This one is easy, it's from an Eastern Rosella, a very pretty parrot.

                         This one is from another parrot, it's from the crest of a Sulphur Crested Cockatoo.

                                              This is probably from a black and white Magpie.

This is probably another one from a Sulphur Crested Cockatoo.

Since my topic at the moment seems to be birds, I thought that I would photograph the feathers in situ that I came across on my morning walk and see if I could identify the ex-owners of them.