Part 4
The genus _Chaetura_, to which the needle-tailed swift belongs, is easily distinguishable from the genus _Apus_ (to which the common swift and Alpine swift belong) by the wedge-shaped tail in which the shafts of the feathers are longer than the webs and protrude like spines. The tail in the only species (_Chaetura caudacuta caudacuta_) occurring in the British Isles, compared with that of the Alpine swift, is very short. It is almost square, and has ten feathers, which are very stiff and the shafts of which project 4-6 mm. (·156-·234 inch) beyond the web in a stiff point like that of a needle or spine.[19]
The shafts of the primaries are very strong and the wings very long. Gould[20] says, in reference to the spine-tailed swift, in a passage which is quoted in Seebohm:[21] “The keel or breast bone of this species is more than ordinarily deep and the pectoral muscles more developed than in any of its weight with which I am acquainted.” Probably the last-mentioned facts largely account for its superiority in speed over the Alpine swift.
In an article entitled “The Twelve Swiftest Birds of Australia,”[22] in which Mr. E. S. Sovenson gives the views of himself and various friends of his as to the relative speed of Australian birds, he says that after long observation he and they have no hesitation in stating that the spine-tailed swift is the swiftest Australian bird, and states that its speed has been computed at 180 miles an hour.
“Besides its swiftness,” he writes, “it is almost tireless of wing, being second only in that respect to the frigate bird, the bird of eternal flight. Both have very long wings in relation to the body--an indication of rapid flight. The swift, a bird of passage which crossed the wide sea after breeding in Japan, is not known to alight in Australia, where it spends a considerable time hunting its insect prey in the upper air.”
In _A History of the Birds of Europe_,[23] Dresser writes: “The present species (_Acanthyllis caudacuta_ or _Chaetura caudacuta caudacuta_) and _Acanthyllis gigantea_ are said to be the swiftest birds in existence. Tickell says that he never witnessed anything equal to the prodigious swiftness of its movements.”
_Chaetura caudacuta cochinchinensis_ (which is to be found in Malacca, Sumatra, and Cochin China) is a form of the spine-tailed swift allied to that species (_Chaetura caudacuta caudacuta_) which is so rare a visitor here. I have examined and compared numerous specimens of these three species of spine-tailed swifts, and it would seem practically certain, in view of their similarity in size and structure, that their speed must be similar.
Mr. E. Stuart Baker, who has made experiments as to the speed of the _Chaetura nudipes_ and the _Chaetura cochinchinensis_, writes:[24] “Both these species have a normal flighting speed of something very nearly approaching 200 miles an hour, enormously in excess of the powers of any other bird with which I am acquainted. In North Cachar, Assam, these birds used to fly directly over my bungalow in Haflang, flying thence in a straight line to a ridge of hills exactly two miles away, and when over the ridge at once dipping out of sight. We constantly timed these swifts and found that stop-watches made them cover this distance in from 36 seconds to 42 seconds, _i.e._ at a rate of exactly 200 miles an hour to 171·4.”
Writing of the _Chaetura nudipes_ Mr. W. T. Blanford, F.R.S., says:[25] “This and the other large spine-tails are, I believe, absolutely the swiftest of living birds. Their flight far exceeds that of the Alpine swift, and I doubt if any falcon can approach them in speed. They are generally seen in scattered flocks that play about for a time and disappear at a pace that must be seen to be appreciated.”
The same ornithologist refers[26] to the _Chaetura indica_ or brown-necked spine-tailed swift, which is a larger species (length about 9 inches, tail 2·6--wing 8--tarsus 6·8), as being “equal or possibly even superior in speed to _Chaetura nudipes_--so wonderful is their flight that Mr. H. R. P. Carter remarked that a flock of Alpine swifts, passing over immediately after some of the present species, ‘seemed to fly like owls after the arrow-like speed of the spine-tails.’”
I think, therefore, that if the speed in horizontal flight is alone to be considered, the spine-tailed swift is the fastest bird which flies in the British Isles, that the Alpine swift comes next; then come the northern falcons (or as they are usually called, gyr-falcons) and the peregrine falcon, in the order named, except in the case of a very short flight, in which case the Golden Plover and teal, being faster off the mark and better sprinters, will fly more quickly than the falcons, though they will, when the latter really get going, be gradually overtaken.
There remains for consideration the speed of the golden eagle and falcon in their downward flight, when stooping at their prey. There is no certain method of comparing their respective speeds in this unique kind of flight either with one another or with the speed of other birds which never fly in this way. In considering the question of the relative speed of the two birds in this particular kind of flight, I will first deal with the matter on principle and then consider such evidence of eye-witnesses as I have been able to obtain. The falcon has of course one great advantage over the eagle as regards equipment for swift flight. He has the long pointed wings typical of the true falcon, whereas the eagle has rounded wings. As between birds of similar size and spread of wings, the bird with pointed wings is faster than the one with rounded wings. Thus a blackcock is undoubtedly faster than a pheasant although their bodies are about the same size, or to be more accurate the blackcock is rather smaller than the pheasant. A striking instance of this was recently given in the _Field_[27] by Mr. G. Denholm Armour, who wrote: “Some years ago a friend asked me to come to Argyllshire late in the autumn to shoot some black-game which lived in the birch and fir woods hanging along the lower parts of the hills.
