Ural owl
The Ural owl is a large nocturnal owl. It is a member of the true owl family, Strigidae. The Ural owl is a member of the genus Strix, that is also the origin of the family's name under Linnaean taxonomy. Both its common name and scientific name refer to the Ural Mountains of Russia where the type specimen was collected. However, this species has an extremely broad distribution that extends as far west as much of Scandinavia, montane eastern Europe, and, sporadically, central Europe, thence sweeping across the Palearctic broadly through Russia to as far east as Sakhalin and throughout Japan. The Ural owl may include up to 15 subspecies, but most likely the number may be slightly fewer if accounting for clinal variations.
This forest owl is typical associated with the vast taiga forest in Eurosiberia, although it ranges to other forest types, including mixed forests and temperate deciduous forest. The Ural owl is something of a dietary generalist like many members of the Strix genus, but it is usually locally reliant on small mammals, especially small rodents such as voles. In terms of its reproductive habits, Ural owls tend to vigorously protect a set territory on which they have historically nested on a variety of natural nest sites, including tree cavities and stumps and nests originally built by other birds but now, in many parts of the range are adapted to nest boxes made by biologists and conservationists. Breeding success is often strongly correlated with prey populations. The Ural owl is considered to be a stable bird species overall, with a conservation status per the IUCN as a least concern species. Despite some local decreases and extinctions, the Ural owl has been aided in central Europe by reintroductions.
Description
Like most Strix species, it has a broad, rounded head with a correspondingly round facial disc, barring a tiny V-shaped indentation. The Ural owl has, for an owl, an exceptionally long tail that bears a wedge-shaped tip. In colour, it tends to be a plain pale greyish-brown to whitish overall, with a slightly darker grey-brown to brown back and mantle with contrasting whitish markings. The underparts are pale cream-ochre to grey-brown and are boldly overlaid with dark brown streaking, without crossbars. Many variations are known in overall plumage colour both at the subspecies level and the individual level. However, the Ural owl usually appears as a rather pale grey-brown owl, usually lacking in the warmer, richer colour tones of many other Strix owls, with distinct streaking below. In flight, a Ural owl shows a largely buffish-white underwing marked with heavy dark bars around the trailing edge and tip, while the long white tipped tail often appears slung downwards. Their flight style is reminiscent of a buzzard but with deeper, more relaxed wing beats, with their style of flight often giving the appearance of quite a large bird. The eyes are dark brown, being relatively small and closely set to each other, which is opined to give them a less "fierce" countenance than that of a great grey owl. The eyes are reminiscent of an almond in both shape and colour. The bill is yellowish in colour, with a dirty yellow cere. Meanwhile, the tarsi and toes are covered in greyish feathering and the talons are yellowish brown with darker tips.The Ural owl is a rather large species. Full-grown specimens range in total length from, which may render them as roughly the eight longest owl species in the world. Wingspan can vary in the species from. Like most birds of prey, the Ural owl displays reverse sexual dimorphism in size, with the female averaging slightly larger than the male. Reportedly talon size and body mass is the best way to distinguish the two sexes of Ural owl other than behavioral dichotomy based on observations in Finland. Weight is variable through the European part of the range. Males have been known to weigh from and females have been known to weigh from. Voous estimated the typical weight of males and females at and, respectively. It is one of the larger species in the Strix genus, being about 25% smaller overall than the great grey owl, the latter certainly being the largest of extant Strix species in every method of measurement. Body masses reported for some of the more southerly Asian species such as brown wood owl and spotted wood owl show that they broadly overlap in body mass with the Ural owl or are even somewhat heavier typically despite being somewhat smaller in length, being somewhat stockier in build yet shorter tailed than the Ural owl. Despite having no published weights for adults, Père David's owl seems to also be of a similar size to the Ural owl as well. Among standard measurements, in both sexes, wing chord can measure from across the range and tail length can from. Among extant owls, only the great grey owl is certain to have a longer tail. Though less frequently measured, the tarsus may range from and, in northern Europe, the total bill length measured from. The foot span can regularly reach around in full-grown owls.
Vocalizations and ear morphology
The song of the male is a deep rhythmic series of notes with a short pause after the first two notes, variously transcribed as wohu... huw-huhuwo or huow-huow-huow. The phrase repeats at intervals of several seconds. The male's song may carry up to to human perception but usually is considered not quite that far-carrying. Peak singing times in Finland during springtime are 10 pm-12 am and more intensely at 1-3 am, which differed from the peak times for nest visits. The female has a similar but hoarser and slightly higher pitched song, giving it a more "barking" quality. Not infrequently, Ural owls will duet during courtship. In addition, a deep, hoarse heron-like kuwat or korrwick is probably used as a contact call. These are more elongated and harsher than the kewick note made by tawny owls. Young beg with hoarse chrrreh calls, again similar to the ones by young tawny owls but deeper. Vocal behavior tends to peak in early spring until the young leave the nest, most often during incubation and nesting in the form of prey delivery countercalling. The alarm call, which is typically delivered during territorial rounds, of the male is coincidentally analogous to the territorial song of the short-eared owl, which is considered a somewhat hollow sounding hoot. The alarm call is audible at up to away. The Ural owl also has a particularly menacing bill-snapping display. In total, Swedish biologist reported that about nine different calls were uttered by Ural owls. Despite the range of calls, the species is generally very quiet for a large owl and may not vocalize even at peak times for perhaps up to nearly 2 days.The ears of the Ural owl are quite large, averaging about on the left and on the right with the pre-aural dermal flap measuring about. In fact their ears are amongst the largest recorded in owls. In combination with their large ears, the well-developed facial disc shows the importance of sound to hunting to this and other owl who hunt in boreal zones. While the Ural owl was found to be aurally overdeveloped compared to other Strix such as the barred owl it was found to be underdeveloped in comparison to owls more confined to true boreal type habitats, like the great grey owl and the boreal owl.
