It has a more grey-brown plumage with no red tinge, unlike other subspecies. It has grey streaks on its belly and white spots on its secondaries, inner wing-coverts and nape.[2] It was described by French ornithologist Louis Pierre Vieillot in 1817 as Strix fusca.[4] Austrian ornithologist Carl Eduard Hellmayr noted that it closely resembled the Australian boobook and concluded it was probably a subspecies of the latter,[5] and Mayr classified it as a subspecies in 1943.[6] Genetic and call analysis show it to be markedly divergent to the Australian populations of the Australian boobook, leading Gwee and colleagues to suggest it be reclassified as a separate species.[7] Its calls are shorter and more frequent than the Australian boobook.[8] It was reclassified as a distinct species in 2019.
^Hellmayr, Carl Eduard; Haniel, C.B. (1914). Die Avifauna von Timor (in German). Stuttgart: Im Kommissionsverlag der E. Schweizerbartschen Verlags Buchhandlung. p. 102.
^Gwee, Chyi Yin; Christidis, Leslie; Eaton, James A.; Norman, Janette A.; Trainor, Colin R.; Verbelen, Phillippe; Rheindt, Frank E. (2017). "Bioacoustic and multi-locus DNA data of Ninox owls support high incidence of extinction and recolonisation on small, low-lying islands across Wallacea". Molecular Phylogenetics and Evolution. 109: 246–58. doi:10.1016/j.ympev.2016.12.024. PMID28017857.