Beaks and Bills 



231 



and Black Skimmers. Except in their bills these birds 

 are almost identical in structure, but the bill makes a 



Fig. 1()9.— Bill of Tern. 



Fig 170— Bill of Skimmer 

 Closely related birds which differ in their feeding habits. 



i^ast difference in the appearance of a bird, as is very 

 apparent when these two species are seen flying about 



