These canaries only have lipochrome colouring in their primary feathers. The rest of their plumage lacks this colouring and the birds are white there.
However, the white is not as bright and pure as it is in recessive white canaries.
Dominant white canaries can also have dark pigments (melanin) in their plumage. We then refer to them as dominant white-grounded canaries.
History
The dominant white mutation apparently appeared in the mid-17th century in what was then the Electorate of Bavaria, because in 1677 the Augsburg physician Dr. LUCAS SCHRÖCK (1646 to 1730) – also known by the Latinised form of his name, ‘Schroeckius’ – reported snow-white canaries for the first time.
Another physician and member of the German Academy of Natural Scientists ‘Leopoldina’, Dr. ROSINUS LENTILIUS (1657 to 1733), recounted in 1702 that in Nördlingen, Swabia, a poor weaver eagerly bred canaries in any colour he desired and did good business with his birds. White canaries were commonplace for him.[1], [2], [3]
The Parisian natural scientist JEAN-CLAUDE HERVIEUX DE CHANTELOUP (1683 to 1747) also listed the colours he knew in his work, including ‘all white canaries with red eyes’ (Tous les Serins blancs aux yeux rouges). He may have simply invented the red eyes, by analogy with white mice, rats and rabbits. He quotes the then rather high price of 15 livres for white male canaries without spots (Serin blanc sans tache). A foreman earned three livres a day. Even spotless white females still fetched eight livres.[4]
For a long time, nothing more was heard or written about white birds. They apparently disappeared and only reappeared more than 200 years later. Once in East Prussia and again in Aschersleben at the breeder BIBRACK.[5] Here, too, it was German states where this white mutation occurred. That is why they were also called ‘German white’.
White is not equal to white
White is the sum of all colours, the sum of all wavelengths in the visible range, and therefore not really a colour at all. This means that we humans perceive the colour impression of pure ‘white’ whenever a colourant-free material (feathers or feather parts) reflects all wavelengths of visible light. With black, the opposite is true: all visible wavelengths are absorbed and nothing is reflected.
With this knowledge of physical and biological processes, we have found the reason why the white of dominant whites is not as bright as that of recessive whites: there must still be (very few) lipochromes present in the feather! This was also described by Dr HANS DUCNKER and JULIUS HENNIGER: ‘German white canaries only appear pure white at first glance. In reality, they show microscopic traces of yellow in each feather, which cannot be seen with the naked eye.’[1]
‘They were not pure white, but showed … a slight yellowish tinge. So they were not actually a “white” variety, but only almost fat-colourless “coloured” canaries with the highest attenuation of the respective fat colour.’[4]
Anyone who has washed the plumage of their lightened dominant white birds before exhibitions will have noticed that the plumage simply does not become ‘clean’ or bright white. This is because the wet feathers stick together and absorb more light than dry, loose plumage. What is not white cannot be whitewashed!
We humans always strive for the maximum, the extreme – even in bird breeding. Perhaps this is why dominant whites are no longer so popular, because their white is not so bright and pure. This view may also be reflected in the sometimes undifferentiated evaluation of brightened dominant white birds at bird shows. Far too often, the somewhat dull white of dominant whites is compared and judged against the standard of the brilliant white of recessive whites.
Another characteristic of dominant whites is the lipochrome-coloured edges of their flight feathers. Yellow or red lipochrome must be clearly visible on the outer edges of the flight feathers. Occasionally, birds are found that also have lipochrome in other areas of their plumage or a slight coloured lipochrome tinge over their entire plumage. Both are considered faults in evaluations. Other body parts (skin, fat, internal organs) and the egg yolk of dominant whites have normal colouring. The horny parts (beak, legs, toes, claws) are normally horn-coloured in lightened dominant white birds.
All melanin birds can also carry the dominant white trait. We then refer to them as dominant white-grounded. Naturally, any lipochrome veil that may still be present in their plumage is not visible or – in the case of very light melanin colours – only very faintly visible. However, the fat-coloured edges of the flight feathers must also be clearly visible in all dominant white-ground melanin birds. This is often very difficult to see, especially in undiluted black and brown melanin birds. Lipochrome edges in yellowivoor are even less visible in these birds and are therefore often referred to as recessive white-ground.
