Even though we can't discern any colors in these photos, we can still ID this raptor as a Swamp Harrier or Australasian Marsh Harrier by its long, broad wings with 5 dark "fingers" on wing tip when in flight; prominent white rump; long tail rounded at tip; hooked bill (you can just make this out in first photo) and white area on wing next to "fingers".
The Swamp Harrier is a new species to our Photographic Life List, which now stands at 752.