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The Family Tree: Genetics for the Novice Breeder
By Maureen O'Steen

Perhaps it is time to define some commonly used terms in articles and conversations concerning cockatiel genetics. Many novice breeders have expressed confusion to me about the following terms:


  • SPLITS: A split refers to a cockatiel carrying a hidden factor in its genetic background that may be produced when it is bred (a normal male split to cinnamon will show no hint, but it can produce the color visually in an offspring). A male cockatiel may be split to any or all mutations, recessive or sex-linked. A female may be split only to recessive mutations.

  • GENES: The element within the chromosome concerned with the transmission and development of hereditary characters or traits.

  • CHROMOSOMES: Any of the bodies in the nucleus of a cell that contain genes. They are the carriers of heredity and appear as rod like structures in cells about to divide. Chromosomes always travel in pairs.

  • MUTATION: A spontaneous change in the genetic code. In cockatiels, these changes have resulted in the many different colors we now find common. All cockatiels but the grey normal are mutations. Genes for mutations in cockatiels are inherited by one of two modes, simple recessive and sex-linked.

  • SIMPLE-RECESSIVE: Normally referred to as recessive. Both parents must be at least split to the same recessive mutation in order to produce a visual offspring.

    • Recessive Mutations: Fallow, Pied, Silver, Whiteface

  • SEX-LINKED: Genes that control color are contained in two completely different types of chromosomes. As the name implies, sex-linked are contained in the chromosomes that control the sex. Only males are capable of being split to a sex-linked mutation. Regardless of what the parents were visually, if a female chick does not visually show one of the sex-linked mutations, she does not carry the gene.

    • Sex-linked Mutations: Cinnamon, Lutino, Pearl

  • PHENOTYPE: A term to define a bird’s visual color make-up.

  • GENOTYPE: A term to define a bird that is carrying recessive color mutation genes and does not show it visually.

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