The answer has a lot to do with where the eggs are laid. If the eggs are in a nest of leaves and twigs, speckled green and brown eggs will be difficult for egg-eating predators to find. On a rocky ledge, gray and black spots will help to hide the egg. White eggs are easier for predators to spot, so birds that have white eggs usually lay them out of sight, inside tree hollows or in burrows. In places where many birds are nesting near each other, such as rocky sea cliffs, different markings may help the parents recognize their own nests.
The breeds that lay white-shelled eggs are more prolific and eat less feed, so they were the more profitable choice for factory farming here in the U.S.
Most animal eggs taste the same.
[Edited 2005-03-28 23:43:23]