Description of the Slate Budgerigar; a Review
Ludwig Auber 1941,
Auber examined two "Slate-blue" specimens and I quote from his Thesis the following;
-The birds show on the underside and the rump a dull blue shade which does not show the
least violet suffusion. As in the "recessive grey" birds, these regions show a thrush-like
mottling owing to the fact that each feather becomes distinctly darker in terminal direction.
The rump is here also darker than the underside. The undulations are distinctly black. The
cheekpatch is of a dark dull blue colour without any violet shade.
Steiner (1939) suggested that the peculiar dull shade in these birds might be brought about
by the presence of melanin in the cortex as well as in the medulla. The examination of an
intact feather in reflected light shows, indeed, many round and indistinct black spots on an
intensely blue background. We have seen, on the other hand, that a similar pattern in the
"recessive grey" birds is caused by medullary pigmentation immediately beneath the cortex.
This state is also found in the "slate-blue" variety.
In sections of rump feathers a peculiar arrangement is found in the medulla. The large
vacuoles, each surrounded by a dense pigment corona, are lying close to the inner wall of
the cortex. Sometimes the vacuole itself touches the cortex, while in other cases cortex and
vacuole are separated by the pigment corona. Between these peripheral vacuoles, more or
less large areas of unpigmented medullary substance reach the cortex, while communicating
in the centre of the medulla, to form there too a large area. Examination of dry sections
shows that this unpigmented portion of the medulla is of entirely canalicular structure. It
shows exactly the same colours in reflected and in transmitted light, as those seen in the
corresponding feathers of the wild-type and the "skyblue" birds. In this way a blue, and not
violet shade of the feathers is produced, while the dull component is provided by the
superficial position of the isolated pigment coronae. We may thus characterize this structure
as due to an "inversion of the optical media".
The same arrangement may be observed in the medulla of the dark bars of the undulated
feathers and also in the barbs of the cheek-patch.
The factor causing this atypical direction of growth of the medullary cells apparently
affects the whole plumage.- End of quotation.
Taylor and Warner 1961,
In slates three shades exist, light, medium and dark, but these shades differ from one
another very much less than skyblue, cobalt and mauve differ.
It is notoriously difficult to describe unusual colours in words, but the word "slate"
conveys very well the actual body colour of these birds: bluish-grey might be an alternative
description. The cheek patches of slates are of a deep violet colour, somewhat similar to
the cheek patches of mauves.
The incorporation of the slate gene into birds of the green series has a darkening effect on
the colour of the feathers.
C.H.Rogers 1970, 1976
This colour is sex-linked, and like the violet and grey characters it has the effect of
altering all the green and blue series birds having it in their makeup
The slate green series birds are very similar to the violet greens. They may be
distinguished from violet greens by the fact that the cheek flashes are deep in colour and
quite dull, and that the undulations are also much duller than those of the violet greens. The
slate light green shade is similar to that of a pale dark green, the slate dark green is a dull
deep dark green tone without flecking, and the slate olive green shade is extra deep level
The blue series slate has a distinct colouring of the body shade; the cheek flashes are a
deep dull violet, and the undulations are also dull. It is only in the blue series that the slate
colouring is clearly seen. In actual fact the slate mauves are the darkest coloured of all
Budgerigars and consequently are the nearest to the much sought after blacks so far bred.
The first slate Budgerigar ever bred was born in may 1935 in the aviaries of T.S.Bowman
of Carlisle and this mutation soon turned out to be sex-linked.
The name slate given to these birds in the first case by T.S.Bowman was an apt one as it
described their body colour extremely accurately. Their wingmarkings are very clear cut
black on white with dull deep blue long central tail feathers and cheek patches of dull
violet. Their body colour shows a slight bluish undertone and is quite distinct from the pure
level clear grey shade of the dominant greys. The most outstanding difference between this
mutation and the greys is that the latter have black long central tail feathers with no trace
whatsoever of blue.
For a time slates were being bred by a few interested colour breeders but they never
caught on as exhibition birds, mainly I feel due to the appearance of the easier to breed
australian dominant greys. The most interesting slate form to be bred in these earlier days
was a slate cinnamon white blue hen that was raised in the aviaries of W.G.Roderick of
Purley, Surrey. She was in actual fact a white of deep suffusion and her slate suffusion
could be clearly seen, even though it was softened and diluted somewhat by the cinnamon
character. As far as I have been able to trace she is the only example of this particular
combination to have been bred.
Inte Onsman, 1992
My experiences with slates.
When I bred my first slate in 1982 I was more or less forced to prove one way or another
that this was actually a slate, and I started making cross sections just like Auber already did
in 1941. It was an exiting experience to see the first cross section under the microscope and
fortunately I was able to make some pictures.
The internal structure of the barbules is quite unique and differs greatly from Australian
grey and English grey. In order to examine whether the sl gene acts within the pigment
cells or in the feather follicles, several dominant pied slates were developed.
It is a well known fact that white-spotting is characterized by absence of pigment cells.
Partial absence of pigment cells in dominant pied birds may be the result of genetically
defective skin or feather follicles, or genetically defective pigmentcell precursors, or
both, depending on the genotype of the bird involved.
Feathers were plucked from the unpigmented regions of the slate pied specimens and cross-sections were made. It was found that the typical slate stucture was present in these cross sections and therefore I would like to suggest that the slate gene (Fig.1) acts in the feather follicle rather than in the pigment cells (melanocytes). During the first ten years my first goal was to establish this mutation and prevent it from fading out and I succeeded. One can consider a recessive mutation established when at least 10% of the total amount of birds in the aviary carries the recessive gene. A dominant character can never be established in this way, one has to breed constantly with dominant mutations to prevent them from disappearance. It took me about ten years to establish my strain of slates and during that time I was also able to investigate the crossing-over (c.o.) value between opaline (op) and slate (sl) as described in my article about crossing-overs in the sex-chromosome of the male Budgerigar.
Although my slates have not yet reached show quality, I am convinced that body size in
this rare mutation is easy to improve, the sl gene does not suppress body size and growth
rate in these birds also seems to be normal. Mortality rate was pretty high during the first
years, but that was due to the fact that the "godfather" of my strain was a weak cock so I
had to outcross many times to improve quality.
To upgrade this variety the use of light greens/blue or sky blues are recommanded, the
use of greygreens is not recommanded because of the involvement of the Australian grey
The G gene in these birds suppresses the typical slate structure and greygreen slates are not easy to distinguish from the non greygreen slates. It is quite obvious to see that the white areas in dominant pied slate-blue specimens are extremely white and also the SF slate-blue spangles I bred last year are very attractive in appearance. My next goal is to try to develop a cinnamon slate but after trying this for a whole season I failed so far. Testmatings between opaline and slate and also between opaline and cinnamon showed that cinnamon (cin) and slate (sl) map very close together on the sex-chromosome, and therefore it will take some time to breed a cinnamon slate. The chance on getting a crossover between cinnamon and slate must be very small, but if I succeed eventually, I will let you know.
Consulted and cited Literature:
 Auber L., (1941) The Colours of Feathers and their Structural Causes in Varieties of the Budgerigar, Melopsittacus undulatus Thesis, University of Edinburg; p.p.111-113  Rogers C.H., (1987) The World of Budgerigars Nimrod Press, Alton, Hampshire; p.p.94-95  Rogers C.H., (1970) Budgerigar Guide The Pet Library LTD; p.p.146-147  Steiner H., (1939) Der gegenwartige Stand der Domestikation des Wellensittichs und seine zuchterische Bedeutung Der Zuchter Vol.2 no.7; p.p.184-192