Hard to believe these two are the same species. This male (Green) followed the female for 20 minutes before I lost sight of them Always hovering just above her as she fed.
This could be The Cairns Birdwing (Ornithoptera euphorion) which is Australia’s largest endemic butterfly species, with females reaching a wingspan of up to 16 cm. Males are usually a few centimetres smaller. But given it was taken in Bamaga (these were wild butterfly’s not in a butterfly farm) I think it could be a closely allied species, the New Guinea or Priam’s Birdwing (Ornithoptera priamus) reaches 19 cm and is the largest butterfly species found in Australia, but it is not endemic.
These were taken in Bamaga, far North Queensland, Australia
Canon EOS 300D