I was out early in the meadows and found myself among a flock of swifts hawking for insects. Usually they are high overhead but, perhaps because it was early morning and the insects were only just becoming airborne, the swifts were flying around my head, close enough for me to hear their passage through the air. They seemed to hurtle past at a great rate, wings flickering or outstretched in a glide, but are they really swift? Not for the first time, I tried to compare their speed with that of other birds. Greenfinches, linnets and skylarks obliged by flying past at about the same height. The swifts made it difficult because they would not fly in straight lines, but I came to the conclusion that there was no obvious difference between the swifts, eponymous symbols of speed, and the commonplace aerial plodders going from A to B. My rough-and-ready comparisons are supported by reliable figures of cruising speeds taken from radar measurements. The swift has been logged at 23 kph, the house sparrow at 35 and the starling at 34. It makes sense for swifts to fly slowly when feeding. They spend the daylight hours on the wing searching for aphids and other small insects that drift in the air, so their requirement is economy rather than speed. This is backed by scientific research. It takes much less energy to keep a swift airborne than a songbird of equal size. Swifts are really amazing because they feed, sleep and even mate on the wing. Like the seals in the sea, they are tied to terra firma only by the need to raise a family.
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