Tawny Owl Strix aluco Scientific name definitions

Medium-sized owl with deep black eyes; strictly nocturnal and infrequently seen. Brown to gray-brown overall with big rounded head. Favors woodland, forest, parkland, urban areas and churchyards with large trees; tends to roost well hidden in foliage during the day, when may be detected by tracking down the excited sound of small birds mobbing the owl. Comes out at night to hunt in clearings and more open areas. Most often detected by its quavering hoots and kee-wik! shrieks, given at night.

37–39 cm; wingspan 94–104 cm; male average 440 g, female average 553 g (nominate aluco). Medium-sized owl with noticeably stocky body, large and round head  ; plumage polymorphic , with intermediates. Nominate race mostly grey-brown, facial disc generally pale with some darker concentric rings, crown with dark centre bordered by pale bands; upperparts heavily mottled brown with darker shaft streaks, outer webs of outer scapulars and upperwing-coverts with large white or cream spot at tip; underparts streaked dark and with variable thin cross-bars; tarsus and most of toes feathered; iris blackish-brown; bill horn-coloured to pale yellowish; toes grey. Morphs vary mostly in ground colour of plumage, from deep rufous-brown to dark grey: rufous morph rufous-chestnut to rufous-cinnamon above, facial disc deep rufous-cinnamon with contrasting white arcs from above each eye and from lower cheek joining at base of bill; intermediate birds have hindneck and crown buff to pale cream-yellow with broad black streaks, remainder of upperparts buff-brown to grey-brown with less distinct narrow dark bars and vermiculations, and facial disc off-white with grey concentric lines; grey morph pale buff to grey-buff above, sometimes mixed with white on crown and hindneck; dark grey morph has plumage dominated by narrow dense black bars on crown and hindneck, dense dark grey vermiculations on rest of upperparts, and pale grey facial disc with much dark grey barring and mottling. Juvenile paler, plumage noticeably loose, even shaggy, and more finely barred. Races differ in colour and size, but difficult to distinguish owing to large individual variation: <em>sylvatica</em> smallest, usually rufous-brown or tawny-chestnut; siberiae distinctly paler, with much white.

The very similar Maghreb Owl Strix mauretanica is parapatric with the Tawny Owl, separated only by a 15 km strait, and yet they do not show clinal variation; Tawny Owls are smaller, pale and less heavily transversely marked above and below, and much more variable in color (at least in most races) than Maghreb Owl. The Himalayan Owl S. nivicolum is also similar, but is allopatric and is also darker and more coarsely marked than Tawny Owl, with broadly banded wings, tertials, and tail (1 Rasmussen, P. C., and J. C. Anderton (2005). Birds of South Asia: the Ripley Guide. Lynx Edicions, Barcelona, Spain. Close ). The sympatric Ural Owl Strix uralensis is very much larger and much paler, while the Desert Owl Strix hadorami, with which Tawny Owl is sympatric only in the Levant, is very much paler, has yellow eyes, and inhabits more xeric environments.

Closely related to S. butleri; formerly considered to include latter (including newly described S. hadorami) as a race. Has hybridized with S. uralensis (2 Hamer, T.E., Forsman, E.D., Fuchs, A.D. and Walters, M.L. (1994). Hybridization between Barred and Spotted owls. Auk. 111(2): 487–492. Close ). Until recently, included S. nivicolum (with ma and yamadae) as subspecies, which differs in having entirely different song (a double huhu, repeated with a space of several seconds, vs the two-stage huuu (long pause) wu-hrrruuu of aluco (4); considerably darker plumage (dark brown vs grey-brown, greatly reduced white admixed with grey) (2); markedly more strongly barred tail (2); overall similar size but shorter tail (160–192 mm vs 205–220 mm in published data) (at least 1). Geographical limits of races obscure; nominate aluco intergrades with siberiae, and sylvatica with sanctinicolai. Several additional races named, but considered probably not acceptable because of species’ considerable individual variation and polymorphy; populations from Iberia, Asia Minor and Middle East sometimes separated as clanceyi (included in sylvatica), those from SW Russia as volhyniae (now in nominate) and those from S Caspian as obscurata (subsumed within willkonskii). Based on morphology, voice, and mtDNA the North African taxon mauritanica is now treated as a separate species (3 Brito, P. H. (2005) The influence of Pleistocene glacial refugia on Tawny Owl genetic diversity and phylogeography in western Europe. Molecular Ecology 14:3077–3094. doi: 10.1111/j.1365-294X.2005.02663.x Close , 4 Doña, J., Ruiz-Ruano, F.J. and Jovani, R. (2015). DNA barcoding of Iberian Peninsula and North Africa Tawny Owls Strix aluco suggests the Strait of Gibraltar as an important barrier for phylogeography. Mitochondrial DNA. Close , 5 Robb, M. (2015). Undiscovered Owls: A Sound Approach Guide. The Sound Approach, Poole, UK. Close , 6 Gill, F., D. Donsker, and P. Rasmussen (Editors) (2021). IOC World Bird List (v11.1). Close ). Seven subspecies recognized.

