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brown owl
Tawny Owl (Strix aluco) Calls of a Tawny Owl? / I

Tawny Owl ( Strix aluco ) calls of a Tawny Owl ? / i
Audio file / audio sample

Systematics
Class : Birds (aves)
Order : Owls (Strigiformes)
Family : Real owls (Strigidae)
Genre : Strix
Type : brown owl
Scientific name
Strix aluco
Linnaeus , 1758

The tawny owl ( Strix aluco ) is a medium-sized owl species with a distribution from Europe to Western Siberia and Iran . It is also found in Southeast Asia. In Central Europe the tawny owl is the most common owl together with the long- eared owl. It is only missing in tree-poor areas. Tawny owls need richly structured landscapes as breeding areas, in which forests and groups of trees alternate with open areas. He is a cave breederwhich, in addition to tree hollows, also breeds in wall holes, rock caves and attics. It prefers to eat mice, but if there is a shortage of mice, it can switch its diet to small birds.

Characteristic for this crepuscular and nocturnal species of owl is a compact shape with a round head and a bark-like plumage. From September to November and in early spring, the male's song of territory can be heard from far and wide.

The Tawny Owl was bird of the year 2017 in Germany .

description

Appearance of adult tawny owls

The tawny owl reaches a body length of 40 to 42 centimeters and weighs between 330 and 630 grams. Females tend to be heavier than males. The average weight of forest chewing twigs caught in Germany is 560 grams, while males are 120 grams lighter. The physique is compact, the head appears large in relation to the body size. Feather ears like those of the long-eared owl are missing. The face veil is framed dark and predominantly monochrome beige-brown. Above the face veil there are two whitish lines of color, which are particularly noticeable in the dark color morphs . The thick beak is strongly curved and usually sulfur yellow with a horn-colored to light gray beak base. The wax skin looks swollen and is slightly greenish. The iris is black-brown, the pupil blue-black. The eyelids are bald and pale red. The claws are gray at their roots, then turn a horn-brown color and end in a black tip.

Portrait of a tawny owl, the two whitish lines of color at the upper end of the facial veil are clearly visible.

Tawny owls come in various color morphs in Central Europe. This ranges from a gray color variant to a brown to a rusty brown. The basic color of the plumage is not determined by age or gender, as has long been assumed. Rather, it represents an adaptation to different habitats. The different color morphs can certainly occur in the same area and also mate with one another. Couples with different basic colors often have young ones with both color variants.

The plumage is very loose, which makes the tawny owl appear larger than it actually is. The top of the body is generally darker than the underside of the body. The plumage has a bark-like camouflage color : the shoulders and wings have light-colored droplet spots that look like sunspots in the semi-darkness of the forest and thus increase camouflage. A comparable plumage color with drop spots can also be found in a number of other birds such as the scops owl , reversible neck , pygmy owl and goat milkers , which prefer to stay near trunks during the day. The feathers on the upper side of the body each have longitudinal stripes that branch off to the side. This branching is denser, especially on the back and the upper tail-coverts, so that the plumage looks more washed out here. The flight feathers are brown, with the outer legs having whitish, the inner legs pale brown cross bars.

Geographical variations in appearance

The nominate form Strix aluco aluco

Although the color morphs occur everywhere in Europe, brown to rust-brown tawny owls dominate in the humid climates of Western Europe. In the Dutch dune area, eighty percent of the tawny owls living there have rust-red plumage. The gray morph is more common in the eastern range. In the extreme north, however, all tawny owls have gray plumage. The tawny owl subspecies living in Siberia and Central Asia have gray and white plumage. The North African subspecies is dark gray-brown. Those found in South and East Asia have transversely and not longitudinally striped plumage. These species also have fine lines around the face veil.

The Siberian and Scandinavian subspecies are twelve percent larger and forty percent heavier than Western European birds. This corresponds to Bergmann's rule , according to which in endothermic animals , i.e. H. in mammals and birds , the individuals of a species are larger in the colder areas of their range than in the warmer ones.

