Sprout
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Sprout ( Luscinia luscinia ) at a ring in Hungary |
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| Luscinia luscinia | ||||||||||||
| ( Linnaeus , 1758) |
The sprout ( Luscinia luscinia ) is a songbird from the flycatcher family . It is the north-eastern sister species of the nightingale and very similar to it. Its distribution area borders on that of the nightingale. In Europe, it replaces them in the north and east, with the distribution limit running diagonally through Central Europe. In northern and eastern Germany there is a narrow area of overlap in which both species occur and also reproduce together. However, only the male offspring of such compounds are capable of reproduction. The sprout is a long-distance migrant that overwinters in the southern part of Africa. The European populations are loop pullers .
Naming
Presumably the name of the sprout comes from sprout in the sense of spot, skin spot (e.g. in "freckle") and can be traced back to the clouded to spotted chest markings of the sprout. Since both the nightingale and the sprout were popular as cage birds in previous centuries, the eponymous reference to this feature, which is often barely recognizable when observing in the field, is understandable.
In other languages, the name of the scion shows the close relationship to the nightingale, e.g. B. English thrush nightingale (= "thrush nightingale") or Dutch Noordse Nachtegaal (= "Nordic nightingale"). In the Nordic languages, e.g. B. in Swedish, it is the other way around, here the scion is the Näktergal , while the German "Nachtigall" is the Sydnäktergal (= "Südnachtigall"). The French names rossignol philomèle (nightingale) and rossignol progné (sprout) draws on Greek mythology to express the relationship between the two species: Philomela and Progne are two sisters who are transformed into nightingales (or nightingale and swallow).
description
Appearance
The sprout is very similar to the nightingale. It is colored reddish to olive brown on top, the wing and tail feathers are dark reddish brown. Overall, the scion is a bit darker and less colorful than the nightingale. The underside is beige to cream-colored and, in contrast to the nightingale, clearly darkly cloudy or even slightly speckled in the breast area. The under tail-coverts are slightly darkly spotted or banded, those of the nightingale are monochrome light. The dark eye has a light edge. The beak is slightly more compact than that of the nightingale, dark brown and slightly lighter on the underside. The feet are light brown.
The shoot is about 16-17 cm long and weighs on average about 22-27 g (well-fed birds before the migration up to 34 g). The wing length averages about 90 mm (81–98 mm), the average tail length 70 mm (63–76 mm). There is hardly any difference between males and females, and even determination based on measurements and weight is not always clear. In the case of specimens with extreme dimensions, however, a clear allocation can be assumed: a wing length over 91 mm is a male with relative certainty, and a wing length less than 85 mm is a female.
In the field, the sprout can hardly be distinguished from the nightingale. A sure feature, which can only be checked in the case of ringings or dead finds, is the length of the 10th, outer hand swing . In some families of songbirds, including the flycatcher, this is greatly reduced. In the sprout it does not extend beyond the outer hand covers, in the nightingale it is longer than this.
The species shows no significant geographic variation, subspecies are not described.
Youth apparel and moult
The downs of the nestlings are blackish, their locking throats are intensely yellow to orange, the edges of the beak are yellowish. The small plumage and wing feathers grow by the 35th day, the thrust is fully grown on the 40th day.
The juvenile dress is spotted like a thrush and very similar to that of the robin , but the distinctive distinguishing feature from the latter is, in addition to the typical proportions, the reddish tail. The head plumage has beige to ocher colored tips that form teardrop-shaped spots and are clearly separated from each other by the dark feathers. The underside of the head, chest and belly are similarly spotted like scales, but overall beige to light gray. In contrast to the nightingale, the clouding of the chest remains in adult birds, but is usually much more washed out than in juvenile plumage. Like the head feathers, the dorsal plumage shows the beginnings of light-colored edges, the upper wing coverts show very clear spots at the tips. The rest of the plumage, wings, rear back and belly area and the thrust are already colored like the adult bird.
The juvenile moult is a partial moult in which only the small plumage is changed; Hand covers and a part of the arm covers are preserved like the large plumage. The juvenile moult begins a few days after the large plumage has finished growing at around one month of age and takes about 20 days. The moulting occurs earlier and almost twice as fast as the nightingale, as the time from leaving the nest to moving away is much shorter. In Central Europe, the moulting season falls around the middle of July. The fully grown bird in the first year (autumn / spring) retains the pale speckles of the juvenile dress on the upper wing coverts due to the partial moult. However, due to wear and tear, this feature can become less pronounced in spring, making it more difficult to distinguish it from adult birds.
