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What the sources say

Tawny OwlStrix aluco

Every figure, record and mechanism on the Tawny Owl profile was written from a source, and this is the working table behind it: 47 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Animal Diversity Web, University of Michigan

Strix aluco (tawny owl). Animal Diversity Web, University of Michigan.

The page sayslopsided ears
The source saysTheir two ear openings have different structures and are located asymmetrically on the head for directional hearingNote: 'lopsided' for 'located asymmetrically'
The page saysMature broadleaf woodland with old, hole-bearing trees, parks and large gardens, and some conifer forest
The source saysTawny owls live in open, deciduous, or mixed forest or woodland, agricultural areas with trees, parks, cemeteries, and large gardens ... While sometimes found in mature conifer forests as well, they prefer mature broadleaf trees, such as ancient oaks with large holes for nesting.
The page saysacross the Palearctic from Iberia to China and Korea
The source saysStrix aluco can be found across the Palearctic Region from the Iberian Peninsula to as far east as China and Korea
The page saysMostly woodland rodents, plus other small mammals, amphibians, beetles, worms, and birds
The source saysTawny owls prey on a variety of animals, ranging from mostly woodland rodents to other small mammals, amphibians, birds, beetles, and worms.
The page saysAsymmetrical ear openings that let it locate a sound from the tiny difference in when it reaches each ear
The source saysTheir two ear openings have different structures and are located asymmetrically on the head for directional hearing ... These owls can use the minute differences in the time of arrival of sound at each ear to locate the source.
The page saysA Hunter That Finds Prey By Ear
The source saysThese owls can use the minute differences in the time of arrival of sound at each ear to locate the source.Note: heading; the owl uses sound to locate its source
The page saysA tawny owl hunts mostly between dusk and dawn, and for a night hunter, hearing is crucial
The source saysHearing is a crucial sense for a nocturnal hunter. ... Tawny owls hunt primarily between dusk and dawn.
The page saysIts eyes sit at the front of its head with a 50 to 70 percent overlap between their fields, which gives it more binocular vision than birds that hunt by day
The source saysTawny owl eyes are at the front of the head, with a field overlap of 50 to 70%. This overlap enables greater binocular vision than birds that hunt during the day.
The page saysIts two ear openings are built differently and set asymmetrically on the head, and the left one tilts downward to catch sounds from below
The source saysTheir two ear openings have different structures and are located asymmetrically on the head for directional hearing ... The left ear tilts downward to catch sounds coming from below.
The page saysThe owl locates a sound from the tiny difference in when it reaches each ear
The source saysThese owls can use the minute differences in the time of arrival of sound at each ear to locate the source.
The page saysIt perches and watches, then glides down silently to catch its prey on the ground, covering it with its wings and killing it with its feet and claws
The source saysThey perch and watch for prey, then use silent gliding flight to catch their victim on the ground, extending the wings to cover the prey and killing it with feet and claws.
The page saysRain is its weak spot: the noise of rainfall easily interferes with its hearing, and prolonged rain can leave it unable to hunt and starving
The source saysthis acute hearing can be easily interfered with by the sound of rainfall. Prolonged rain can bring about an inability to hunt and inevitable starvation.
The page saysIt averages 38 centimeters long with a 99-centimeter wingspan
The source saysAverage length 38 cm ... Average wingspan 99 cm
The page saysIts range runs across the Palearctic, from the Iberian Peninsula east to China and Korea and south to Iran and the Himalayas
The source saysStrix aluco can be found across the Palearctic Region from the Iberian Peninsula to as far east as China and Korea and south to Iran and the Himalayan mountain range.
The page saysIts diet is mostly woodland rodents, with other small mammals, amphibians, beetles and worms, and birds make up a bigger share of it in towns and cities