The basic color of the plumage is genetically determined and studies in Finland and Italy suggest that the gray morphs among the tawny owls have a higher reproductive rate, a better immune system and are less infested by parasites than the brown morphs. Since the tawny owls do not show any preferences regarding the plumage color when choosing a mate, the selection pressure on brown color morphs is not very strong. The studies carried out in Italy also show that the plumage color is an evolutionary adaptation to different habitats. Tawny owls with a brown basic color occur mainly in forest areas. In Finland, on the other hand, gray tawny owls dominate in accordance with Gloger's rule .

Flight image

The wings of the tawny owl are rather short, broad and rounded compared to other owl species; the wingspan is up to 96 cm. Tawny owls are agile fliers who can maneuver safely and quickly even in dense trees. Compared to that of the long-eared owl, their flight pattern is plump, long-tailed and broad-winged. Tawny owls fly with rapid flapping of their wings. The basically straight flight is repeatedly interrupted by longer gliding phases.

Appearance of boys

Tawny owl as branchling

Newly hatched chicks are dense and relatively short gray-white colored. The legs are also covered with a dense downy plumage that extends to the claws. Only on the back of the running joint there are no downs. Their wax skin is still flesh-colored. It changes color very quickly to a gray-pink with a pink base. The egg tooth falls off between the 6th and 7th day of life. The eyes are initially closed and only open between the 8th and 11th day of life.

From about the 14th day of life, the first downs appear on the back, which have a wave-shaped pattern. Depending on the color morph, this and the woolly-looking intermediate dress are pale brownish or greyish white and have dense brown, gray or rust-brown banding. It is relatively unusual that this transverse striation is followed by a longitudinally striated adult plumage. At around six weeks of age, the next moult begins, during which all feathers are changed except for tail feathers, wings and the large hand covers. The development of this dress is completed in just under five months. The young now look very similar to the adult birds, but can still be clearly distinguished up to the third calendar year on the basis of the large feathered moult.

Vocalizations

Tawny owls have a large repertoire of sounds, the individual calls of which vary greatly in volume and timbre. In contrast, tawny owls have very few instrumental sounds . The flight is noiseless. They only let a squeak be heard when they are aggressively aroused .

The typical call of the tawny owl is the elongated, howling "Huh-Huhuhu-Huuuh" uttered by the male, which is mainly heard during the courtship season. This call is followed by a stretched Huuuu after a short pause, followed by a kicked Hu and at the end of the verse a full-sounding roller two to three seconds long. The length and shape of the stanza depends on the state of excitement of the owl. The males, whose calls are individually so characteristic that they can be distinguished by them, call both sitting on a waiting and flying. The call repertoire of the male also includes a trilling wuwuwuwu ..., which can be heard especially when showing the nest cavity and immediately before mating.

The female gives a rough “Kuwitt”. This call is particularly common during courtship when males and females take turns calling. Also stone and Raufußkauz in their respective Rufrepertoires a "Kuwitt" ring. The Tawny Owl's “Kuwitt” is, however, sharper. This call can occasionally be heard from male tawny owls. With this call he indicates his location, but occasionally even lets him hear it in call duels with the female.

Young tawny owls that are still sitting in the nesting hole beg for food with soft “zigzigzick” calls. With increasing age, this call changes into a hoarse “Kszik” and even later into a “Pitjäh”, which then turns into the “Kuwitt” of the adult tawny owls via “Kewick” sounds.

distribution and habitat

Distribution map of the tawny owl (excluding the Himalayan tawny owl)

In the Palearctic, the tawny owl inhabits the deciduous and mixed forests of the temperate and Mediterranean zones up to the southern edge of the boreal coniferous forests. The distribution of the tawny owl is disjoint , it occurs in two spatially separated areas in Europe and East Asia. The western distribution area extends from Western Europe and northwest Africa to Iran and Western Siberia. The small eastern distribution area includes the Central Asian republics - except Turkmenistan - as well as Afghanistan and northern Pakistan. This is followed by an area that extends across the Himalayas to China and Korea and is populated by the closely related Himalayan tawny owl . This is sometimes still listed in the literature as a subspecies of the tawny owl.

