The Papuan Harrier is a raptor of grasslands and wetlands on New Guinea. A 2009 paper reports fieldwork in Papua New Guinea under the historical subspecies name Circus spilonotus spilothorax.
The paper recorded a typical form and a melanistic form, with the dark form more common in lowlands than in the highlands. This summary is limited to the color forms stated in that study.
In the eastern lowlands of Papua New Guinea, nests were reported in tall grass and reeds. The study describes ecology in lowland grasslands and wetlands.
An extinction-risk assessment has not been added yet.