The plumage is rich, but smooth and snug. Ideal for all bird keepers is a pure blue dove, as the background of all the feathers, and in each feather, an edge very narrow and defined steel blue.   But this perfection is not easy to achieve. 

Thus, the background ranges from silver-gray to a dark slate blue; however, the proper and desirable shade is a light blue (bluish gray) without any mixture, or a pure dove blue, which is the middle ground between these two shades and is essentially a gray with a bluish tint.

Each feather, with the exception of the tail feathers, must have a very narrow border around its entire length (not just at the tips)—a border that is uniform in width, clearly defined, and a dark, glossy steel gray (not black)—and even the wing coverts and the undertail coverts must not be entirely black but rather have a blue undertone.

El fondo azul claro (paloma) del plumaje es el más difícil de obtener, por lo cual no se suele ser muy severo cuando es algo más claro u oscuro (azul pizarra); pero no debe tirar ni azul de pizarra oscuro o negruzco ni a la ceniza y blanco de plata, e igualmente debe estar libre.

First: For all yellow and brown rust-colored patches on the chest and underbelly, as well as on the shoulders and back—which frequently appear on pale-colored males—see "disqualifications" to distinguish those caused by the sun.

Second: Splash black and dark specks, producing the dissolution of the drawing of the edge, as well as feathers and whitish marks.

The feather pattern (see photo above) is even more important to many poultry breeders, who, at this stage and for birds that must be slender, allow for no compromise (strict selection); this does not mean, however, that one should focus solely on a well-defined edge while neglecting the true background color, which is light gray.

The weeping and the mozzetta, which are the most difficult to obtain in pure color, should not in any case be truly black and lustrous, but always appear in a shade of blue, if this is very dark as if it is a steel gray, very different from the feathers of the back.

The rectrices and gorges of the male should be blue, slate, uniform and more pure as possible.

In the female, in consequence of the same formation of pens, the drawing of the edge is more uniform, without the head, tail and rectrices; the tail is blue only.

A unique genetic trait of this breed, the Andalusian Blue hen, is the consistent production of offspring that includes not only blue chicks but also black ones.

Con el cruce, blanco sucio o splash y el negro, que se han utilizado en los cruzamientos originales hace ya muchas generaciones, sirve para realizar estas gallinas azules.

By way of explanation. The bluish-gray color of this breed is due to the presence of a single dose of the “Bl” allele when combined with the “E” allele (of the e gene, or of the e allelic series) which produces totally black birds.

Its effect consists of a partial dilution of melanin, which is responsible for the black color. Therefore, when it acts in a double dose, it suppresses it almost entirely, resulting in birds that are white with black and blue markings. Consequently, in “EE” birds, the following three cases occur:

• E E bl bl: Black, no melanin dilution.
• E E Bl bl: Blue, with partial melanin dilution.
• E E Bl Bl: Blancas, manchadas; hay eliminación casi total de melanina.

In this race is not present in the allele “Co” (columbian), at least in the Spanish variety; and that has hidden, as all of our breeds blackthe allele “s” (gold).

All females carry the blue genes, and when bred with black-and-white or other blue individuals, the resulting offspring, in turn, produce many blue offspring.

When it comes to breeding stock, the ideal approach is to use both the best roosters and those with the deepest blue color, paired with well-built hens, and this will yield good results.

About 50 % All the chicks will be blue.

The other 50 % It will be available in black, white, and combinations of black and off-white.

Spanish breeds related to the Andalusian Blue include the Black Castilian, the Catalan del Prat, and other Mediterranean laying hens.