STEERING 63 



have supple waists and poor steerers comparatively 

 stiff ones, the Duck being a good deal the stiffest 

 of those I have examined. 



It is difficult to account for the difference between 

 the two Kestrels, but there is no doubt that the 

 Duck is, of the birds in question, decidedly the 

 stiffest. In fact these measurements make it a priori 

 probable that suppleness of waist counts for 

 a good deal. The result of the sideways bend 

 must be that the bird is thrown on to its side — the 

 attitude which is assumed when a sudden turn is 

 to be made. 



For steering purposes, then, a bird has various 

 methods at his disposal. He can take unequal 

 wing-strokes or bend at the waist. Either of these 

 means will put him in the attitude in which we 

 see him steering to right or left, one wing pointing 

 downward, the other upward. And he can use 

 his tail as a rudder. Some birds may, no doubt, 

 steer partly by means of their feet, but I doubt 

 whether a foot is a very effective rudder. The 

 Duck's webbed feet do not seem to make him an 

 adept at turning. 



