The Eastern grass owl is a medium-sized, slim owl with long slender legs that are sparsely feathered. The heart-shaped facial disc is white in the male and pale orange buff with dark speckles in the female. It is outlined by a narrow pale ruff with dark edging at the bottom. The eyes are relatively small (for an owl) and have buff and black ‘tear’ marks below them. The upper parts of the owl are chocolate and buff while the underparts are pale, flushed orange-buff and highly spotted. The wings are rather long and broad, barred dark brown and buff with silvery spots. The underwing is white with fine dark spotting and darkish wing tips. The undertail is white with several narrow dark grey bars.
There are two distinct populations of the Grass Owl. One is found on the flood plains of large rivers from Cape York to Manning River New South Wales. The other is found on grasslands of the Barkly Tableland and Channel country of Western Australia.
Grass owls hunt at night, often in association with other owls in the same area. They search from 4 m to 5m above the ground, gliding and hovering frequently. The prey is mostly located by the owl’s acute hearing. When located, the owls twist and plunge almost vertically, headfirst, the talons lunging down at the prey at the last moment. Prey items include small mammals, particularly rodents, as well as insects and birds. On capturing the prey, the owl usually remains on the ground eating.
Eastern grass owl nests are usually in open grassy areas under dense tussocks of grass or sedges. The nest consists of a scraped hollow or a flimsy platform of trampled plant stems. Only the female incubates the eggs and the male brings food during the night and roosts with her during the day. The young are brooded by the female for several weeks after hatching and after four to five weeks both adults hunt. After two months the young are fully fledged and ready to fly.