The source saysTawny owls prey on a variety of animals, ranging from mostly woodland rodents to other small mammals, amphibians, birds, beetles, and worms. Birds represent a larger percentage of their diet in urban areas
The page saysA pair defends its territory year-round, with minor changes to the boundaries each year
The source saysThe pair defend their territory year-round with minor changes to boundaries each year.
The page saysstakes it out with screeching calls, threats or fights in mid-flight
The source saysThese owls are highly territorial and establish their territories with screeching calls, threatening behavior, or in fights mid-flight.
The page saysTerritories run from about 0.12 to 1 square kilometer, smaller in dense woodland and larger where prey is scarce
The source saysRange territory size 0.12 to 1 km^2 ... Territory size of tawny owls depends on the habitat and availability of preferred prey. Territories can range from 30 acres in heavy woodland to 175 acres average in a beechwood forest with less vegetation. In Norway, where prey density is low, territories range about 255 acres.Note: 30-255 acres is roughly 0.12-1.03 km², matching ADW's own range figure
The page saysTalons Aimed at the Eyes
The source saysTawny owls defend their nest and young fiercely, even in the daytime, striking with sharp talons at the intruder's head and eyes.Note: blockquote lead
The page saysA tawny owl defending its nest and young strikes with its talons at an intruder's head and eyes, and mothers guarding a brood attack even people and domestic animals
The source saysTawny owls defend their nest and young fiercely, even in the daytime, striking with sharp talons at the intruder's head and eyes. ... Tawny owl mothers aggressively defending their broods, even against humans and domestic animals
The page saysTawny owl plumage varies from rufous-brown to greyish-brown, with lighter grey-and-white birds in the northernmost parts of the range
The source saysThese owls exhibit geographic variation in color. They can be rufous-brown; greyish-brown with the mottled plumage ... or lighter grey and white (in the northernmost parts of their distribution).
The page saysA sound reaches one of its ears a tiny fraction of a second before the other, and the owl uses that difference to work out where it came from
The source saysThese owls can use the minute differences in the time of arrival of sound at each ear to locate the source.Note: paraphrase: one ear hearing the sound 'before' the other is what 'minute differences in the time of arrival of sound at each ear' means
The page saysIts ears sit under the feathers of its facial disc, which let sound straight through, supported by a movable flap of skin
The source saysThe ears are underneath the facial disk feathers, which are transparent to sound and supported by the movable pre-aural flap.
The page saysRain is the catch: the noise of rainfall easily interferes with its hearing
The source saysthis acute hearing can be easily interfered with by the sound of rainfall.
The page saysYes, if someone comes too close to its nest or young, which it defends fiercely even in daylight
The source saysTawny owls defend their nest and young fiercely, even in the daytime
The page saysIts flight is silent, so the first warning can be the strike itself
The source saysTheir silent flight give them the ability to attack without notice.Note: the cause is the source's own: silent flight 'give[s] them the ability to attack without notice'
The page saysOwls from Siberia and Scandinavia are bigger than western European birds: about 12 percent larger and 40 percent heavier, with wings roughly 13 percent longer
The source saysSiberian and Scandinavian subspecies are 12% larger and 40% heavier than western European tawny owls, with 13% longer wings.
The page saysdangerLevel: Medium
The source saysTawny owls defend their nest and young fiercely, even in the daytime, striking with sharp talons at the intruder's head and eyes.Note: Settles #732: it attacks people at the nest and can injure them, so not Low (effectively harmless); no source describes a death, so not Deadly.
The page saystags: carnivore
The source saysTawny owls prey on a variety of animals, ranging from mostly woodland rodents to other small mammals, amphibians, birds, beetles, and worms.Note: Settles #732: replaces insectivore, since insects are a minor share of a mostly rodent diet.

