Southern boobook taxa (southern plus Tasmanian boobooks and moreporks) as a single species. Examining both morphological and genetic (cytochrome b) characters in 2008, German biologist Michael Wink and colleagues concluded that the southern boobook is distinct from the morepork and Tasmanian boobook (which they proposed to be raised to species status as "Ninox leucopsis"), and that it is instead the sister taxon to the barking owl ("N. connivens"). A 2017 study by Singapore-based biologist Chyi Yin Gwee and colleagues analysing both multi-locus DNA and boobook calls confirmed a sister relationship of "N. n. novaeseelandiae" and "N." ("n.") "leucopsis" and their close relationship
Southern boobook August to October in Queensland, from September to November in New South Wales and southern Western Australia, July to September in central and northern Western Australia, in October and November in Victoria, and in September to December in South Australia. The southern boobook nests in holes in trees between 1 and 20 m (3–70 ft) above the ground. The holes are generally vertical, and mostly in eucalypts, though other trees such as coast banksia ("Banksia integrifolia") have been recorded. Some sites are reused by the species for up to 20 years, especially if broods have been successfully raised in them