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Endless flights of swans who arrive here because they think our dark and chilly island is the most blissful place on earth

Swanfall. A good word: a great spectacle. Swan after swan after swan, falling from the wintry sky as if cold were the most blessed thing in the world.

It's one of the greatest sights that Britain can offer: endless flights of swans who arrive here because they think our dark and chilly island is the most blissful place on earth.

Human observers may feel the cold bite into the marrow of their bones as temperatures plummet this week, but for these swans it's like landing on the beach in Barbados. And their first job is to get their towels on the sun-loungers.

So the birds sort themselves out: who is the most important, who gives way to whom. It's a family thing: they go at it in gangs of up to half-a-dozen, united in purpose.

Parents and the offspring they have raised that year fly in from the Arctic together, so no wonder they find our winter balmy. They return to traditional sites, and once they have made their descent to the lake — water- skiing in on big black feet — they settle the question of dominance.

Family groups will have face-offs with each other. No fighting: just a noisy demonstration of strength: synchronised neck-waving while making a noise like a bugle. Numbers matter: a family of six will force a family of four to back down, but there are other factors, some of them unclear even to the most clued-up observer.

Once the league table is sorted out, they co-exist amicably and socially, so long as no one crosses the line. They hang out together all winter, often foraging in fields by day before returning to the lake when dusk falls in mid-afternoon — a luxuriously long day by the standards of an Arctic winter.

The noise, the honking and the bugling, fills the skies as the birds come in on their evening flight: proud-looking, stiff-necked birds with great yellow beaks, dramatically unlike the swans that we have with us all year.

These are whooper swans and Bewick's swans: often collectively referred to as wild swans.

We tend to measure the wild winter by the birds that fly south in the autumn to escape the chill, such as swallows and swifts, cuckoos, warblers and nightingales.

But for plenty of birds, Britain in winter is a haven of warmth and shelter and food.

We're an island, and that's of great relevance to our shifting population of birds. The Gulf Stream ocean current keeps our weather milder than the rest of continental Europe.

Meanwhile, what could be more English than a blackbird? You'll see plenty. But a closer look will tell you a rum thing: they all seem to be cock birds. The females are browny and dull-looking: only the males are black with those banana-coloured beaks.

You wonder how there could be enough females for them when it's spring and time to breed.

But many of them aren't British in the sense of being hatched here, breeding here and living here all year round. A lot of those you see in winter breed in Scandinavia, Poland, Russia and the Baltic. They come here to escape the continental winter.

The females tend to fly further south, to winter in warmer places than Britain, places where the food supply is more certain. But for the males, the closer they are to the breeding-grounds, the earlier they can get back.

For the cock blackbirds in your garden, the waders on the estuary and the swans who take over the lake, Britain in winter is a subtropical paradise

The earliest birds get the best territories and defend them by singing to stake their claim. By the time they've done so, the females make their leisurely way back, ready to meet a great blackbird with an inviting spread of territory and the sexiest singing voice in the neighbourhood.

So the male birds' winter stay in Britain is, in fact, a kind of extended stag weekend.

Here's a way to understand what winter really means. Wrap up well this week and take a walk along a river estuary. Our island has hundreds of them, and they tend to be the bleakest places on earth, hence the need for at least one more layer than you think physically possible.

But it's here you can look for birds that come in their thousands to revel in the comparative kindness of our climate and in the abundant food on offer.

The mud exposed by the outgoing tide is covered with long- legged birds that paddle and poke their beaks into this gloopy silt in search of the millions of wormy creatures that live there.

But you can also savour the joys of winter just by looking through the window at a garden or from the car as you pass a park.

That English robin that seems to have hopped from a Christmas card may be a Russian: continental birds fly through Britain in the autumn on their way to somewhere warmer, and a good few of them decide to go no further.

Then there are the winter thrushes: birds we see only in the colder months. If it wears a lavish eyebrow it's a redwing, if it flies away and shows you a black tail — clucking a little like a chicken — it's a fieldfare. Both thrushes breed in Scandinavia and Russia and come here for winter holidays.

But perhaps the best tip for winter birding is to go to supermarket car parks. They are the ideal habitat for one of the most dashing winter visitors of them all: birds that look raffish and a shade disreputable.

They're waxwings, unpredictable birds that arrive sometimes in ones and twos, more often in small groups, sometimes in decent-sized flocks.

And like planners of supermarkets: they're mad for berries. Supermarket car parks tend to be planted with low-maintenance, berry-laden cotoneasters, and waxwings often descend on them.

Or they will take a fancy to a suburban street, one on which the householders share their taste for berries, and hang out for a day or a week.

There are times when Britain feels like an Arctic wasteland, at least to those of us who live here. But some of our visitors see the place in a different way.

For the cock blackbirds in your garden, the waders on the estuary and the swans who take over the lake, Britain in winter is a subtropical paradise.

Even in winter, our island — the wild parts that remain — represents the future, hope, and life.