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Cockatiel colour genetics
Cockatiel colour genetics
Cockatiel colour genetics
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The science of cockatiel colour genetics deals with the heredity of colour variation in the feathers of cockatiels, Nymphicus hollandicus. Colour mutations are a natural but very rare phenomenon that occur in either captivity or the wild. About fifteen primary colour mutations have been established in the species which enable the production of many different combinations. Note that this article is heavily based on the captive or companion cockatiel rather than the wild cockatiel species.

Mutations (list)

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  • Anti-Dimorphic (ADM) Pied/Recessive Pied
  • Ashenfallow, incorrectly known as either Recessive Silver and/or Silver Fallow in the past
  • Bronzefallow/Brownfallow
  • Cinnamon
  • Dilute, incorrectly known as Pastel Silver in the past
  • Dominant Silver/Ashen Dilute
  • Edgedilute, incorrectly known as Spangled Silver in the past
  • Faded
  • Sex-linked Ino/Lutino/Albino
  • Palefaced Ino/Creamino
  • Non-sex-linked ino/Recessive Ino
  • Opaline/Pearl
  • Palefaced, often incorrectly known as Pastelfaced
  • Pallid, often incorrectly known as Platinum
  • White-faced
  • Dominant Yellowcheeks
  • Sex-linked Yellowcheeks
  • Yellow-suffusion, incorrectly known as Emerald and/or Olive

Cockatiels started with a normal grey colour, and then mutations began popping up because of specific breeding. The first mutations that occurred were pieds, cinnamons, Lutinos and pearls.[1] The next mutations to occur were white-faces, silvers and albinos. Recently, an orange-crested cock with orange cheek patches extending into the face and crest has occurred; this is a newly discovered mutation.[1]

Normal grey (non-mutated)

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A perfect example of a normal grey cockatiel.

The normal grey or wild-type cockatiel is one whose colour genes have no mutations. A normal grey cockatiel's plumage is primarily grey with prominent white flashes on the outer edges of each wing. The face of the male is yellow or white, while the face of the female is primarily grey or light grey, and both genders feature a round orange area on both ear areas, often referred to as "cheek patches". This orange colouration is generally vibrant in adult males, and often quite muted in females and young cockatiels. Visual sexing is often possible with this variant of bird.[2] A normal grey cockatiel with some white or yellow feathers on the back of their head is split to the recessive mutation Pied.[1]

White-faced

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A white-faced cockatiel (sleeping)

White-faced cockatiels have their psittacofulvin (yellow and orange) pigments deactivated by the blue gene, resulting in cockatiels with absolutely no psittacofulvin pigments whatsoever. This is a result of the same genetic mutation as the genuine Blue genetic mutation in all typical parrot and parakeet species. Consequently, White-faced cockatiels are mainly grey with more or less white throughout their plumage. White-faced cocks display brilliant white faces while hens display basically grey faces with some white streaks. With the availability of the Whiteface mutation, the cockatiel's wide colour varieties are divided into 2 main classes (or series):

  1. Yellow base: with psittacofulvin (yellow and orange) pigments.
  2. White base: without psittacofulvin pigments

Some white-faced cockatiels have entirely white bodies and red eyes. Albino isn't entirely correct terminology, although they are sometimes referred to as such. Albino animals have the Blue genetic mutation, but cockatiels do not have the Blue gene. The more appropriate name for this mutation would be the White-faced Lutino.

Lutino

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The Lutino sex-linked recessive mutation is a perfect example of a type of cockatiel that are the hardest to sex visually. Lutinos lack eumelanin pigment (enabling black, brown, grey colours and tones) and are consequently yellow to yellowish-white with orange cheek-patches. Adult female Lutinos as well as immature Lutinos of both sexes display yellow bars, dots and/or stripes on the underside of their tail feathers. Mature males, however, can be sexed visually by their always displaying solid white coloured undersides of tail feathers.[3]

Unfortunately, a good number of cockatiels of all Lutino mutations and varieties, such as Pale-faced Lutino and Opaline Lutino, are affected with a transmittable genetic flaw. This flaw enlarges the bald spot below the crest, due to irresponsible and excessive in-breeding and a general lack of effort, ethics, and responsibility in breeders to breed it out. Breeders who have been working on reducing the bald patch have been greatly successful in reducing its size.[1]

A pet lutino cockatiel. Note the lack of dark pigment, including in the beak, eyes, feathering, feet, skin and toenails.

Pied

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Pied cockatiel plumage patterns vary significantly between one individual to another, giving rise to cockatiel breeders and hobbyists' "Heavy Pied" and "Light Pied" distinctions. Unfortunately, the degree in piedness remains genetically unpredictable. However, breeding heavily pied specimens together generally produces a higher percentage of heavily pied offspring than breeding lesser pied specimens together. Ultimately, the "Pied" mutation causes the bird to lack a majority of the typical grey plumage on the breast, belly, and head. Thus "Pied" cockatiels are characterized by the degree of their yellow or yellow-white colouring in these areas. Last but not least, there are the exceptional Clear-pied individuals that are solid yellowish-white or solid white just like Lutino and/or albino but with normal blackish eyes and out of ADMpied (recessive pied) parentage.

