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 nuthatch. 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 different from those
proper to their species and to the other species of the same genus, we
might expect that such individuals 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 vertical position on a post, but not so stiff as in the typical
wood-peckers, and a straight, strong beak.
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