“Our method was to place ourselves in a break in the line of woods at the bottom of the hill, sending two or three men to drive the wood towards us. The result was usually very high birds flying downhill and very fast. On several occasions at the same time came a blackcock and a cock pheasant, of which there were a few in almost every drive. Incidentally, most of the pheasants we shot were old birds with long spurs, so were very strong on the wing. In each case--and I noticed several--the blackcock outflew the pheasant by what seemed to be about 50 per cent in pace, leaving him as a racing car would a ‘runabout.’
“The chance of comparison was very interesting, being between birds of much the same weight and size, both started under the same conditions, and I think ‘doing their best.’ Had the blackcock come alone, I think his much slower wing beat would have made one think him the slower flier of the two.”
The blackcock and grouse have wings exactly alike--but the blackcock is heavier than the grouse and much faster.
With the exception of the difference in the wings mentioned above, the structure of the eagle and falcon is very similar, and as has been pointed out, the larger of two birds of similar structure once it gets going is almost invariably faster, owing no doubt to its superior muscular power and driving force.
In comparing the downward flight of the eagle and falcon it is also necessary to recollect the advantage which the former has by reason of its much greater weight.
It is difficult to obtain thoroughly reliable records of the weights of the golden eagle and the different falcons; but so far as I can ascertain, the weight of the eagle varies from 8½ to 12½ lb., that of the gyr-falcon from 3 to 3¾ lb., and that of the peregrine from 2 to 3 ounces under 2 lb. to 2¾ lb., in each case of course the female bird being heavier than the male.
But for the resistance of the air, all bodies, light or heavy, small or large, would fall at the same rate. In fact, however, as velocity increases a notable air resistance is set up which increases rapidly. The velocity of a body falling freely _in vacuo_ is over forty miles per hour at the end of two seconds, over sixty at the end of three seconds, and so on.
We all know by experience the great force exerted by a wind of a velocity even as low as thirty miles an hour, which most people would call a hurricane. But it is not perhaps so generally known that in proportion to its weight, other things such as shape and specific gravity being similar, a small body experiences much greater resistance than a large body. The resistance of the air to the fine particles of vapour which constitute a cloud is such that they only fall at the same rate of a few feet per hour. And in the case of two birds of similar shape and specific gravity, but one eight times the weight of the other, the larger bird would ultimately attain a velocity roughly twice as great as the other, if both fell for a sufficient distance to attain their limiting velocities, _i.e._ the velocity at which the resistance offered by the air is equal to the attraction of gravity. Similarly if the one bird were four times the weight of the other, the velocity ultimately attained under the conditions mentioned would be roughly one and a half times as great as the other.
In “Notes by an Old Stalker” in the _Field_ for September 9, 1922 (p. 370) there appears the following interesting account of a duel between a golden eagle and a peregrine which the writer himself witnessed:
“Although by a long way our most powerful bird, the eagle is by no means a match for some much smaller combatants. Once I saw an eagle soaring placidly along when from a range of precipices immediately below him a falcon shot up into the air. Without a moment’s hesitation he attacked the giant bird. The eagle at once joined combat, and through the telescope I could see his efforts to hit his adversary with beak and wing. One blow from either and it would be all over with the falcon; but the latter evidently realised this and regulated his tactics accordingly. The movements of the eagle were slow and cumbrous compared to the rapid action and lithe activity of his adversary. Every time he dodged the eagle’s stroke and, wheeling rapidly, got in his blow before the huge bird could recover himself. That the eagle was in a great rage was evident, for I could hear him emitting sounds that resembled nothing so much as the bark of a terrier. Finally, realising the hopelessness of the contest, he took to flight. I previously knew that the eagle was fast on wing, but the speed he now exhibited was a revelation to me. With half-extended, half-curved wings, showing never a tremor, he cleft the air straight as a bullet. The falcon pursued, but, being left hopelessly behind, soon gave up the chase.”
The flight of the eagle here described was obviously a glide or downward flight, when, as I have pointed out, gravity would assist his speed to a greater extent than it would in a bird of less weight--the peregrine.
