Darkgreen opaline cock x skyblue hen

The facts

Sire: darkgreen opaline cock
Dame: skyblue hen

    Expected offspring
  • darkgreen cock/opaline, blue
  • lightgreen cock/opaline, blue
  • darkgreen opaline hen/blue
  • lightgreen opaline hen/blue

    Observed result
  • yellowface type 1 cobalt cock
  • lightgreen cock
  • lightgreen opaline hen
  • darkgreen cock
  • lightgreen cock
  • darkgreen dilute opaline hen

Analysis

There are two unexpected factors in our offspring: yellowface and dilute

Yellowface

Yellowface type 1 birds actually is a combiantion of a yellowface type 1 allele (blyf1) and a true blue allele (bl). The blue allele comes from the skyblue dame, so the yellowface type 1 gene must come from the cock. So the cock is split for yellowface type 1:
Sire: darkgreen opaline cock/yellowface type 1

In theory the hen could also be a double factor yellowface type 1: blyf1/blyf1. Such a bird looks exactly like a normal blue bird. In that case the cock is split for normal blue.
If you want to know more about these two types of blue read Gene function in Yellowface Budgerigars - Part 1 When is a Yellowface not a Yellowface? by Peter Berghman.

Dilute

To get dilutes, a recessive factor, both parents need to carry the dilute gene. Since both parents aren't dilute, they must be split:
Sire: darkgreen opaline cock/yellowface type 1, dilute
Dame: skyblue hen/dilute

Conclusion

Sire: darkgreen opaline cock/yellowface type1, dilute
Dame: skyblue hen/dilute

    Expected offspring
  • darkgreen cock/opaline, blue
  • lightgreen cock/opaline, blue
  • darkgreen opaline hen/blue
  • lightgreen opaline hen/blue
  • yellowface type 1 cobalt cock/opaline
  • yellowface type 1 skyblue cock/opaline
  • yellowface type 1 cobalt opaline hen
  • yellowface type 1 skyblue opaline hen
  • darkgreen cock/opaline, blue, dilute (x2)
  • lightgreen cock/opaline, blue, dilute (x2)
  • darkgreen opaline hen/bluei, dilute (x2)
  • lightgreen opaline hen/blue, dilute (x2)
  • yellowface type 1 cobalt cock/opaline, dilute (x2)
  • yellowface type 1 skyblue cock/opaline, dilute (x2)
  • yellowface type 1 cobalt opaline hen/dilute (x2)
  • yellowface type 1 skyblue opaline hen/dilute (x2)
  • darkgreen diltue cock/opaline, blue
  • lightgreen diltue cock/opaline, blue
  • darkgreen diltue opaline hen/blue
  • lightgreen diltue opaline hen/blue
  • yellowface type 1 cobalt diltue cock/opaline
  • yellowface type 1 skyblue diltue cock/opaline
  • yellowface type 1 cobalt diltue opaline hen
  • yellowface type 1 skyblue diltue opaline hen
(x2) means twice as probale as the other lines.

    Offspring
  • yellowface type 1 cobalt cock/opaline [possibly split dilute]
  • lightgreen cock/blue, opaline [possibly split dilute]
  • lightgreen opaline hen/blue [possibly split dilute]
  • darkgreen cock/blue, opaline [possibly split dilute]
  • lightgreen cock/blue, opaline [possibly split dilute]
  • darkgreen dilute opaline hen/blue

(C) Bert Raeymaekers