Taxonomy of the tawny owl

The tawny owl was first described by Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae in 1758, under its current scientific name Strix aluco. The binomial derives from the Greek strix "owl" and Italian allocco "tawny owl" (which in turn comes from the Latin ulucus "screech-owl"). Some early descriptions upon review were found to have somehow conflated the very different barn owl by describing it with the same scientific name Strix aluco, which in turn engendered some confusion.Allen, J. A. (1908). The case of Strix vs. Aluco. The Auk, 25(3), 288–291.

The tawny owl is a member of the wood-owl genus Strix, part of the true owl family Strigidae, which contains all species of owl other than the barn owls. Conservatively, about 18 species are currently represented in this Strix genus, typically being medium to large sized owls that are characteristically round-headed and lacking ear tufts, which acclimate to living in forested parts of various climatic zones.Holt, D.W., Berkley, R., Deppe, C., Enríquez Rocha, P., Petersen, J.L., Rangel Salazar, J.L., Segars, K.P., Wood, K.L. & Marks, J.S. (2019). Typical Owls. In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.Sibley, C. G., & Ahlquist, J. E. (1990). Phylogeny and classification of birds: a study in molecular evolution. Yale University Press. Four owls native to the neotropics are sometimes additionally included with the Strix genus, though some authors include these in a separate but related genus, Ciccaba.Wink, M., El-Sayed, A. A., Sauer-Gürth, H., & Gonzalez, J. (2009). Molecular phylogeny of owls (Strigiformes) inferred from DNA sequences of the mitochondrial cytochrome b and the nuclear RAG-1 gene. Ardea, 97(4), 581–592. Strix owls have an extensive fossil record and have long been widely distributed.Mlíkovský, Jirí (2002): Cenozoic Birds of the World, Part 1: Europe . Ninox Press, Prague. The genetic relationship of true owls is somewhat muddled and different genetic testings has variously indicated that Strix owls are related to disparate appearing genera like Pulsatrix, Bubo and Asio.Lee, M. Y., Lee, S. M., Jeon, H. S., Lee, S. H., Park, J. Y., & An, J. (2018). Complete mitochondrial genome of the Northern Long-eared Owl (Asio otus Linnaeus, 1758) determined using next-generation sequencing. Mitochondrial DNA Part B, 3(2), 494–495. Tropical species, such as the mottled owl (Strix virgata) and the African wood owl (Strix woodfordii), the latter once considered a close relative to the tawny owl, morphologically differ from and have smaller outer ear areas than tawny owls.van der Weyden, W. J. (1975). Scops and screech owls: vocal evidence for a basic subdivision in the genus Otus (Strigidae). Ardea, 63, 65-77.

The tawny owl is thought to be a close relative of the Ural owl. Authors have hypothesized that the origin of the divide between these two species followed the Pleistocene continental glaciations, which segregated a southwest or southern group in temperate forest (i.e. the tawny) from an eastern one inhabiting cold, boreal ranges (i.e. the Ural). After retreat of the continental ice masses, the ranges more recently penetrated each other.Voous, K. H. (1964). Wood owls of the genera Strix and Ciccaba. Zoologische Mededelingen, 39(46), 471–478.Salomonsen, F. (1931). Beretning om en Rejse til Færøerne. Dansk Orn. Foren. Tidsskr, 25, 3–37. While the life history details of the tawny and Ural owls are largely corresponding, the species nonetheless have a number of morphological differences and are largely adapted to different climates, times of activity and habitats.Scherzinger, W. (1980). Zur Ethologie der Fortpflanzung und Jugendentwicklung des Habichtkauzes (Strix uralensis) mit Vergleichen zum Waldkauz (Strix aluco). Bonn. Zool. Mongr, 15. Strix fossil species from the Middle Pleistocene (given the name Strix intermedia) in the Czech Republic, Austria and Hungary indicate from leg and wing bones an owl of intermediate form and size between Ural and tawny owls.Jánossy D. (1972). Die mittelpleistozäne Vogelfauna der Stránská skála. – In: Musil R. (ed.): Stránská skála I. – Anthropos (Brno) 20: 35–64.Jánossy D. (1976). Die Felsnische Tarkő und die Vertebratenfauna ihrer Ausfüllung. Karsztés Barlangkutatás 8: 3–106.Jánossy, D. 1978. Új finomrétegtani szint Magyarország pleisztocén őslénytani sorozatában [A new fine stratigrafic level in Paleontological series at Hungarian Pleistocene]. Földrajzi Közlemények 26(1–3): 161–174.Mourer-Chauvire, C. (1975). Faunes d'oiseaux du Pléistocene de France: systématique, évolution et adaptation, interprétation paléoclimatique. Geobios, 8(5), 333-IN11. However, fossils of a larger and differently proportioned Strix owl than a tawny owl, identified as Strix brevis, from Germany and Hungary from before the Pleistocene (i.e. Piacenzian) suggest a more complicated evolutionary and distributional history.Becker, C., & Pieper, H. (1982). Zum Nachweis des Habichtkauzes Strix uralensis in einer neolithischen Seeufersiedlung der Schweiz. Der Ornithologische Beobachter, 79, 159–162. A hybrid was recorded in captivity between a male Ural and a female tawny owl, which managed to produce two offspring that were intermediate in size and had a more complex song that was also shared some characteristics with both species' vocalizations.Scherzinger, W. (1983). Beobachtungen an Waldkauz-Habichtskauz-Hybriden:(Strix aluco x Strix uralensis).

