Mating Pair of Unidentified Birds

by Donna
(Tannum Sands Qld Australia)

I love these birds that have taken to nesting in a large gum tree at the back of our house in Tannum Sands, Central Queensland....but they are driving me insane researching to identify them. They are not anywhere in my bird books and i haven't had any luck online either. They have baby blue chests, dark grey heads, bright orange beaks and feet, bright purple feathers under their beak, and white markings under their wings. They make a very quiet sound and don't make it often....like (an elongated small A sound, not capital A sound)... "aaa" "aaa" "aa" "aa" "aa". I thought they were parrots at first, but now that i have captured some closer photos i think they are some kind of bird of prey?
Hope someone can help :)