A pearl-pied cockatiel.

Throughout parrot species, the ADMpied gene negates the male's ability to display his species' dimorphic features. This leads to ADMpied cockatiels being notoriously difficult to sex visually but being excellent examples for studies in genetic traits. However, in monomorphic species (i.e. conures, lovebirds, macaws, rosellas, etc.) the anti-dimorphic feature cannot be expressed while piedness still is. Therefore, Pied specimens of these species are called either Recessive Pied and/or Harlequin in budgerigar.

Cinnamons and pearls

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Cinnamon and pearl mutations are sex-linked recessive. In Cinnamons, the eumelanin pigment are partially oxidized. Eumelanin granules are stopped at the brown stage of their development to end up in their natural black colour state. They have a speckled complexion, with white spots on their secondary feathers and deep brown on their primaries.

The pearl cockatiels' gene does not have any visual effect on the colour pigments in the bird but instead, it affects the distribution of the colours that are already present. It actually decreases the spread of the grey family of pigments (melanin) and increases the spread of the yellow pigments (psittacofulvin). Individual feathers over most of a Pearled bird will have more of the yellow family of pigments visible, giving them a scalloped pattern.

Males do not retain the pearled colouring, but lose it soon after their first molt. Though this pattern may not be visible, it is not essentially gone, but is just covered up by more grey pigment.[4]

Combined mutations

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Cockatiel specimen combining the opaline and ADMpied mutations.

There are a tremendous number of colour varieties (combined mutations), including ADMpied Cinnamon, White-faced Lutino, Opaline Cinnamon, Creamino, White-faced Cinnamon, White-faced Opaline.

Mutations can appear both individually or in a wide variety of combinations such as albino, Pearled Lutino, White-faced Pied, and Opaline-Cinnamon. Still fairly hard to find is the rather new yellow-suffusion mutation.[1] Cockatiels do not actually have green pigment in their plumage, thus yellow-suffusion specimens don't either. The yellow suffusion combined with underlying black (or pure brown in Cinnamon specimens) pigmentation produces an illusion of greenish tones giving rise to the genetically incorrect common names of Emerald for this trait.

Other features

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Many mutations retain the normal features (black eyes, grey beak, grey feet/skin, and black toenails) of wild-type (grey) cockatiels. However, Fallow and Lutino mutations have pink to red eyes, pink feet/skin, white-tipped clear (pink) toenails and pinkish-white beaks. Also, Cinnamon specimens look quite essentially alike wild-type (a.k.a. normal grey) specimens, with the exception of being pure-brown and hatching with wine-red eyes (which turn to brown between 5–15 days of age) and displaying dark brown eyes in adulthood.

Sex-linked mutations such as Cinnamon, Lutino, Opaline, Pallid and/or sex-linked Yellowcheeks have a higher ratio of female to male offspring due to the mode of inheritance.[5][6][7]

Sexing without sexual dimorphism

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As mentioned above, some mutations don't allow sexing by their feather patterns. This is because some mutations don't vary between males and females. One method of sexing cockatiels involves checking their pelvic bones.[1] This idea is similar to how human pelvic bones differ, where females have wider hips to allow for childbirth; female cockatiels can have wider and more flexible pelvic bones to account for egg laying. This method isn't always accurate when genes cause females to have a narrower pelvis.

Another way to sex cockatiels is by their behaviour. Males tend to be more vocal and also have an easier time mimicking noises.[1] Males also sometimes "strut". This behaviour is categorized by sticking their chest out and parading around, sometimes pacing, typically accompanied by whistling.[1] Females are usually quiet and they're more likely to hiss and bite.[1]

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

Cockatiel colour genetics

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Cockatiel colour genetics encompasses the hereditary traits governing the diverse variations in the (Nymphicus hollandicus), a small native to and widely kept as a , where spontaneous mutations combined with have produced numerous color morphs beyond the wild-type . These mutations primarily affect (responsible for and dark tones) and lipochrome (yellow, orange, and red pigments), leading to established varieties such as lutino (all-yellow with red eyes), pearl (spotted white and yellow patterns that change with age and sex), and pied (white or yellow patches on a base). Key genetic mechanisms include sex-linked recessive , seen in lutino, pearl, and mutations carried on the Z chromosome, where males require two copies to express the trait while females need only one; autosomal recessive , as in pied, , and recessive silver, requiring two copies from both parents; and rarer dominant forms like dominant silver, which express with just one copy. Since the mid-20th century, aviculturists have documented at least a dozen primary mutations, with combinations yielding over 100 varieties exhibited in shows, though for rare colors like whiteface (lacking orange cheek patches) or yellowface (golden cheeks) can pose health risks such as reduced immunity or vision issues in lutinos. Emerging mutations, including (softened tones, dominant to whiteface), olive/spangled (greenish mottling, recessive), and dilute (emerald-like sheen), continue to expand diversity, primarily through as wild populations show only the normal grey. Understanding these genetics aids ethical breeding practices, emphasizing to mitigate issues like the immune vulnerabilities observed in some color variants.

