Pewter Cockatiel

Fifteen different Cockatiel colour mutations are currently established in aviculture, including Grey, Pied, Pearled, Cinnamon, Whitefaced, Lutino, Albino (aka. Whitefaced Lutino) and Yellowcheeked Cockatiels. Mutations in captivity have emerged in various colors, some quite different from those observed in nature. In 1949 the species began to spread throughout the world, with the creation of "wild," and then "pied" mutation developed in California in the United States. There are many mutations of Cockatiels with varied colors, they are: Silvestre, Harlequin, Lutino, Cinnamon, opaline (Pearl), Cara Black, Silver, Fawn, Albino (there is a pattern and not just albino genetic mutations), Pastel, Silver and Recessive silver dominant.

http://en.wikipedia.org/wiki/Cockatiel