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 grasshoppers, crickets, beetles, cockroaches, moths, wolf spiders, and huntsman spiders were also consumed. A study in Victoria found that larger animals were eaten, including Baillon's crake ("Porzana pusilla"), common ringtail possum ("Pseudocheirus peregrinus") and feral rabbit ("Oryctolagus cuniculus"). Using a fence, branch, or telegraph pole as a perch or vantage point from which to hunt, the southern boobook pounces on prey then retreats to a tree or elevated place to eat it. It often hunts in open areas near trees, and also where prey is likely to congregate, such as mice near haystacks or barns, or flying insects near street-