Olá,
Há periquitos que parecem "punks" e que não têm qualquer problema :p Deve-se a uma mutação:
Crested Budgies
The Budgie & Parakeet Place Colors and Mutations Guide: Crested
Crested is a unique mutation. In this variety,
the feathers on the very top of the budgie's head point askew from normal, forming a crest. There are generally three types of crests. In the full-circular crest, the head feathers radiate in a full circle from a central point on the head, forming what may look like a Beatles haircut. In the half-circular crest, the feathers radiate from a central point only halfway or part way around the head. In the tufted crest, the feathers point up or backwards from the others near the front of the head, forming a tuft. There are also some variations of crested budgies where feathers on the back/wings grow askew and stick up.
Não sei se é isto, mas aqui fica a informação :p Se calhar fotos tiradas de outros ângulos ou + próximas, ajudavam

Cumprimentos,