On upcurved wing, I scoured the wind,
So high above the earth midst stars.
Deep blue hues from clearest sky,
Stolen, carried back to earth.
Hidden deep, I kept them warm,
My russet breast a mother's cloak.
A nest of twigs, a watchful eye,
Sheltered in a dark blue spruce.
Soon to live, quick to grow,
Feathery sprouts on naked wings.
Hatchlings learn to flap and leap,
Then soaring, back to deep blue sky.
The picture of American Robin eggs on the left was taken deep inside my Wichita Blue Spruce. I thought the spruce was a surprising home for a robin, but it made good sense in afterthought. What other plant could host a nest as protected from the wind, rain, and harsh sun and so hidden from predators? The nest was totally invisible until I got too close with pruning shears and Mother Robin exploded into flight. Perched on top of the gazebo, she scolded me while I took pictures, chasing me from the garden with a sharp tongue until she was sure I wouldn't return.
In these days of Internet miracles, with the complete knowledge of Mankind available at a mere whisper of beckoning electrons, I was not surprised that posing "Why are robins eggs blue?" to Ask.com, would result in the return of some information. I'm happy to report, however, that this particular mystery remains mostly unsolved even by minds of a species that has proven the existence of the Higg's Boson. We do know that most birds contain pigment glands that deposit colors on the egg during passage through the oviduct, and we know that robin eggs contain biliverdin, a blue-green breakdown product of heme and a powerful antioxidant. Various theories for egg coloration in general include camouflage, protection from solar radiation, or as an aid in egg identification by Mama. It has been noted that healthier female robins may have bluer eggs which may have some selective effects on the species. Like everything else Darwin-related, that means that the blue color may just be all about procreation. One 2010 study in Behavioral Ecology and Sociobiology by Philina English and Robert Montgomerie suggests that male robins invest twice as much energy to help feed nestlings when the eggs are more colorful. Can't you just picture it? Somewhere, sometime, male robins must sit around drinking beer and saying "Hey, get a load of the blue eggs under that chick over there! Wowsa!"
But why blue? The actual reason, for this particular bird species to have this particular blue color otherwise described as Hex triplet #00CCCC, or sRGB color "0, 204, 204" or commonly as "Robin Egg Blue," is still unknown. And I, for one, pray God that it remains unknowable because I like a little mystery to remain in my world.