Peach-faced lovebirds are one of the most common of the nine species of lovebird. In the wild, the bird has a peach-colored face, while the body is mainly green with some blue and black. In captivity, according to Doug Bedwell of the African Lovebird Society, at least 17 different mutations exist, with more than 100,000 possible color combinations. Not all color combinations retain the peach-colored face, but they are still all the same species, peach-faced lovebirds (Agapornis Roseicollis). To predict what colors the offspring of any two peach-faced lovebirds will be, you need to know the traits of the different colors and have some knowledge of the two birds' parents.
You'll need a basic understanding of genetics to predict what colors the babies of two peach-faced lovebirds will be. Each color is represented by a gene, or in some cases, by a chromosome attached to the sex gene. Each parent contributes one gene to each baby.
The genotype refers to the bird's actual genetic inheritance, and the phenotype refers to the physical expression of the genotype -- the appearance of the bird. For example, the normal green color is dominant, but a green bird (phenotype) can have a green gene from one parent and a Dutch blue gene, which is recessive, from another parent (the genotype). Or, it can have two green genes, one from each parent.
If one parent is a Dutch blue color, then you know that it only has two Dutch blue genes, since Dutch blue is a recessive color. Mate that Dutch blue bird with a bird that you know is pure green (having only two green genes), and you will have all green babies, each with a recessive Dutch blue gene. But when you mate those offspring (brother to sister), you can get different combinations, including a pure Dutch blue color -- some babies will inherit a Dutch blue gene from each parent, others will inherit a green gene from each parent, and the rest will inherit one green gene and one Dutch blue gene.
A bird must have two of the recessive genes in order to be that color. If it inherits one of the recessive genes and one of the dominant genes, it will have the dominant color, but will be able to pass on the recessive gene to its offspring as well as the dominant gene.
The recessive colors, according to the African Lovebird Society, are:
American Yellow and Japanese Yellow
Australian Recessive Pied
Dominant Colors and Partial Dominant Colors
American pied and green are the two dominant colors of peach-faced lovebirds. If a bird has even one gene for either of these colors, that is the color you will see on the bird.
The partial dominant colors are the dark factor and violet. These are not actual colors, but factors that alter the bird's genetic color. So if a a green bird has two dark factor genes, it will be an olive green instead of light green. If it only inherits one dark factor gene, then it will be a medium green. The violet factor causes a richer, deeper coloring and also adds a violet or purple hue.
Sex-Linked and Other Characteristics
Sex-linked characteristics are carried on the sex chromosomes that determines the sex of the bird. These are the Lutino, American Cinnamon, Australian Cinnamon, Lacewing and Opaline. Both male and female birds can have these factors, but the factor is only carried on the X chromosome. In birds, two X chromosomes (XX) make a male, and an XY pattern is a female. This can be confusing because it is the opposite of humans and other mammals, which require an XY to make a male.