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It's something revealed only in the light.
Though they're one of the most recognizable backyard birds in America, the distinctive coloration of the aptly-named Blue Jay is not what it appears to be.
The reality of this bird's plumage is a uniquely constructed attribute that reveals the complexity through which color occurs in the natural world.
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Throughout nature, what the human eye perceives as color is primarily controlled by the interaction between light and what are referred to as pigments.
Some pigments, like chlorophyll, create the effect of the color green in the leaves of plants.
Others, like porphyrin, are responsible for the color red in birds.
But these simple examples obscure the real complexities through which most color is perceived.
The coloration of many organisms, for instance, is determined by several pigments acting in tandem.
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Pigmentation may change with time as well.
Every year during the fall, as levels of chlorophyll decrease in deciduous plants, pigments such as carotenoids are revealed,
and produce the vibrant hues of yellow and orange characteristic of the season.
Over longer lengths of time, the effect of pigments may be impacted by the prolonged influence of outside forces.
Long-term exposure to the sun's UV radiation may cause pigments to fade in older organisms.
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But few organisms reveal the full extent of color's complexity as effectively as the Blue Jay.
As one of the most common birds in the eastern United States, its distinctive blue feathers are familiar to many.
These feathers, however, reveal a discrepancy between the presence of pigments and the colors of an organism.
Despite the Blue Jay's appearance, its feathers contain no blue pigments.
How these feathers are perceived as blue is a process that's dependent on the interaction between the feathers' microscopic structure and
one great outside force acting on them.
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The sun is the luminary that reveals the final effect of the Blue Jay's feathers.
When there's little sunlight, Blue Jays appear much more dull in coloration, but in full sunlight, the same birds gain their more recognizable hue.
This change is the result of light interacting with a network of tiny keratin molecules in the Blue Jay's feathers.
When light reflects off of keratin, light's visible spectrum is divided, red and yellow hues are negated, and the only color that's reflected
is the color blue.
It's by this same process that the sky itself appears blue.
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The Blue Jay's unique mechanism of coloration, while in one aspect very different from that of other organisms,
reveals the common route through which color in general is perceived.
The effect of light on the Blue Jay's feathers is undoubtedly a remarkable occurrence, but its role is the same throughout the natural world.
Light's presence, and the interactions that it has with everything exposed to it, only furthers its place as perhaps the greatest force
dictating the course of life on this planet.
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