Classification by Steiner
The classification system, developed by Steiner, can be used for mutations of all birds, brown and multi coloured birds. This classification is based upon changes in the production of colouring pigments and the buiding of feather structure. In the Bourke's this colouring elements are: brown eumelanin, red and yellow psittacine and blue structure in some featherfields. Thusfare we saw in the Bourke examples of total albinism, dilutism, flavism, erythrism and changes of the bluestructure.
Melanin (Eumelanin and Phaeomelanin)
. Hypo melanism = formation of melanin below-normal
2. Hyper melanism = formation of melanin above-normal
Lipochrome (all kinds of Carotenoide and Psittacine)
3. Hypo chromatism = formation of lipochrome below-normal
4. Hyper lipochrome- formation of lipochrome above-normal
Feather structure (Structural colours)
5. Mutative changes of the structural colours
Appreciation: This classification is the best survey I could found in literature.
01.The system is descriptive, has a clear structure and is therefore easy to use. Overlap between categories has been avoided.
02. The classification can be applied to brown and multicoloured birds as well.
03. The classification system is focused upon function changes of the production of pigments and altering the feather structure by mutation. The division is based upon: (M) melanin pigments , (L) lipochrome pigments (psittacine, carotenoids, etc) and (S) structure of the feather.
04. The classification system is to use for division of colour varieties but mutation factors also.
05. The name giving is based on an analysis of the change in the functioning of the genes. This refers to all aspects of production, transport, distribution and dropping of pigments in the growing feather and the changes in the building of the feather structure.
06. Steiner distinguishes a hypo- and hyper function of pigment production. This gives a very useful further division in sub sections.
07. In his work he makes a clear difference between colour varieties ("Farbenvarietäten") and genetic factors ("Erbfaktoren"), between phenotype and genotype.
08. His starting point is that the same mutation can happen in all bird species. Using the same name for the same mutation is important.
09. In the description of colour varieties he is using descriptive terms and discusses the names giving by breeders in different countries like Germany, Austria, France like may green, jade, etc. In the description he is using the standard given in the norm atlas of Ostwald. In the name giving he counts for the differences between the species.
10. Because the function changes of pigment production and building feather structure was chosen as a starting point it is possible to order the cause (mutation factors) and the results (the colour varieties) in the same classification.
11. Steiner made a useful difference between loss-mutation, like loosing yellow pigment, and win-mutations, like some structural changes of the feather.
12. The classification is seen as a model that can be extended when new mutations arrive or new insight is gained, without affecting the overall structure of the model. The categories can be expanded. Sub categories can be added. The classification seems to be very usable.