They do change, the amount of crest depending on the season, age. They change the color of their beaks too. 🙂 Reply ↓
H.J. Ruiz - Avian101 
If I am correct, the royals have more of a crest on the head.
They do change, the amount of crest depending on the season, age. They change the color of their beaks too. 🙂