The tawny owl is a bird of the lowlands in the colder regions of its range. In Scotland it breeds at altitudes up to 550 meters above sea level. In the Alps it occurs at altitudes of 1800 and in Turkey of 2350 meters. A subspecies that is now counted as part of the Himalayan tawny owl breeds in Burma at altitudes of 2,800 meters above sea level.

Tawny owls are distinct resident birds that do not leave their territory even in winter. Only the young migrate in different directions as soon as they have fledged. The dispersion period of the young birds coincides with the autumn mating of the tawny owls. During this time, the parent birds drive the offspring out of their territory. Most of the young tawny owls usually settle not far from the territory of the parent birds. The dispersion distances differ depending on the geographical location. While juvenile tawny owls in Switzerland or Germany disperse a median of 6 km, juvenile Finnish tawny owls cover a median of 17 km to their breeding area.

Although the tawny owl prefers old deciduous and mixed forests , it is also often found in coniferous forests and in the cultivated landscape . The tawny owl is generally very adaptable and, for example, breeds in rabbit caves in the dune landscape of the Netherlands with few trees. It also colonizes urban habitats . Tawny owls also breed in parks, cemeteries and in avenues and gardens with old trees. If it remains undisturbed, it also breeds in close proximity to humans. Therefore, breeding occurs relatively often in barns or in the chimneys of old houses.

nutrition

The tawny owl is predominantly nocturnal. He usually spends the day in protective cover, which he only leaves in the event of disturbance or extreme cold. Its activity phase begins around the time of twilight, when for most people color vision ends in the wild. The breeding area is usually integrated in the hunting area. The size of the hunting area varies depending on how rich in structure the area is, how numerous prey there are and whether a corresponding number of stand guard is available. The districts can therefore only be eight to twelve hectares in size, but also cover an area of ​​65 to 75 hectares. A tawny owl usually uses a territory once it has conquered for the rest of its life. Familiarity with the area is an essential prerequisite for surviving even with fluctuations in the populations of the most important prey animals.

The tawny owl beats mammals up to the size of squirrels .

The hunt usually takes place in an almost silent search flight along forest edges or paths as well as meadows and fields near the forest. If he hears the soft whistling of the mice, he usually reacts with an abrupt change of direction and flies in the direction of the sound source. If the flight hunt is unsuccessful, he usually flies to high seat guards, which give him an overview of areas of his hunting ground that are rich in prey. These raised hides are often only fifty to seventy centimeters above the ground. He remains in this hide waiting for up to an hour. During this time he often chokes out his vaults . High seat and flight hunting usually alternate several times during the night. The food requirement of a tawny owl is around 60 to 70 grams per day. That corresponds to about four field mice . The hunting season ends at dawn.

The food spectrum of the tawny owl is very broad. The composition depends on the respective range of prey. In good mouse years, the diet consists largely of voles and real mice . They can make up as much as 75 percent of the prey spectrum. The tawny owl can strike prey that corresponds to its body weight. He therefore also beats rabbits and squirrels . A British study showed that brown rats play a major role in the diet of tawny owls in the summer months . Birds make up an average of around 15 percent of its prey spectrum. For tawny owls that live in urban habitats, the proportion of birds in the diet is generally higher. Studies have shown that tawny owl populations living in the urban area of Berlin feed 70.7% on birds and 29.3% on small mammals and frogs. In exceptional cases, tawny owls live almost exclusively from bird hunting. During the flight hunt, tawny owls specifically seek out the mass sleeping places of small birds and cause them to fly up by suddenly clapping their wings. He grabs cave-breeding birds from the breeding cave with the help of his long legs. In Central Europe, up to 100 species of birds have been counted that are struck by the tawny owl. These include sparrows and finches , but also jays , pigeons and magpies . In addition, however, practically all animals of suitable size in the respective habitat are eaten, including shrews , frogs , fish , beetles and earthworms . The tawny owl locates earthworms mainly acoustically by remaining motionless in one place for up to ten minutes. If the worms leave their tunnels, it grabs them with its beak and pulls them completely out of their tunnels.