In the case of a bird of prey descending from a height on its quarry, the nearer its downward flight is to the vertical the faster will it descend. In coming down on its prey, neither the eagle nor the falcon completely closes its wings, probably because if it did so, it would lose control. This is also true of the gannet or solan goose, which has been described as the largest and noblest-looking of our sea fowl. The great speed which a bird of large size can attain in downward flight can to some extent be realised by watching the gannet when he drops head first as he descends perpendicularly on to the fish in the water. I have carefully examined and compared the skeletons of the eagle and peregrine and have tried to form some idea as to the relative muscular power and driving force of the two birds, and bearing in mind the facts stated above, and the greatly superior size and weight of the eagle, it seems reasonable to conclude on principle that the eagle is probably faster than the gyr-falcon or peregrine in a downward flight, assuming that both birds are putting forth all their powers.
As regards the evidence of eye-witnesses, I have discussed this question with many stalkers. The majority of them have never seen the eagle stoop at its quarry and strike it a blow which sends it to the ground as the peregrine so often does--though they have seen the eagle seize its quarry in the air or pounce on it on the ground and carry it off. Only a few of these, however, have any doubt as a result of what they have heard from other stalkers and keepers that the eagle on occasion does adopt the former method.
It is, however, an undoubted fact that although the eagle generally captures birds which he is pursuing by seizing them in his talons or, to use the falconer’s term, binding on them, he occasionally stoops on and strikes them in the air, sending them hurtling to the ground in the same way as the peregrine does.
The reason why the eagle so rarely adopts this method is probably because it can secure its prey without doing so, and further if it were to exert all its powers when descending from a considerable height at an angle near the vertical on a grouse, blackcock, or ptarmigan (which do not usually fly very high above the ground), it would incur a serious risk of injury in consequence of being carried on by its impetus and dashing against the rocks or ground after striking down its prey.
The interesting, and I think significant, fact is that although some of these stalkers with whom I have discussed the question think that the peregrine probably flies faster than the eagle, every one of them who has seen the eagle kill its quarry in this way (and I know several) has told me that in his opinion the eagle in its final rush is faster than the peregrine. It is also important in this connection to bear in mind the fact on which Major Radclyffe lays such stress--that it is an optical illusion to imagine that a smaller-sized bird is flying faster than a larger bird of similar shape and make, and that, as he says, ninety-nine sportsmen out of a hundred would probably tell you that a snipe flies faster than a woodcock--whereas the converse is true. An old keeper in the North, whom I have known for many years, told me that he had seen the eagle stoop at and strike his quarry in this way on two occasions, and that it moved in its final downward flight with the same lightning-like rapidity as the peregrine.
John Finlayson, the head stalker at Killilan, wrote to me last February as follows: “I have once plainly seen the eagle driving after grouse and striking it down very similar like what the peregrine falcon does. It happened at the north end of Corrie-ach. I was going up to Patt from Mulbuie way. A covey of grouse came tearing down from the low end of Aonachbuie in front of me, about 300 yards away, and an eagle in hot pursuit, wings gathered up, and making a swishing noise; going through the air it struck one down, with a cloud of feathers knocked out when it did so. The eagle glided up a little, then balanced and dropped down where the bird fell; it was a little over a ridge out of my view; when I got up to the place I saw the eagle well up the glen going fast with the bird in its talons.”
My gamekeeper, Donald McIver, who has lived all his life in Ross-shire, on one occasion saw an eagle strike and kill a blackcock. This is his account of it. “In the forest of Strathconan, where I was for a number of years, I once saw a very fine sight of an eagle pursuing a blackcock. The blackcock got up at the head of a very deep corrie and came over at a very great height. The eagle was about and soon after it. I could see him overtake the bird, and I would say that he struck him the same way as the peregrine does with his claw. I saw something drop, but could not make out what it was at the time; then the eagle doubled in the air and caught the bird before it reached the ground. None of the other eagles I have seen after their prey have struck it like this in the air. They have always clutched at their prey, but this time the eagle struck the bird and went right past him. I was not far off, and could hear a tremendous noise of the wings. When the eagle doubled back and caught the bird in the air I would judge that the bird would be as high up as three hundred feet, and when he doubled back I should think he was not fifty.
“Perhaps the narrowness of the corrie might be the reason for him taking the bird in the way he did--I went to the place and found the head of the blackcock; there was about three inches of skin hanging to the head, a tear like what would be done with the claw. This is the only time I ever saw an eagle kill a bird in the air, but it was a grand sight. This happened in January 1895, in Corrie Vullin, Strathconan.”
This amazing feat in aerial gymnastics is no doubt also performed on rare occasions by the peregrine. One of the most experienced of living falconers wrote to me as follows: “I have seen a very celebrated falcon which I owned for years bring off a remarkable trick several times. She used to strike at the back of the grouse’s head, and I have seen her just scalp the grouse, taking a piece out of its skull not as large as a pea, and thus killing the bird in mid-air just as if it was shot; often, when the grouse was high above the ground, I have seen the falcon then take a sharp turn in the air as the grouse was falling, like a spinning leaf, and pick it up in her feet before it could touch the ground--a very wonderful sight.”
