I think an eclipse male-- dark bill, blueish tail.
Singing from the top of a small post.
Steadfastly refused to give me a shot of anything but his ass.
Male right, and eclipse male (non-breeding) left. Differs from females in having blue tail and blackish bill (instead of brown and orangey-brown).
Most likely Superb Fairy-wren, but I suppose could also be Variegated.
Maluridae is a family of small, insectivorous passerine birds endemic to Australia and New Guinea. Commonly known as wrens, they are unrelated to the true wrens of the Northern Hemisphere. The family includes 14 species of fairywren, 3 emu-wrens, and 10 grasswrens.