A favourite walk from our house is along the pier to the red-and-white lighthouse, now redundant, that still stands guard over the entrance to the estuary. The pier runs south through the rocks and mudflats below the tideline before turning east alongside the channel of the river Tweed as it flows out to sea. On the south and east side of the pier a high wall shields you from the wind but also blocks your view of the beach on the far side. To catch a glimpse of the scuttling sanderling and oyster catchers working the shoreline you have to pause a moment, stand on tiptoe and peer over the top. By the time the pier reaches the lighthouse at the end it is well out to sea. It feels like the blunt-nosed prow of a ship sailing through the waves that surround it, heading out to sea.

On a fine afternoon last week I took a walk along the pier. I was due to give a Zoom talk later on about my novel Cuthbert of Farne and I needed to clear my head. It was a fine, unusually still afternoon. The mild weather had brought clouds of small flies out of hibernation, flying to and fro, settling on the wall for a while before rising again.  I walked along the first stretch of the pier, then rounded the corner to head east. As I started down this section, a small flock of birds flew over the wall from the north. I was immediately surprised. I am familiar with the usual repertoire of birds seen on the pier; shore larks, sparrows, wagtails, starlings, even the more uncommon visitors like reed bunting from the scrub beyond or purple sandpiper sheltering against bad weather. These birds were nothing like any of them. They were larger than a linnet, and plump, but not as large as a thrush. What made them so striking was their colour. Some of them were almost completely white, shining in the sunshine. Others were a ruddy buff colour, and others again striped black and white. When they took flight, their wings opened with a sudden startling flash of white. They were in pursuit of the flies I had seen. At first they pecked around on top of the wall, then flew down onto the pier itself. One side of the pier is concreted over, but on the seaward side the original stonework is still exposed, great blocks of creamy pink sandstone, worn and hollowed out by the weather. Patches of grass and tiny flowers grow in the cracks between the blocks, and the hollows fill with rainwater. The birds descended onto the stones. They pecked away at the flies and took it in turn to bathe in the hollows. I stood very still. Although I was close they took no notice of me at all. I felt as if I had passed through an invisible door and entered upon the birds’ world. The sun shone on the rose-coloured stones, on the absorbed, chirping birds. The wind blew the flies here and there.The pier is always busy; on a sunny afternoon there are always people coming or going. But no-one came. Time seemed held in abeyance. I thought of St Cuthbert and how he had loved the birds of his Farne retreat. Perhaps he watched snow buntings too, pecking on the whinstone in the March sunshine. Fourteen centuries fold up in a moment.

Then walkers came, the birds flew off and the spell was broken. As soon as I got home I hurried to the bird book. There was no doubt about the identification. Snow buntings. Just 60 breeding pairs left in Scotland. These were likely migrant visitors from the Arctic. They had flown 3000 miles, yet they turned up on Berwick pier as if they had always lived there. As if it were no surprise to find themselves there.

Emily Dickinson wrote: ‘I hope you like birds. It is economical. It saves going to heaven.

I would be happy if heaven turned out to be full of snow buntings.

Then, only a few days later, I took a walk along the clifftop path to the north of Berwick. The cliffs are formed of the same pale pink sandstone as the pier, massive blocks and columns piled on top of each other. At their base the soft stone has been eroded away into caverns and strange fluted pillars. The most spectacular formation is a high sandstone arch reaching out into the sea, the tides constantly sucking to and fro beneath it. The seas there are often rough but that day it was calm, long lines of surf sliding shore-wards over the skin of the sea.

As soon as I drew close I sensed something had changed since my last visit. Above the noise of the waves beating against the rocks, there was a new strident clamour. I picked out circling specks of white. At once I understood. The kittiwakes had arrived! Soon I could distinguish the cries distinctly.  Kittiwake! Kittiwake! They were circling around the cliffs, rising at their leisure on the thermals and dropping again, taking possession of their summer quarters. Some had already chose their ledge on the cliff and were tucked snugly against the rock.

Although I had forgotten to look out for them, the kittiwakes are expected visitors, and yet their arrival is no less miraculous than the snow bunting. They have spent all winter out at sea in the north Atlantic, surviving storm and freezing weather. At some moment they must turn, all together, and fly back across the trackless ocean, back to the familiar sandstone cliffs where they were hatched and bred. When they arrive it is as if they had never left. There is no uncertainty, no settling-in time. A zoologist friend once said to me, ‘The great thing about animals (and birds) is that they always know exactly what they are supposed to be doing.’ It’s so true.

They are instinctually at one with the natural world that supports them. Perhaps that’s why Emily Dickinson thought they were holy; whole-y. And why we find such joy in their presence. We humans have lost that sense of one-ness; instead, we are intent on despoiling the natural world we all depend on. Like the snow bunting, kittiwake are on the red list of conservation concern. Nowadays bird joy is undershot with jeopardy. Will they be here again next year?