Genetics
Duncker and Henniger attributed the mutation ‘German white’ to a fat colour development factor. If one allele is missing, we get the German or dominant white (Ff), which can still form remnants of lipochrome. If both alleles are missing, these birds should be pure white (ff). However, he claims that these birds die in the egg. He did not write where he got this knowledge from. To date, no statistics have been published on this.
Today, we know that there is a gene group called EDC (Epidermal Differentiation Complex) on chromosome 25 of canaries.[6] In all animals, the genes of this complex encode enzymes that are involved, among other things, in the differentiation of keratin cells (keratinocytes) in the skin – and the hair or feathers that grow there. Mutations in these genes often have drastic effects on the skin. In humans, severe keratinisation disorders of the epidermis, including tumours, are known to occur; in cattle and dogs, a congenital EDC gene defect is known to be fatal even at the embryonic stage.[7]
The ‘dominant white’ mutation could also cause similar disorders. In single-factor (heterozygous) dominant whites, it is assumed that the keratin cells of the feathers inhibit the storage of lipochromes already formed in the body, or that storage is only permitted at an early stage of youth. This may lead to faster keratinisation of the feather keratin or to slower storage of lipochromes in the feathers. This would also explain why the affected feather areas (the feathers that were formed first) still show lipochrome deposits. Single-factor birds are fully viable, fertile and healthy, as only the fat colour deposits in the feathers are affected by the mutation.
In birds with two factors (homozygous), serious physical defects are expected to occur, as these birds are not viable and die in the egg. This is why it is referred to as a ‘lethal factor’. Geneticists distinguish between dominant and recessive lethal factors, among other things. Dominant lethal factors cannot be maintained in a breeding stock, as even single-factor carriers die before birth or sexual maturity. A recessive lethal factor only has a fatal effect on offspring if this factor is homozygous.[8] In animal breeding, such a gene in its heterozygous form can have desirable effects on the phenotype (e.g. dominant white and/or feather crest in canaries). Our viable, very vigorous – because heterozygous! – dominant white birds may therefore be carriers of a recessive lethal allele!
Some dominant whites store more lipochrome in their feathers than others. These differences are due to gene expression. This means that the allele pair Wd+_Wd (in Henniger Ff) can cause lower or slightly higher enzyme activity, thereby increasing or decreasing the amount of lipochrome storage. All different phenotypes caused by gene expression can be selected in one direction or the other through selective breeding. This would make it possible, for example, to breed dominant whites with completely red primary feathers.
Breeding dominant white canaries
The trait ‘single-factor dominant white’ (Wd+_Wd) is inherited independently of sex (autosomal) and dominantly with variable expressivity in relation to full-fat colours.
Theoretically, this pairing will produce offspring that are half lipochrome-coloured and half dominant white.
Pairing dominant white/dominant white-based canaries with each other is said to result in the death of 25% of double-factor offspring (Wd_Wd). However, this is not confirmed by the practical experience of breeders in other countries!
In the Germany, for ethical and animal welfare reasons, mating two dominant white canaries with each other is prohibited! (see expert opinion on §11b of the Animal Welfare Act[9])
Vital dominant white/dominant white-based canaries are therefore always single-factor, always possessing the alleles Wd+ and Wd.
Dominant white canaries can be bred across all lipochrome colours (yellow, yellow ivory, red, red ivory). However, the required lipochrome-containing edges of the primary feathers are difficult to recognise in dominant white ivory birds. In the C.O.M., German white and German white-ground canaries with red primary feathers are currently not permitted! It was not until 2018 that the DKB judging group FPMCE decided to re-admit dominant white/dominant white-ground birds with red in their flight feathers to the DKB.
Since there cannot be any lipochrome-coloured birds that are split dominant white, special care must be taken to ensure that there are always enough dominant whites in the breeding stock. It is quite possible, especially in small breeding stocks, that no or very few dominant whites will hatch in a given year. However, this may be reversed the following year.
When breeding brightened dominant white birds in particular, care must be taken to ensure that the lipochrome colour of the coloured partners is not too intense. If this is not taken into account, a yellow or red colour veil may spread across the entire plumage of the dominant white offspring.
