158 THE UNIVERSITY OF THE STATE OF NEW YORK 



American bittern Nu BiA9 



Note legs being lifted to normal position during flight. Note 

 also position of wings and determine their direction of movement. 



Green heron Nu HeH8 



Compare with the preceding. 



Canvasbacks Nu Ca9 



Heavy bodied, short legged birds have difficulty in rising. 

 ■Note the positions of the feet and also of the wings in the dif- 

 ferent birds. 



Scaup ducks Nu DuS9 



The tail of the duck is poorly developed. Note how the webbed 

 feet are being used as rudders. 



Baldpate Nu Bel 



This bird is about to alight and its feet are used to help check 

 the momentum. Compare with preceding. 



Mallards Nu Mc82 



Note the position of the feet and decide whether the birds are 

 just starting flight or have been under way for some time. 



Mallard Nu Mc84 



Compare with the preceding and make same decision. 



c The tail 



The tail of a bird, aside from the feathers borne upon it, is a 

 short compact structure showing the same tendency to bring all 

 weight toward the center of equiUbrium. The number of feathers 

 borne upon it varies with different species, but in all perching 

 birds the number is twelve. In the earliest known birds (the 

 archseopteryx) the tail was long like a lizard's and the feathers 

 were borne along each side. The shortening of this structure has 

 doubtless aided the power of flight. The tail is the steering organ 

 during flight and a bird without a tail is like a ship without a 

 rudder. It is likewise used to check the bird's momentum when 

 it is about to alight. 



Tree swallow Nu SuT6 



The bird started for its nesting hole but swerved just as the 

 photographer snapped it. Note the position of the tail. 



