Or, take as an example the web-footed family:
Do not all the geese and the innumerable host of ducks quack? Does not
every member of the crow family caw, whether it be the jackdaw, the jay,
or the magpie, the rook in some green rookery of the Old World, or the
crow of our woods, with its long, melancholy caw that seems to make the
silence and solitude deeper? Compare all the sweet warblers of the
songster family--the nightingales, the thrushes, the mocking-birds, the
robins; they differ in the greater or less perfection of their note, but
the same kind of voice runs through the whole group.

These affinities of the vocal systems among the animals form a subject
well worthy of the deepest study, not only as another character by which
to classify the animal kingdom correctly, but as bearing indirectly also
on the question of the origin of animals. Can we suppose that
characteristics like these have been communicated from one animal to
another? When we find that all the members of one zooelogical family,
however widely scattered over the surface of the earth, inhabiting
different continents and even different hemispheres, speak with one
voice, must we not believe that they have originated in the places where
they now occur, with all their distinctive peculiarities? Who taught the
American thrush to sing like his European relative? He surely did not
learn it from his cousin over the waters. Those who would have us
believe that all animals originated from common centres and single
pairs, and have been thence distributed over the world, will find it
difficult to explain the tenacity of such characters, and their
recurrence and repetition under circumstances that seem to preclude the
possibility of any communication, on any other supposition than that of
their creation in the different regions where they are now found. We
have much yet to learn, from investigations of this kind, with reference
not only to families among animals, but to nationalities among
men also....

The similarity of motion in families is another subject well worth the
consideration of the naturalist: the soaring of the birds of prey,--the
heavy flapping of the wings in the gallinaceous birds,--the floating of
the swallows, with their short cuts and angular turns,--the hopping of
the sparrows,--the deliberate walk of the hens and the strut of the
cocks,--the waddle of the ducks and geese,--the slow, heavy creeping of
the land-turtle,--the graceful flight