A pediatric nutritionist is a registered dietitian (R.D.) that has specialized in nutrition for children, so you must first become a registered dietitian. You could enroll in a bachelor's degree program accredited by the Commission on Accreditation for Dietetics Education.
Here is part 1 of Cockatiel Types and Descriptions which covers 5 types of cockatiel types including whiteface, lutino, albino, normal greys, and pied. Each ... Here is part 1 of Cockatiel Types and Descriptions which covers 5 types of cockatiel types including whiteface, lutino, albino, normal greys, and pied. Each slide gives a bried description of what each type looks like, and includes a photo. Please watch part 2 for more types. Thanks for watching. :) I own none of the photos shown in the following video.
Pied cockatiels have patches of white and yellow on areas that are typically not those colors in other mutations. Pied patterns vary widely, but according to the National Cockatiel Society, it is preferred that they are 75 percent pied and 25 percent the color the bird would normally be (such as grey or cinnamon).