If the tawny owl has captured a mouse, it first kneads it between the catches and then devours it head first. Larger prey and the food for the nestlings are shredded. If the food becomes jammed in the throat when it is swallowed, it is taken out again with one of the catches.

Tomb of a tawny owl

Reproduction

Pair formation and courtship

Tawny owls are usually sexually mature in the reproductive period following hatching. They mate for life and are basically monogamous birds. If a partner is lost, the surviving bird remains in the breeding area regardless of gender and mates with one of the tawny owls that roam around without direction. A couple's territory is defended by the couple all year round. Its boundaries hardly change over the years.

The pair bond loosens after the young have been reared, and from June to October the tawny owls spend the day in different resting places. The first courtship phase in October and November, which is often referred to as mock or autumn courtship, is used to find the partners of an already existing pair or to find a new partner if one of the pair's birds has died. The beginning of this courtship phase can be recognized by the increasing calls of the tawny owls. As the pair bond increases, the tawny owls seek out daily dwellings that are closer together and occasionally rest in the same place of the day.

The calls subside in December and pick up again from January. In March, the courtship reaches its second peak, when the singing of the tawny owls can be heard almost every evening. The owls usually call alternately. The calls end when the partners meet at a common meeting point. In the first few days the owls avoid touching each other and repel their partner with screeching noises and hissing. Increasingly, they tolerate being close to each other and occasionally scratch each other's head and neck plumage. The call duels end when the male begins to prey on the female.

Nesting place and clutch

Egg ( Museum Wiesbaden Collection )

The choice of nesting place begins in the time of the Hochbalz and continues until the time of copulation . According to the observations of the ornithologist Manfred Melde , the male chooses suitable nesting holes and, clinging to the edge of the nesting hole, calls out to the female, flapping its wings. The final choice of nest cavity is made by the female.

When nesting is mostly tree holes, sometimes rock niches and old crows and birds of prey nests . Suitable breeding sites in buildings or artificial nesting holes are also accepted. As soon as the female has decided on a breeding cave, she begins to clean it and remove any nesting material that may have been brought in by starlings or squirrels. Tawny owls lay their eggs directly on the floor of the breeding cave. The female no longer hunts before laying her eggs. It is supplied with food by the male. The male announces himself by shouting, whereupon the female flies towards him and takes over the prey.

In the southern distribution area tawny owls begin to breed from February. In Central Europe they usually breed from March. Tawny owls that breed in urban areas start their breeding business up to a month earlier; Occasional “winter broods” between November and January, ie directly after the autumn balz, are also occupied. The clutch usually consists of two to four eggs. However, clutches can have just one egg or up to seven eggs. The eggs are elliptical to spindle-shaped and measure an average of 46.7 by 39.1 millimeters. Their skin is smooth and has a slight sheen. Occasionally the shell has small nodules or longitudinal grooves. Eggs are usually laid at night. The laying interval is between two and four days. Tawny owls only raise one brood each year. If there is a loss of clutch, however, there is lag.

Rearing the young birds

Three young tawny owls

The average incubation period is 28 to 30 days. The female breeds alone. The young hatch at the intervals at which the egg was laid. The hatching process usually takes one, rarely two days. Newly hatched tawny owls weigh an average of around 28 grams and are completely blind during the first nine days of life. The female parent bird herds the young for the first ten days and feeds the young with small parts of the prey. The feeding method differs significantly from that of the birds of prey . The fledglings are fed during their days of life while sitting under the female parent bird's belly. The female lowers her head, but remains seated on the young.

The males and from the tenth day of life also the females bring very large amounts of food during the nestling days. These are placed around the nest cavity. Especially in the first days of nestling, when the young birds are not yet eating very much, the amount of feed can far exceed the requirement. There is known a case in which four Jungkäuze mice in a rich year in their nest cavity in a layer of 38 mice field and a tit sat.

