This is not a sight you see very often in Australia. Helmeted Guineafowl are an introduced species present in a few scattered locations around the continent. They are nowhere in abundance, only existing in a few locations and usually as a result of an escape from a farm, park or zoo.
This small group obviously have the run of the grounds of the Western Plains Zoo on the outskirts of Dubbo. I am assuming that this population is a self-sustaining group living permanently in the grounds of the zoo and feeding upon food left for other birds and animals.
This species is native to Africa but is often kept in small domesticated populations in various places around Australia. I assume that there are also some self-sustaining feral populations too.
My next door neighbour has about a dozen which often stray onto our property. I wrote about them here.