A number of owls that were considered conspecific with the tawny owl are now widely considered to be separate species as a result of conclusive genetic studies. These consist of the desert or Hume's owl and its sister species,Heidrich, P., & Wink, M. (1994). Tawny owl (Strix aluco) and Hume's tawny owl (Strix butleri) are distinct species: evidence from nucleotide sequences of the cytochrome b gene. Zeitschrift für Naturforschung C, 49(3–4), 230–234.Kirwan, G. M., Schweizer, M., & Copete, J. L. (2015). Multiple lines of evidence confirm that Hume's Owl Strix butleri (AO Hume, 1878) is two species, with description of an unnamed species (Aves: Non-Passeriformes: Strigidae). Zootaxa, 3904(1), 28–50. the recently separated and range-restricted Omani owl (Strix butleri)Robb, M. S., Sangster, G., Aliabadian, M., van den Berg, A. B., Constantine, M., Irestedt, M., Khani, A., Musavi, S.B., Nunes, J.M.G., Willson, M.S. & Walsh, A. J. (2016). The rediscovery of Strix butleri (Hume, 1878) in Oman and Iran, with molecular resolution of the identity of Strix omanensis Robb, van den Berg and Constantine, 2013. Avian Research, 7(1), 7. and the little-known Himalayan owl (Strix nivicolum).Del Hoyo, J., Collar, N. J., Christie, D. A., Elliott, A., & Fishpool, L. D. C. (2014). HBW and BirdLife International Illustrated Checklist of the Birds of the World: non-passerines (Vol. 1). Barcelona: Lynx Edicions.Sibley, C. G., & Monroe Jr, B. L. (1993). A world checklist of birds. Ann Arbor, MI: Edwards Brothers Inc. In all three separated species, there is no evidence that the tawny owl breeds in the same areas as them, making each species allopatric, though the desert and tawny's range nearly abuts in some parts of the Middle East such as northern Israel.Dov, A.B., Atar, A., Baruchi, E, Levi, K. & Sapir, N. (2017). Breeding biology of Desert Owl in Israel. Dutch Birding, 39, 285–307. Also, in the Western Himalayas, both the tawny and Himalayan owls are known to occur, but there is likely a gap of several hundred kilometers in distribution with tawny mostly restricted to the Pakistani side, whilst the Himalayan is rarely found west of Himachal Pradesh.Marcot, B. G. (1995). Owls of old forests of the world. Gen. Tech. Rep. PNW-GTR-343. Portland, OR: US Department of Agriculture, Forest Service, Pacific Northwest Research Station. 64 p, 343. Furthermore, the desert and Omani species pair and the Himalayan species are considerably different based on superficial appearance (far more so than true tawny owl subspecies), in addition to having distinct voices and appearing to have slightly different nesting habits than tawny owls.Owls of the World: A Photographic Guide by Mikkola, H. Firefly Books (2012),

Subspecies The tawny owl subspecies are often poorly differentiated, and may be at a flexible stage of subspecies formation with features related to the ambient temperature, the color tone of the local habitat, and the size of available prey. Consequently, various authors have historically described between 10 and 15 subspecies. The total number of subspecies was once considered as totaling at 11 subspecies but is now reduced due to the separation of the Himalayan owl and its own further two subspecies down to about eight subspecies. The currently recognised subspecies are listed below.