The young birds leave the breeding cave between 29 and 35 days old. When jumping out of the cave, many tawny owls fall to the ground. They then try to get to a scrub or a thick-barked tree that they can climb up. As so-called branchlings , they are looked after by the parent birds there. At around 50 days of age, they are able to follow the female parent bird 40 to 50 meters in flight. From around 70 days they fly around the nest box within a radius of 200 meters. They are cared for by the old owls until they are around 100 days old. In the fourth month of life, the distance from the breeding site increases. Your wanderings are undirected. Most of the tawny owls ringed in the first months of life are found at a distance of 20 kilometers.

Defense of the young birds

The adult birds rigorously defend their nesting holes and branches. They also attack people who come too close to the boys. Living beings perceived as troublemakers are usually attacked from behind without warning in a silent direct flight. In humans, the owl grazes the head and shoulder area with its wings and claws. The attacks only end when the disturber moves away from the narrower territorial area. The attacks can lead to bleeding flesh wounds. One of the best-known victims of a tawny owl attack is the British nature photographer Eric Hosking , who was so violently attacked by tawny owls while taking pictures near the nesting hole that he lost an eye.

Causes of mortality

The eagle owl is one of the predators that also beat tawny owls .

The tawny owl's predators include other species of owl such as the Ural owl and eagle owl, as well as birds of prey such as the goshawk and buzzard . Pine marten occasionally raid nests and some cases have been reported of jackdaws building their nests on a brooding forest chew, resulting in their deaths and those of the young. According to the results of a Danish study, the red fox is also an important predator of the tawny owl, which mainly prey on branchlings. 36 percent of the branches die before they can fly. The mortality rate is subject to seasonal fluctuations: Of 100 young tawny owls that leave their breeding cave in April, 86 survive the phase until they become independent. In contrast, out of 100 tawny owls that leave their nest box in June, only 42 survive this development phase. Adult birds show an increased mortality rate in April and May, which is probably related to the increased activity and the stressful foraging for the adolescent boys. Out of 100 two-year-old owls only 55 reach the next year of life. The highest age that has been determined so far for a wild owl ringed as a branchling was 18 years and eight months. The oldest wild tawny owl in Switzerland was, as evidenced by a ring find, even 21 years and 11 months, certainly an exception. A tawny owl kept in captivity reached an age of 22 years.

Duration

The range of the tawny owl covers at least 10 million square kilometers. Large-area surveys of this kind are methodologically difficult; for the stocks of larger areas there are only rough estimates. According to the IUCN, the European population in 2006 comprised around 500,000 to 1,000,000 breeding pairs. The Tawny Owl is not endangered in its population. It is also assumed that stocks have remained stable over the past three decades. Large populations are found in France (100,000 breeding pairs), Spain (530,000 breeding pairs), Russia (100,000 breeding pairs) and Poland (70,000 breeding pairs). The population in Germany is estimated at around 64,000 breeding pairs. The tawny owl has expanded its range in Belgium , the Netherlands, Norway and the Ukraine . Declines have been observed in Finland , Estonia , Italy and Albania .

Systematics

The tawny owl was first scientifically described in 1758 by Carl von Linné in his Systema naturae . The species still bears the scientific name it was given back then. The tawny owl belongs to the genus Strix , which in turn belongs to the family Strigidae . Except for the barn owls, this family includes all of the owls in the world.

The closest relatives of the tawny owl are the Ural owl, the North American barred owl and the omaniac owl . The oman owl, which inhabits the mountainous and desert regions of the Arabian Peninsula and Sinai , was for a time considered to be conspecific with the tawny owl. In the old to Middle Pleistocene occurring Strix intermedia is classified sometimes as a direct ancestor of the tawny owl.

Between 10 and 15 different subspecies have been described for the tawny owl . Today, eleven subspecies are generally recognized, three of which are included in recent literature as the Himalayan tawny owl (Strix nivicola).

This tawny owl is probably a member of the subspecies S. a. sylvatica
subspecies

(Parenthesized subspecies are subspecies of the Himalayan tawny owl.)