Fundamentals

Wild-Type Coloration

The wild-type , also known as the normal , exhibits a characteristic that serves as the baseline for all color in the Nymphicus hollandicus. The body feathers are predominantly medium to dark , produced by the full expression of eumelanin pigments, which provide the structural responsible for black and tones in feathers. The head features a bright crest and face, accented by vivid orange cheek patches (ear coverts) bordered in , while the wings display prominent flashes or spots on the greater coverts. The tail is primarily with three distinct black bars running parallel across the feathers, and the underside is solid in males or barred in females. This coloration pattern not only aids in within the arid Australian habitats where wild cockatiels originate but also reflects the balanced deposition of both melanin-based and psittacofulvin-based pigments. Sexual dimorphism becomes evident in adult wild-type cockatiels around six to nine months of age, with males displaying more vibrant and uniform coloration compared to females. Adult males have a solidly bright face, including the forehead, throat, and crest, paired with intense orange cheek patches and a solid tail underside without barring; their wing undersides are also solid black. In contrast, adult females retain a more subdued appearance, with the face showing pigmentation overlaid by barring or stippling, duller orange cheek patches lacking white borders, and a tail underside featuring bars similar to those on the dorsal surface; their wing undersides exhibit or barring. Juveniles of both sexes initially resemble females, with barred patterns, until the post-juvenile molt reveals the male's brighter traits. This dimorphism is hormonally influenced and enhances mate selection in the wild. Genetically, the wild-type coloration results from the homozygous dominant at key loci controlling pigment production and distribution, allowing unrestricted synthesis of eumelanin for and elements alongside psittacofulvins—unique polyene pigments produced endogenously by parrots—for the and orange hues. Eumelanin is deposited in the barbs and rachis to create the body and dark markings, while psittacofulvins concentrate in the facial and tail regions, providing protection against UV degradation. The wild-type are dominant over most recessive , ensuring that heterozygous carriers express the full normal ; for instance, such as lutino disrupt eumelanin production but are masked in the presence of a single wild-type . This genetic foundation underscores the wild-type as the ancestral form from which has derived over 20 recognized color variants in captivity.

Inheritance Modes

Cockatiels exhibit color variations through mutations governed by principles, adapted to the avian . In this system, males possess two Z (ZZ) and are homogametic, while females have one Z and one W (ZW) and are heterogametic. The determines the sex of offspring by contributing either a Z (resulting in male ZZ progeny) or a W (resulting in ZW progeny), with the contributing a Z to all offspring. This chromosomal arrangement influences the inheritance of sex-linked traits, distinguishing it from the XY system in mammals. Sex-linked recessive mutations in cockatiels occur on the Z . Females, being hemizygous for the Z , will express the if they inherit a single mutant from their father, as there is no second Z to mask it. Males require two mutant (one from each parent) to display the , appearing normal if carrying only one (homozygous normal or heterozygous). Birds expressing the are termed "visual," while those carrying the hidden recessive but appearing normal are called "split" for the . This pattern allows for sex-specific expression and is common in certain color-altering genes. Autosomal recessive mutations are located on non-sex chromosomes and require an individual to be homozygous for the recessive to express the , regardless of sex. Offspring from a carrier parent (heterozygous) and a normal parent will all appear normal but 50% will be split carriers. Both parents must carry the for a 25% chance of visual offspring in predictable crosses. This mode enables the propagation of traits without complications. Dominant mutations express in heterozygotes, appearing in offspring inheriting just one copy from either parent, irrespective of sex. In cockatiels, such mutations can show dosage effects, where a single copy (single-factor) produces a moderate and two copies (double-factor) intensify it, resembling incomplete dominance. The normal gray wild-type typically dominates over recessives but can be overridden by these dominant variants. Complex color phenotypes in cockatiels may arise from polygenic inheritance, involving multiple s contributing additively to traits like overall pigmentation intensity, or epistatic effects, where one masks or modifies another's expression in combinations. These interactions provide prerequisites for understanding multi-mutation birds but are less common than single- modes in established varieties.

