How to recognize a male carrying the black breast mutation

The purpose of this article is not to establish an unstoppable rule for the recognition of a gray male carrying the black breast mutation. Rather, it aims to gather clues that can help you identify it.
For this, each point of detail of the mutation is resumed, as I observed during the selection of my black chestnut strain.

Before starting to analyze each possible clue, it seems important to me to bear in mind that the black breast mutation modifies the shape of the drawings. To identify a carrier of the black breast mutation, I also advise you to take into account all the clues described in this article.

Let's proceed and analyze the phenotype of a gray, black-breasted head to the rectrices compared to a gray carrying the black breast mutation. To identify each descriptive terms used, you can use this diagram : Descriptive terms in zebrafinch.

1. Mustachial trait

Black breast (pn) : The moustachial line will be pronounced and intense black.
Black chest carrier (/ pn) : The moustachial line may be more pronounced than on a gray, however this does not constitute for me a sufficient index.

2. Tear Trait

Black chest (pn) : The line of tear disappears (ideally following the standard) or only a fine line remains.

1 trait de larme pn 1

Black breast carrier (/ pn) : Different cases depending on the force of expression of the mutation in the carrier.

- The line of tear is present and end :

2 trait de larme porteur pn 1

- The line of tear is present and wide :

3 trait de larme porteur pn 1 png 1

- In some cases the tear line of a black breast carrier may also be absent. The other clues will have to be trusted to know if it is a carrier or a full black breast.

3. The cheeks

Black Chest (pn) : The cheek pattern will extend up and back of the head.

4 extension joues pn avec fleches 1  5 extension joues nuque pn 1


Black chest carrier (/ pn) : The cheek pattern will be irregular and you will usually see an overflow of the cheek upwards.

6 extension vers le haut de la joues porteur pn 1


In some cases the wearer black chest may have a cheek identical to a gray. In this case, it will be necessary to rely on other possible indices.

4. Chin, throat and chest

Black breast (pn) : The darkest intense possible going up as far as possible towards the chin.

7 menton gorge et poitrine pn 1

Note that the zebra is no longer present.

Black chest carrier (/ pn) : The chest bar will usually be wider than a gray one; The zebra from the beak to the breast bar will be present.

8 menton gorge et poitrine porteur pn 1

5. Drawings of the flanks

Black breast (pn) : uniformly covered with elongated white dots.

9 flancs pn 1

Black chest carrier (/ pn) : Equipped with white dots ranging from round to elongated.
For reference, here are the flank points of a gray :

10 points des flancs d un gris 1

The drawing of the flanks slightly elongated or having an imperfect round shape will not be a sufficient clue. This can be part of a defect in the gray (non-carrier).

6. Drawings of remiges

Black chest (pn) : Removes and wing covers secondary and tertiary edged with a brown and orange-brown border.

11 dessins remiges pn

Some black breasts may not present these borders depending on the level of selection made by the breeder.

Black chest carrier (/ pn) : Some bearers can be observed with more or less remiges with the drawing described above. Here again, the "force" of expression of the mutation will play its role.

12 remiges d un gris 1

7. Fathers' drawings

13 comparaison dessin rectrices 1

In a gray the drawing of the rectrices will have to be strictly horizontal and rectilinear.
In the 2nd case "Black chest carrier gray", you can be between the defect of rectrices of a gray or a black chest bearer. It is therefore necessary to be careful and not to assert an analysis without taking into account the global nature of the bird.
Finally 3rd case, the black chest will have this drawing going towards the end of the tail, (oriented in the direction of the pen). Some black chest wearers may also have more or less this feature.


If one or more of these clues clearly modifying one of the drawings is convincing on your zebrafinch, its genotype includes the black breast mutation. However, remain cautious, other mutations may also interfere in the interpretation of the phenotype.

Among the carriers you will find a lot of intermediary. Which will be more precisely, between the phenotype of a gray :

14 male gris anglais 1

And that of a gray chest black :

15 male gris poitrine noire 1

The black-breasted wearer will stand as an intermediary on all or only some of the drawings (see the case of the carrier example below).
In other cases, the less detectable, the black breast carrier may have the phenotype of a gray (that is to say without evidence revealing the black breast mutation).
In the latter, only a verification by mating can give you a certainty.

Example of a black breast bearer :

16 gris porteur poitrine noire


Indices indicating the presence of the black breast mutation :

- Very fine tear line.
- Cheeks overflowing upwards.
- Precise smoothed in the flight feathers.
- Drawing of the elongated flanks.

Indices indicating that it is a carrier of the mutation black breast (non-mutant) :

- The zebra are present.
- The drawing of the rectrices remains that of a gray.

To resume what I could observe by raising black breast.
Among the carriers born from gray x gray pn, gray / pn x gray / pn or gray pn x gray / pn couplings, some showed a definable phenotype according to their proven genotype and others (more rare) could have the phenotype of a gray or very close to it. It can therefore be said that some zebrafinch with a gray phenotype can be genetically carrier. Conversely, we must avoid confusing the defect that can have a gray with a gray carrier of the black breast mutation.

The phenotype gives us interpretable indications, the exercise being difficult, generalities or hasty statements may seem unreliable. A conscientious breeder and experienced in the mutation, with a wary eye, will be the best able to translate the phenotype of a possible black breast carrier or better yet will trace the genealogy of a bird from his strain.

To identify a carrier of the black breast mutation, it is therefore important for me to have precisely in mind the phenotype of a gray and that of a black breast, know all the changes involved in this mutation. The knowledge of each point of detail will bring you or advance you to the answer.

carrier Drawing Black breast