Budgerigar colour genetics

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Melopsittacus undulatus at Chai-Negev, Revivim, Israel. Melopsittacus undulatus Revivim 4.jpg
Melopsittacus undulatus at Chai-Negev, Revivim, Israel.

The science of budgerigar color genetics deals with the heredity of mutations which cause color variation in the feathers of the species known scientifically as Melopsittacus undulatus . Birds of this species are commonly known by the terms 'budgerigar', or informally just 'budgie'.

Contents

Background

The wildtype (natural-coloured or wild occurring) budgerigar's color is called Lightgreen. The feathers of most parrot species, including budgerigars, contain both a black type of melanin named eumelanin along with a basic yellow pigment named psittacofulvin (psittacin for short). Some other parrot species produces a third pigment named advanced-psittacin which enables color & tones ranging from oranges, peaches, pinks to reds. When these feathers are exposed to a white light source, such as sunlight, only the blue part of the spectrum is reflected by the eumelanin granules. This reflected blue light passes through the yellow pigment layer, resulting in the green colouration known as lightgreen in only the budgerigar and/or green in any other naturally green coloured parrot species.

The many color variations of budgerigars, such as albino, blue, cinnamon, Clearwinged, the various Fallows, Grey, Greygreen, Greywing, Lutino, Mauve, Olive, Opaline, Spangled, Suffused and Violet are the result of mutations that have occurred within specific genes. There are actually at least thirty-two known primary mutations established among budgerigars. These can combine to form hundreds of secondary mutations and color varieties which may or may not be stable.

As is true with all animal species, color mutations occur in captivity as do in the wild. This has been demonstrated when captive-bred budgerigars have developed mutations that had only been previously recorded amongst wild populations.

Classification of mutations

Because of albinism this budgerigar has virtually no eumelanin pigment. This, together with the Blue mutation which removes the yellow pigmentation, produces a nearly pure white colouration along with clear (orange) beak, pink feet/skin, white-tipped clear (pink) toe nails and red eyes. White domesticated budgerigar.jpg
Because of albinism this budgerigar has virtually no eumelanin pigment. This, together with the Blue mutation which removes the yellow pigmentation, produces a nearly pure white colouration along with clear (orange) beak, pink feet/skin, white-tipped clear (pink) toe nails and red eyes.

Basic groups

Each of the thirty-two primary mutations belong to one of the four basic groups of mutations classified in parrot species genetics:

Dominance relationship

These mutations are inherited through one of the following dominance relationships.