Sex-Linked Mutations

Lutino

The Lutino mutation represents a classic example of a sex-linked recessive trait in cockatiels, characterized by the complete suppression of eumelanin production. This results in a bright body , vivid orange cheek patches, and striking red eyes, as the absence of dark allows blood vessels in the iris to show through. The beak, feet, and toenails appear pale or flesh-colored due to the lack of in soft tissues. In contrast to the wild-type cockatiel, where eumelanin imparts dark barring and overall tones, the Lutino exhibits no such pigmentation, creating a uniform, eye-catching appearance. Sexual dimorphism is subtle but observable in mature birds over one year old: males develop a fully bright face without markings, while females retain a paler, yellowish face and display fine barring on the underside of their tail feathers. Genetically, the Lutino allele resides on the Z chromosome, adhering to sex-linked recessive patterns in cockatiels' (males ZZ, females ZW). A visual Lutino male (homozygous Z^{ino}Z^{ino}), when paired with a normal female (Z^{+}W), produces 100% visual Lutino daughters (Z^{ino}W) and 100% normal-appearing sons split for Lutino (Z^{ino}Z^{+}). Conversely, a visual Lutino female (Z^{ino}W) paired with a normal male (Z^{+}Z^{+}) yields 100% normal daughters (Z^{+}W) and 100% normal-appearing sons split for Lutino (Z^{+}Z^{ino}). This ensures that visual Lutinos can only be produced if the carries the , making targeted breeding predictable but requiring careful tracking of splits in males. The Lutino mutation was first documented in in , , , when breeder Cliff Barringer observed it arising spontaneously from a pair of normal grey cockatiels; it was subsequently refined and popularized by Mrs. E. L. Moon, curator at Florida's Parrot Jungle. As the inaugural sex-linked in cockatiels, its emergence marked a significant advancement in avian color breeding. Lutino cockatiels carry a heightened of genetic baldness, often manifesting as a bald patch on the behind the crest, particularly if both parents are carriers of the separate bald gene—a fault linked to early during establishment. This condition results in bare, featherless skin rather than plucking or nutritional issues, though it does not typically impact overall health or lifespan. Lutinos are distinct from albino cockatiels, which require the additional autosomal recessive Whiteface to eliminate phaeomelanin (yellow pigment), producing a fully white bird instead of the characteristic yellow Lutino coloration.

Cinnamon

The Cinnamon alters the structure of in cockatiels, preventing the oxidation process that converts pigments into the black or shades typical of the wild-type coloration, thereby producing a warm tone without reducing the overall pigment quantity. This results in where the body feathers are replaced by light to deep cinnamon- hues, while the and orange psittacofulvins in the face, crest, and remain intact and vibrant. The patches retain their orange pigmentation, and the white bars are preserved, creating a softer, warmer overall appearance compared to the cooler tones of normal greys. Eye color is unaffected in adults, remaining solid black and fully pigmented, distinguishing it from mutations that eliminate entirely. The beak, legs, and feet exhibit a pale fawn or beige coloration. cockatiels may exhibit genetic baldness, such as a bald patch behind the crest, linked to early in the mutation's development, though this is not universal and does not affect overall health. As a sex-linked recessive carried on the Z chromosome, Cinnamon follows the standard avian sex-determination pattern where s (ZZ) must inherit the gene from both parents to express the , while females (ZW) display it if they receive the mutated from their father. This mode parallels other sex-linked traits like Lutino, but whereas Lutino eliminates eumelanin production leading to its absence, Cinnamon modifies the melanin's chemical structure to halt further darkening. Breeding outcomes typically yield a 50:50 split of visual and split offspring when pairing a visual hen with a split , enabling early genetic planning in . Visual identification of Cinnamon cockatiels is straightforward in adults, with the uniform body and retained yellow/orange elements providing clear markers, though ideal specimens avoid "marbling" or uneven overtones on the back and wings, which can arise from incomplete expression or environmental factors. Juveniles hatch with a temporary or dark pinkish that darkens to black within two weeks, and their downy gradually reveals the brown tones as feathers emerge, similar to wild-types but with muted intensity. Sex dimorphism persists but appears subdued: mature males develop a yellow face and brighter crest upon molting, while females retain the juvenile barred and patterns, often with less vivid yellow on the face and occasional additional yellow suffusion in the chest. The is among the most prevalent and earliest recognized sex-linked variations in cockatiels, originating around 1950 in and refined in by the late 1960s, making it a staple in breeding programs often used alone or in combinations for its reliable expression and aesthetic appeal.

Pearl

The Pearl mutation, also known as Opaline, is a sex-linked recessive in cockatiels that modifies the distribution of pigments in the , creating a distinctive scalloped of pearl-like spots formed by yellow or white edges on the feathers. This is most prominent in juvenile birds of both sexes, appearing as striped or spotty markings on the back, wings, and crest during the development of pin feathers. After the first molt, males typically lose the visible pearling as increased production covers the , resulting in a more uniform coloration, though some may exhibit a subtle mottled or dusty appearance. In contrast, females retain the full pearl lifelong, often with additional yellow pigmentation on the face, enhancing their visual distinctiveness. Pearl cockatiels may show genetic baldness, such as sparse feathers or a bald patch behind the crest, associated with during the mutation's early establishment, but this varies and generally does not compromise health. As a sex-linked recessive on the in the avian , Pearl expression differs by sex. Females (ZW) always display the if they carry the on their single , as there is no opposing wild-type on the W chromosome. Males (ZZ), however, require the Pearl on both s to be visually affected, while heterozygous males serve as carriers (splits) without showing the full pattern. This inheritance pattern was first established in in 1967 and results in variable patterns among offspring, necessitating to refine desired traits. Genetically, the Pearl mutation redistributes existing without altering base colors, thereby retaining wild-type psittacin and levels while shifting their placement to produce the scalloped effect. In breeding programs, it is prized for enhancing the aesthetic appeal of females through their persistent patterning, allowing breeders to produce visually striking birds while pairing it compatibly with many other mutations.

