There are also a variety of trills and chirrups associated with breeding. Lesser Sooty Owls hunt mainly small mammals, but also take insects and some birds. They generally hunt from low perches and take prey on the ground. May. Pairs usually become more noisy at the start of the season with frequent 'bomb whistling'. Sometimes several pairs may be within earshot of each other, their calling clearly territorial.
Pairs perch close together with high-pitched trilling.
The nest is usually a large hollow in the trunk or a main limb of a living tree, often Rose Gum. The female may occupy the hollow for many weeks before laying, going out briefly only once or twice each night. Generally 2 eggs are laid, but sometimes 1. Incubation is 40-42 days and the young have downs of sooty grey. Fledging is at about 3 months.