Biological arms race leads to unique egg colors and patterns

To ward off the cuckoo finch, every host bird lays eggs of different color and pattern, thus leading to a wealth of colorful eggs.

New research by Claire Spottiswoode and Martin Stevens reveals that the biological arms race between cuckoos and host birds can escalate into a competion for unique egg colors and patterns. Variations in eggs seem to act like the complicated markings on a banknote: complex colors and patterns act to make host eggs more difficult to forge by cuckoos.