Yellowcheek

The sex-linked Yellowcheek (SLYC) mutation in cockatiels is a recessive genetic variant that specifically alters the pigmentation of the cheek patches by inhibiting the production of orange psittacofulvin, the responsible for the typical bright orange coloration, resulting in pale yellow cheeks instead. This change reveals the underlying yellow psittacofulvin layer, creating a more subdued facial appearance compared to the wild-type orange. Unlike body-wide mutations such as Lutino, which eliminate eumelanin across the entire , Yellowcheek targets only the facial cheek patches, leaving the rest of the bird's coloration intact. In the sex-linked recessive form, the is Z-linked, following the same as other sex-linked recessives like Lutino or Pearl, where males are ZZ and females ZW. Phenotypically, it produces a more intense pale cheek patch due to complete inhibition of orange psittacofulvin, with visual s showing heads and golden- cheeks, while visual females retain gray faces but display cheeks. Breeding outcomes include: a visual SLYC paired with a normal female yields 100% visual females and 100% split males; a split male (normal appearance) paired with a normal female produces 50% split females and 50% normal males, with no visual offspring in the first generation. This variant emerged in the early 1990s through the work of German breeder Bruno Rehm and has since become widely established in global . The SLYC mutation impacts by reducing the brightness of the cheek patches, a key secondary sexual characteristic, leading to less contrast between the sexes in facial coloration; males still develop yellow heads at maturity, but the pale cheeks create a softer overall face in both genders, distinguishing it from mutations like Whiteface that eliminate cheek pigmentation entirely. This mutation combines well with melanin-reducing traits like Pied or to enhance visual variety without masking the Yellowcheek effect.

Autosomal Recessive Mutations

Pied

The Pied mutation in cockatiels is an autosomal recessive trait that disrupts production, resulting in random or patches on the otherwise body . This leads to a variable spotting pattern, with expression ranging from light "dirty" Pieds featuring minimal splotches to heavy Pieds where much of the body is or , accented by on the wings and . The pattern is unpredictable, as no two birds exhibit identical markings due to the irregular removal of melanocytes. Inheritance follows an autosomal recessive mode, requiring both parents to carry at least one copy of the gene (either as visual Pieds or "split" to Pied) to produce visual , with a 25% chance of homozygous Pied chicks from two split parents. Split birds may show subtle indicators, such as small white or yellow spots on the head, aiding identification. The mutation is anti-dimorphic, meaning it eliminates the typical seen in wild-type cockatiels, requiring DNA testing for sex determination in visual Pieds. A notable subtype is the Clear Pied, also known as Bull's Eye Pied, where the bird appears almost entirely or with no markings and retains eyes, distinguishing it from mutations like Lutino that feature red eyes. Another variation is the Anti-Dimorphic Pied, emphasizing the loss of sex-linked visual cues. Breeders often select for heavier expression through line breeding, pairing light Pieds to produce progressively clearer patterns over generations, though heavy Pieds can emerge from lighter parents. The Pied mutation is one of the earliest recognized in cockatiels, first appearing in 1949 in the aviaries of Mrs. R. Kersh and D. Putnam in , marking it as the inaugural captive mutation for the species. It quickly became widespread due to its striking appearance and relative ease of breeding.

Whiteface

The Whiteface mutation in cockatiels is an autosomal recessive that eliminates the production of psittacofulvins, the and orange pigments responsible for the facial coloration seen in wild-type birds. Unlike the wild-type, which features a face and orange cheek patches, Whiteface individuals exhibit a white face, white tail markings, and white cheek patches against a retained body coloration in the yellow series. This mutation specifically targets psittacofulvin pigments without altering , resulting in normal black eyes and structural elements such as wing markings and body feathering. Visually, it produces a cleaner, more contrasting appearance compared to the warm tones of wild-type s, with the absence of /orange creating a blue-like structural effect akin to "blue" mutations in other parrot species. The Whiteface trait divides colorations into two primary series: the series, represented by -bodied Whitefaces, and the white series, which emerges when combined with other mutations that remove . Inheritance follows an autosomal recessive pattern, requiring both parents to carry at least one copy of the Whiteface gene (homozygous or split) to produce visual offspring; birds heterozygous for the mutation appear normal but can pass it on. The Whiteface gene interacts epistatically with (lutino) mutations, where it masks residual yellow pigments, leading to complete white plumage in combinations. In breeding, the Whiteface mutation serves as a foundational component for deriving albino (Whiteface combined with lutino) and creamino (Whiteface combined with lutino and ) varieties, enabling the production of all-white or pale birds with red eyes. This recessive nature makes it valuable for selective pairing to introduce the trait without immediate visual expression, supporting diverse color line development in .

