The Genetics of Color of Lovebirds

These are some of the more common terms you will hear when discussing the colors of parrots. However, these only scratch the surface.
Split: When a lovebird is said to be split to a certain color, the lovebird carries the color genetically but does not express it visually. It can pass this color to its young, depending on the mode of inheritance of the particular color. If you have two green birds split blue, they both look green but can have blue progeny. this gets more complicated when you have lovebirds split for sex-linked or sex-lined recessive colors. Splits are commonly written as the visual color, followed by a slash, then the split color. For example, green/blue denotes a visually green lovebird split blue. This convention will be used throughout this chapter. Because of splits, two lovebirds can be the same phenotype (they look the same) but be different genotypes (they carry different genetic information). This is why people are sometimes surprised by a baby in their clutches of peachfaced lovebirds. If you have two green lovebirds and lutino hatches in a clutch, you can be sure this baby is a hen because only a male can be split lutino and he can pass it only to his daughters.
Sex-linked: Colors that are sex-linked can be passed from the parent of one sex to babies of the opposite sex either as a split (hens to male babies) or as a visual color (cocks to female babies). To get babies of both sexes in the sex-linked color, both parents must carry the color, either visually or as a split. Only males can be split to a sex-linked color. Hens either show the color visually or do not carry it.
Dominant: You often hear about a color being dominant. Maybe you are a beginning breeder who put together a green hen and blue cock. You got all green babies and cannot figure out why you did bot get any blue babies. The reason is that green is a dominant color. Both parents must be blue, either visually or as a split, for the babies to express blue visually. Babies from the pair where only one parent is blue will be visually green, split blue. If you have two green parents split blue, you will get some visually blue babies.
Autosomal dominant: Genetic inheritance of an autosomal dominant trait depends on whether one or both parents carry the mutation. Pied is an example of an autosomal dominant mutation. If you have one green parent and one pied parent, some or all of the babies will be pied. If you have two pied parents, all babies will be pied.
Autosomal incomplete dominance: Both parents must show the color for babies to show it. However, the degree of the effect will vary depending on its expression in the parents. Violet factor is a good example of this. Violet can look very different in babies than in their parents. The appearance of both parents has impact on the apperance of progeny. A difference in appearance also occurs if both parents carry single or double violet factor. It either shows this color or does not carry it. However, double dark factors can obscure violet factors, which has led to the misconception that lovebirds can be split violet.
Inheritance of Lutino in Peachfaced Lovebirds*
Mother Father Females Babies Male Babies
Green Green/Lutino Green Green/Lutino
Lutino
Lutino Green Green Green/Lutino
Lutino Green/Lutino Green Lutino
Lutino Green/Lutino
Lutino Lutino Lutino Lutino**

* The color creamino can be substituted for Lutino to find the results for two lovebirds of the ground color blue.
** Breeding two red-eyed parents together is not considered a good practice. Your healthiest clutches with the highest percentages of lutino babies will come from the pairing of a lutino hen and a green split lutino cock.

Autosomal complete dominance: There will be no difference in appearance whether single or double factor. However, the number of factors influences the number of young inheriting the factor by increasing the percentages of babies showing this variety.
Autosomal recessive: Both parents must carry the mutation, either visually or as a split, for it to show visually in progeny. Two lovebirds split to an autosomal recessive color will have some babies of that color as well as babies that are their visual color. For example, a pair of white Fisher's split ino can have both white and albino babies. However, for sex-linked autosomal recessive mutations, such as lutino in peachfaced love birds, inheritance is as shown in the table below.
AS you can see if you put a hen who has a sex-linked recessive color with a cock who does not carry this color either visually or as a split, you will not get any babies that visually carry the color. However, all your males will be split to the sex-linked recessive color and can therefore pass it on to their daughters.

Peachfaced Lovebirds: Modes of Inherutance
Color Mode of Inheritance
Green Dominant
Blue Autosomal recessive
Pied Autosomal dominant
Ino (lutino or creamino) Sex-linked recessive
Cinnamon Sex-linked recessive
Dark Factors Autosomal incomplete dominant
Violet Factors Autosomal incomplete dominant
Whitefaced Autosomal recessive
Orangefaced Autosomal incomplete dominant

Masked Lovebirds: Modes of inheritance
Color Mode of Inheritance
Blue Autosomal recessive
Dilute Autosomal recessive
White Autosomal recessive
Ino A Autosomal recessive
Dark Factors Autosomal, codominant, incompletely dominant

Fisher's Lovebirds: Modes of Inheritance
Color Mode of Heritance
Blue Autosomal recessive
Dilute Autosomal recessive
Ino Autosomal recessive
Yellow* Autosomal recessive
Dark factor Autosomal. codominant, incompletely dominant
Violet factor Autosomal dominant


* A yellow/ino Fisher's results from the pairing of one ino parent and one yellow. These lovebirds are heterozygotic. They are yellow with black eyes. The overall color is more muted than seen in lutinos. Putting two yellow/ino Fisher's together will produce some lutino babies.

lovebird color geneticsModes of Inheritance
The tables above can guide you in determining how to pair parents to get the colors you would like in your babies. A number of other colors occurs, but these are the most commonly bred in these species.

The modes of inheritance for Fisher's and masked are quite similar to those for other eye-ring species. Note that most mutations are autosomal recessive, which means both parents must either visually show the mutation or carry it as a split for babies to show the mutation. Ino is not sex-linked in Fisher's or masked lovebirds.

This text has shown only the tip of the iceberg when it comes to the genetics of color inheritance in lovebirds. Many books are totally devoted to this topic. You are encourraged to do further reading if you plan to start a color breeding program

Source: http://lovebirdlovers.com/color-genetics/41-color-genetics/73-genetic-terminology.html