There are not only colouration mutations, but also budgies with different kinds of striping patterns, and extremely rare variations. I'll summarize them in a few posts. This is the first one:
- The wild budgerigar
- Base Colour
A yellow-based budgie results in the classic green variety (the wild bugerigar) and a white-based budgie results in the common blue variety (picture on the left). You can see the base colours in the mask feathers (area above beak and ceres and also to the left and right of the beak) and between the black stripes of the head and the wings.
- Dark Factor
Dark factor basically is the same as the level of darkness in the blue feather structure in the body feathers. Wild budgies have no dark factor, so they are light green. One dark factor in a green (yellow-based) budgie results in a dark green colour.
Two dark factors in a green budgie result in the "olive variety" '(see picture below)
The same goes for white-based budgies:
Left: Blue budgie with no dark factor = Sky Blue Budgie.
Middle: Blue budgie with one dark factor = Cobalt Budgie.
Right: Blue budgie with two dark factors: Mauve Budgie.
That is a lot of colours and information... and it's only the beginning! For more details, go to http://www.budgieplace.com/colorsguide.html