JlLY, 1901.] 



KNOWLEDGE. 



149J1 



The development of considerable aiiiplitudo in such 

 swells must require a good deal of time, and it is not 

 unreasonable to think of those which come iu upon our 

 westeni shores as having graduallv grown (in spite of 

 intervals of partial subsidence) during a run of ot'OO 

 miles from the shores of America, experiencing at inter- 

 vals the force of westerly gales. 



THE RELATIVE SPEEDS OF SOME COMMON 

 BIRDS. 



By Chakles a. Witchell. 



The llight of a bird is usually so devious that its speed 

 is not easy to determine; and when the journey is 

 directly from one point to another the uncertainty in 

 the mind of an onlooker as to wliere the flight will end 

 is a further hindrance to accurate observation. A bird 

 in the open, again, flying across the plane of vision and 

 far from a fixed point, requires the preconception of 

 its distance from us before yielding any data of its speed. 

 The difficulty of the SHlbject. indeed, must be urged as 

 the most reasonable excuse for the diversity of rate at 

 which birds have been stated to fly. even by careful 

 observers. The subject of flight is a large one. on which 

 the reader cannot do better than consult the article in 

 Professor Newton's Did ntnanj nf Hirdx. 1 do not pro- 

 pose to ent«r into it further than to mention some 

 incidents I have seen in which the relative speeds of 

 some common birds have been tested by the birds 

 themselves, or they have provided man with a means to 

 readily gauge their celerity for a few moments. 



The commonest test of such speed is the pigeon-race, 

 but in this the direction of the wind in relation to the 

 birds may be considered the dominant influence. The 

 questions of distance and familiarity with the course 

 also arise. Independently of aid from the wind, 40 

 miles per hour would seem to be about the full speed 

 for a good pigeon flying a long distance. I have had 

 some experience in this matter, having " timed " for a 

 good many races of the Southern Counties Club years 

 ago. I am speaking, of course, of flight at a moderate 

 elevation, such as pigeons generally affect. With the 

 data available, none would dream of saying that a pigeon 

 could fly at. say, 70 miles per hour against a moderate 

 wind. 



With regard to wild birds generally, not having such 

 sure data for guidance the imagination has been allowed 

 fuller play, with the natural consequences. 



The swift affords a common illustration. The writer 

 of an article in the Dudij .\V(/w thought that the swift 

 could distance any falcon, and attain a speed of 150 

 miles per hour. I saw an adult male hobby falcon in 

 the flesh, shot on a swift which it had overtaken in fair 

 flight. A friend of Major Hawkins Fisher had seen a 

 similar incident ; and he himself bears witness to the 

 wild alarm aroused in some hirundines by the appear- 

 ance of a hobby from which they sped away, instead of 

 mobbing it as they would have a slower hawk. Also, 

 one of Major Fisher's peregrine falcons, even after the 

 usual tethering of such captives, was able to chase a 

 swift up and dowai the sky for a minute or more. 



One day, travelling by express train through a 

 valley, I noticed that the trees proved the wind to be 

 blowing gently in the direction of our travel ; and I 

 also observed that the swifts pa.ssing along the valley. 

 even " with " the wind, did not move so fast as the train, 

 which was not exceeding the rate of some 45 miles per 



iiour. The birds seenied lo be flying at; their usual 

 pace when feeding. 



Another bird whose speed seems to be over-estim.-ilc-il 

 is the sparrow-hawk. 1 have seen it compared to a. 

 cannon-ball in celerity; but the suggestion is absuril, 

 A bird which arrives on the scene at full speed has ;i 

 great advantage over others sedately feeding, so far as 

 the chances of dclivei'ing an attack are concerned ; and 

 this may be partly tlie reason why so many of the 

 smaller birds rise on the wing when alarmed liy (he 

 sight of a hawk. It is as tliougli they considered (hat, 

 givc:i a fair start, (licy might disregard (lie eucniy. 

 Wc^ seeing a Hnch or a starling taken in a monieiit. 

 often do not weigh the fact that the victim was hardly 

 on the wing, and probably rising, when the bird of 

 prey came like a whirlwind and overwhelmed it. The 

 sparrow-hawk docs not more than any other like a 

 long " stern-chase, " but prefers to attack with the 

 advantage of a surprise when darting from a tree or 

 around the corner of a wood, or when stooping with 

 splendid speed from a poise several hundred yards above 

 the ground. Even if it discovers its prey when traver- 

 sing the country at a lower elevation, it has still the 

 power of a fair monicntum to take full advantage of 

 the chance of a swooping rush at the prey, which is 

 probably on the ground. Of course, when a rook is 

 watched chasing a sparrow-hawk across the sky, there 

 is nothing to show that the latter is seriously trying to 

 fly at speed. On the contrary, it generally seems in 

 such a case tihat the hawk is relying mainly on its 

 soaring powers to avoid the attack. And it is remark- 

 able indeed with how little apparent effort the hawk 

 will soar up and up from the rook, which, all the while, 

 is obviously exerting itself frantically. On the other 

 hand, it is generally to be seen that when the birds 

 are flying at a level, the rook has no difficulty in over- 

 taking the hawk, who. after a turn or two. begins to go 

 up. as already stated. The kestrel seems more often to 

 evade its enemies by a turn of speed, though it also takes 

 to the soar readily. Last autumn I saw a fine female 

 kestrel harried by two peewits, which swooped at it 

 alternately very prettily and with surprising per- 

 sistence. At last the hawk, seemingly tired of " putting 

 out ' (as a falconer would say) these active birds, went 

 straight ahead apparently as hard as it could ; and then 

 one could see that the peewits were not able to overtake 

 it, though they followed to some distance. The same 

 tiling happened with the crow : the latter chased the 

 hawk, but was at last outflown in a sheer straight 

 flight. 



Keturiung to the sparrow-hawk, it is by no means 

 always successful in taking a small bird, even when the 

 chase is over an open field. 1 have never seen it 

 attempt to take a lark that had anything of a fair 

 start. I never saw a kestrel attempt this prey; and I 

 have seen a skylark go singing past a hovering kestrel 

 (seemingly only a few yards distant) as unconcernedly 

 as though the latter had been a pigeon. 



One unsuccessful flight by a sparrow-hawk was very 

 pretty to witness. A fieldfare was attacked far from 

 covert of any kind. The quarry wont off at its best, 

 and the hawk raced after it, and 'overhauled it; but the 

 fieldfare, with a ready turn (an upward turn it seemed) 

 put out the hawk and gained several yards start, to 

 r(;turn upon its former course, with the hawk speeding 

 after, as before. Another turn saved the fieldfare, and 

 back it went, for the third time, apparently covering 

 just the same ground ; and once more the upward spring 



