CHAPTER II. 
THE LIVING BIRD. 
Factors of Evolution —If while in the fields we ob- 
serve birds with an appreciative eye, we shall soon be 
impressed with the great diversity shown. in their strue- 
ture and habits. The Fish Hawk plunges from the air 
into the water and grasps its prey with merciless talons. 
The Hummingbird daintily probes a flower. The Wood- 
pecker climbs an upright trunk, props itself with its 
stiff, pointed tail-feathers, while with its chisel-shaped 
bill it excavates a grub and then impales it with its 
spearlike tongue. These birds tell us a wonderful story 
Fie. 2.—End of spearlike tongue of Pileated Woodpecker. (Much enlarged.) 
of adaptation to the conditions of life, and, knowing that 
they have descended from a common ancestor, we ask, 
“Why do they now differ so widely from one another ?” 
Biologists the world over are trying to satisfactorily 
answer this question, and it is impossible for me to 
even mention here all the theories which they have 
advanced. However, some knowledge of the most im- 
portant ones is essential if you would study the relation 
between the bird and its haunts and habits. The Dar- 
win- Wallace theory of Natural Selection, in more or less 
14 
——— 
