Birds That Lay Blue Eggs

Ans: This coloration occurs due to the deposition of the bile pigment biliverdin when the shell forms in the shell gland just before oviposition. Depending on the amount deposited, shades of the eggs vary from light to dark, such as bright or dark blue, blue-green, or pale ice blue.

Ans: The blue coloration protects the egg from UV rays that can easily damage the eggs, impact the incubation period, and affect the development of chicks. Eggs with a dark blue shade will be better protected from harmful sunlight; however, they may get overheated under direct sunlight, killing the un-hatched chicks. On the other hand, eggs with a light blue shade do not overheat but have a high risk of developmental problems caused by UV rays.

Ans: The shade of a blue egg can indicate many things; for example, bright blue eggs usually indicate the mother bird’s good health and the possibility of the hatchlings being strong and healthy. When there are different colored eggs in the same nest, it indicates brood parasites such as brown-headed cowbirds and common cuckoos that lay eggs in other birds’ nests and rely on other birds to raise the hatchlings as “foster” chicks.
Also, smaller blue eggs, or those with brighter and more intense color, indicate that those are laid during the earlier parts of the nesting cycle than the larger ones with less intense color, which suggests that they have been laid later.