“A peregrine can fly faster than a merlin, but it would not be so quick in turning and following a bird.
“I think a peregrine can fly faster than a teal or golden plover, though, as you observe, the latter are quicker off the mark.”
There are very few recorded instances, as far as I have been able to ascertain, in which a hawk has killed the common swift. In two of these there was no evidence as to whether the hawk had not taken the swift by surprise. But there is at least one recorded instance in which a swift has been killed by a hobby in fair flight. This is to be found in that delightful book, Field Studies of some Rarer British Birds,[15] by Mr. William Walpole Bond. The description of the race is so vivid that, with the author’s kind permission, I reproduce it here.
“On June 14, 1907, as I lay in a spacious clearing of a big Sussex woodland, a sudden swirl of wings gave me instant pause in my meditations. Looking up, my eyes were held by a swift coasting earthwards in frantic haste, hotly pursued by a hobby not many yards in his wake. I literally held my breath with excitement, for here was an occurrence of dreamland only. Speeding on about a level with the tree-tops both birds measure the length of the long glade in fractional time, and the hawk gains almost imperceptibly.
“Then the pursued makes a mighty effort; he rises gamely, even slightly increasing his lead. Indeed it seemed he might shake off his deadly courser. Alas, my friend, it is to no purpose; the hobby has responded to your challenge, and now exhibits speed for which—glorious flier though he be—I should never have given him credit. Mounting with ease above his prospective prey, the lithe hawk compels him to describe an arc and once again to start a life—or death—struggle in a headlong slant across the clearing. That flight is his last—the swift has shot his bolt. Now inches only separate the birds, you could cover both with a very large handkerchief. Next instant the hawk rises straight and stoops strongly, pursuer and pursued become one. Binding to his quarry the hawk is away over the trees at my back without so much as the most momentary pause in the continuation of his eminently successful ‘shikar.’ Indeed, this continuity of action was possibly the most pleasing part of a praiseworthy performance, since you might reasonably have expected a break—however trivial—after what must have been a long and arduous chase. As a fact, the death-stroke was so featly and rapidly administered that, except that where a moment before there had been two birds there was now only one, and that a muffled clap and a few small dusky feathers twirling aimlessly in the summer breeze suggested some sort of untoward happening, it was difficult to realise that anything unusual had taken place.
“I have seen the irresistible death-stoop of the peregrine, the lightning rush of the tiny merlin, I have watched the earthward plunge after prey of buzzard, eagle, kite, and harrier; I have revelled in the agile snatch of the sparrow-hawk, in the silent hovering of the kestrel; and all have I enjoyed. Here was something quite different and even far better. Never have I seen skill so superb as was displayed by that hobby.”
It would therefore seem that the hobby, which is a peregrine in miniature, flies faster than the common swift even on a horizontal flight, but it is worthy of note that in both stoops referred to in this delightful description, the hobby gained by reason of gravity. True, he also gained altitude, but this may have been better manœuvring for position and not necessarily a greater speed. As the peregrine flies faster than the hobby, being a bird of the same structure but larger, the peregrine could no doubt overtake and kill the common swift if it would take the trouble to pursue so small a bird.
Next, as to the Alpine swift. This bird is much larger than the common swift—in length 8 inches as compared with 6·75 inches—whilst their wings are 8·45 inches and 6·8 inches respectively, and as the two birds are of the same structure, one would naturally expect that the Alpine swift would be much the faster flier. The flight of the Alpine swift, like that of the blackcock, which is probably the fastest flier amongst game birds with the possible exception of the capercailzie, is very deceptive.
Colonel Meinertzhagen, in the article already mentioned, describes some observations from an aeroplane in regard to the flight of a large flock of common swifts feeding at an altitude of 6000 feet over Mosul in Mesopotamia. He describes how they circled round the aeroplane, which was flying at 68 miles an hour, and easily overtook it. In commenting on this case he says: “The case of the Mosul swifts is interesting. The birds were probably not on passage but simply feeding. It is known that swifts travel great distances in search of food and ascend great altitudes.
“In the Middle Atlas of Morocco, in the Himalayas, in Crete, and Palestine, 4000 or 5000 feet and 50 miles or so in distance seems nothing to these incomparable fliers. I have had splendid opportunities of observing the Alpine, common, and spine-tailed swifts (Chaetura), and it has been a great disappointment to me that I have never been able to get a satisfactory estimate of their rate of flight, as they never continue on a level course. On a small island on the coast of Crete I was recently given a good exhibition of what an Alpine swift can do. I was watching some of these birds feeding round cliffs in which several pairs of Eleonora’s falcons were about to breed. Now, this delightful falcon is no mean flier, and as these swifts passed their cliff, the falcons would come out against them like rockets. The swifts would accelerate and would seem to be out of sight before the falcons were well on their way. So confident were the swifts in their superior speed, that every time they circled round the island they never failed to ‘draw’ the falcons, and seemed to be playing with them. I may add that these same falcons have little difficulty in overhauling and striking a rock-pigeon—itself no mean performer. I have also seen on record the case of falcons and swifts somewhere in India, where the former failed time after time to come up with his quarry. I, unfortunately, cannot trace the reference.