These owls are characterised by their rounded head and short legs. They are moderately-sized to large birds, the largest in Australia being the endemic Powerful Owl Ninox strenua. Two other endemic species are the Tasmanian Boobook N. leucopsis and Christmas Island Hawk-Owl N. natalis. A further four resident species have endemic subspecies, Rufous Owl N. rufa, Barking Owl N. connivens, Southern Boobook N. boobook and Tasman Boobook N. novaeseelandiae . A further three species occur in Australia as vagrants.