Why are flamingos pink?

Actually, they aren't. They are born with grey feathers, which gradually turn pink in the wild because of a natural pink dye called canthaxanthin that they obtain from their diet of brine shrimp and blue-green algae. Flamingos in zoos would often lose most of their pink colouration until keepers started adding synthetic canthaxanthin to their diets. Curiously, the same ingredient is sometimes added to sausages that we export to the continent.