If this doesn't beat all

Finally, from under Mama dove two nestlings have appeared. I figured somebody had to be living "downstairs", because the parent had been resting high in this deep nest, but nothing could have prepared me for GREEN babies.  Not a trick of light. They're green. How? Why? What? Genetic?  I have no idea, but if this doesn't beat   all. Ecologically modern babies?  I'll keep documenting them.