SEX-LINKED MUTATIONS
Many writers have attempted to explain and detail the rules relating to
Sex-Linked inheritance in Zebra Finches, but the illustrations as shown on the
following pages make it much easier to follow. The Australian birds that belong
to this group are Fawn, Chestnut Flanked, Marked White, and Cream Backed
Zebras.
The term “Sex Linked” is used because the sex and colour of these birds is
determined by their genetic (or internal ) make-up. Therefore it is imperative
to realize that the colour of the cock and character of his genes for another
colour if any, also colour of the hen, will play an important role in
transmission of colour to young birds in the different sexes.
One example shown is when a Marked White cock is mated to a Grey hen . If the
cock is pure Marked White and the hen is pure Grey, their young will be grey
coloured cocks and Marked White hens. The young grey coloured cocks will carry
hidden genes for Marked White and are termed “split Marked White,” which is
written on paper as Grey/Marked White, the visible colour being shown before
the hidden colour form. It should be noted that hens cannot be split for
a Sex-Linked colour, i.e. they cannot carry hidden genes for any Sex-Linked
colour form.
Where birds are shown on the illustrations as Greys or Marked Whites, this
refers only to pure Greys and pure Marked Whites.
If the breeder wishes to breed Fawns, all he or she need do is substitute the
word “Fawn” in each instance where the words “Marked White” are shown on the
illustrations. The same method of substitution can also be used for the
other Sex-Linked mutations.
Zebras of both sexes can carry Recessive genes such as Pied or White, which may
not show in their feathering. If these colours appear in your young birds their
parents are not of a pure Sex-Linked colour form, or are not pure Greys.