132 THE FLIGHT OF BIRDS 



glide he generally hits off the up-current, but not in- 

 frequently he fails and has to put in a few strokes. 

 Small pieces of paper thrown over the stern show that 

 the up -current is not always at the same distance 

 behind the ship. Hence this method of advance, 

 though a very gay and lively one, has, whenever I 

 have observed it, been lacking in precision. How- 

 ever, when the conditions are not perfect, the Gull 

 may be trusted to make the best of a bad job. I 

 have just been watching some Gulls that were 

 following a small steamer. The wind was blowing 

 nearly at a right angle to the vessel's course. There 

 was an up-current available, but apparently an 

 unsatisfactory one, for there was never an advance, 

 except for a few moments, without very distinct 

 wing-beats. The Gulls faced the wind and, while 

 almost uninterruptedly beating with their wings, 

 advanced nearly sideways, right wing leading. Had 

 there been no up-current, such a style of flight would, 

 I believe, have been impossible. They must have 

 been inclining their bodies slightly downwards, from 

 the left side to the right, so as to induce movement 

 in the direction desired. I am quite aware that 

 birds, when they wish to advance at right angles 

 to an ordinary horizontal wind, make a half-turn 

 towards it, so as not to be swept out of their course. 

 But here was an instance of a much more complete 

 turn and an advance almost sideways. 



Clever as the Gull is at such methods of advance, 

 the Shearwater, to my mind, is a yet more perfect 

 master of the art. He does not require any steamer 

 to help him. If only there are waves and a wind, 

 he has all the conditions that he wants. He keeps 



