Jap Bluebird eggs are sometimes a pale sky blue, typically with a slight greenish tint. Sometimes, they are often white, which is believed to be resulting from an absence of the pigment biliverdin. This attribute blue coloration is a defining characteristic of the species, readily distinguishing their nests from these of different birds.
The distinct coloration serves a number of functions. For ornithologists and birdwatchers, it aids in species identification and nest monitoring. The pale coloration might also have evolutionary advantages, probably camouflaging the eggs towards the nest lining or reflecting daylight to forestall overheating. Finding out egg coloration contributes to a broader understanding of avian biology, together with genetics, evolution, and breeding conduct. Traditionally, pure dyes mimicking this distinctive hue have been prized.
