The Cinnamon Cockatiel, also known as the Isabelle Cockatiel or the Cinnamon Tiel, is a a sex-linked recessive mutation. It lacks the cool gray found in the common Grey Cockatiel and in many of the other color mutations. The warmth of the cinnamon coloring is enhanced even more with the yellows in the head and tail. The color of a Cinnamon’s plumage can range from a warm tannish-gray to a chocolate brown. There are some other pretty variations of the Cinnamon that include the Cinnamon Pearl Cockatiel and Cinnamon Pied Cockatiel.