The age dress no longer shows any staining of the wing covers. As with the nightingale, a distinction can be made between three clothes according to age: the youth dress, that of the annual birds and that of the adult birds from the second year.
behavior
On the ground the sprout moves like a thrush hopping and a little more sedate than the nightingale. While this often puts the tail upright when it pauses and when excited, the sprout often moves it to the side, turning it obliquely , as is typical for stranglers . The wings are usually raised slightly. If the tail is bobbed up and down in excitement, in contrast to the nightingale, the strongly slowed final upward movement is missing. In arousal or threatening pose, e.g. B. in territorial disputes, the tail is fanned out vertically.
When singing, the male sits upright with a sloping tail, usually in a waiting area that is not too high and is sometimes open. At times of the formation of the territory, when the territory is defended with loud singing, the sprout often almost loses its fear of humans.
The flight is fast, easy and fluttering on the final approach. Most of the time, only short stretches of open terrain are flown over straight, without sharp changes of direction, whereupon the bird immediately takes cover again. Resting and sleeping places are usually in close cover within bushes. The sprout likes to bathe extensively, often in the evening hours.
voice
Reviergesang
The territory song of the males is very similar to that of the nightingale. It is also often performed at night and, due to its volume, can be heard up to a kilometer away under favorable conditions. Like the nightingale, it is very melodic, varied and powerful. The singing is clearly divided into stanzas, z. T. are separated from each other by short pauses. These consist of individual elements, which are usually simply repeated and sometimes slightly changed in the course of the stanza. The sprout usually repeats these elements more often (about 4 to 10 times) than the nightingale (usually only 2 to 3 times). The stanzas are therefore often longer than in the nightingale, the individual elements are performed more slowly and often - as in the song thrush - clearly separated from each other.
Various authors from the 19th century tried to imitate the lyrics of the song and used names such as David , Fillip , Judith or Jakob (e.g. David David David David David ... ) for some phrases , which is particularly important for the clearly separated, describes song thrush-like rows well.
The sprout generally lacks the "sob strophe" typical of nightingales, a series of fluting sounds that increase in power in a slow and then faster crescendo . For this purpose, stringed, pipe-singer-like snarling sounds are woven into the singing with noticeable regularity, often described as a "Schnatter phrase". The particularly loud rows of "Tschuck", "Tschjock" or "Tschjack" sounds are called "castanets phrase". Overall, the Sprossergesang lacks the sounds of the nightingale, which are often referred to as "plaintive" or "melting".
Day and night singing can vary in stanza length and the length of the intervals between stanzas. At night, the elements within the stanzas are often repeated more frequently and faster in succession, the stanzas also follow one another in faster succession.
"Mixed singer"
The song is usually the best way to distinguish it from the nightingale. Here the bird watcher has the difficulty that there are also "mixed singers" in the overlapping area of the two areas of distribution (often referred to as "two sounders" in older literature) who have the singing characteristics of both species. These mixed singers are - as far as could be clearly determined - mostly sprouts.
Singing activity
Singing activity varies greatly; in areas with high population densities, the stronger stimulation from neighbors can lead to a sharp increase in the frequency of singing, up to and including uninterrupted singing. Males without females also sing more often and more intensely. Males who sing throughout the night are generally less audible during the day, while males who stop singing towards the middle of the night also sing frequently and for a long time during the day.
Courtship song
The courtship song, which is usually performed when the females arrive after the formation of the territory has been completed, is quieter, but also faster and livelier with shorter interruptions. It can usually be heard in the morning. Occasionally the female will also respond with a short vocal motif. The female does not hear any noticeable singing.
Calls
The most frequent alarm call is sharp, rough and piercing and a little drawn, similar to the "Hüit" of the nightingale, but less ascending and harder, so more of a sharp "Fiet", similar to the corresponding call of the chaffinch, but not quite as short and metallic . This call can also be given in urgent rows in the event of excitement, for example a danger in the vicinity of the nest. Also when you are excited you can hear a strong, gruff “Chrrrrr” or “Krr” and a short “Dak”, which are somewhat reminiscent of the sounds of the black redstart . As with the latter ("huit-tek"), these are often attached to the brief alarm call described above.
distribution
The breeding area of the sprout extends from Eastern and Northern Europe to Central Asia. It is mostly in the temperate and continental climatic zone and extends into the boreal coniferous forest.
