing that his starlings were my starlings, and all his sadness and anger mine. He writes of the joy of the child whose father encourages him to look at starlings, a sight that pierces the boy like a story, a story more than a song. He will never forget that evening, the silhouette of the roofs, the starlings by the lamps .

• Field Notes from A Hidden City: An Urban Nature Diary by Esther Woolfson is published by Granta, priced £16.99