Bird lore - Project Puffin

The Audubon Societies 51
different. Similarly but not in exactly the same way the color-effects on the
surfaces of smooth or peculiarly grooved feathers will be different. Rainbow
colors, or iridescence, are produced by light on some feathers of the latter
description. We are all familiar with the gleaming, scintillating plumage of the
Hummingbird, or the iridescent colors of the common Crackle. Only the tips
of metallic feathers show color, and these show it only on the upper side. The
laws explaining this strange action of light on feathers are found in the study
of physics. They do not belong to elementary bird-study, but for all who go
out in the field to observe birds it is not unimportant to have an inkling of
these few facts about the coloring of feathers.
A great variety of patterns as well as of colors is characteristic of feathers.
Comparatively few birds or species of birds have plain feathers. Markings
may be regular, forming a sort of pattern, as on the head of the Woodcock or
the breast of the Flicker, or they may be confined to a few feathers, forming
wing-bars, tail-spots, patches or bands on the breast or elsewhere. How they
are changed by wear will be referred to in the next exercise. Much study has
been devoted to the colors and patterns of feathers. It is known that some birds
are protected by their plumage, inasmuch as the color and pattern of their
feathers blend so perfectly with the immediate vicinity of their feeding- and
nesting-areas that they are practically invisible when quiet. If an enemy
appears, their surest means of defence is to keep still until actually flushed.
Just how important protective coloration is to birds in general is not known,
but it seems to be true that species like the Ruffed Crouse or Whip-poor-will,
for example, are far more invisible to the ordinary observer than highly colored
species like the Scarlet Tanager.
There is still another fact of much interest about the color of feathers, that
is, unnatural, or what is better known as abnormal color. Normal color, as we
know, is what is regularly found in healthy birds that feed on a regular diet.
Abnormal color is found oftentimes in imhealthy birds or in those that are fed
on a peculiar diet. It is not uncommon to find caged birds showing unnatural
or abnormal colors. Red canaries may be reared on a certain diet. Sometimes
birds that ordinarily are green or orange or quite red look almost wholly
yellow; but this is an abnormal condition. Occasionally, one hears of a white
Crow, or a white Robin. Such birds, for other reasons, have no coloring-matter
in their feathers. More rarely one hears of a black Sparrow or an almost black
Blue Jay, and this is the result of too much coloring-matter in the feathers.
Changes in climate also affect the plumage of certain species.
Feathers, we learn, therefore, are not only compHcated in structure, but their
colors and markings are very diverse. Natural or normal coloration is due to
three causes: first, coloring-matter; second, coloring-matter and structure with
reference to hght; and, third, structure alone with reference to light. The
colors and patterns of feathers may sometimes serve to protect a bird when it
is still, but not all birds are protectively colored and marked.