Source
02

BTO BirdFacts, British Trust for Ornithology

Tawny Owl. BTO BirdFacts, British Trust for Ornithology.

The page saysa 'too-whit-too-woo' that takes two birds to make
The source saysthe familiar 'too-whit-too-woo' call which is actually made by two birds
The page saysLive adults weighed by British ringers average about 396 grams for males and 502 grams for females
The source saysWing length and body weights are from live birds ... Female 502.2±58.6 g (400-600 g, N=179) Male 396±44.6 g (335-482 g, N=37)Note: 502 rounds BTO's 502.2 g female average; BTO's current ringing biometrics replace ADW's older 420/520 g averages
The page saysBritish ringing records put a tawny owl's typical life expectancy at 4 years once it reaches breeding age, and the oldest ringed bird lived 23 years, 5 months and 27 days, a record set in 2016
The source saysTypical life expectancy of bird reaching breeding age 4 years ... Maximum age from a ringed bird 23 years, 5 months, 27 days (set in 2016)
The page saysIt lives in woodland throughout Britain, though not on the Northern Isles, the Outer Hebrides or treeless uplands, and it is absent from Ireland
The source saysTawny Owls are resident in woodlands throughout Britain but absent from the Channel Islands and Ireland ... Within Britain they are absent from the Northern Isles, Outer Hebrides, some of the smaller Inner Hebridean islands, the Isles of Scilly and treeless upland areas elsewhereNote: 'some' qualifies the smaller Inner Hebridean islands, which the sentence leaves out; the islands and uplands it names are stated flatly
The page saysTwo Birds, One Hoot
The source sayswhich is actually made by two birdsNote: heading
The page saysThe familiar "too-whit-too-woo" is made by two birds: the female calls the "too-whit" in answer to the male's hooting "too-woo."
The source saysIt is the source of the familiar 'too-whit-too-woo' call which is actually made by two birds – the female is responsible for the 'too-whit' part when she answers to the male's hooting 'too-woo'.
The page saysthe owl's 'too-whit-too-woo' takes two birds: one calls the 'too-whit' in answer to the other's hooting 'too-woo'
The source saysthe familiar 'too-whit-too-woo' call which is actually made by two birds – the female is responsible for the 'too-whit' part when she answers to the male's hooting 'too-woo'.Note: vibe.reason, settled in #732 (was mood only).

Source
03

RSPB, Royal Society for the Protection of Birds

Tawny owl. RSPB, Royal Society for the Protection of Birds.

The page saysBroad rounded wings
The source saysBroad rounded wings and a short tail
The page saysBuilt Like a Woodpigeon
The source saysThe Tawny Owl is an owl the size of a Woodpigeon.Note: heading
The page saysA tawny owl is about the size of a woodpigeon: a rounded body and head with no ear tufts, and a ring of dark feathers around its face surrounding its dark eyes
The source saysThe Tawny Owl is an owl the size of a Woodpigeon. It has a rounded body and head, with a ring of dark feathers around its face surrounding the dark eyes. ... Rounded head with no ear tufts

Source
04

Brommer, Ahola & Karstinen 2005

Brommer, Ahola & Karstinen (2005). The colour of fitness: plumage coloration and lifetime reproductive success in the tawny owl. Proceedings of the Royal Society B: Biological Sciences.

The page saysGrey or Brown: A Coat That Comes With Consequences
The source saysGrey-coloured male and female owls had a higher lifetime production of fledglings, and grey-coloured male (but not female) owls produced more recruits during their lifetime than brown individuals.Note: heading; the consequences are the fitness differences
The page saysThe colour is highly heritable, and a 26-year study of a population in southern Finland found it mattered for more than looks
The source saysa population of tawny owls (Strix aluco) in southern Finland, using 26 years of data ... Colour was a highly heritable trait and was under selection.
The page saysgrey males and females produced more fledglings over their lifetimes than brown owls did, and grey males also produced more young that went on to join the breeding population
The source saysGrey-coloured male and female owls had a higher lifetime production of fledglings, and grey-coloured male (but not female) owls produced more recruits during their lifetime than brown individuals.Note: 'young that went on to join the breeding population' defines 'recruits'
The page saysThe study found that selection worked through survival, not through fecundity
The source saysSelection on colour was mediated through viability selection and not through fecundity selection.Note: 'survival' for 'viability selection'
The page saysPlumage colour is highly heritable
The source saysColour was a highly heritable trait
The page saysIn a southern Finnish population followed for 26 years, owls scored from pale grey to reddish brown fell into two clusters, a grey morph and a brown morph, in both sexes
The source saysin southern Finland, using 26 years of data on individually marked male and female owls. Colour was scored on a semi-continuous scale from pale grey to reddish brown. Colour scoring was repeatable and showed a bimodal distribution (grey and brown morph) in both sexes.
The page saysThe mix of colours stayed stable through the study, and the owls did not choose mates by colour
The source saysDuring the study period, colour composition was stable in the study population in both sexes. The sexes did not mate assortatively with respect to their colour.

Source
05

The IUCN Red List of Threatened Species 2024

Strix aluco. The IUCN Red List of Threatened Species 2024: e.T22725469A264546097.

The page saysLeast Concern
The source saysLeast ConcernNote: IUCN category read through GBIF's copy of the Red List; iucnredlist.org refuses scripts

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.