These findings are useful for predicting the sorts of environments that birds nest in, but can also explain why some birds species, like the village weaverbird, produce eggs with a variety of colors, from white to dark greenish-blue.
Why Are Robins’ Eggs Blue?

Curious: how do light levels explain the weaverbird eggs variety of colours? The light level isn’t changing in a nest, so I would have though their eggs should all have the same colour.