colors of the visible light spectrum are well represented in avian coloration. For
astounding array of bird colorations and patterns is part of what draws many
people into birding. Later, as one develops more birding skills, he or she
finds mottled grey and brown colors and patterns equally intriguing.
Color is the
major identification criterion used by birders and non-birders. If a non-birder
were asked the names of the birds in the photographs above, he or she would
probably answer correctly. Coloration can be simply observed, as in this
example, but is actually much more complex than I imagined.
ago, I read Geoffrey E. Hill’s book, National
Geographic Bird Coloration to expand my birding knowledge and skills. The topic
I found most interesting was how bird coloration is produced.
common pigments are melanins and caroteniods, which produce black, brown,
rufous, red, yellow, and orange. Melanin, the animal world’s universal
colorant, is found in both the plumage and skin of most birds. This pigment is
made in the body by amino acids. Melanin produces caps, rings on bills, and
markings such as masks, bars, spots and stripes; these give the bird its
characteristic appearance. If a bird is lacking melanin, those places that
would normally be colored are non-pigmented, making it an albino bird. There
are two classes, eumelanin, and phaeomelanin.
is found on both feathers and bare parts (unfeathered areas such as legs and
bills). Shades range from light gray
to deep black. It is what makes Red-winged Blackbirds black and the Gray
Catbird gray. Hill explains how eumelanin is like the toner in a copy
machine: the more toner, or eumelanin,
that is deposited, the blacker the area.
is found on feathers and probably colors bare parts as well, but scientists
have never isolated it. It is usually deposited on feathers in combination with
eumelanin, imparting earth tones, such as rufous, chestnut, golden, and
yellowish hues. Like eumelanin, the amount of pigment deposited on the feathers
determines the intensity of the color. Together, eumelanin and phaeomelanin can
produce complex feather patterns in birds such as Marbled Godwits.
are the second most common pigments. They produce yellow, the most common, red,
and orange. There are more than twelve types of carotenoids; contrast this with
melanin, with only two forms. Unlike melanin, carotenoids cannot produce elaborate
patterns within feathers. Another difference between the two common pigments is
that carotenoids cannot be made by the body like melanin can. Carotenoids are in
the food birds consume; after digestion, these pigments are absorbed into the circulatory
system and carried to the appropriate places. Some are carried unchanged, but
some are chemically altered before being deposited. If a certain pigment is
absent or deficient in a bird’s diet, plumage of that pigment will be drabber
or even a different color.
are not the only ways feathers are colored. Structural coloration is the other
way, the structure being the microscopic layers, specifically barbs and
barbules, of the feather. Barb microstructure creates non-iridescent
coloration, while iridescent coloration is created by the barbules. There are
three types of structural coloration: white,
non-iridescent and iridescent coloration. This type of coloration is the result
of how light interacts with the feather structure: how wavelengths of light are reflected,
absorbed, amplified, or interfered with.
birders think of white as being produced by pigments, a default “color”, but white
is actually created by feather structure. Non-iridescent colors are short
wavelength colors, blue, indigo, violet, and ultraviolet. These colors are
non-glossy and visible in all lights and angles. For example, no matter at what
angle you view a Blue Jay, it is always the same royal blue.
such as Common Grackles, iridescence is produced by layers of
light-transmitting substances and melanin, which reflect light in the barbules.
The more layers involved, the brighter the display. Display colors, as birders
know, depend on light; without the right lighting conditions and viewing
angles, iridescent plumage is dark.
can also be a mixture of the two coloration methods. For example, when pigments
such as yellow caroteniods are deposited on feathers with non-iridescent
structural coloration, green or olive coloration is produced.
discovered from reading this book, coloration is not as simple as selecting a
crayon from the box and depositing color in the desired location on the bird. Whether
colored by pigments or microstructures, each species has its own kind of
beauty. As the kaleidoscope mesmerizes with its variation of colors and
patterns, bird coloration can produce the same fascination. From the violet gorget of the Costa’s Hummingbird
to the red of the Vermilion Flycatcher, the avian rainbow offers a beautiful
palate for our enjoyment. Take time to carefully observe and enjoy the colors
and patterns of birds and read this book for yourself. There are many more
fascinating topics included that I think young birders (actually any birder)
author: Alexandria Simpson is an avid, sixteen-year-old birder from Santa Anna, Texas. While she wishes she could say she has been birding all of her life, instead she has spent the last four years making up for lost time. She wants to become an ornithologist and someday read scientific papers without falling asleep. Her photography, illustrations, and writings have won awards at local, state, and national levels. She currently serves as one of the student blog editors for The Eyrie.