162 BIRDS AND MAN 



great height, they would descend to the earth again, 

 to disappear behind a neighbouring cHff. And on 

 each occasion they exhibited that wonderful aerial 

 feat, characteristic of the raven, and rare among 

 birds, of coming down in a series of long drops with 

 closed wings. I am inclined to think that a strong 

 wind is necessary for the performance of this feat, 

 enabling the bird to fall obliquely, and to arrest the 

 fall at any moment by merely throwing out the wings. 

 At any rate, it is a fact that I have never seen this 

 method of descent used by the bird in calm weather. 

 It is totally different to the tumbling down, as if 

 wounded, of ravens when two or more are seen toying 

 with each other in the air — a performance which is 

 also practised by rooks and other species of the crow 

 family. The tumbling feat is indulged in only when 

 the birds are playing, and, as it would appear, solely 

 for the fun of the thing ; the feat I am describing 

 has a use, as it enables the bird to come down from a 

 great height in the air in the shortest time and with 

 the least expenditure of force possible. With the 

 vertical fall of a bird like the gannet on its prey we 

 are not concerned here, but with the descent to earth 

 of a bird soaring at a considerable height. Now, 

 many birds when rushing rapidly down appear to 

 close their wings, but they are never wholly closed ; 



