[3] Apart from records of vagrants, circumstantial evidence that at least part of the population makes long-distance seasonal migrations is that most sightings, and the highest reporting rates, of the bitterns in southern Australia occur in spring and summer, with the birds largely absent in autumn and winter.

[5][6][7] In New Guinea the bittern is found seasonally in the reed beds of the Waigani Swamp near Port Moresby from November to April, only being reliably recorded elsewhere on the island from the lowlands of the Trans-Fly region.

[10] The birds are mainly found in freshwater wetlands, where they inhabit dense emergent vegetation of reeds and sedges, and inundated shrub thickets.

They are also occasionally found in brackish and saline wetlands such as mangrove swamps, Juncus-dominated salt marsh and the wooded margins of coastal lagoons.

They are skulkers of reed beds, walking in a crouched posture with head extended forward, crossing patches of open ground rapidly, stalking their prey at the water's edge.

When alarmed they will assume the cryptic posture typical of many bitterns, standing still with the head and bill extended vertically upwards.

Threats include various ongoing wetland degradation factors such as salinisation, drainage and the diversion of water for irrigation, as well as the destruction of nesting habitat by inappropriate burning regimens.