Fallow

The Fallow in cockatiels is an autosomal recessive trait that dilutes the pigments in the to light brown or cocoa tones, while preserving the and orange coloration on the head, crest, and wing patches. Affected birds exhibit distinctive eyes, along with pale pinkish beaks, feet, and skin, and reduced or absent white iris rings. This primarily impacts eumelanin (dark pigments), resulting in a softer, warmer appearance compared to the wild-type body. As an autosomal recessive mutation, requires homozygous expression for the to appear, meaning both parents must carry the , and will only show the trait if they inherit the recessive from each. Heterozygous carriers appear normal but can pass the to progeny. The mutation follows standard patterns independent of . Several variants of the exist, distinguished by subtle differences in tone and intensity, all sharing the autosomal recessive but arising from distinct genetic loci. Bronze Fallow produces a warmer brown dilution with burgundy-red eyes and moderate eumelanin reduction, often resulting in laurel-green feathers on the body; it is not allelic with Ashen Fallow. Pale Fallow features greater dilution, yielding a near-yellow body with a light green hue and bright red eyes. Ashen Fallow (also known as Smokey Fallow) lightens to a pale, silvery tone, while Dun Fallow shows minimal plumage change resembling a diluted but with very bright red eyes. Breeding between different types typically produces normal offspring carrying splits for each. The mutation differs from the sex-linked in its recessive inheritance and the presence of eyes, which are absent in birds that retain dark eyes. The eyes in cockatiels produce effects similar to those in the sex-linked Lutino mutation but occur through an autosomal mechanism. cockatiels remain relatively rare in , with some variants like Dun particularly scarce due to breeding challenges. The mutation is associated with overall weakness in affected birds, potentially limiting population growth and vitality, though no severe health issues beyond reduced vigor and eye pigmentation changes are widely reported.

Recessive Silver

The Recessive Silver, synonymous with Ashen Fallow (also known as Smoky Fallow), is a variant of the mutation and an autosomal recessive in cockatiels that primarily affects production, resulting in a diluted coloration (see Fallow subsection for general traits). Visually, it lightens the typical grey body feathers to a pale silver or light grey tone, often with a subtle ashen glaze, while the orange cheek patches and yellow crest remain largely unaffected due to preserved psittacin pigments. A hallmark feature is the bright red eyes present from hatching through adulthood, along with pinkish beaks, feet, and toenails, which distinguish it from non-mutated greys. This dilution can make yellow suffusion more prominent in the plumage, enhancing a softer, muted overall appearance. Inheritance of Ashenfallow follows an autosomal recessive pattern, meaning both parents must carry at least one copy of the recessive for to express the , with a 25% probability of visual Ashenfallow when two carriers are paired. Birds heterozygous for the (split) appear phenotypically normal but can pass the to progeny. The interacts with other melanin-reducing dilutions, potentially producing subtly varied that are challenging to identify without confirmation, though it is not allelic to Bronze Fallow and thus does not interfere in that manner. Due to associated poor vigor in some lines, breeding recommendations emphasize pairing visual Ashenfallows to strengthen the and minimize health issues like reduced vision quality. Historically, the mutation emerged in during the 1950s and was further developed in by the 1960s, where it gained recognition in circles. Early included terms like Silver Fallow or simply Recessive Silver, but these have been updated to Ashenfallow to reflect its status as a true fallow-type dilution rather than a distinct silver variant, avoiding confusion with dominant forms. Its subtlety often leads to misidentification as a dilute , particularly in young birds or when combined with other mutations like Recessive Pied or Pearl, though the persistent red eyes provide a clear diagnostic trait similar to those in Fallow mutations. Despite its establishment in European and American breeding programs, Ashenfallow remains relatively uncommon owing to breeding challenges.

Dominant Mutations

Dominant Silver

The Dominant Silver mutation, also known as Dominant Edged or Ashen Dilute, is an autosomal dominant in cockatiels that primarily dilutes the grey pigment in the . In heterozygous birds (), the body feathers are lightened to a pastel silver- or ashen tone, with a subtle brownish and scalloped wing patterns resembling a diluted version of the normal ; the head and crest retain a darker "skullcap" appearance, while eyes remain black, and legs and are dark . Homozygous birds (double factor) exhibit even greater dilution, resulting in a nearly lutino-like with a pale greyish-beige over the body, a pronounced darker skullcap, and retained dark eyes, legs, and , distinguishing them from recessive silver variants. This mutation follows autosomal dominant inheritance, meaning a single copy of the from either parent is sufficient to express the silver in offspring, with no sex-linkage involved. When bred to a normal grey, approximately 50% of progeny will display the single-factor silver coloration, while pairings between two single-factor silvers yield 25% normal greys, 50% single-factor silvers, and 25% double-factor silvers. The acts by reducing dark to a silver tone without affecting or structural pigments, and young chicks initially appear similar to normals with down before the dilution becomes evident post-fledging. As the first dominant mutation identified in cockatiels, Dominant Silver originated in the United Kingdom in 1979 within the aviaries of breeder Terry Cole, where it was established and crossed into other varieties by 1988. Prior to this, all known cockatiel color mutations were recessive or sex-linked, making Dominant Silver a significant breakthrough in avian genetics for the species. Breeders are advised to exercise caution when pairing Dominant Silver birds, particularly avoiding combinations with other melanin-reducing mutations such as lutino, , or , as these can mask or unpredictably alter the silver expression. Selective breeding with normals, pearls, or pieds is recommended to maintain clear phenotypes and vitality, as the mutation is generally robust but benefits from . Double-factor production should be monitored, as extreme dilution may lead to less vibrant birds, though no has been reported.

