Strix aluco Linnaeus, 1758
Common names: Tawny owl, Brown owl [En], Chouette hulotte, Chat-huant [Fr], Bosuil [Nl], Waldkauz [De], Allocco [It], Cárabo común [Es], Χουχουριστής [Gr], Alaca baykuş [Tu]
IUCN Status: LC (Least Concern)
Rodopoli, SERRES ● Greece
Description: It is a robust medium-sized owl, 37–46 cm in length, with an 81–105 cm wingspan. Its large rounded head lacks ear tufts, and the facial disc surrounding the dark brown eyes is usually rather plain. The nominate race has two morphs which differ in their plumage colour, one form having rufous brown upperparts and the other greyish brown, although intermediates also occur. The underparts of both morphs are whitish and streaked with brown. Feathers are moulted gradually between June and December.
This species is sexually dimorphic; the female is much larger than the male, 5% longer and more than 25% heavier.
Biology: The tawny owl flies with long glides on rounded wings, less undulating and with fewer wingbeats than other Eurasian owls, and typically at a greater height. The flight of the tawny owl is rather heavy and slow, particularly at takeoff. As with most owls, its flight is silent because of its feathers' soft, furry upper surfaces and a fringe on the leading edge of the outer primaries.
Hearing is important for a nocturnal bird of prey, and as with other owls, the tawny owl’s two ear openings differ in structure and are asymmetrically placed to improve directional hearing. The tawny owl’s hearing is ten times better than a human’s, and it can hunt using this sense alone in the dark of a woodland on an overcast night, but the patter of raindrops makes it difficult to detect faint sounds, and prolonged wet weather can lead to starvation if the owl cannot hunt effectively.
The tawny owl hunts almost entirely at night, watching from a perch before dropping or gliding silently down to its victim, but very occasionally it will hunt in daylight when it has young to feed. This species takes a wide range of prey, mainly woodland rodents, but also other mammals up to the size of a young rabbit, and birds, earthworms and beetles. In urban areas, birds make up a larger proportion of the diet, and species as unlikely as mallard and kittiwake have been killed and eaten.
Prey is typically swallowed whole, with indigestible parts regurgitated as pellets. These are medium-sized and grey, consisting mainly of rodent fur and often with bones protruding, and are found in groups under trees used for roosting or nesting.
Tawny owls pair off from the age of one year, and stay together in a usually monogamous relationship for life. An established pair’s territory is defended year-round and maintained with little, if any, boundary change from year to year. The pair sit in cover on a branch close to a tree trunk during the day, and usually roost separately from July to October. Roosting owls may be discovered and “mobbed” by small birds during the day, but they normally ignore the disturbance.
The tawny owl typically nests in a hole in a tree, but will also use old European magpie nests, squirrel drey or holes in buildings, and readily takes to nest boxes. It nests from February onwards in the south of its range, but rarely before mid-March in Scandinavia. The typical clutch of two or three eggs is incubated by the female alone for 30 days to hatching, and the altricial, downy chicks fledge in a further 35–39 days.] The young usually leave the nest up to ten days before fledging, and hide on nearby branches.
The parents care for young birds for two or three months after they fledge, but from August to November the juveniles disperse to find a territory of their own to occupy. If they fail to find a vacant territory, they usually starve.
Habitat: This species is found in deciduous and mixed forests, and sometimes mature conifer plantations, preferring locations with access to water. Cemeteries, gardens and parks have allowed it to spread into urban areas, including central London. The tawny owl is mainly a lowland bird in the colder parts of its range, but breeds to 550 metres in Scotland, 1,600 m in the Alps, 2,350 m in Turkey, and up to 2,800 m in Myanmar.
Distribution: The tawny owl has a distribution stretching discontinuously across temperate Eurasia from Great Britain and the Iberian Peninsula eastwards to western Siberia. The subspecies S. a. mauritanica extends the range into northwest Africa. This essentially non-migratory owl is absent from Ireland (probably because of competition from the long-eared owl), and only a rare vagrant to the Balearic and Canary Islands.
The tawny owl has a geographical range of at least 10 million km2 and a large population including an estimated 970,000–2,000,000 individuals in Europe alone. This species has expanded its range in Belgium, the Netherlands, Norway and Ukraine, and populations are stable or increasing in most European countries. Declines have occurred in Finland, Estonia, Italy and Albania.
Wikipedia, Tawny owl
BirdLife International. 2016. Strix aluco, The IUCN Red List of Threatened Species 2016.