The beauty of bird eggs

These are Common quail eggs, with different hues and markings.

Birds belonging to burrow or hole nesting species tend to have white eggs. Birds nesting in the open, however, need to camouflage their eggs, and they do so exquisitely. First, the ground colour is acquired as pigment during shell formation. Later, superficial markings are added. Brown and black speckles and blotches are the result of the breaking down of blood pigments. Bile pigments produce green and bluish hues. Some species, such as Grebes, depend on mud and rotting nest vegetation to stain and splotch their whitish eggs. The largest egg is a Yellow-legged gull, a subspecies of the Herring gull found in Northern European countries. The middle one is a Common quail and the thirds a European starling.