Confusion with similar owl species
The Ural owl is a fairly distinctive looking bird but can be confused for other owls, especially with others in the Strix genus. The extralimital North American barred owl appears quite similar, the main feature differentiating the two being the Ural owl does not have concentric lines on its facial plate. The tawny owl is much smaller with a conspicuously shorter tail and a relatively larger head. The tawny species, which occurs variously in grey, brown and red morphs, has underparts with dark shaft-streaks and crossbars, as opposed to the heavy but straight streaking of the Ural owl. The great grey owl is larger than the Ural owl with a huge head and relatively even smaller yellow eyes while their facial disc has strong concentric lines. In colour, the great grey is distinctly more solidly uniform and somewhat dark greyish than the Ural owl. An unlikely species to mistake a Ural owl is the Eurasian eagle-owl which is much larger with prominent ear tufts, a squarish head shape and orange eyes as well as with distinctly different markings. Long-eared owls are much smaller and slimmer, with prominent ear-tufts, orange eyes and more prominent dark markings. More similar than any in Europe, the closely related Père David's owl does not occur in the same range as Ural owls but is darker in plumage, also with a facial disc marked with darker concentric lines. Due to its partially diurnal behaviour during warmer months, some authors consider it confusable with the very different looking Eurasian goshawk.Taxonomy
The Ural owl was named by Peter Simon Pallas in 1771 as Strix uralensis, due to the type specimen having been collected in the Ural mountains range. While the Urals fall around the middle of the species' distribution, some authors such as Karel Voous lamented that a more broadly appropriate than Ural owl was not derived for the English common name. In other languages, the species is referred to as Slaguggla, or "attacking owl", in Swedish, Habichtskauz, or "goshawk-owl", in German or as the "long-tailed owl" in Russian. The Ural owl is a member of the Strix genus, which are quite often referred to as wood owls. Conservatively, about 18 species are currently represented in this genus, typically being medium to large sized owls, characteristically round-headed and lacking ear tufts, which acclimate to living in forested parts of various climatic zones. Four owls native to the neotropics are sometimes additionally included with the Strix genus but some authorities have also included these in a separate but related genus, Ciccaba. Strix owls have an extensive fossil record and have long been widely distributed. 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.The tawny owl is thought to be a close relative of the Ural owl. Authors have hypothesized that the origin of the species divide followed Pleistocene continental glaciations segregated a southwest or southern group in temperate forest from an eastern one inhabiting cold, boreal ranges. The species pattern is mirrored in other bird species, i.e. the European green woodpecker from the more northern transcontinental grey-headed woodpecker. After retreat of the continental ice masses, the ranges more recently penetrated each other. While the life history details of the tawny and Ural owls are largely corresponding, nonetheless the species have a number of morphological differences and are largely adapted to different climates, times of activity and habitats. Based on Strix fossil species from Middle Pleistocene in variously the Czech Republic, Austria and Hungary show from leg and wing bones indicate an animal of intermediate form and size between Ural and tawny owls. However, fossils of a larger and differently proportioned Strix owl than a tawny owl, identified as S. brevis, from Germany and Hungary from before the Pleistocene and as well as diagnosed Ural owl fossils from disparate southerly deposits in Sardinia from the Early Pleistocene and in Middle Pleistocene deposits in the Pannonian Basin as well as much later during the early Holocene from far to the west in Belgium, France and Switzerland suggest a more complicated evolutionary and distributional history. 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.
Some species in America, such as namely the barred owl, are at times thought to be so closely related as well to the extreme that the Ural and barred and spotted owls, have been considered to potentially be part of a species complex or even within the same species. However, there is no evidence nor likelihood that the Strix owls between America and Eurasia ever formed a continuous population given their adaptation to well-forested areas as well as the fact that the barred owl is more ecologically similar to the more generalized tawny owl, despite being of intermediate size between tawny and Ural owls, and that the tawny does not range anywhere close to the boundary between North America and Russia as does the Ural. Certainly the most ambiguous aspect of the relations of Ural owl is the Père David's owl which has both historically and currently been considered either an isolated subspecies of the Ural owl or a distinct species. It is thought that the Père David's is likely a glacial relict of the mountainous forest of western China where plant and animal life often remain reminiscent of pre-glacial life. Recent study has indicated that the Père David's owl is valid species based on appearance, voice, and life history differences, though genetic studies have shown a somewhat muddled diversity between races of the Ural owls species complex. It has been recognized by The Clements Checklist of Birds of the World but BirdLife International and IUCN still classify it as a subspecies of the Ural owl.