26 THE AUKS 



non-biting surface of the wing. In sub-aquatic flight, on the contrary, 

 the most effective stroke is delivered downwards and backwards, the 

 least effective one upwards and forwards." In aerial flight the line 

 of the body is inclined slightly upwards, in the other slightly down- 

 wards. The difference is explained by the fact that, while forward 

 movement is the object in both cases, the sub-aquatic flier, being 

 lighter than water, has to keep itself from rising, while the aerial 

 flier, being heavier than the air, has to keep itself from falling. 1 



The fish, when brought by guillemots to the ledge, is either dropped 

 there for the young to pick up, or is snatched by the latter before it 

 touches ground. What is the procedure in the case of the razorbill 

 I have been unable to find out. 



Both species drink salt water. The same fact has been noted in 

 the case of the sandgrouse. 



The following are two little domestic scenes described from life 

 by the pen of Mr. E. Selous, who has recorded in greater detail than 

 any one the life of guillemots on the ledges during the time that the 

 young are hatched. 



The first illustrates the act of feeding the chick : " The chick, 

 when a very substantial fish is brought in for him, is asleep under 

 his mother's wing, and both parents seem averse to disturbing him. 

 The one with the fish seems quite embarrassed. He approaches, 

 stands still, looks at his partner as if for advice, shuffles about, turns 

 this way and that, and several times, bending his head, gives a choked 

 and muffled jodel, for his mouth is almost too full to speak. Still the 

 chick sleeps on, and still the parents seem to doubt the advisability 

 of waking him. At length, however, they admit it to be necessary. 

 The father shuffles up into his usual position, the mother rises by 

 slow and reluctant stages, as though apologetically, and finally stirs 

 the chick several times with her bill till at last he rouses. Then, in 

 a moment, he busks up, and, seizing the large fish, swallows it in a 

 whole-hearted gulp." 2 



1 Animal Locomotion, p. 92. * The Bird Watcher in the Shetland.?. 



