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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 32

long time guarded their secret jealously. It involves,
however, merely the addition of sweet red pepper to a
special food given a yellow canary when molting and
growing new feathers. The blood absorbs the red from the
vegetable product and passes it into the developing feather,
giving the usual yellow a distinct orange tint. The
orange may be deepened by protecting the bird from
strong light until the feathers are completely grown and
the color is set. The handsome shade of orange produced
by these methods persists, of course, only until the next
molt, when the normal yellow plumage is resumed unless
the red-pepper treatment is repeated.
Few birds are plainly and uniformly colored; the vast
majority exhibit a pattern which may be relatively simple
or highly complex. Examination of large numbers of birds
and mammals seems to show that pigment is laid down in
definite areas. For example, many species of plovers have
a dark ring about the neck (Plate i i). Many kinds of
birds, from sparrows to ducks, reveal dark patches on the
sides of the head, or definitely marked colored areas occur
on the sides of the body; for example, the brown of the
male chewink or of the chestnut-sided warbler. Similarly
we frequently find light or white markings indicative of
nonpigmented areas in certain locations; examples are
the superciliary stripe above the eye in the song sparrow,
or light areas on the sides of the body and elsewhere
(Fig. 4.)
After careful study of a large number of species Dr.
Glover M. Allen has found the pigmented areas in birds so
definitely arranged that there seem to be six main points
of centralization. The first of these is an area in the center
of the crown, and the remaining five occur in pairs located
on the cheeks, the sides of the neck, the shoulders, the
sides of the body, and the rump. This theory considers
the wings as projections from the shoulder areas and the
tail as continuous with the rump. In uniformly colored
birds, like those species of crows or ravens which are
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