The Grass Owl is a nomadic wanderer and preys on small nocturnal mammals. However, it is fairly specialised in its range and habitat. The colour tone on their back, patchy tawny-brown on the Grass Owl, help distinguish it from its close cousin the Barn Owl, that is freckled pearl-grey in this area.
The Grass Owl only lives in coastal heath and flood-plains grasslands across northern Australia. There seems to be two main populations, one throughout coastal eastern Queensland into Barkly Tablelands and the Northern Territory. Wandering parties occasionally reach the Murray-Darling plains of western Arnhem Land but not often remain long. The coastal population seems moderately stable and permanent; however the inland population fluctuates with the rise and fall of its prey.
The coastal population preys mainly on the Canefield Rat and other rodents. The inland population's primary prey is the Longhaired Rat.
The Grass Owl breeds anytime, but mainly March - June after Monsoonal rains. Their nests are scrape or a platform of plant stems under tussock, with a 10m long tunnel under vegetation. 3-8 eggs are laid on alternate nights. The female incubates and the male roosts with her by day and brings food by night, and both parents feed the young.