An excellent specimen will have symmetrical markings, preferably in a 75% Pied to 25% melanin (in this case gray) ratio. The Pied portion of the plumage can range from yellow to white. Birds showing only pied in a few of their wing, crest or tail feathers are considered to be “splits” or “carriers” and not visually pied.
It is impossible to visually sex a Pied cockatiel.
Pied is a very common pattern. The pied mutation causes areas of white/yellow to fall where there would normally not be any. Like a piebald horse has patches of colored areas and white areas, a pied tiel is the same that it has patches of normally colored and patterned areas, and other areas are a solid yellow/white. The patches can vary from one or two yellow/white flight or tail feathers, to being almost totally white/yellow with only a few colored feathers, and everywhere in between!! The unique thing about pied cockatiels is that even though it is a recessive trait, (a tiel can carry the gene for being pied, and pass it on to it’s offspring, without being pied itself) you can see when a tiel is carrying the pied gene. All those cockatiels with a yellow/white spot on the back of the head� they are all �split to pied’. It just means they carry the gene and have the potential to produced pied babies, but they themselves are not actually pied.
The other unique thing about the pied gene is that it overrides the normal face/sex-linked coloration. Where a normal adult male will get the bright head, and the female retain the dull head, in the pied mutation, the way a pied baby is when it is young, is the same as it’ll be when it’s older. Whether it has a dull head, a bright head, or patches of both on it’s head and face, it doesn’t make a difference to what gender it is, and it will always stay the same. A bright-faced pied tiel does not make it a male, nor does a dull-faced pied tiel make it a female. In other words, you cannot differentiate the sexes of the pied cockatiels by looking at them!