98 HABITS AND INSTINCTS OF ANIMALS. CHAP. IV. 



flying, swimming, walking, running, and diving ; and 

 are performed in very different ways and degrees. 



(120.) Flight is, to most birds, of the utmost im- 

 portance, and has been thus ingeniously described : 

 " When a bird is on the ground, and intends to fly, he 

 takes a leap, stretches his wings from the body, and 

 strikes them downward with great force : by this stroke 

 they "are put into an oblique direction, partly upwards, 

 and partly horizontally forwards. That part of the 

 force tending upwards, is destroyed by the weight of 

 the bird ; and the horizontal force serves to carry him 

 forward. The stroke being completed, he moves up 

 his wings, which, being contracted, and having their 

 edges turned upward, meet with very little resistance, 

 from the air. When they are sufficiently elevated, he 

 makes a second stroke downwards, and the impulse of 

 the air again moves him forward. These successive 

 strokes act as so many leaps. When the bird wants to 

 turn either to the right or left, he strikes strongly with 

 the opposite wing, and this impels him to the proper 

 side. The tail act slike the rudder of a ship, except 

 that it moves him upward or downward, instead of 

 sideways. If the bird want to rise, he raises his tail ; 

 and if to fall, he depresses it : whilst in a horizontal 

 position, it keeps him steady." * 



(121.) The modes of flight in birds are, perhaps, 

 as numerous as the families into which they are di- 

 vided ; so that a few of the most conspicuous need only 

 be mentioned. The greater part of the birds of prey 

 (Rapiores) soar to an amazing height, as if a certain 

 elevation was necessary for them to discover their prey : 

 when that is discerned, they suddenly dart down al- 

 most perpendicularly upon their victim. Buzzards, 

 says White, sail round in circles, with wings expanded, 

 and motionless : it is from their gliding manner, that 

 the former are fitill called, in the North of England, 

 gleads ; from the Saxon verb, glidan, to glide. The 

 kestrel, on the contrary, has a peculiar manner of 



* Bing. Anim. Biog. vol. i. p. 23. 



