The Fan-tailed Cuckoo is the classic often-heard but seldom-seen bird. Recently it has been trilling away and I was surprised by the timing. Normally the trilling is a spring/breeding event, but the trilling has been happening locally (e.g. in Coogoorah Park) since the middle of May.
The male trill is a pleasant downward sound lasting around one second. Normally one trill at a time, but there can be multiples together. Apparently the male also has a sad pee-whoo noise although I have not noticed this call. The female bird calls less often and has a different trill and I have not heard/identified this call either. The links give examples of the calls, and hopefully will help you get some thrills from identifying those trills!
And here is a photo to confirm the id if you find the source of the trill. The bird is around 25cm long.
Fan-tailed Cuckoo
James Orton