162 THE UNIVERSITY OF THE STATE OF NEW YORK 



The ducks have rather short pointed wings and they, too, can 

 develop great speed. The diving ducks, Uke the scaups and can- 

 vasbacks, that fly relatively short distances and depend more 

 upon diving for safety, have shorter wings than the dabbling 

 ducks, like the black ducks and baldpates, that fly longer dis- 

 tances to their feeding grounds and depend entirely upon flight 

 for safety. 



Scaup ducks Nu DuS7 



Compare with the preceding, making similar observations. 

 Both the scaups and mergansers are "diving ducks," although 

 the mergansers do not belong in subfamily Fuligulinae, which 

 are the real diving ducks. 



Baldpates Nu Bc8 



The baldpates are dabbling ducks. Compare with the preced- 

 ing. The difference in relative length of wings is not great, but 

 it is observable. 



Black ducks Nu DuB8 



Compare with the preceding slides and determine from the 

 photograph alone in which group of ducks the black ducks 

 belong. 



Geese Nu GpC9 



In which group would you put the geese? 



A short, narrow wing requires incessant beating to drive the 

 bird along and such we find in the hummingbirds, whose wings 

 vibrate so fast as to be indistinguishable. 



Hummingbird Nu HuR 



In hovering before flowers, even as in direct flight, the wings 

 are moved so rapidly that the camera records only a blur even 

 in 1/500 of a second. 



3 Disuse of wings 



When the bird does not use its wings very much or learns to 

 find its food and escape its enemies without them, the wings 

 become weak and more or less useless. Some birds, indeed, have 

 entirely lost the power of flight and depend wholly upon diving 

 or hiding. 



Virginia rail Nu RV9 



The rails live in the marshes where they are able to skulk and 

 hide in the marsh vegetation and seldom have to fly. Their 



