100 THE FLIGHT OF BIRDS 



it is possible for them to swim, and the smallest with 

 which it is possible for them to fly. The wing-beats 

 during flight are marvellously rapid ; there is visible 

 a rapidly-moving body and a blur on either side 

 where the wings are working with terrific speed. 

 The Water- Ouzel searches for his food among the 

 weeds in the bed of fast-running streams, and he, 

 too, has short wings that he plies with very great 

 rapidity. 



The rolling flight of Partridges and Grouse is very 

 striking. When you put them up, they never, till 

 they have got some distance off, keep on an even 

 keel. Probably this rolling flight makes it less easy 

 for big birds of prey to swoop down upon them with 

 true aim, and it may help them to glance at a 

 pursuing enemy. In fact, the Partridge and the 

 Grouse are still, in their habits, adapting themselves 

 to an environment of raptorial birds rather than to 

 an environment of sportsmen and gamekeepers. 

 The zigzagging flight of the Snipe — a very spirited 

 and characteristic performance — is a different thing ; 

 the line of flight is a zigzag, but at the same time 

 there is the rolling that we see in the Grouse's flight. 

 It is well calculated to confuse the aim of an assailant, 

 whether he be a bird of prey or a novice with a gun. 



The way in which the long-necked and the long- 

 legged birds carry their necks and their legs is inter- 

 esting. The Duck and the Goose stretch their necks 

 forward to their full length. This may be because 

 the breastbone that carries the heavy flight-muscles 

 is very long, so that the head and neck are used to 

 balance the weight farther back. The Heron flies 

 habitually with his neck bent — a remarkable fact 



