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Wetmore, Alexander, 1886-, et al. / Warm-blooded vertebrates

Chapter III: color and its arrangement,   pp. 25-38 PDF (5.6 MB)

Page 25

IN spite of the dull appearance of many avian species,
birds, as a class, are greater brilliancy of
color than any other group of animals. The resplendent-
hued tropical fishes compose but a small fraction of all
fishes, and bright-colored lizards, turtles, snakes, and
amphibians are much more exceptional in. their respective
groups. Few mammals are endowed with brilliancy of
color. Only among insects do birds meet serious rivalry
in beauty and variety of color; but here their larger size
gives them the advantage and, except for a few giant
moths and butterflies, birds eclipse their insect rivals.
We may unhesitatingly, therefore, assign to birds pre-
eminence in color in the animal world (see Plates 28 and
Three factors determine the coloration we see in feath-
ers: First, the presence of pigment; second, refraction of
light due to the outer conformation of the barbs or bar-
bules; and, third, both pigmentation and refraction.
The pigments are divided into the fatty pigments, called
the lipochromes, and the black pigments, called the
melanins. Red, known scientifically as zooerythrin, is
the most common of the fatty pigments and is seen at its
best in such birds as the flamingo, the scarlet ibis, the
scarlet and summer tanagers, the cardinal, certain parrots,
and the cock of the rock. It occurs in the form of finely
divided particles, which, when the feather is first formed,
may be held in solution in an oily fluid and which in
some birds may permeate also the fat of the body. Thus

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