The western limit of distribution runs through southern Norway , northern Jutland and the Danish islands , through northern and eastern Germany, north-eastern Hungary , the Bulgarian and Romanian Danube lowlands to the Danube Delta .
In Northern Europe, its distribution extends to a line that runs between the 62nd and 65th degrees of north latitude, in Northern Asia it follows about 60 ° N. In the east, the area goes to Krasnoyarsk , on the western foothills of the Altai southwards, along 50 ° N through Kazakhstan, along the southern Urals to the northern edge of the Sea of Azov and the mouths of the Dnieper and Dniester to the Danube Delta.
hikes
The sprout winters in eastern Africa south of the Sahara. According to the IUCN , it is found there in an area of 3.9 million km². It can often be found from southern Ethiopia , in the eastern parts of Kenya and Tanzania , in most of Zambia , in southern Malawi and in Zimbabwe . But it also occurs as far as eastern Namibia and in northern South Africa to the Transvaal .
European sprouts pull loops and move south across the eastern Mediterranean, Asia Minor and the extreme east of the African continent. The Finnish populations move almost exactly to the south, those of the western Baltic Sea region more towards the south-southeast. The withdrawal takes place - as ring finds show - on a route further to the east. While the Balkan Peninsula is widely flown over on the approach, it is mostly only touched to the east on the retreat.
The birds from the Siberian populations migrate to their winter quarters via Iran and the Arabian Peninsula.
External system
The sprout is the north-eastern, monotypical sister species of the nightingale. Its distribution area is complementary to that of the nightingale, whose European nominate form replaces the sprout in southern and western Europe. In Asia, the distribution areas of the two nightingale subspecies africana and hafizi border the area of the sprout to the south. Presumably, the two species originated from allopatric speciation due to geographical isolation during the last ice age. In Central Europe, both species show an approx. 60–100 km wide overlap zone, which in Germany runs roughly along the ice margins of the last Ice Age and which probably arose during the postglacial expansion.
Although the species pair is repeatedly cited as a prime example, this is not uncommon. Haffer (1989) places the two species in a group with about 80 closely related pairs of species in Eurasia, which occur parapatric and show neighboring or slightly overlapping areas of distribution.
In the described overlap zone, the two species occur in the same habitat with slightly different preferences. The breeding area is not only defended against individuals of its own, but also against the other species. At breeding sites that are suitable for both species, the wetter locations are evidently first colonized by the sprout before it also moves into other areas, including those near the settlement. There is also joint reproduction, but with limited success: only the males are capable of reproduction.
Since both species were badly decimated in previous centuries and the spread and decline tendencies in the jointly populated area do not provide an absolutely clear picture, it is controversial whether the sprout displaces the nightingale, which has been claimed by some authors. Among other things, the occurrence of the nightingale is essentially limited by its susceptibility to cooler climates to the north.
habitat
From a large-scale perspective, the sprout, like the nightingale, is almost exclusively a breeding bird in the river plains. It can also be found in suitable places outside the latter, but then mostly in much lower settlement densities.
It prefers moist hardwood locations on fertile soils. In contrast to the nightingale, which also inhabits light forests with a lush layer of shrubbery, the sprout seems to avoid larger forests. He prefers more fragmented, small-scale or mosaic-like forest structures such as field trees, shrub islands in low moor areas or river banks rich in trees and bushes.
Decisive for the choice of the habitat are light-poor thickets with up to 100% foliage cover, which lack a layer of herbs so that the sprout can find its food on the ground. However, these should alternate with more open areas overgrown by a dense herbaceous layer of perennials or young shrubs, which offer suitable nest locations and where the chanting of the territory can be heard from far and wide.
Often the nightingale is found in riparian willow trees, but also in the peripheral areas of alder swamps or by willow, alder or ash saplings scrubby silting areas and fen meadows . On Hiddensee, the sprout colonizes the sea buckthorn thickets, which are common there and mixed with hawthorn and elder , and has high population densities there.
Most populated trees are 3 to 13 m high, 13 to 17 year old poles. Studies in Finland have shown that woody plants seem to be suitable for sprouts only in a certain phase of succession . If the trees reach a height of about 3 m or more, the habitats are well accepted by the sprout, the greatest settlement densities are reached at a height of 8–12 m, habitats with taller or fully grown trees are mostly abandoned over time. The breeding success also seems to be closely related to the height of the trees.
