i have a crested budgie and i was woundering if anyone knew there mode of inheredence

there is actuallty four kinds of crest but only 3 of those are recognised by the show standerd

the tuft is a few feathers on the head sticking straight up

half circular is where on the top of the head the feathers sticking up form the shape of a half circle

the full circle is where it has a complete circle on the head of feathers sticking up

 

the hellicopter is the one not recognised and it is a full circuar with anoter crest between the sholders