Northern Boobook Ninox japonica Scientific name definitions

29–33 cm; male 167·5 g, female 168·2 g (mean of ten birds of each sex (1 Lin, W.-L., Lin, S.-M. and Tseng, H.-Y. (2012). Breeding ecology of the Northern Boobook Ninox japonica totogo in central Taiwan. Forktail. 28: 164–166. Close ) ); wingspan 66–70 cm. Medium-sized boobook, hawk-like in appearance. Plain chocolate-brown above with a few white marks on scapulars  ; head and neck greyish brown; underparts  whitish with rufous-brown streaks; tail brownish with pale bars; irides golden-yellow ; cere dull greenish; tarsi sparsely feathered. Race <em>florensis</em> slightly paler and larger (wing 222–245 mm, tail 134–140 mm) than nominate (wing 203–225 mm, tail 107–127 mm) (2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, UK. Close ).

Editor's Note: This article requires further editing work to merge existing content into the appropriate Subspecies sections. Please bear with us while this update takes place.

Until recently was considered conspecific with N. scutulata (then incorporating also N. randi and N. obscura), but differs distinctly in vocal characters and in part also mensurally (3 King, B.F. (2002). Species limits in the Brown Boobook Ninox scutulata complex. Bull. Brit. Orn. Club. 122(4): 250–257. Close ), and species status accepted here even though these may not be enough (or not sufficiently enumerated) to score 7 under the scoring system used herein. Population previously named ussuriensis now treated as florensis; sometimes synonymized with nominate. Birds from Ryukyu Is, Taiwan and Lanyu I previously separated as race totogo, but recent genetic analysis (4 Lin Wen-Loung, Severinghaus, L.L., Tseng Hui-Yun and Lin Si-Min (2013). Genetic differentiation between migratory and sedentary populations of the Northern Boobook (Ninox japonica), with the discovery of a novel cryptic sedentary lineage. Journal of Ornithology. 154(4): 987–994. Close ) (including known breeders, known migrants, and topotypes of sedentary individuals on Lanyu) revealed co-existence of two clades in E Asia, one containing resident breeders in Taiwan, the other containing migrants present only in non-breeding season (at which time the two were found together); topotypes of sedentary totogo from Lanyu clustered with nominate japonica, suggesting that treatment of former as a race unwarranted; sedentary Taiwanese population may represent a unique cryptic lineage. Proposed form macroptera (described from Mindoro) included within nominate (5 Dickinson, E. C., and J. V. Remsen, Editors (2013). The Howard and Moore Complete Checklist of the Birds of the World. Fourth edition. Volume 1. Aves Press, Eastbourne, UK. Close ). Two subspecies currently recognized.

Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Favours lowland deciduous forests with tall trees, wooded parks and gardens, but also uses conifers and mixed forests, shrines and temples (6 Brazil, M. (1991). The Birds of Japan. Christopher Helm, London, UK. Close , 2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, UK. Close ); found from sea-level to 1700 m elevation on breeding grounds and in lowland rainforests on wintering grounds (2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, UK. Close ). On Taiwan, eight of ten nests in secondary forest from 350–700 m elevation, two nests in wooded suburbs with many roads and buildings at 70 m (1 Lin, W.-L., Lin, S.-M. and Tseng, H.-Y. (2012). Breeding ecology of the Northern Boobook Ninox japonica totogo in central Taiwan. Forktail. 28: 164–166. Close ).