The sprout often breeds near water. In many cases, nests were found 50–100 m away from bodies of water or running water. However, proximity to water does not seem to be a mandatory criterion for the choice of breeding site. If no acceptable habitat can be found near water, the breeding areas can also be located far away from it. The reason for the frequent proximity of water to nesting sites is therefore probably the fact that suitable habitats are often near water anyway.
Settlement density
The sprout likes to settle in groups, the district locations are about 50–100 m apart. Wherever it settles in groups, the populations are usually more stable than elsewhere, where the settlement densities obviously fluctuate depending on the weather conditions during the phase of territorial occupation.
In less suitable habitats such as parks or moist coniferous forests, the settlement densities are low (usually well below 4 breeding pairs per 10 ha), in alder forests and field trees they are between 4 and 12 bp./10 ha, depending on suitability (see habitat). On very good ones Locations (e.g. bushy moorland and river edges), settlement densities of up to 16 bp / 10 ha can be achieved.
food
The sprout looks for most of its food on the ground or the lower herbaceous layer. In the other cases it is collected from branches and twigs, from the lower regions of the shrub layer or, less often, from the air in high leaps. It consists mainly of arthropods . For the most part (75–95%) these are insects , but also woodlice ( Isopoda ), double-pods ( Diplopoda ) and arachnids ( Araneida ). It is noticeable that unlike the nightingale, earthworms apparently hardly play a role.
Adult birds feed to a large extent on small beetles (mainly weevils ) and ants as well as earwigs and bedbugs . Smaller animals such as dust lice and plant lice are also read from branches and leaves. Locusts , cicadas or dragonflies are less common prey. The nestlings are usually fed larger, but softer food with a low chitin content . Again, the insects predominate, especially beetle larvae, butterfly caterpillars ( Lepidoptera ) and small flies. The proportion of other arthropods is usually higher than that of adult birds because of the isopods and arachnids that are often fed.
In late summer and autumn, berries (e.g. blackberries and currants ) and other fruits (e.g. elderberries , mulberries , buckthorn or dogwood ) expand the food spectrum.
Reproduction
The sprout leads a monogamous seasonal marriage. There is only one annual brood. Mating or second broods were not detected. These are also rather unlikely due to the short breeding season.
Arrival and formation of the territory
The males begin to sing in the wintering areas from around February, and they retreat around March. Overall, the migration times for the sprout are similar to those of the nightingale, but it usually arrives a little more than a week later than this and also moves back to the winter quarters earlier, so that the breeding period for the sprout is overall shorter than that of the nightingale.
In Germany, the arrival time in the breeding area is around early to mid-May. First the older males arrive at the breeding grounds and occupy their territories. The loyalty to the location is very high in the Sprossermännchen, so the territories of the previous year are often re-occupied. If their nature no longer corresponds to the living space requirements, e.g. B. through the natural development of the colonized woody plants (see habitat), a new breeding ground is sought. The establishment of the territory can therefore take up to two weeks.
The one-year-old males follow a little later, but these often do not breed or try unsuccessfully to colonize an area, so that the proportion of annual birds in the breeding population is usually low (approx. 10%).
Due to cold weather or a lack of stimulation from rivals, the chant of the territory can sometimes only be heard a few days after arrival and sometimes even then quite hesitantly, so that the first arrival is probably often registered later than it actually takes place.
Pair formation and courtship
The females arrive about up to a week, sometimes up to 10 days later. Around this time, the males begin to hear the loud, far-reaching territorial song, which the females use to orient themselves when looking for the breeding grounds. In contrast to the males, the females are not very faithful to their location. The pairs usually get together for one breeding season. Nothing is known about mating, probably because of the short breeding season these do not take place. Also cases of polygyny , e.g. B. the mating of a male with several females are not documented for this species.
An arriving female is immediately courted by the male with courtship singing and accompanied in the search for food at a short distance. The male flies to surrounding branches and mates with rapid wings and constant fanning, lifting and folding of the reddish tail. It often adopts a pose in which it stands up conspicuously with its rear body almost upside down. On the ground, the female is then balled around with stiff steps and hanging wings about half a meter away, with the tail - also hanging down - being dragged over the ground. After half a lap the male changes direction, every now and then jumping around the female several times in a high arc. If the female tries to move away, the male pursues it with courtship singing or soft calls and flies around it. After pair formation, the female follows the male and shows possible nesting sites with spread wings.
If the pair bond becomes closer, the courtship singing can no longer be heard - instead, soft contact sounds ("tack") appear, the couple stays close to each other during the day and sleeps in close proximity to each other.