Occurs almost throughout Europe from Britain and Scotland through southern Fennoscandia to western Siberia, south to the southernmost Iberian Peninsula, through the Levant, western Iran, and the western Himalayas east to Kashmir.

Open and semi-open forest, woodland, farmland with trees, parks, larger gardens in villages and towns, and tree-lined urban avenues; also rocky areas with sufficient tree and bush cover; avoids large unbroken forest tracts, wetlands and treeless plains, as well as very windswept, frosty or arid climates; occurs from fringe of boreal zone through temperate regions and steppe to Mediterranean and related montane zones. For hunting, requires richly structured habitat with plenty of lookout posts, including sparse woodland, clearings, avenues, cemeteries, hedgerows and gardens, especially among mature trees, and with some preference for access to water. Mainly in lowlands, but ranges up to 2350 m in Turkey and to similar elevations in Turkestan.

Resident. Breeding adults remain in territory all year. Juveniles disperse by late autumn, in temperate areas usually within radius of a few km of natal site; in Fennoscandia, dispersal up to 20 km, but once 745 km into Lappland, and individuals disperse in all directions.

Small mammals, from small rodents and shrews up to size of squirrels and young rabbits, and small birds up to size of pigeon; also amphibians, reptiles, earthworms, snails, beetles and other insects, occasionally fish; in urban areas, largely birds, small rodents and other prey taken as available; pellets often contain soil and plant remains, and sometimes composed of soft wood or sawdust. In pellet study in England, mice and voles found to constitute 56·4% of prey, and larger mammals 34·7% of diet; in Scotland, wood mouse (Apodemus sylvaticus) most commonly taken mammal prey and House Sparrow (Passer domesticus) most frequently identified bird prey. Diet shifts from mainly mammals in winter to primarily birds in breeding season, and from small prey to medium-sized (> 30 g) prey; in E Bohemia, fed mainly on Microtus voles, but in poor vole years switched to other food. In C Italy, frogs (Rana italica and R. dalmatina) eaten more in winter than in summer and were not taken in urban territories (7 Manganaro, A., Pucci, L., Ranazzi, L. and Salvati, L. (2001). Frogs as prey of Tawny Owls Strix aluco in central Italy: a comparison with diets from central Europe. Alauda. 69(4): 550-552. Close ). Relative proportions of prey taken considered to reflect availability, rather than food specialization. Diet from stomach contents of 65 males and 93 females in Spain showed that males tended to take a narrower range of prey species than females and hunted in forests for voles; females hunted more in open habitats and took more murid rodents than did males (8 Villarán Adánez, A. (2000). [Sex-specific comparative analysis of diet in the Tawny Owl Strix aluco in the Iberian Peninsula]. Ardeola. 47(2): 203-213. In Spanish with English summary. Close ). In C Turkey, small-scale study recorded both small mammals (76·3%) and birds in diet, with Turkish hamster (Mesocricetus brandti) and Tristram’s jird (Meriones tristrami) most prevalent among the former group, while two rallids, Spotted Crake (Porzana porzana) and Corncrake (Crex crex), constituted comparatively unusual avian prey (9 Nedyalkov, N. and Boev, Z. (2016). Diet of Barn Owl Tyto alba and Tawny Owl Strix aluco in central Anatolia, Turkey. Sandgrouse. 38(1): 79–81. Close ). Chiefly nocturnal, hunting between dusk and dawn; occasionally diurnal. Prey typically located by sound. Hunts mostly from perch , turning body occasionally; makes frequent short flights, returning to same perch; glides or drops on to prey, extends wings on impact to cover or strike prey; where habitat includes open ground, often flies slowly, with frequent intermittent glides, makes zig-zag searches, and hovers; reported to take fish from water surface while in flight, or by wading in shallows. Forages for earthworms by flying down to ground and waiting motionless until it appears to hear a sound, then rotating head and stretching neck, hopping forward, repeating head movements, and finally making 2–3 long leaps with wings partially spread to peck up worm. Bats and large insects also seized in flight. Usually consumes food on elevated perch.

Long, quavering hoot , followed by faint monosyllable, a short pause, and then extended soft tremolo which falls in pitch; during courtship also long trills; also soft quit calls probably as contact, and sharp ke-wick in excitement or aggression.

