How Cuckoos Lay Deceptive Blue Eggs: It's in Their Genes

Now, scientists at the Norwegian University of Science and Technology (NTNU) have solved one piece of the egg puzzle: The gene that causes cuckoos to lay blue eggs is determined by the mother alone. "The enigma for scientists is the distinct colors and patterns of eggs mimicking different host species," said lead study author Frode Fossøy, a research scientist in the Department of Biology at NTNU. Male birds have ZZ and females have ZW, and so the gene for blue eggs could be carried on th