The evolution of corellas in Australia has been, and still is, influenced by the activities of white man and the subsequent changes to the landscape, particularly in Western Australia, but the situation in eastern Australia is different.

In the late 20th century there was a virtual explosion of corellas into various areas in the eastern states where they had never been seen before. What is interesting is that quite often, these are mixed flocks of Little and Long-billed Corellas and there are claims that some of these birds have originated from aviary escapees. The important point is that to my knowledge there are no properly documented reports of interbreeding (in the wild anyway) or birds showing intermediate characters.

In Western Australia the situation is quite different. In the far south-west we have what could be called the archetypal Western Corella, subspecies "pastinator", a bird that superficially resembles a Long-billed Corella with an elongated upper mandible that has developed from their principal method of feeding, digging for underground bulbs. A classic case of convergent evolution. Further north in W.A. between Perth and Geraldton occurs the subspecies "derbyi", a not-so-long billed form of Western Corella which, if you look at the pictures below, is much more Little Corella like, certainly in facial characters. In some places like Three Springs, these birds occur alongside real Little Corellas and the inference is obvious - whether there is interbreeding is not clear but the opportunity is there.

So, if you are going to W.A. and hope to see a Western Corella my message is, go down to Manjimup, or Tone Bridge.