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Colour Mutations

For the main article on this topic, see Budgerigar genetics

Budgerigars in an aviary

There exist presently at least 32 primary mutations in the budgerigar enabling hundreds of possible secondary mutations (stable combinations) and colour varieties (unstable combinations which occur in single individuals but have not become fixed in a breeding line).

The Australian-recessive-grey-factor, the English-recessive-grey-factor, the BrownWings, the DarkWings, the Faded, the NSL-Ino and the SaddleBack mutations are either highly uncommon, extremely rare, or went 'extinct' again.

Most of the primary mutations belonging to one of the 4 basic groups of mutations classified in parrot genetics:

• Albinism: melanins are absent in all tissues and structures (e.g. feathers). It is divided into 2 sub-groups; Complete Albinism and Incomplete or Partial Albinism;
• Leucism: melanins are absent, but virtually only in the feathering. Analogous to albinism, Total Leucism and Local Leucism variants are known;
• Dilutism: melanins are incompletely reduced, virtually only in the feathering;
• Melanism: melanins, especially eumelanin, are increased; in parrots, this affects virtually only the feathering.

The primary mutations are inherited according to the following patterns:

• autosomal; the mutation is on an autosome. These make up the largest group and are futher divided:
  • autosomal-Complete-Dominant (A-C-D), in which the allele, if at least one is present, causes full expression of the trait to the complete suppression of recessive variants.
  • autosomal-Incomplete-Dominant (A-I-D), in which the allele, if at least one present, causes full expression of the trait, but incomplete suppression of recessive variants.
  • autosomal-Co-Dominant (A-Co-D), in which the the allele causes full expression of the trait and some or complete suppression of recessive variants, depending on whether one or two copies of the dominant alleles, respectively, are present.
  • autosomal-recessive (A-R), in which the allele causes full expression of the trait, but only if two copies of the gene are of the recessive allele.
  • autosomal-Poly-Genic (A-P-G), in which a trait is produced by interaction of several genes, of which most if not all need to be present in mutant allele form for the trait to be expressed.
• sex-linked; unlike in humans, where the male sex chromosomes are XY and female ones XX, males have ZZ and females ZW sex chromosomes in birds. These mutations are called Sex-Linked-recessive (S-L). They are carried on the Z chromosome; thus, females will always express a trait for which the allele is present, as they can only have one copy of it, while males will express the trait only if both gene copies are of the mutant allele form.

"Autosomal" is often replaced by "NSL" (Non-Sex-Linked).

List of primary mutations

Mutations are grouped according to locus and/or phenotype. Indicated by a star is the allelic variant causing the phenotype. *wt means wild type. Inheritance pattern is given of the locus in regard to other loci (if applicable), and of the alleles in regard to each other.

Base color
bl-Locus (Blue): A-Co-D with regards to other base color mutations (but see below)

• *wt (Yellow-base): A-C-D, and is also A-C-D in regard to blII mutations. Base color green below, yellow above.
• *bl (White-base): A-R. Completely lacks yellow; Base color blue below, white above.

D-Locus (Dark-Factor): A-Co-D with regards to base color mutations.

• The mutant allele is A-I-D. It produces a spectrum of 3 increasingly darker hues of belly color. I the basic color variants (green/yellow and blue/white), these are called "light green", "dark green" and "olive", or "sky blue", "cobalt" and "mauve", respectively.

blII-Locus (BlueII or Yellowface): A-Co-D with regards to base color mutations, except bl*wt where the effect simply cannot be seen. Interaction of the two alleles is poorly understood.

• *yf (YellowFacedBlue or YellowFaceI): only the face is yellow, somewhat lighter than in bl*wt.
• *gf (GoldenFacedBlue or YellowFaceII): The face as in *yf, the rest of the body has a yellowish hue.

