Beaks and Bills 245 



very rapidly, as we can see in Figs. 190 and 191. There 

 are many resemblances between hummingbirds and in- 

 sects, due entirely to the similarity in their feeding habits. 

 Certain flowers are especially adapted in structure to 

 attract certain bees or moths, which in return unconsciously 

 cross-fertilize the blossoms; and certain of the various 

 bills of hummingbirds reflect the exact contour of the 

 corollas in which the birds seek their food. Among 

 hummingbirds the various shapes of bills of other groups 

 are reproduced again. Humming through the air about 

 us in the tropics speed miniature avocets, ibises, stilts, 

 mergansers, and we realize, as never before, the never- 

 ending devices of Nature, providing for the needs of all, 

 from the greatest to the least; endless patterns paral- 

 leling each other, but never identical. Indeed, in the 

 great family of South American birds known as Wood- 

 hewers the diversity in shape, size, and direction of bills 

 is so great that it seems as if not a niche, or crack, or hollow 

 in the bark of any tree in the forest where these birds 

 abound would afford a safe retreat to an insect! 



It remains to mention the woodpecker's bill, which 

 is used chisel-like, for excavating his home as well as 

 in boring for grubs. With his beak the nuthatch ham- 

 mers his acorns, and the tailor-bird sews his nest. The 

 thick conical beaks of all sparrows and finches are for 

 cracking seeds; while the weaker, more slender beaks 

 of warblers, thrushes, and wrens reflect a diet of insects. 



Among the finches is a group of several species which, 

 by a thrust of the bill, have at their command a new 

 source of food, one which there are none to dispute with 



