There is a pertinent observation in the trenchantly-titled book A Field Guide to Zambian Birds Not Found In Southern Africa by Dylan Aspinwall and Carl Beel. A summary of bird habitats in that country begins “Sky. This is the most widespread habitat in Zambia.”

It has to be said that the sky is a widespread habitat in this country as well. Wherever you go, you have an excellent chance of finding some. And it is a very good idea to look at it. A habit of sky gazing is one of the most rewarding things that a person can acquire.

You can find sky from train windows. There is decent quality sky above motorways. You can see good sky from office windows; you can see sky as you traipse between train and office. You can see sky from pub gardens; you can see sky on dog-walks.

Sky is a good place to see birds, because birds can fly: and that’s a miracle, is it not? Flight is something humans dream about, fantasise about, and mimic in dozens of different sports. But birds can actually do it: and when we see a bird in flight, few of us can prevent a small lifting of the heart in response.

The warmer months are the best ones for sky gazing. It is the time of the aerial specialists, the martins, swallows and swifts. The swifts are for a few short weeks, dark sickle silhouettes, so exclusively creatures of the sky that the non-nesting birds will not perch even once in the entire length of their stay, feeding and sleeping on the wing. Swifts even mate on the wing, a thought worth considering when seeking your next incarnation.

But birds cross the sky at any time of year, and will reward the sky-gazer at any season. For lightness, buoyancy, and casual mastery of the winds, you can’t beat a black-headed gull. Crows, ragged black bundles, frequently take to the sky for; it seems no good reason other than that it’s a great place to be riding the winds, sideslipping, and generally despising gravity as a thing for wimps.

Any season might bring you a V-shaped straggle of geese, generally Canada geese, honking their way from one body of water to another. You might see the huge arched wings and slow wing beat of a heron, looking far too big to be a British bird.

Motorway skies are haunted by kestrels, hovering impossibly still over the disturbed and sooty grasses of the roadside. They are birds of sight, and the creaseless din of the traffic doesn’t get in the way of successful hunting. Field voles who fail to go in for sky-gazing pay a daily price.

To the west of the country, buzzards hang in the sky like great tea trays, mewling to each other in far-carrying voices. On the M40 and from the Chilterns train line, you can, amazingly, see red kites, cool and elegant, dominating the skies: a bird that has returned to this country in what might be the most successful reintroduction scheme ever.

Let me finish up with one of my great sky moments. I was in London, on the Millennium Bridge, gazing purposefully at the great chimney of the Tate Modern. As I watched, a bird took to the sky: and it was no pigeon.

It was a peregrine falcon, and it made a long 270-degree arc over the Thames, across the embankment, cutting inland and finally vanishing behind the dome of St Paul’s. And I was lost in wonder while all around me, people who had not acquired the habit of sky-gazing hurried by, grumpy and out of sorts with city life, unaware that the way to escape, even if only for a minute, was above their heads.