168 TRANSITIONS OF ORGANIC BEINGS, 



Of diversified habits innumerable instances could be given: 

 I have often watclied a tyrant flycatcher (Saurophagus sul- 

 phuratus) in South America, hovering over one spot and 

 then proceeding to another, like a kestrel, and at other 

 times standing stationary on the margin of water, and then 

 dashing into it like a kingfisher at a fish. In our own 

 country the larger titmouse (Parus major) may be seen 

 climbing branches, almost like a creeper; it sometimes, 

 like a shrike, kills small birds by blows on the head; and I 

 have many times seen and heard it hammering the seeds of 

 the yew on a branch, and thus breaking them like a nut- 

 hatch. In North America the black bear was seen by 

 Hearne swimming for hours with widely open mouth, thus 

 catching, almost like a whale, insects in the water. 



As we sometimes see individuals following habits differ- 

 ent from those proper to their species and to the other 

 s.pecies of the same genus, we might expect that such in- 

 dividuals would occasionally give rise to new species, 

 having anomalous habits, and with their structure 

 either slightly or considerably modified from that of their 

 type. And such instances occur in nature. Can a more 

 striking instance of adaptation be given than that of 

 a woodpecker for climbing trees and seizing insects in the 

 chinks of the bark? Yet in North America there are 

 woodpeckers which feed largely on fruit, and others 

 with elongated wings which chase insects on the wing. 

 On the plains of La Plata, where hardly a tree grows, 

 there is a woodpecker (Colaptes campestris) which has two 

 toes before and two behind, a long-pointed tongue, pointed 

 tail-feathers, sufficiently stiff to support the bird in a verti- 

 cal position on a post, but not so stiff as in the typical wood- 

 peckers, and a straight, strong beak. The beak, however, 

 is not so straight or so strong as in the typical woodpeckers 

 but it is strong enough to bore into wood. Hence this 

 Colaptes, in all the essential parts of its structure, is a wood- 

 pecker. Even in such trifling characters as the coloring, 

 the harsh tone of the voice, and undulatory flight, its close 

 blood-relationship to our common woodpecker is plainly 

 declared; yet, as I can assert, not only from my own ob- 

 servations, but from those of the accurate Azara, in certain 

 large districts it does not climb trees, and it makes its 

 nest in holes in banks! In certain other districts, however, 



