Birds. 6717 



or four to a dozen birds dash off with amazing velocity, the wings of 

 now one and now another being elevated, motionless, above the 

 body, but the tips kept backwards (a manoeuvre, I think, very unusual 

 with Hirundinidoe), and in this position shoot along with wonderful 

 impetus, the whole so close together that a lucky shot might bring 

 down half-a-dozen. I take great pleasure in watching them. No 

 bird seems to spend more of its time in amusement, or betrays more 

 exquisite pleasure in the exercise of the wonderful gifts bestowed 

 upon it. Often, when in the forest after other objects, I hear the 

 shrill * wee-wee ' far over the tops of the trees, the birds themselves 

 of course invisible. Towards the middle of the day they generally 

 disappear, and are again to be seen towards afternoon, when they 

 practise the same manoeuvres till towards sunset. If there be heavy 

 rain, they come up with it, and, either before or after it, dash about 

 low over the ground in the manner described by your correspondent. 

 Then is the best opportunity the naturalist is likely to get for pro- 

 curing specimens. To hit them when skimming low would be a diffi- 

 cult feat, and one I do not attempt ; but they often rise about thirty 

 feet, and come up slowly against the wind, evidently catching drifting 

 insects. They are then within the capabilities of an ordinary marks- 

 man. With regard to the gyrating column, the question has often 

 occurred to me whether this is to be considered as a mode of feeding 

 or not ; 1 think not, from the extreme steadiness of every bird ; but 

 that it is a mere concerted movement for collecting before making a 

 change of hunting-ground for the whole flock, or perhaps simply a 

 mode of enjoying their life and powers. I have often been amused 

 by watching a Cathartes join them, and steadily keep his place in the 

 crowd till it disperses. This arises, I imagine, not from any predi- 

 lection of the swifts for such strange company, but from an odd 

 inclination the John Crows have to join any gyrating bird, probably 

 supposing that, as they only gyrate steadily when there is something 

 near in their way of eating, other birds do the same. They often 

 join the chicken hawk in the same way, merely, I think, to see what 

 he has in his eye, for he sweeps along utterly indifferent to his train 

 of black attendants. But in the case of the swifts this curious habit 

 is in one respect fortunate, as, the rate of gyration of these Vulturidae 

 in ordinarily calm weather being well known, it enables me to say 

 that that of Acanthylis is little, if anything, faster. If there be much 

 wind the velocity is greatly increased, and they soon break up. 

 Other birds are also deceived in the same way. I once noticed 

 Hirundo euchrysea attack one that was gyrating lower than the rest, 