First description by (Authors in brackets indicate that the subspecies was initially assigned to a different genus.) Distribution area Mark
S. a. aluco Linnaeus , 1758 Northern and Central Europe from Scandinavia to the Mediterranean and the Black Sea brown to gray nominate form
S. a. sylvatica Shaw , 1809 Western Europe including Great Britain more roughly drawn as nominate form
( S. a. Nivicola ) ( Blyth , 1845) Nepal to southeast China , northern Burma and Thailand Himalayan tawny owl Strix nivicola ; on top only spotty (not dashed), two light wing bands, broadly banded umbrella feathers and a distinctive white spot on the front breast
S. a. biddulphi ( Scully , 1881) Northwest India and Pakistan especially in gray morphology
S. a. willkonskii ( Menzbier , 1896) Palestine to Northern Iran and the Caucasus with a coffee-brown morph
S. a. mauritanica ( Witherby , 1905) Northwest Africa from Morocco to Tunisia and Mauritania Wingspan 20% larger than the nominate shape
S. a. sanctinicolai ( Zarudny , 1905) Western Iran and Northeast Iraq bright desert shape
( S. a. Ma ) ( HL Clark , 1907) Northeast China and Korea light form of the Himalayan owl
S. a. harmsi ( Zarudny , 1911) Turkmenistan especially in gray morphology
S. a. siberiae Dementiev , 1933 Central Russia from the Urals to Western Siberia bigger, brighter and with a lot of white
( S. a. Yamadae ) Yamashina , 1936 Taiwan dark form of the Himalayan tawny owl

Human and Tawny Owl

Nest box suitable for tawny owls.

Tawny owls are relatively seldom observed by humans because of their nocturnal and crepuscular life. The long drawn-out reputation, on the other hand, is known to many people, as it is often used in films to underline a nighttime mood. William Shakespeare already quoted the characteristic call in Act 5, Scene 2 of Lost Love Labor:

“Then nightly sings the staring owl, Tu-whit; Tu-who, a merry note, While greasy Joan doth keel the pot "

The calls described by Shakespeare are, however, the duet of a pair of tawny owls. The female calls “Kuwitt” and the male answers with “Hu”. The call of the female, which can also be heard similarly from the little owl and the rough owl , is interpreted in popular superstition as “Come with me!” Of the unloved “bird of the dead”.

NABU and LBV voted the tawny owl as bird of the year 2017. The species was chosen to represent all owl species in order to promote the preservation of old trees with caves in the forest or in parks and to create a broader public for the needs of cave-dwelling animals.

