Waders and Water Birds
Of waders and water-birds I was able to get only eleven kinds, and
of these only three (including a rail confined to the damp summits
of the islands) are new species. Considering the wandering habits
of the gulls, I was surprised to find that the species inhabiting
these islands is peculiar, but allied to one from the southern
parts of South America. The far greater peculiarity of the
land-birds, namely, twenty-five out of twenty-six being new
species, or at least new races, compared with the waders and
web-footed birds, is in accordance with the greater range which
these latter orders have in all parts of the world. We shall
hereafter see this law of aquatic forms, whether marine or fresh
water, being less peculiar at any given point of the earth's
surface than the terrestrial forms of the same classes, strikingly
illustrated in the shells, and in a lesser degree in the insects of
this archipelago.
Two of the waders are rather smaller than the same species brought
from other places: the swallow is also smaller, though it is
doubtful whether or not it is distinct from its analogue. The two
owls, the two tyrant-flycatchers (Pyrocephalus) and the dove, are
also smaller than the analogous but distinct species, to which they
are most nearly related; on the other hand, the gull is rather
larger. The two owls, the swallow, all three species of
mocking-thrush, the dove in its separate colours though not in its
whole plumage, the Totanus, and the gull, are likewise duskier
coloured than their analogous species; and in the case of the
mocking-thrush and Totanus, than any other species of the two
genera. With the exception of a wren with a fine yellow breast, and
of a tyrant-flycatcher with a scarlet tuft and breast, none of the
birds are brilliantly coloured, as might have been expected in an
equatorial district. Hence it would appear probable that the same
causes which here make the immigrants of some species smaller, make
most of the peculiar Galapageian species also smaller, as well as
very generally more dusky coloured. All the plants have a wretched,
weedy appearance, and I did not see one beautiful flower. The
insects, again, are small-sized and dull coloured, and, as Mr.
Waterhouse informs me, there is nothing in their general appearance
which would have led him to imagine that they had come from under
the equator. (17/1. The progress of research has shown that some of
these birds, which were then thought to be confined to the islands,
occur on the American continent. The eminent ornithologist, Mr.
Sclater, informs me that this is the case with the Strix
punctatissima and Pyrocephalus nanus; and probably with the Otus
galapagoensis and Zenaida galapagoensis: so that the number of
endemic birds is reduced to twenty-three, or probably to
twenty-one. Mr. Sclater thinks that one or two of these endemic
forms should be ranked rather as varieties than species, which
always seemed to me probable.) The birds, plants, and insects have
a desert character, and are not more brilliantly coloured than
those from southern Patagonia; we may, therefore, conclude that the
usual gaudy colouring of the intertropical productions is not
related either to the heat or light of those zones, but to some
other cause, perhaps to the conditions of existence being generally
favourable to life.