[3] The depth of the green or blue suffusion varies in individual birds, but is always more intense towards the vent and on the rump.
The throat spots, head and neck striations, and wing markings are a medium brown on a yellowish ground.
This pairing was made in 1938, and from three nests eight black-eyed youngsters were bred, proving the varieties were distinct.
In the early 1960s C Warner and T G Taylor obtained English Fallows from two different sources, although allegedly from the same breeder.
In 1964 John Papin of California wrote[9] that in America no less than five distinct Fallow varieties existed.
The numbers of all varieties of budgerigar in captivity declined dramatically during the war years and when aviculture restarted in earnest in the late 1940s English Fallows were very rare.
Later, English, German and Scottish Fallows were proved to be distinct and separate mutations by test matings made independently by T G Taylor,[4] Mrs Amber Lloyd of Walton-on-Thames[4] and Frank Wait,[12] and qualified names were then introduced to distinguish them.
The English Fallow is an autosomal mutation causing recessive changes to the form of the melanin pigment.
In its visual effect, the English Fallow mutation is recessive to its wild-type allele, so a bird possessing a single English Fallow allele (the heterozygote, fe+/fe) is identical in appearance to the wild-type light green.
That is, the presence of a single wild-type allele is sufficient to permit the full production and normal distribution of the black melanin pigment.