swell

literature

Web links

Commons : Tawny Owl  - Collection of images, videos and audio files
Wiktionary: Tawny Owl  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ a b Heintzenberg, p. 42.
  2. ↑ a b Bezzel, p. 312.
  3. ↑ The Tawny Owl as Bird of the Year 2017 on the website of the Naturschutzbund Germany (accessed on January 11, 2017)
  4. ↑ a b c d Mebs et al., P. 226.
  5. ↑ Melde, p. 11.
  6. ↑ Report, p. 6.
  7. ↑ Report, p. 9.
  8. ^ A b c d Karel H. Voous, Ad Cameron (Illustrator): Owls of the Northern Hemisphere . Collins, London 1988, ISBN 0-00-219493-7 , pp. 209-219 .
  9. ↑ Carl Bergmann: About the relationship between the heat economy of animals and their size . In: Göttingen Studies . tape 3 , no. 1 , 1847, p. 595-708 .
  10. ↑ Jon E. Brommer, Ahola Kari, Teuvo Karstinen: The color of fitness: plumage coloration and lifetime reproductive success in the tawny owl . In: Proceedings - Royal Society of London. Biological sciences . tape 272 , no. 1566 , 2005, pp. 935-940 , doi : 10.1098 / rspb.2005.3052 , PMC 1564093 (free full text).
  11. ↑ Paolo Galeotti, Roberto Sacchi: Differential parasitaemia in the tawny owl (Strix aluco): effects of color morph and habitat . In: Journal of Zoology . tape 261 , 2003, p. 91-99 , doi : 10.1017 / S0952836903003960 .
  12. ↑ a b Heintzenberg, p. 43.
  13. ↑ a b c Melde, p. 77.
  14. ↑ Melde, p. 78.
  15. ↑ Kevin Baker: Identification Guide to European Non-Passerines. In: BTO Guide 24 , 1993, pp. 284-287
  16. ↑ a b c d e Hans-Heiner Bergmann, Hans-Wolfgang Helb, Sabine Baumann: The voices of the birds of Europe - 474 bird portraits with 914 calls and chants on 2,200 sonograms. Aula-Verlag, Wiesbaden 2008, ISBN 978-3-89104-710-1 , p. 309 and p. 310.
  17. ↑ Melde, p. 14.
  18. ↑ Melde, p. 16.
  19. ^ Strix aluco . BirdLife International , accessed March 1, 2016 .
  20. ↑ Mebs et al., P. 227.
  21. ^ Adrian Aebischer: Tawny Owl Strix aluco. In: Owls and Owls. 2008, p. 213.
  22. ↑ Mebs et al., P. 228.
  23. ↑ a b c d e David Snow, Christopher M. Perrins (eds.): The Birds of the Western Palearctic concise edition (2 volumes) . Oxford University Press, Oxford 1998, ISBN 0-19-854099-X , pp. 907-910 .
  24. ↑ a b c Heintzenberg, p. 45.
  25. ^ Dani Studler: Distances and directions of dispersing Tawny Owls (Strix aluco) in Europe from 1910 to 2015. In: Dispersion des Waldkauzes , 2017, pp. 33–37.
  26. ↑ a b c d Heintzenberg, p. 44.
  27. ↑ Melde, p. 17.
  28. ↑ Melde, p. 53.
  29. ↑ Melde, p. 21.
  30. ↑ Melde, p. 19.
  31. ↑ Bezzel, p. 315.
  32. ↑ Bezzel, p. 314.
  33. ↑ Victor Wendland: 14-year-old observations on the reproduction of the tawny owl. In: Journal of Ornithology. Vol. 13, No. 3, 1972.
  34. ↑ Melde, p. 20 and p. 21.
  35. ↑ Melde, p. 18.
  36. ↑ Melde, p. 51.
  37. ↑ a b Melde, p. 54.
  38. ↑ Melde, p. 56 and p. 57.
  39. ↑ Melde, p. 58 and p. 59.
  40. ↑ a b c d e Heintzenberg, p. 47.
  41. ↑ a b c d e f Collin Harrison, Peter Castell: Field Guide Bird Nests, Eggs and Nestlings. revised edition. HarperCollins Publisher, 2002, ISBN 0-00-713039-2 , p. 198.
  42. ↑ Melde, p. 59.
  43. ↑ Melde, p. 65.
  44. ↑ Mebs et al. P. 239
  45. ↑ Melde, p. 68.
  46. ↑ Melde, p. 71.
  47. ↑ a b Melde, p. 72.
  48. ↑ Eric Hosking, Frank W. Lane: An Eye for a Bird: The Autobiography of a Bird Photographer . Hutchinson & Co., London 1972, ISBN 0-09-104460-X , pp. 20 .
  49. ↑ Peter Sunde: Predators control post-fledging mortality in tawny owls, Strix aluco . In: Oikos . tape 110 , no. 3 , September 2005, pp. 461-472, , doi : 10.1111 / j.0030-1299.2005.14069.x .
  50. ↑ a b c Melde, p. 86.
  51. ↑ http://www.strixaluco.ch/ - Population study in the southern Zürcher Weinland - Switzerland
  52. ↑ D. Jánossy: The Middle Pleistocene bird fauna of the Stránská skála. In: R. Musil (ed.): Stránská skála I. Anthropos (Brno), 20, 1972, pp. 35-64.
  53. ↑ Handbook of the Birds of the World Alive, Strix nivicolum ( Online , accessed March 1, 2016)
  54. ↑ NABU press release. Environment / Bird of the Year. NABU and LBV: Tawny Owl is Bird of the Year 2017. Caves wanted for the silent hunter of the night. October 13, 2016