Nest building
The 10–15 cm wide nest is built exclusively by the female. It is usually erected on or near the ground; either at the foot of trees or bushes, in brushwood heaps or in the herb layer, e.g. B. in the protection of blackberries , dog roses , meadowsweet , ground grass , nettles or wood anemones . If the nest is on the ground, a 6–8 cm wide, not very deep nest hollow is often created. Nests were found very rarely between branches at a height of 1 or more meters. From the outside, the nest is held together by a thin layer of stalks or twigs, otherwise it usually consists of the leaves of the surrounding trees ( alder , birch , willow or poplar ) and is lined with soft material such as fine stalks, roots or animal hair. Occasionally the nest consists of just one material, such as B. in one case from previous year's alder leaves or in another from reed leaves , which became finer and finer towards the inside. Sometimes the nest is camouflaged from above with some dry leaves. The nest building takes about four, less often up to seven days. It can be delayed if a nest has to be dug first.
Clutch and incubation
In Central Europe, oviposition begins about two weeks after the nightingale, begins in mid-May and reaches its peak at the end of May. The clutch consists of 4–6, more rarely 3 eggs, which are quite variable in shape and olive green or brown. Mostly there is no spot. Occasionally there is a thick, brown cloud and black dashes at the obtuse end. They are on average 22 × 17 mm in size and weigh about 13.8 g when fully weighted. In contrast to those of the nightingale, they are slightly heavier and darker in color.
Incubation begins when the penultimate or last egg is laid and takes about 13 to 14 days. Incubation may begin more often than with the nightingale with the penultimate egg, which would result in a shorter incubation period. The incubation - and later the huddling - is done exclusively by the female, which - unlike the nightingale - is hardly fed by the male. In short breeding breaks, the length of which is between two minutes and a quarter of an hour, it looks for some food near the nest. During this phase, the male continues to let his territory singing, but is less exposed than before the start of breeding.
Rearing boys
The young are huddled exclusively by the female who looks for food in the breaks in between. The feeding of the young is initially done by the male, but it often happens that it first gives the food to the female. From about the second day onwards, the female also takes part in the search for food.
Most of the mornings are played. If the length of the humping phases up to the third or fourth day is between 1 and 39 minutes (average 10.4 minutes), it is greatly reduced when the young develop the first fletching. In one brood, for example, on the 6th day, an average of 4.8 minutes was hovered, in another brood only at night from the fourth day.
The nestling period is usually between 10 and 11, less often 12 days. If necessary, the young birds leave the nest sooner in case of danger; in bad weather this can be delayed for a few days. After flying out, the young are fed for about 2 to 3 weeks.
Inventory development
Due to the attention that the scion received as a cage bird, the development of the population can be traced back to previous centuries. Sprout and nightingale were caught in such quantities because of their song that entire populations were probably wiped out or at least severely decimated. A bird dealer operating across Europe in 1877, for example, had bird catchers under contract in 53 locations, which enabled him to sell 800–1000 nightingales and sprouts annually. Contemporaries have already noticed that such overexploitation was not without consequences, they complained about falling catch numbers or the declining quality of the chants, since in the thinned populations the singing males could hardly learn from one another or stimulate one another.
As early as the 13th century, restrictions were issued against catching, and from the 15th century there were the first fishing and trade bans. In some cases, a “ nightingale tax” was levied as a restrictive measure , and this was in place until the end of the 19th century.
In the case of sprouts, bird trapping in combination with a decline in habitat led to strong declines, particularly at the western limit of distribution. Extensive holdings in the Pannonian lowlands , the Austrian Danube floodplains , on the Tisza , in South Moravia and westwards to the Elbe near Magdeburg were extinct by the first decade of the 20th century at the latest.
It wasn't until the 1920s that the trend slowly began to reverse. In Northern Europe, where there was presumably declines due to intensive forest grazing in the 19th century, there was an increase in population and an expansion of the area in the 1960s-1980s. A little later, in the 1970s, this trend began in Poland, and since the 1990s it has also started to spread in East Germany, where breeding season observations have repeatedly been made in places relatively far away from closed settlement.
Today the European population seems to be quite stable with 3.7–6.9 million breeding pairs, and the species is not listed in any endangerment category.
Historical
In the past centuries a whole culture of connoisseurs and lovers developed around the singing of the nightingale and the sprout. In addition to the emphasis on other species, a distinction was made between “good” and “bad” singers within the genus and species. Nightingales and sprouts from certain regions or habitats were preferred as “housebirds”, which in some cases led to a lively trade among keepers throughout Europe, as bird lovers wanted to get into possession of particularly good “bat”.
