252 THE STRUCTURE AND LIFE OF BIRDS chap. 



others. The Swallow, like the Kestrel a first-rate 

 steerer, comes second. The Duck, who turns in a long 

 curve and with labour, has the stiffest waist of all. It 

 seems probable that a bird alters his balance in order to 

 change direction much as a skater does. Supposing 

 that he is curving to the right on the outside edge 

 on the right foot, the skater turns to the inside 

 edge (on the same foot), and curves to the 

 left by swinging the weight of his shoulders across. 

 And this is done by contracting the muscles at the 

 waist which lower the left shoulder. A bird may well 

 change balance in a similar way, swinging his hind- 

 quarters to right or left according to the direction 

 in which he wishes to go, and beneath the feathers 

 the process may not be visible to us. Certainly 

 the head is often turned at the moment of wheeling, 

 apparently to help the movement. Occasionally, how- 

 ever, like a good skater who despises conspicuous helps 

 to a change of equilibrium, such as a swing of the leg, 

 a Gull may be seen looking to the right while he slowly 

 turns to the left. It is these slow turns, when there is 

 almost certainly no beat of the wings, and during which 

 the head is occasionally turned the other way, that 

 make me think a bird alters his balance by a bend at 

 the waist as a skater does. In the more rapid turns 

 there may well be a momentary unequal beat of the 

 wings that defies detection. 



Stopping. Use of the Bastaiti Wing. 

 When a Pigeon in mid -flight wishes suddenly to stop 

 he alters the inclination of his body, which has been 

 nearly horizontal, and, relaxing the muscles that had 



