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 vertical 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 woodpecker.

Even in such trifling characters as the colouring, 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 observations, 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, this same woodpecker, as Mr.Hudson states, frequents trees, and bores holes in the trunk for its nest.