Dark
Factor in Peachfaced Lovebirds
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.
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