Why are the robin's eggs blue?

I was just wondering why some birds have colored eggs, i.e. the robin. Their eggs are not camoflauged in any way.

Curious, since we have a nest on our front porch flower planter—

The babies have already left the nest.



It may be to prevent brood parasitism. Robins push foreign eggs from nest parasites like cowbirds out of their nests. Being able to distinguish their eggs from the parasite’s ones seems to help them more than having camouflaged eggs. These pages mention this theory:

But I’m no bird expert and shame on everybody knowing more about birds than I (should be quite a bunch) for letting this thread drop to the second page still unanswered.