Season typically Feb–Jul; egg laying occasionally begins in late Jan (10 Lykov, E.L. (2012). [A case of early breeding of the Tawny Owl (Strix aluco) in Kaliningrad]. Berkut 21(1–2): 204-205. In Russian with English summary. Close ). Monogamous (socially and genetically (11 Saladin, V., Ritschard, M., Roulin, A., Bize, P. and Richner, H. (2007). Analysis of genetic parentage in the Tawny Owl (Strix aluco) reveals extra-pair paternity is low. Journal of Ornithology. 148(1): 113-116. Close )), pairs for life; occasionally bigamous. Nest in hole in tree, also in cliff or building; often uses old nest of Eurasian Magpie (Pica pica) or drey of squirrel (Sciurus); sometimes in hole in ground or among tree roots; readily accepts nest box ; fidelity to nest-site marked, although occasionally changes if site deteriorates or is disturbed; in Europe, average territory size from 10–12 ha in optimum habitat to 60–70 ha in poor habitat; vocal responses to intruders found to be largely sex-specific. Clutch size 2–9 eggs, usually 3–5, laying interval 2–4 days; female incubates and broods, fed by male; incubation 28–30 days; hatching asynchronous, chick with white down ; young brooded until 15 days old; fratricide occurs when food short; fledging period 32–37 days, but will leave nest at 25–30 days and hide on nearby branches; on basis of large sample of radio-tagged young, fledglings stopped begging from their parents 56–84 days after leaving nest (12 Sunde, P. (2008). Parent-offspring conflict over duration of parental care and its consequences in Tawny Owls Strix aluco. Journal of Avian Biology. 39(2): 242-246. Close ). One instance of suspected double brooding in Spain (13 Zuberogoitia, I., Martínez, J.A., Iraeta, A., Azkona, A. and Castillo, I. (2004). Possible first record of double brooding in the Tawny Owl Strix aluco. Ardeola. 51(2): 437-439. Close ). In Belgian study, of 256 eggs laid 24% did not hatch, of 195 young hatched 94% fledged, average brood size at fledging 2·06, varied depending on vole numbers; in Sweden, mortality in first year of life 71%, in second year 44%, in third year 48%; in Switzerland, mortality in first year 49%, in second and third years 25%. In long-term study in UK, productivity of males and females increased with age for first 3 and 9 years of reproductive life, respectively, then declined (14 Millon, A., Petty, S.J., Little, B. and Lambin, X. (2011). Natal conditions alter age-specific reproduction but not survival or senescence in a long-lived bird of prey. Journal of Animal Ecology. 80(5): 968-975. Close ). In Denmark, predation of radio-tagged juveniles mostly from mammals in first few days after fledging and from raptors about two months after fledging (15 Sunde, P. (2005). Predators control post-fledging mortality in Tawny Owls, Strix aluco. Oikos. 110(3): 461-472. Close ). Age of first breeding 1–2 years. Oldest ringed bird 18 years 10 months.

Not globally threatened (Least Concern). CITES II. Generally common throughout range. European population in mid-1990s estimated at c. 400,000–560,000 pairs, plus substantial numbers (up to 100,000 pairs) in W Russia and up to 20,000 pairs in Turkey: largest numbers in France and Germany, with c. 85,000 pairs in each, and c. 70,000 pairs in Poland and over 50,000 pairs in Spain; good numbers of pairs also in Croatia (20,000–25,000), Latvia (20,000), Sweden (15,000), Greece (15,000) and Belarus (10,000); British population estimated at around 20,000 pairs. Appears to be fairly stable or slightly increasing in C Europe, and possibly decreasing in N & S. In Britain, declined in 19th century through human persecution, but increased over much of that region from c. 1900 to 1930 (and in some areas to 1950), apparently stabilizing in mid-1970s at figure then put at 10,000–100,000 pairs (upper limit regarded as over-optimistic). Some expansion in range in Netherlands and Belgium, aided mainly by maturation of forest. Considered common in C parts of Russia, but less so in N, and scarce in Caucasus. In England, despite wide variations in numbers of prey and of fledged young produced, a studied population of adults remained notably stable; stability was maintained by those young that failed to find a territory either starving or moving outside area, which in most cases led to mortality; regulation of the population studied was thus due to territorial intolerance acting to produce subsequent mortality. Clutch size, offspring production and chick survival did not differ between 210 rural and 60 urban territories in S Finland (16 Solonen, T. and Ursin, K.A. (2008). Breeding of Tawny Owls Strix aluco in rural and urban habitats in southern Finland. Bird Study. 55(2): 216-221. Close ).