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www.katharinasittiche.de - Dark Factor - The Lineolated Parakeet - Bolborhynchus lineola!
Dark Factor

Autosomal co-dominant heredity - Dark factor

The dark factors lead to a few more lovely colour varieties at the Lineolated Parakeets.
The plumage marking remains. Sometimes the intensity is even increased, so parts of the bird might look completely black. Beaks and feet usually don't show any differences to that of the green birds, sometimes they might be a little bit darker or greyish.

In the green line the single factor bird is called dark green. As assumed, this bird is a little bit darker than the normal green bird. Sometimes the bluish glimmer of special parts is emphasised, especially in the head region.

The additional second dark factor leads to another, even darker bird. So the whole bird shows up in a luscious olive green.

Dunkelgrün Olive
Photo: Borchard/Fiedler
Dark green Lineolated Parakeet
Mutation in olive (left) beneath a green Lineolated Parakeet

Photo: Regina Graf
Lineolated Parakeet in cobalt.
Similar observations one can make at the blue line. The cobalt turquoise birds own one dark factor. The bright turquoise plumage of the normal turquoise birds changed into a lovely dark blue to violet.

The double factor, mauve coloured bird is nearly grey, with only a shadow of blue-violet. In my opinion this is a very interesting colour mutation, which seems to be a black-and-white photo, compared to the otherwise bright, luscious colours of the Lineolated Parakeets.

Photo: Borchard/Fiedler
A mauve coloured bird.

Of course the dark factors exist at the Inos as well as at all other known colour mutations. But there no specific denotations had been given; because the variations in lightness, which result from the presence or absence of dark factors, can't be distinguished from the normal variations in colour intensity, which occur in Inos anyway. Because even without dark factors there are nearly white to yellow-cream-coloured birds at the Creaminos. Also at the Lutinos the colour palette ranges from light, bright to a dark yellow. Therefore potentially present dark factors can be noticed just by analysing the heredity schemes.

different colours
Photo: Borchard/Fiedler
From left to right: Lineolated Parakeets in turquoise, mauve and olive.

Here you can find a few examples for the heredity of the dark factor!

The reason for the darker colours of the birds with one or two dark factors is independent from the amount of available melanin, which is the same as in wild type birds. The dark factor is a famous example for the alteration of the so called "structural colour". In this case the genes, which are responsible for the depth of the cloudy layer, are mutated. If the layer thickness is changed, the incoming light will be scattered in a different way. So, at animals with a dark factor, the depth of the cloudy layer is less as at the wild type.