Southern boobook their upperparts. The tips of their feathers are white and fluffy, remnants of the nestlings' down. These are worn away over time, persisting longest on the head. The feathers of the head, neck and underparts are fluffier overall. Immatures in their second and third year have plumage more like adults, though their crowns are paler and more heavily streaked. On mainland Australia, it could be confused with the barking owl or the brown hawk-owl ("Ninox scutulata"), a rare vagrant to the northwest, although the southern boobook is easily distinguished by its squat posture and distinctive pale border to its face
Southern boobook the nest with food. A purring or braying call is used by both sexes as a contact call around the nest and (more quietly) when bringing food to nestlings, or by the female to beg for food from the male. The female makes a low trill during courtship and nesting. Growls, high-pitched yelps, and screeches can be made when attacking intruders. The southern boobook maintains and defends a territory in breeding season; whether this continues for the rest of the year is unclear. It retires to densely foliated spots in trees in the daytime, each individual often having several roosting