Strix uralensis

Strix uralensis

The Ural owl (Strix uralensis Pallas, 1771) is a bird belonging to the Strigidae family.

Systematics –
Domain Eukaryota,
Kingdom Animalia,
Suborder Eumetazoa,
Superphylum Deuterostomia,
Phylum Chordata,
Subphylum Vertebrata,
Superclass Tetrapoda,
Class Aves,
Order Strigiformes,
Family Strigidae,
Subfamily Striginae,
Genus Strix,
Species S. uralensis.
The following subspecies are recognized within this species:
– Strix uralensis subsp. daurica Stegmann, 1929;
– Strix uralensis subsp. fuscescens Temminck & Schlegel, 1850;
– Strix uralensis subsp. hondoensis (A.H.Clark, 1907);
– Strix uralensis subsp. japonica (A.H.Clark, 1907);
– Strix uralensis subsp. liturata Lindroth, 1788;
– Strix uralensis subsp. macroura Wolf, 1810
– Strix uralensis subsp. momiyamae Taka-Tsukasa, 1931;
– Strix uralensis subsp. nikolskii (Buturlin, 1907);
– Strix uralensis subsp. uralensis Pallas, 1771;
– Strix uralensis subsp. yenisseensis Buturlin, 1915.

Geographic Distribution and Habitat –
The Ural owl (Strix uralensis) is a large, nocturnal owl with a wide distribution, extending westward to Scandinavia, the mountainous regions of Eastern Europe, and sporadically to Central Europe, then across the Palearctic throughout Russia to Sakhalin and Japan.
Its habitat is not tied to any particular forest type. In its main distribution area in Scandinavia and the Russian taiga belt, it inhabits forests dominated by spruce, dotted with birch and alder, with a rather open tree structure. The Ural owl’s habitats are often found on the edges of clearings, cleared areas, or peat bogs. Standing or slow-flowing waters are also preferred habitats. In addition to the presence of open areas with a good supply of small mammals, sufficient nesting opportunities are essential, whether in the form of natural cavities, nest boxes, or old raptor nests. The species does not colonize dense, contiguous forests and also avoids steep slopes. In its southern breeding areas of East Asia, the Ural owl extends into the zone of evergreen broadleaf forests. During the winter, it may even reach the vicinity of residential areas.
The remaining populations in central and southern Europe prefer open, mixed beech forests with little undergrowth; light, sunny slopes with border structures such as meadows, pastures, and clearings, as well as bodies of water, appear to be ideal. Where the Ural owl coexists with the long-eared owl, the latter colonizes denser forest areas, while the Ural owl prefers more open forests and open, varied structures. Where Ural owls are not persecuted, they do not avoid the vicinity of human settlements; however, in central and southern Europe, the species is decidedly hemerophobic, meaning it is shy of humans. In these distribution areas of central and southern Europe, the Ural owl is considered a mid-mountain dweller. In reality, however, there does not appear to be a clear preference for colonizing a particular altitude range, provided suitable habitat structures are present. The preference for mountainous areas in central Europe may be a consequence of habitat destruction at lower altitudes.
In general, the Ural owl’s space requirements are quite large relative to the species’ size, about three times greater than those of the tawny owl. In the Ural owl’s mid-mountain habitats in Scandinavia, approximately 5-7 pairs nest per 100 km², with nesting distances of between two and four kilometers. However, in optimal areas with excellent food availability, significantly higher population densities have been observed: for example, in 1992 near Krakow, three pairs nested in a forested area of just 10 km². Even higher settlement densities, up to 10 territories per 10 km², are hypothesized based on more recent studies in southern Slovenia.

Description –
The Strix uralensis is a medium-large nocturnal bird of prey belonging to the genus Strix, which also includes the common owl (Strix aluco), resembling it in shape but clearly distinguishing it from others in size, proportions, and habitat.
Its body length varies from 50 to 62 cm, while its wingspan can reach 115–134 cm. Females are generally larger and more robust than males.
Its weight ranges from 500 to 1,300 grams, with significant seasonal and geographic variations.
Its plumage is grayish-brown, sometimes tending towards ash gray or light brown, with clearly visible dark vertical streaks on the chest and belly.
The upperparts (back and wings) display a more irregular, camouflage-like pattern, useful for camouflage in the undergrowth.
The tail is long and narrow compared to other tawny owls, with light and dark horizontal bands—a diagnostic trait that aids recognition even in flight.
The facial disc is broad and round, very prominent, light in color, surrounded by a thin darker ring.
The eyes are black or dark brown, contributing to an intense and penetrating expression. Unlike many European owls (such as the long-eared owl), the Ural owl does not have yellow eyes, making it easily distinguishable.
It lacks ear tufts, unlike other owls such as the eagle owl or the long-eared owl.
The beak is yellowish, robust, and curved, suited to tearing prey.
The legs are covered with thick, long feathers, reaching to the talons. This serves to protect them from the cold and from prey bites.
The talons are strong and well-developed, suitable for catching small mammals even in snowy or wooded environments.
The Ural owl’s flight is slow, silent, and sweeping, aided by its long tail and broad wings. In flight, it appears more elongated than the common owl.
Its long, tapering tail is one of its most distinctive features, visible from afar and often compared to that of a hawk.
It is a highly vocal species, especially during the breeding season. The male’s call is a deep, prolonged, and monotonous howl, similar to a “wuuuh… wuh-wuh-wuh,” which can be heard from far away.
The female emits higher-pitched sounds and moans during mating or to communicate with her chicks.

