We do not currently know of any antonyms for cockatiel.
The noun cockatiel is defined as:
Nymphicus hollandicus, a small, rather atypicalcockatoo with a distinctive pointed yellow crest. Comes in many color mutations such as White Face Gray, White Face Pearl, Fallow, Pearl Pied, Cinnamon Pearl, and White Face Pied. Native to Australia but most known in aviculture.