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 
