When people first hear of the Olive Cockatiel an
instant image comes to mind of an olive-green coloured bird. Unfortunately in
most cases this is not what what breeders find and they are often very
disillusioned by the true appearance of this mutation. Emerald is
another term used for this mutation and as is the same as with using the term
Olive, it is very misleading. A more correct term that describes this mutation
more accurately is 'Suffused'.
Cockatiels have the ability to produce only psittacin
(yellow and orange) pigments and melanin pigments. They can not produce
the structural colours required to give visual or green colouration. Because
of this it is impossible for cockatiels to be Olive in colour.
The effect that is in fact seen in the Australian Olive
mutation is due to a dilute gene that reduces the amount of melanin
deposited in the feathers. This reduction in melanin is the greatest of all
the dilute mutations and as a result allows the normally hidden yellow
pigments to become more visible.
This suffusion of grey melanin pigments and yellow
psittacin pigments gives a combined visual appearance of an olive cockatiel.