Scientists identify first 'naturally iridescent' bird eggs

A new study in the Journal of the Royal Society interface describes the eggs of the tinamou, a.k.a. the "mountain hen," which is native to Central and South America. The bird eggs were recently identified as "the first known naturally iridescent eggs," according to Discovery News.

The eggs create a color-changing optical illusion when viewed from different angles. Using chemical analysis on the eggs, the scientists from the University of Akron found that the eggs' appearance is thanks to an "extremely smooth cuticle." The cuticles are made of calcium carbonate and calcium phosphate, and they may also include organic compounds, including proteins and pigments.

Discovery News explains that "not all color is pigment based" — the iridescence is also because of the way the eggs reflect light. When the researchers removed the eggs' cuticles, the eggs lost the iridescence but maintained a background coloration, implying that the eggs' appearance is due to both pigments and iridescence.

The scientists suggest in the study that the eggs' unique appearance may help the birds find the eggs more easily and to differentiate between eggs from different mothers. The researchers also speculate that the eggshells' reflective surface could protect the embryos from solar radiation. - - Meghan DeMaria