An old friend of mine, who is head stalker in one of our best-known deer forests and whose veracity I have every reason to accept, told me an interesting story which further illustrates what fine feats in the air the peregrine falcon can perform. He said that on one occasion he saw a falcon strike and carry off a crow. As the falcon was circling higher and higher up, carrying off this crow, it was mobbed by a considerable number of other crows. For some time it ignored them, continuing its steady upward circling flight until one crow, becoming rather bolder than the rest, provoked the falcon into retaliation. Dropping the crow it was carrying, the falcon stooped on the troublesome crow, struck and killed it and, turning with extraordinary rapidity, caught in the air the dead crow which it had been carrying, and then recommenced its upward flight without further trouble from the crows.
The marvellous speed of the golden eagle and peregrine in their final rush, when stooping from a height at their quarry, must be seen to be believed. Few persons have been so fortunate as to have this opportunity in the case of the golden eagle, although this grand bird is often to be seen in some forests and has no doubt increased in numbers in recent years. On the other hand, there are of course many persons who have seen both the wild peregrine and the trained gyrfalcon and peregrine strike down their quarry.
The well-known ornithologist and wild-fowler, Mr. W. H. Robinson of Lancaster, in a letter in the _Field_ of January 28, 1922, after stating from his own experience that the peregrine can overtake the golden plover and the curlew with the greatest ease, says:
“To my mind one of the fastest things I have ever witnessed is the last effort of a peregrine in chase of a wild duck when, fast as is the accelerated speed of a mallard, it seems almost to be standing still in the air when the peregrine stoops over it.”
Any one who has seen this, as I am glad to say I have, will assuredly echo these words.
It is of course pure speculation whether, in the comparatively short flight of an eagle or falcon stooping in its final downward rush at its prey, its speed exceeds the maximum speed of the spine-tailed swift. Those, however, who have seen the last effort of the eagle or falcon in a flight of that unique kind will never believe, without scientific demonstration to the contrary, that any other bird in the British Isles can fly faster.
V
A GOOD DAY IN THE FOREST OF COIGNAFEARN
Towards the end of a September several years ago I was so fortunate as to be invited to stalk at Coignafearn, which has always been famous for the size and weight of its deer. On reaching the lodge on a Saturday night, I heard that the head stalker had met with an accident, fortunately not a bad one, but possibly serious enough to prevent his going out with me on the following Monday. He had been out in the forest the day before I arrived, and on going up to a stag to bleed him, the stag had given a sudden unexpected plunge, which had caused the stalker to inflict on himself a nasty wound in his right leg with his knife, which was open in his hand; another instance that no one, not even the oldest and most experienced of stalkers, can be too careful on these occasions. On Monday morning he was much better but not fit to go with me. The season was well advanced, and my host was very anxious to kill the usual number of stags as soon as possible. It was therefore arranged that I should act as my own stalker, and take with me a watcher named Maclennan. I had also two gillies with me and a couple of ponies, and my host told me that he would be only too glad, if I could manage it, if I would kill as many stags as could be brought in. Maclennan had never acted as stalker, but as there is nothing I like better than to do the stalking myself, I was very pleased with this arrangement, for Maclennan knew the ground thoroughly, and I felt sure that his assistance would be invaluable; indeed, without him I could of course have done practically nothing, as the ground was strange to me. We were in the forest and spying by 10 A.M., and very soon we saw a good stag with some hinds. The stalk was unsuccessful, but it was not long before we spied another good stag, and without much difficulty I managed to get into a good position within about 150 yards, and shot him through the heart. He proved to be a good eight-pointer, and weighed 15 stone clean. Shortly after this we spied a large herd of deer which were very restless, continually on the move. There were several good stags in the herd, and these were roaring and fighting and driving the hinds about. Two of them in particular, which looked like the heaviest, engaged in a battle which lasted for some time; but gradually one of them showed signs of being worsted and, watching his opportunity, suddenly turned tail and bolted. It is rarely that battles of this kind end fatally--only once have I met an eye-witness of such an occurrence. The battle was between a switch and a ten-pointer. The combatants were fighting on the side of a hill and were very evenly matched. My informant, the stalker at Attadale, said that after some time the switch, taking advantage of being on slightly higher ground, charged his adversary and, getting past his guard, pierced his side with his antlers. The ten-pointer immediately fell to the ground dead. The stalker ran up and found that the dead stag had been pierced through the heart by his conqueror.
The stag with the best horns is generally not the best fighter and is frequently driven out by a switch-horn or “caberslach,” whose long skewer-like antlers are the most effective horns for fighting. The best fighter of all is, however, the hummel--a stag which has no horns at all, and which is in consequence a very heavy beast.