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
Anatomical terms of bone a condyle, particularly the medial epicondyle of the humerus. These terms derive from Greek. An "eminence" refers to a relatively small projection or bump, particularly of bone, such as the medial eminence. A "process" refers to a relatively large projection or prominent bump, as does a "promontory" such as the sacral promontory. Both "tubercle" and "tuberosity" refer to a projection or bump with a roughened surface, with a "tubercle" generally smaller than a "tuberosity". These terms are derived from "Tuber" (). A "ramus" () refers to an extension of bone, such as the ramus of the mandible in the jaw