Biology –
The Strix uralensis is an opportunistic predator. It feeds primarily on small mammals such as voles, mice, squirrels, and young hares, but can also hunt birds, amphibians, and insects. Hunting occurs primarily during twilight and at night, taking advantage of its silent flight and highly developed vision and hearing.
The breeding season begins in late winter or early spring, usually between March and April. The pair is monogamous and tends to remain in the same territory for several consecutive years.
It does not build a true nest, but uses natural cavities in old trees, old raptor nests, or rock niches or artificial nest boxes.
The female lays 2 to 6 eggs, with an average of 3–4.
The female alone incubates the eggs for about 27–35 days. During this time, the male is responsible for foraging.
The young leave the nest (still unable to fly) at around 4–5 weeks, but are fed by their parents for several more weeks, until they are fully independent at around 2–3 months.

Ecological Role –
The Ural owl plays a key role in temperate and boreal forest ecosystems, primarily due to its apex predatory status and sensitivity to environmental changes. Its presence is often an indicator of the conservation status and biodiversity of forests.
This predator feeds primarily on small mammals, especially rodents such as voles, field mice, lemmings (in the northernmost areas), and squirrels. It supplements its diet with birds, amphibians, reptiles, and insects, depending on seasonal and local availability.
This predatory behavior regulates small vertebrate populations, helping to maintain their balance and preventing excessive demographic cycles, such as rodent population explosions.
In some forest ecosystems, the stable presence of the Ural owl helps limit agricultural damage caused by rodents.
It shares its habitat with other nocturnal birds of prey, such as the long-eared owl (Strix aluco), the Lapland owl (Strix nebulosa), and the eagle owl (Bubo bubo).
Where they coexist, interspecific competition for resources (especially nests and hunting grounds) occurs, but this competition tends to resolve itself through ecological differentiation: for example, the Ural owl tends to occupy more remote, mature, and continuous forest areas than the long-eared owl, which is more adaptable to human-influenced environments.
In some areas of eastern and northern Europe, it has been observed that the expansion of the Ural owl has pushed the long-eared owl towards more marginal areas, demonstrating the species’ ecological competitive strength.
The Ural owl is closely associated with intact, mature, and undisturbed forests, with a large availability of old trees and natural cavities for nesting.
This makes it an excellent bioindicator of the health of old-growth forests and ecological continuity.
Its presence is often used by naturalists and biologists to assess the environmental quality of forests and the effectiveness of forest conservation policies.
It is also highly sensitive to habitat fragmentation: deforestation, clear-cutting, and landscape fragmentation severely compromise its survival at the local level.
As a top predator, it contributes to the stability of forest ecosystems by influencing the structure of underlying animal communities.
Some of its prey partially excavate or create microhabitats useful to other animals; therefore, by controlling their populations, the Ural owl indirectly contributes to the trophic and structural diversity of the environment.
In many areas, it is considered beneficial to agriculture and forestry through rodent control.
However, it is also a vulnerable species to human pressure, such as the felling of mature trees and the reduction of nesting sites, for which it is protected in several European countries.
It is classified as Least Concern on the IUCN Red List. In Italy, it is a protected species under Article 2 of Law 157/92.

Guido Bissanti

Sources
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– C. Battisti, D. Taffon, F. Giucca, 2008. Atlas of Breeding Birds, Gangemi Editore, Rome.
– L. Svensson, K. Mullarney, D. Zetterstrom, 1999. Guide to the Birds of Europe, North Africa, and the Near East, Harper Collins Publishers, UK.

Photo source:
– https://inaturalist-open-data.s3.amazonaws.com/photos/469079647/original.jpg
– https://upload.wikimedia.org/wikipedia/commons/f/f7/Strix_uralensis_1838.jpg