Migratory except on Okinawa Is, Miyako Is, Yaeyama Is, Taiwan (including Lanyu) (6 Brazil, M. (1991). The Birds of Japan. Christopher Helm, London, UK. Close , 4 Lin Wen-Loung, Severinghaus, L.L., Tseng Hui-Yun and Lin Si-Min (2013). Genetic differentiation between migratory and sedentary populations of the Northern Boobook (Ninox japonica), with the discovery of a novel cryptic sedentary lineage. Journal of Ornithology. 154(4): 987–994. Close ), and probably also on Calayan I , N Philippines (7 King, B. and Icarangal, N. (2008). Territorial behaviour of the Northern Boobook Ninox japonica, on Calayan Island, northern Philippines. Forktail. 24: 124-125. Close ). Migrants arrive on nesting grounds from early Apr–mid May and remain until late Sept in N to Oct or early Nov farther S (6 Brazil, M. (1991). The Birds of Japan. Christopher Helm, London, UK. Close ). Many migrants winter on the Greater and Lesser Sundas, where they overlap with resident tropical Ninox populations; some also in E China. Record of beach-washed specimen on Ashmore Reef, NW Australia, in 1973, probably japonica (8 Schodde, R. and van Tets, G.F. (1981). First record of the Brown Hawk-Owl Ninox scutulata from Australasia. Emu. 81(3): 171. Close ); other vagrants include live bird photographed on St Paul I, Alaska, in Aug 2005 (9 Yerger, J.C. and Mohlmann, J.D. (2008). First North American record of Brown Hawk Owl (Ninox scutulata) on Saint Paul Island, Alaska. North American Birds. 62(1): 4-8. Close ) and carcass recovered on Kiska I, Alaska, in Aug 2008 (10 Bond, A.L. and Jones, I.L. (2010). A Brown Hawk-Owl (Ninox scutulata) from Kiska Island, Aleutian Islands, Alaska. Western Birds. 41(2): 107-110. Close ).

Diet dominated by invertebrates, especially beetles and moths (6 Brazil, M. (1991). The Birds of Japan. Christopher Helm, London, UK. Close , 2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, UK. Close ). In one study from Japan, 6032 prey items consisted of 5968 insects (99% of total), 62 birds, one lizard and one bat. Hunts at night from perch , taking prey on ground and in foliage.

Breeding adults give a series of deep, double hoots: “ho-ho, ho-ho, ho-ho, ho-ho  ” (6 Brazil, M. (1991). The Birds of Japan. Christopher Helm, London, UK. Close ).

On Taiwan, breeding males start vocalizing in Jan and Feb, pairs form in Feb and Mar, eggs are laid from mid-Mar through Apr and young hatch from mid Apr to mid May (1 Lin, W.-L., Lin, S.-M. and Tseng, H.-Y. (2012). Breeding ecology of the Northern Boobook Ninox japonica totogo in central Taiwan. Forktail. 28: 164–166. Close ). Nests typically are placed in cavities of fairly large trees. Clutch size 3–4; eggs average 20·2 mm × 18·2 mm, 20·4 g; incubation period 25–31 days (mean 26·8 days); nestling period 25–28 days (mean 25·9 days). Nine of 10 nests were successful, producing an average of 2·1 fledglings (including the one failure); overall, 80·8% of eggs hatched, and 86·7% of hatchlings fledged (1 Lin, W.-L., Lin, S.-M. and Tseng, H.-Y. (2012). Breeding ecology of the Northern Boobook Ninox japonica totogo in central Taiwan. Forktail. 28: 164–166. Close ). Nesting occurs later for migrant population in Japan, from late May to late Jul, the birds nesting in natural cavities 4–9 m above ground or in nest boxes (6 Brazil, M. (1991). The Birds of Japan. Christopher Helm, London, UK. Close ). One record of nest in hole of iron bridge in Yamaguchi Prefecture, Japan (11 Kawamoto, M. (1991). [Tree Sparrows Passer montanus nesting near the nest of Brown Hawk-owls]. Strix. 10: 282-284. In Japanese with English summary. Close ).

Not globally threatened (Least Concern). CITES II. No data on global population size or population trends, but no evidence that any populations are undergoing serious declines. Considered to be the most common breeding owl in Japan; common passage migrant in Korean Peninsula in Apr–May and Sept, with a few summer visitors to C & S provinces; rare in SE Siberia. In winter, uncommon in Borneo, and rare in Java; generally uncommon throughout Moluccas and Lesser Sundas, but slightly more common in N Sulawesi region, including Talaud Is and Sangihe.