Of diversified habits
innumerable instances could be given: I have often watched a tyrant
flycatcher (Saurophagus sulphuratus) 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
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
often, 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, like a whale, insects in the water. Even in so
extreme a case as this, if the supply of insects were constant, and if
better adapted competitors did not already exist in the country, I can
see no difficulty in a race of bears being rendered, by natural
selection, more and more aquatic in their structure and habits, with
larger and larger mouths, till a creature was produced as monstrous as
a whale.
As we sometimes see individuals of a species following habits widely
different from those both of their own species and of the other
species of the same genus, we might expect, on my theory, that such
individuals would occasionally have given rise to new species, having
anomalous habits, and with their structure either slightly or
considerably modified from that of their proper type.
Pages:
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230