Table of primary mutations

Mutation(s)Common names & varietiesTypeWild-type symbol (locus)Allele symbolDominance relationship
Dark D Green (Dark Green), D_Blue (Cobalt), DD Green (Olive) & DD_Blue (Mauve)StructuralD+DA-I-D
Blue 1 Blue-seriescolorb+b1recessive with other b-locus alleles except b2, else A-R
Blue 2 Blue-seriescolorb+b2recessive with other b-locus alleles except b1, else A-R
Blue 1-Blue 2 Yellowface Icolorb+b1 / b2(Hetero-allelic mutation produced by crossing Blue 1 & Blue 2 varieties)
Yellowface Yellowface IIcolorb+byfDominant with other b-locus alleles except gf , else A-R
GoldenfaceGoldenfacecolorb+bgfDominant with other b-locus alleles, else A-R
Crest-Factor (C-F)Circular Crested, Semicircular Crested & TuftedStructuralCr+CrA-P-G
Dominant Grey (Australian) Grey & GreygreenStructuralG+GA-C-D
English Grey English Grey & GreygreenStructuralg+gA-I-D (rare or extinct)
Anthracite AnthraciteStructuralAn+AnA-I-D (rare)
Recessive Grey & GreygreenAustralian recessive greygreen & greyStructuralrg+rgA-R (extremely rare or extinct)
Slate Slate (bluish-gray)Structuralsl+slS-L-R
Violet SF Violet (SF Violet Green), SF Violet Blue (Violet Skyblue), DF Violet Green (pure Violet Green) & DF Violet Blue (pure VIOLET), SF Violet D_Blue (show Violet), DF Violet D_Blue (VIOLET Mauve)StructuralV+VA-I-D
Dilute Suffused Green (Dilute Yellow) and Suffused Blue (Dilute White)Dilutiondil+dilsA-R
Clearwing (CW)Clearwing Green (Yellowing) & Clearwing Blue (Whitewing)Dilutiondil+dilcwA-Co-D with dilgw allele,
A-D over dild allele, else A-R
Greywing (GW)Greywing Green & Greywing Blue,Dilutiondil+dilgwA-Co-D with dilcw allele,
A-D over dild allele, else A-R
Greywing-Clearwing Fullbodied-Greywing Green & Fullbodied-Greywing BlueDilutiondil+dilcw / dilgw(Hetero-allelic mutation produced by crossing Clearwing & Greywing varieties)
ADMpied a.k.a. Recessivepied Anti Dimorphic Pied, Danishpied, Harlequin,Local-Leucisms+sA-R
Piebald Australian Pied Australian Pied, Banded PiedLocal-LeucismPb+PbA-C-D
Piednape Continental_Dutchpied & Clearflighted_Dutchpied Local-LeucismPi+PiA-C-D
Clear-PiedBlack-Eyed-Clear (a.k.a. Dark-Eyed-Clear)Total LeucismPi+ ; s+Pi / sA-Co-D Clear Yellow & White morphs produced by combining SF &/or DF Clearflighted_Dutchpied with Homozygous ADMpied a.k.a. Recessivepied
Spangle-Factor (Sp)SF Spangled (showtype / typical mutation) & DF Spangled (clear white &/or clear yellow pure mutation)Total LeucismSp+SpA-I-D
NSLinoNon-Sex-Linked Ino a.k.a. Recessive InoNSL Complete Albinisma+a*aA-R (extremely rare or extinct)
Bronzefallow German Fallow NSL Incomplete Albinisma+abzA-R
Brown &/or SepiaBrownwingedNSL Incomplete Albinismb+bPresumed A-Co-D with only a-Locus alleles, else exclusively/inclusively A-R (extremely rare or extinct)
Faded NSL Incomplete Albinismfd+fdA-R (extremely rare)
PalefallowAustralianfallow. Beigefallow, PalebrownfallowNSL Incomplete Albinismpf+pfA-R
Dunfallow English Fallow NSL Incomplete Albinismdf+dfA-R
Scottish Fallow
(a.k.a. Plumeyed Fallow)
Scottish FallowNSL Incomplete Albinismpl+plA-R
Cinnamon CinnamonSL Incomplete Albinismcin+cinS-L-R
Ino Albino, LutinoSL Complete Albinismino+inoS-L-R
Cinnamon-Ino LacewingSL Incomplete Albinismcin+ ; ino+cin / inoS-L-R cross-over (3% frequency) between Cinnamon & Ino Loci
Sex-linked Clearbody Texas ClearbodyPartial-Albinistic (Par-ino)ino+inoclSL-Co-D with other ino locus alleles, else S-L-R
Blackfaced (BF) Melanismbf+bfA-R
Darkwinged (DW) Modifierdw+dwA-Co-D (only noticeably expressive in combination with dil-Locus alleles and with Greywinged & Suffused)
Dominant Clearbody Easley ClearbodyPigment redistributingCl+ClA-C-D
Opaline OpalinePigment redistributingop+opS-L-R
Saddlebacked (SB) Local-Leucismsb+sbA-R (extremely rare or extinct)

History

In the first few decades of the 1900s, especially in-between World War I and II, the keeping and breeding of the budgerigar had become very popular all around the world. Consequently, various mutations occurred and were soon established during this period.

Timeline

Notes

It is possible that the Greywings mutation survived as the ancestor of all actual Greywings. However, it could be that the mutation lay dormant in asymptomatic mutant specimens until it was re-established between 1918 and 1925. Blue Greywing specimens were produced later on in 1928.

It is possible that all Suffused mutation specimens and their varieties are descendants from the first captive mutant specimens. This would mean that Suffused is the oldest sudden captive-bred color mutation of the Budgerigar species.

References