A mating between dominant white and recessive white canaries will produce 50% fat-coloured birds that are split recessive white. The other half are dominant white split recessive white. These are often significantly better in shape and size, have a more beautiful white colour and a distinct fat colour fringing on the wings. The prerequisite is that the recessive white partners come from a mating of good lipochrome-containing birds.
The use of Ivoor birds in breeding dominant white birds can have a positive effect on the plumage texture. However, in my opinion, the dominant white offspring in Ivoor are not show birds, as the fat colouring on the wings is barely visible.
White and white-grounded birds also have a category (intensive or non-intensive or even the mosaic factor). Since these characteristics are not readily visible in a white bird, special attention must be paid to the plumage texture when mating with white birds. Otherwise, inexperienced breeders may quickly find that the plumage becomes too thin or too loose. As with all coloured canaries, however, there is no way around using intense birds for breeding. Some intense dominant white offspring may also show lipochrome colouring on the wing arches, at the base of the beak, and in other areas of the plumage. A faint lipochrome veil may also be visible. Although such birds are not suitable for exhibitions, they can be valuable for breeding with the right partner.
In addition to a skilful, appropriate selection of breeding partners, a targeted feeding regime can lead to good exhibition birds. Colour feeding before egg laying results in clearly coloured lipochrome zones (primary feathers), which are genetically determined and/or selectively influenced. Until the juvenile moult is complete, feed can then be given as is usually used during the nestling period of mosaic canaries.
Looking to the future
As we have observed, dominant white/dominant white-grounded canaries still possess traces of lipochrome. As Julius Henniger put it, they are ‘...almost fat-colourless “coloured” canaries with the highest reduction in the respective fat colour’. It should therefore be considered whether these birds are fairly assessed using current evaluation practices, or whether a different approach would be more appropriate for these birds.
In mosaic canaries, the colour intensity and uniformity of the defined lipochrome areas and the fat colourlessness of the remaining plumage (‘chalk’) are assessed separately in two evaluation categories. This approach could also be used in future for dominant white / dominant white- grounded canaries. The clearly visible and fat-coloured primary feathers could be assessed under the assessment category ‘lipochrome’ (25 or 10 points) and the remaining white plumage under the assessment category ‘category’ (30 or 15 points).
This proposal to change the judging criteria for dominant whites is currently being discussed in the DKB-TK-FP and in the DKB judging group FPMCE. (Note: This proposal has since been approved and is being implemented in practice).
Perhaps this will pave the way for selecting and breeding white birds with yellow or even bright red large plumage. Julius Henniger predicted these ‘flamingos’ back in 1962, and they would be an attractive counterpart to the white wings.
Sources
[1] Duncker, Hans: Kurzgefasste Vererbungslehre für Kleinvogelzüchter unter besonderer Berücksichtigung der Kanarienvögel und Wellensittiche. Verlag F. Poppe, Leipzig 1929.
[2] Aschenbrenner, Anton Hermann: Der Farben- und Gestalts-Kanarienvogel. Creutz`sche Verlagsbuchhandlung Magdeburg.
[3] Stresemann, Erwin, Zur Geschichte einiger Kanarienvogelrassen.
[4] Jean-Claude Hervieux de Chanteloup: Nouveau traité des serins de Canarie, contenant la manière de les élever, de les appareiller pour en avoir de belles races. Paris 1709. Unter: http://data.bnf.fr/14328857/jean-claude_hervieux_de_chanteloup/ (hier Ausgabe von 1785, Seite 169 und 207).
[5] Henniger, Julius: Farbenkanarien. Ein Lehrbuch für Farbenkanarienzüchter insbesondere über Farbenvererbung. Maximiliansau 1962.
[6] Lopes, R.; Johnson, J.; Toomey, M.; Ferreira, M.; Araujo, P.; Melo-Ferreira, J.; Andersson, L.; Hill, G.; Corbo, J.; Carneiro, M.: Genetic Basis for Red Coloration in Birds. Current Biology, 26, published online ahead of print on 19 May 2016 | doi:10.1016/j.cub.2016.03.076
[7] See: https://en.wikipedia.org/wiki/Ichthyosis
[8] Under: https://www.spektrum.de/lexikon/biologie/letalfaktoren/39032
[9] Under: https://www.bmel.de/cae/servlet/contentblob/631716/publicationFile/35840/Qualzucht.pdf