Dilutistic mutations
dil-Locus (Dilute)

• *wt: A-C-D. Undiluted color.
• *dil (Suffused or Dilute proper): A-R. Black upperside markings are grey, body color much diluted with white.
• *cw (ClearWings): A-R, but A-Co-D with *gw. Little or no upperside markings and bright, but not diluted, body color.
• *gw (GreyWings): A-R, but A-Co-D with *cw. As *dil, but body color at half intensity of wild type.

A combination of the *cw and *gw alleles (FullBody GreyWings) produces a combination of the dilute upperside pattern of *gw and the bright, undiluted body color of *cw.

Local-Leucistic (Pied) mutations
Pb-Locus (Australian-Pied or Dominant-Pied)

• *wt: A-R. Unpied.
• *pb (Piebald): A-C-D bordering on A-Co-D. Some areas lack melanins, resulting in "clear" or unpatterned feathers. These include always a band on the lower belly, a band on the wing bases, and a patch on the back of the head. Birds with two times this allele are often almost completely white.

s-Locus (ADM/Anti-DiMorphic Pied, Danish-Pied, Recessive-Pied, Harlequin)

• *wt: A-C-D. Unpied.
• *s: A-R. Most areas lack melanin. The rump and a patch on the lower belly almost always retain it. The iris never bekomes white with maturity.

Pi-Locus (Continental_Dutch-Pied or Clear-Flighted_Dutch-Pied)

• *wt: A-R. Unpied.
• *pi: A-C-D. The primary remiges are clear, and often also some secondaries, tail feathers and patches on the neck and head.

Total-Leucistic (Clear) mutations
Sp-Locus (Spangle-Factor)

• wt: Unmodified color.
• Sp: A(?)-I-D: A single copy of this allele will result in clear tail feathers and wing feathers with reversed pattern (base color with dark rim instead of black with base color rim). Two copies will create all-clear birds in which the iris becomes white at maturity.

Dark-Eyed-Clear ): is not a genuine primary mutation but a mutation variety produced by the visual combination of ADM-Pied & either Dutch-Pied varieties : A-Co-D

Albinistic mutations :

NSL-Albinism (recessive-albinism) : a-Locus : multiple-allelic-series :

NSL-Ino (recessive-Ino) : a*a : A-R

Bronze_Fallow (german_Fallow) : a*bz : A-Co-D with regards to only other a-Locus alleles &/or always otherwise A-R *This mutation more precisely belongs in the Incomplete-Albinistic mutations but it was necessary to display it's relationship with the a-Locus*

Brown or BrownWings (sepia) : b-Locus : presumed A-Co-D with regards to only other a-Locus alleles &/or always otherwise A-R *This mutation more precisely belongs in the Incomplete-Albinistic mutations but it was necessary to display it's relationship with the a-Locus*

Cinnamon (CinnamonWings) : cin-Locus : S-L-R

Dun_Fallow aka Grey-Brown_Fallow (english_Fallow) : df-Locus : A-R

Faded : fd-Locus : A-R

possible Beige_Fallow aka Pale-Brown_Fallow (australian_Fallow) : pf-Locus : A-R

possible Plum-Eyed_Fallow (scotish_Fallow) : pl-Locus : A-R

SL-Albinism : ino-Locus : multiple-allelic-series :

SL-Ino : ino-Locus : S-L-R

SL-ClearBody : ino*cl : SL-Co-D with regards to only other ino-Locus alleles &/or always otherwise S-L-R

Melanism :

BlackFace : bf-Locus : A-R

Other mutations :

DarkWings : dw-Locus : A-I-D

Dominant-ClearBody : Cl-Locus : A-C-D

Opaline : op-Locus : S-L-R

SaddleBack : sb-Locus : A-R

Slate : sl-Locus : S-L-R

Structural mutations :

Crest-Factor : Cr-Locus : A-P-G

Dark-Factor : D-Locus : A-I-D

Grey-Factor (Dominant-Grey-Factor) : G-Locus : A-C-D

grey-factor (english-recessive-Grey-Factor) : g-Locus : A-R

grey-factor (australian-recessive-Grey-Factor) : ag-Locus : A-R

Violet-Factor : V-Locus : A-I-D