Albinos happen in all areas of nature - in plants, in animals, and even in humans. This is a genetic condition that causes pigments not to be created. This results in a creature that looks white, often with red eyes because you can now see the blood vessels in their eyes. Abinos are very rare, and it is more common for a bird to be partially albino.
Colors can also fade on a bird that has poor nutrition, or faulty body chemistry. Albinos are most often found in certain types of birds - swans, ducks and geese.