Dominant Yellowcheek

The Dominant Yellowcheek mutation in cockatiels is an autosomal dominant genetic variation that primarily affects the pigmentation of the facial region, resulting in a replacement of the typical orange cheek patches with ones while leaving the body largely unchanged. This mutation was first reported in a aviary around 1996, marking it as the eleventh established color mutation in cockatiels and the first truly dominant one recognized . Unlike recessive or sex-linked mutations, Dominant Yellowcheek requires only a single copy of the to express visibly, affecting both males and females equally without sex-specific differences in . In terms of inheritance, the mutation follows an autosomal dominant pattern, where a bird carrying one copy of the Dominant Yellowcheek will produce offspring that are 50% visual for the trait when bred to a non-carrier, and 100% visual when bred to another carrier. Chicks with the often exhibit yellow down feathers, and the trait becomes identifiable at the pinfeather stage as the cheek patches develop without orange tones. There is no visual distinction between single-factor (heterozygous) and double-factor (homozygous) birds, though some sources note that homozygous pairings consistently yield all visual offspring. This dominance distinguishes it from the sex-linked Yellowcheek, which is recessive and requires two copies for expression in males or carrier status in females. Phenotypically, the mutation intensifies yellow lipochrome pigments on the cheeks and face, reducing or eliminating the orange psittacofulvin that normally colors these areas, leading to a clearer, more vibrant appearance. In mature males, the extends to the , creating a uniform head without the contrasting orange cheeks seen in wild-type birds, while females retain a more subdued expression similar to normals but with cheeks. The body remains grey or lutino-based depending on other , with no widespread dilution effects. Regarding interactions with other facial mutations, Dominant Yellowcheek should not be paired with Whiteface varieties, as the latter recessively eliminates yellow pigments, resulting in reduced or absent cheek coloration and compromising the visual expression of the trait. Optimal breeding involves pairing with normals featuring deep orange cheeks to enhance the yellow intensity through , avoiding combinations with other cheek-altering mutations like Pastelface to prevent diluted or inconsistent outcomes.

Combined Mutations

Common Combinations

In cockatiel colour genetics, common combinations of mutations often result in striking visual phenotypes due to interactions such as , where one mutation masks or modifies the expression of another. One prevalent example is the Albino, formed by combining the Whiteface and Lutino mutations, which eliminates all and lipochrome pigmentation, producing a pure with red eyes. Similarly, the Creamino arises from Whiteface paired with , yielding a soft cream or pale body coloration with red eyes, as the Whiteface mutation suppresses yellow tones while dilutes the grey to a brownish hue. Another popular combination is the Pearl Pied, integrating the sex-linked Pearl mutation's lacy, iridescent white markings on the wings and back with the autosomal recessive Pied's irregular yellow or white patches on the body, creating a patterned appearance that highlights both spotting and pearling effects. plays a key role in these visuals; for instance, in Whiteface Lutino combinations, the Whiteface fully masks any underlying yellow lipochrome, resulting in a uniform white that conceals other traits like Pearl patterns. Lutino can partially mask , but residual "bleed-through" from often imparts a subtle dirty or off-white tint to the overall appearance in such multi-mutation birds. Less common but notable combinations include the Cinnamon-Pearl Pied, where Cinnamon's brown dilution of grey feathers combines with Pearl's edging and Pied's patches for a warm, variegated look, and Lutino Pied, featuring a predominantly yellow body interrupted by Pied's white or clear areas. Rare variants, such as those involving the Emerald (also called Olive or Suffused Yellow) mutation, introduce a greenish tint through melanin reduction and redistribution, blending diluted grey with underlying yellow pigments to create an olive-like suffusion across the plumage. These interactions among the established mutations—such as Pied, Lutino, Pearl, Cinnamon, Whiteface, and others—can yield over 32 distinct visual varieties in cockatiels.

