Beaks and Bills Paw 
and Black Skimmers. Except in their bills these birds 
are almost identical in structure, but the bill makes a 
Fic. 169.—Bill of Tern. 
Fic 170 —Bill of Skimmer 
Closely related birds which differ in their feeding babits. 
vast difference in the appearance of a bird, as is very 
apparent when these two species are seen flying about 
