Dark Factor in
by Doug Bedwell
Dark Factor (DF) is a mutation which creates
many interesting color possibilities. DF is a semi-dominant mutation
(sometimes termed partial dominant). This means two things:
1. A bird needs only to inherit the mutation from ONE of its parents to
show the effects of the mutation. A bird which carries a single copy of
the mutation is referred to as a "single dark factor" bird.
2. A bird which inherits the mutation from BOTH of its parents,
referred to as a "double dark factor", will look very different from a
single dark factor bird.
Unlike most of the other
mutations in the Peachfaced Lovebird, Dark Factor does not effect the
bird’s feather pigments in any way. Rather, what is effected is
actually the physical structure of the feathers. (Jim Morris, "Notes on
the Dark Factor", Agapornis World, Oct. 1980). This subtle change in
the feather structure alters way that the feathers reflect light,
causing the bird’s color to be both deeper, and darker.
On most peachfaced, the presence of the dark
factor is most easily identifiable by checking the color of the
bird’s rump. In a normal peachie, the rump will be a bright
tourquoise blue. If a single dark factor is present, the rump will be a
dark royal or navy blue. Double dark factor birds are easily
recognized, as the body is very dark, and the rump is actually grey.
Perhaps the most exciting
aspect of the Dark Factor is the tremendous variety of colors it makes
possible, when it is combined with other mutations. Almost every other
color available in the peachfaced can be produced in three distinct
shades by combining it with the dark factor. This has led to many
beautiful varieties of peachfaced, but also a wide variety of names for
these combinations, which frequently prove confusing to the novice
enthusiast. Though most experienced breeders are familiar with terms
such as "jade", and "slate" many beginning breeders that I have spoken
to have been confused by these terms.
The terms "Jade" traditionally refers to a
single dark factor green, while "Olive" would refer to a double dark
factor green. "Cobalt" refers to a single dark factor Dutch Blue bird,
and "Slate" indicates a double dark factor Blue.
These terms were simple
enough when there were only a few mutations of the Peachfaced to deal
with, and most experienced breeders still use them informally. However,
the generally accepted terms for all single and double factor lovebirds
are "Medium" and "Dark", respectively. Thus, "Jade," "Medium Green,"
and "Single Dark Factor Green" are synonomous. The advantage of the
terms "Medium" and "Dark" is that they are both simpler and more
precisely descriptive than the older terms. Whereas "cobalt" can only
refer to birds in the blue series, and "jade" only to the greens,
"medium" can be prepended to any color description to indicate the
presence of a single dark factor.