I just bought a book on cockatiels and I think it has a section on molting, I'll get it....


"Molting is normal, though, and isnothing to become alarmed about unless you see bald patches (with the exception of the bald patch behind the crest in some lutino cokatiels.)If you do see bald patches, take your bord to an avian veterinarian right away."

Hope that helps.