Breeding Outcomes

Breeding combined mutations in cockatiels requires careful genetic planning to predict outcomes, as interactions between loci can lead to variable ratios of visual phenotypes among offspring. For instance, combining the sex-linked recessive lutino (ino) mutation with the autosomal recessive whiteface (wf) mutation produces visual albinos, which express both traits simultaneously. A representative cross involves a visual whiteface hen (Z^{+}/W ; wf/wf) paired with a visual lutino cock split to whiteface (Z^{ino}/Z^{ino} ; wf^{+}/wf). The resulting offspring ratios are as follows: 25% visual albino females (Z^{ino}/W ; wf/wf), 25% lutino females split to whiteface (Z^{ino}/W ; wf^{+}/wf), 25% whiteface males split to lutino (Z^{+}/Z^{ino} ; wf/wf), and 25% normal males split to lutino (Z^{+}/Z^{ino} ; wf^{+}/wf). This 25% visual albino rate arises from the independent assortment of the autosomal whiteface locus (yielding 50% wf/wf overall) and the sex-linked lutino locus (where all female offspring inherit the ino allele from the cock, but males require two copies to express the trait). Epistatic interactions further complicate breeding predictions, where one masks the expression of another. The , for example, is phenotypically epistatic to many -based , such as or pearl, effectively suppressing their visual effects in homozygous or hemizygous carriers by eliminating production entirely. This masking occurs because acts downstream in the pigmentation pathway, overriding upstream modifications from other loci. Breeders must account for these interactions when targeting specific combinations, as the apparent may not reveal all underlying . Several challenges arise in breeding combined mutations, including the proliferation of recessive carriers and potential in homozygous dominant forms. When pairing birds split to multiple recessives, up to 75% of may carry hidden mutations without visual expression, increasing the risk of unintended propagation and complicating future pairings. For dominant mutations like dominant silver, homozygous individuals (DS/DS) are often inviable or exhibit severe dilution, leading to embryonic and reduced clutch viability; breeders thus avoid such pairings by using heterozygous (DS/+) birds. Sex-linked mutations can skew visual sex ratios—for example, pairing a visual lutino cock with a normal hen yields 100% lutino daughters and 0% lutino sons, potentially unbalancing breeding stock. Ethical breeding practices emphasize health by minimizing , which can amplify genetic defects and reduce overall vigor in cockatiel populations. Related pairings, such as siblings, elevate risks of congenital issues like weakened immunity or skeletal abnormalities; instead, introducing unrelated lines maintains and supports long-term flock health. Reputable breeders prioritize these considerations, conducting genetic tracking to avoid over-reliance on carrier birds and ensuring offspring viability.

Additional Features

Eye and Structural Variations

In cockatiel color genetics, variations primarily arise from that reduce or eliminate production, leading to distinct phenotypes compared to the normal black eyes observed in wild-type and most other . The Lutino (sex-linked ) mutation results in red or eyes due to near-complete absence of in the iris, a characteristic shared with other albinistic forms. In lutinos, eyes start as at and may develop a deeper red tone with age. Similarly, the Fallow and Recessive Silver produce red or eyes through substantial reduction, distinguishing them from non-albinistic variants like Dominant Silver, which retain black eyes. These s are evident from , though they may darken slightly with age as minor development occurs. Structural variations linked to cockatiel mutations often involve changes in beak, feet, and feather distribution beyond plumage. Dilution mutations, such as Recessive Silver, cause lighter gray or pinkish feet and beaks due to partial melanin dilution, contrasting with the dark pigmentation in normal greys. The Lutino mutation extends this effect, resulting in pink feet, pale pinkish-white beaks, and clear (pink) toenails from total eumelanin absence in skin and keratin structures. Additionally, a genetic baldness trait, particularly prevalent in Lutinos, manifests as a bald spot behind the crest on the head, attributed to a featherless area or fault in early mutation lines, often exacerbated by inbreeding. Other non-plumage features include the retention or modification of wing flashes and tail barring patterns influenced by . Wing flashes, the white patches on the secondary , remain pure white in most , including albinistic ones like Lutino, serving as a consistent structural marker unaffected by reduction. Tail barring, typically yellow bands on undertail s in juvenile and normals, persists or alters in certain ; for instance, in some variants, tail s may show unpatterned without barring or exhibit delicate lines at angles, reflecting genetic influences on . Health implications for red-eyed cockatiels stem from the underlying and , where deficiency primarily affects pigmentation, leading to vulnerabilities like decreased resistance. Lutinos, in particular, show heightened susceptibility to such issues alongside other abnormalities like nervous disposition from inbreeding.

Sexing Methods

In wild-type cockatiels, is evident after the first molt around 6-9 months of age, with males developing a bright face and losing barring on the and underwing feathers, while females retain a greyish face and barring. However, certain complicate this visual , as they obscure these distinguishing features; for instance, the Pearl causes immature males to retain the pearly spotting pattern similar to females, and upon maturity, some males may lose it inconsistently, leading to ambiguity. Similarly, the Lutino results in all- that hides barring and underwing spots, making visual differentiation nearly impossible without additional methods. One traditional method involves measuring the width between the pelvic bones by gentle at the bird's vent; females typically exhibit a wider gap to accommodate egg-laying, while males have narrower, more pointed bones. This technique requires experience to avoid injury and is most reliable in mature birds, though its accuracy varies widely due to individual anatomical differences and is generally considered unreliable for young or mutated cockatiels. Behavioral observations provide another non-invasive approach, observing that mature males often display strutting, whistling, and vocal , while females tend to exhibit regressive behaviors like reduced calling or nest-shredding. These cues become apparent post-molt and achieve approximately 80-90% accuracy in experienced hands, though exceptions occur, such as vocal females or quiet males, particularly in sex-linked mutations where hormonal influences may alter displays. The most definitive method is DNA testing, which analyzes genetic markers like the CHD1 gene on via PCR amplification from blood, feather, or fecal samples, producing distinct band patterns: a single band for males (ZZ) and double bands for females (ZW). This approach offers 100% accuracy in controlled studies on cockatiels and is especially valuable for like Pearl or Lutino, where visual and behavioral methods fail, enabling precise breeding and health management without risk to the bird.

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