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. This beak presents variations
in harmony with the functions and protective purposes which it serves.
Thus in those birds that are called Crooked-clawed it is invariably
hooked, inasmuch as these birds are carnivorous, and eat no kind of
vegetable food whatsoever. For this form renders it serviceable to
them in obtaining the mastery over their prey, and is better suited
for deeds of violence than any other. Moreover, as their weapons of
offence consist of this beak and of their claws, these latter also are
more crooked in them than in the generality of birds. Similarly in
each other kind of bird the beak is suited to the mode of life.
Thus, in woodpeckers it is hard and strong, as also in crows and birds
of crowlike habit, while in the smaller birds it is delicate, so as to
be of use in collecting seeds and picking up minute animals. In such
birds, again, as eat herbage, and such as live about marshes-those,
for example, that swim and have webbed feet-the bill is broad, or
adapted in some other way to the mode of life. For a broad bill
enables a bird to dig into the ground with ease, just as, among
quadrupeds, does the broad snout of the pig, an animal which, like the
birds in question, lives on roots. Moreover, in these root-eating
birds and in some others of like habits of life, the tips of the
bill end in hard points, which gives them additional facility in
dealing with herbaceous food
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