Budgerigars carrying the Dark factor are identical to the wild-type Light Greens or Skyblues in every respect except body colour and tail feathers.
[3][4] At the time, Toulouse was the main commercial centre for budgerigar distribution in Europe, handling thousands of imported and aviary-bred birds each year.
Blanchard in 1920,[5] and by George F Hedges in 1923[6] while he was the aviary attendant for Madame Lecallier in France.
[6] She exhibited one (as a Royal Blue) in February 1924 at the Crystal Palace and later that year bred the first Mauves from them.
[3] She called the Mauves French Greys in nest feather, and when adult they were known as Lilacs or Lavenders.
The blue forms of the Dark mutation were far more popular than the Greens and commanded fantastic prices in the mid-twenties.
Early measurements by Duncker and independently by Steiner obtained values of 14% and 7.6% respectively, and T G Taylor and C Warner collected results which showed only 5 cross-overs in 140—a COV of 3.6%.
[8] Included in these were results from T G Taylor's own experiments, in which he found no cross-overs in 86 birds bred.