Around the end of June or early July last summer a young male swift was guided out of the nest by his mother. He fell, flapped his wings a few times and was suddenly flying. Young swifts can fly immediately and within moments he was up in the air in that darting way that swifts move, flying off on his own. For swifts, once in the air are immediately left to their own devices by their parents.

All through the high summer he flew, catching flying insects or drifting spiders for food, until one day in early August he felt that mysterious tug to leave, the call for migration whose effects we can observe but never experience and along with his peers, turned south. He flew down to the coast, then over the channel, down through France and Spain and crossed the Straits of Gibraltar. He carried on down the west coast of Africa, until past the Sahara Desert his journey ended in the tropics of southern Africa.

While we shivered under feet of snow in the coldest winter in a century our swift flew under the hot African sun, feeding in the air, delighting in the sheer joy of flight. Until, some time probably in February he felt that tug again, pulling him back to the land of his birth. Turning northwards he retraced his journey and in approximately mid May he crossed the Channel again to cry his high squealing cry in English evening sunlight.

But why do I tell you all this?

Because the most amazing thing about our swift is that from the moment he left his nest until he flew again in the following English summer he flew non-stop! For the swift is the greatest flying machine ever evolved. He eats on the wing, sleeps on the wing and unique amongst birds, mates on the wing. The frigate bird and the great albatross will glide over the oceans for days or even weeks at a time, but they always return to land to mate and to rest. But the swift will only stop if he pairs with a female and builds a nest with her, and even then the nest is built with material that he finds in the air. It is estimated that over an average lifespan of 7 years a swift can fly 2.5 million miles!

We have one of the great natural wonders of the world whirling and crying over our heads through high summer, and yet few notice, and even fewer know the glory of what they see.

The swifts have left now. I last saw a few in the evening sky on Sunday night; by now they are probably the other side of the channel on their way back to Africa. Their arrival in May each year signals for me the start of summer; and their departure in early August indicates that though the sun is still strong summer is coming to an end and before we know it we’ll be heading into winter.

So when, one evening next spring you hear a high screeling noise way over your head and you see birds with crescent shaped wings whirling through the sky, welcome the swifts back to England, marveling that they have been flying since they left last summer. And point them out to your mates and tell them of the greatest flier on the planet.