After chatting with a few people more knowledgeable than myself, I am
still uncertain as to which species it was that I saw. The location,
Reedbeds Rd Giru, usually has a lot of Spotted Harriers, so it's more
likely that my sighting was in fact the 'hooded' form of a first immature
Spotted Harrier. I spoke with Roy Mackay, who is familiar with Papuan
Harriers after living in PNG for a number of years; and with David James,
who works for the RAOU and contributed a number of chapters for HANZAB.
Roy Mackay observed a male Papuan Harrier near Tolga, Atherton Tablelands,
1/7/1988, and near Atherton 18/7/1989, both of which had the all the
features of normal adult males. He seemed to think adult males not too
difficult to identify, so long as one gets a look at the dorsal plumage as
well the underside.
Troubles start when odd plumaged birds are seen (such as the one I saw).
Roy says there is a melanistic phase of both the male and female Papuan
Harriers. David says there are about 6 stages between juv and adult in the
Spotted Harrier, most of which are not noted in field guides. There is
confusion in separating imm/sub-adult Papuan Harriers from adult Swamp
Harriers in PNG, and Coates reckons that on current knowledge it's
impossible in the field. Swamp Harrier sightings in PNG seem to enjoy
similar status to Papuan Harrier sightings here - sparse unaccepted
It's all a bit of a mess. The closest description to the bird I saw was
the hooded first immature Spotted Harrier description in HANZAB. For
anyone who sights a "hooded" or other odd-looking harrier and wishes
to have a go at identifying it, the following references may help;
Papuan Harrier (Circus spilinotus spilothorax) in North Queensland, with
Comments on Plumages. Author; Roy Mackay. Australian Bird Watcher, Vol 14
(4) December 1991, pp144-146.
Handbook of Australian, New Zealand and Antarctic Birds (HANZAB), Vol 2,
Marchant & Higgins (eds). pp102, 105, Plates 15, 16 (opp p200).
Birds of Papua New Guinea. B.J. Coates. pp 117-119.
HANZAB has detailed info on all known plumages of harriers in Australia,
Roy's article and Coates 'Birds of PNG' have info on adult typical and
melanistic Papuans, and a bit on known juv/imm plumages, and a bit on
differences between Papuan and Pied Harriers. Coates also has reasonable
Papuan Harrier photos.