The quality characteristics are very subjective, even if they are sometimes argued or written about with pseudo-scientific arguments or academic vehemence. JF Naumann , for example, describes the offspring of the Pomeranian Baltic coast as the worst singers, but praises those from the Wörlitz area on the Middle Elbe as the best. “Donausprosser” were particularly popular, which led to the occurrence there being extinct in the second half of the 19th century, although fishing around Vienna was prohibited as early as 1830.
Initially, the naming did not differentiate between the species, but the "nightingales" mainly according to habitat as z. B. named "Mountain" or "Forest Nightingales". Over time, a species classification emerges in which the sprout is referred to as "water" or "Auennachtigall". This - it was speculated - would sing particularly beautifully and loudly, since the throat would always be sufficiently wetted due to the proximity to the water.
An argument arose as to whether the sprout with its powerful singing or the nightingale with its more melodic, plaintive characteristics was the better choice or "to whom the singing crown is due". For example, in view of the larger frequency range of the sprout, it was claimed that the nightingale, compared to a violin, only uses three strings of this instrument, while the sprout uses all four strings. Others claimed that the sprout would make his song neat, clear and according to the rules of poetry, while the nightingale was impulsive and hasty and, instead of giving a clear and precise presentation, too often blurred the individual elements or swallowed clear accents. Opposing voices praised the nightingale as more soulful and creative and emphasized its "greater diversity in song". Business-minded bird traders at that time advised the purchase of both species, diplomatic spirits declared the sprout to be the "King of Singing" and the nightingale the "Queen of Singing".
literature
- UN Glutz von Blotzheim, KM Bauer : Handbook of the birds of Central Europe (HBV). Volume 11 / I: Turdidae / Erithacinae. AULA-Verlag, ISBN 3-923527-00-4 .
- A. Hilprecht: Nachtigall and Sprosser , Die Neue Brehm-Bücherei, A. Ziemsen Verlag, Wittenberg Lutherstadt 1965/1995, ISBN 3-89432-185-7
- J. Sorjonen: Selection of Breeding Habitat by the Thrush Nightingale Luscinia luscinia and its Position in Bird Communities , Ornis Scandinavica , Vol. 11, No. 2 (Jun., 1980), pp. 125-134
- E. Stresemann: The timing of the spring migration with nightingale and sprout , in Ornithological Reports , Carl Winter Universitätsverlag, Heidelberg 1947
- Z. Bogucki, J. Sorjonen: Thrush nightingale (Luscinia luscinia) in WJM Hagemeijer, MJ Blair: The EBCC Atlas of European Breeding Birds - their distribution and abundance , T & AD Poyser, London 1997, ISBN 0-85661-091-7
- R. Lille: Art- and mixed song of nightingale and sprout (Luscinia megarhynchos, L. luscinia) , Journal für Ornithologie 129, 1988, pp. 133-159
Web links
- Luscinia luscinia in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on December 9 of 2008.
- Videos, photos, and sound recordings for Luscinia luscinia in the Internet Bird Collection
- Investigations on the nightingale-sprout hybridization in Frankfurt (Oder)
- Feathers of the sprout
swell
- ↑ a b Hilprecht, 1965 (see literature)
- ^ Ovid Metamorphoses , VI 424 ff.
- ↑ Glutz v. Blotzheim, pp. 105f, s. literature
- ↑ Bellows dimensions in Bauer / Glutz v. Blotzheim (see literature), for example: sex determination in the nightingale )
- ↑ Glutz v. Blotzheim, p. 107f, s. literature
- ↑ Glutz v. Blotzheim, p. 107ff, s. literature
- ^ Farkas (1954) and Voous (1962), cited in Lille, s. literature
- ↑ Stresemann (1948), cited in Lille, p. literature
- ↑ z. BI Hasenfuss in R. Siewing: "Evolution", UTB for Science, Stuttgart, 1987, ISBN 3-437-20385-1
- ^ In I. Newton: "Speciation And Biogeography Of Birds", Academic Press, London / San Diego 2003, ISBN 0-12-517375-X
- ↑ u. a. A. Grüll, G. Fracasso in WJM Hagemeijer, MJ Blair: The EBCC Atlas of European Breeding Birds - their distribution and abundance, T & AD Poyser, London 1997, ISBN 0-85661-091-7
- ^ A b M. Flade: "The breeding bird communities of Central and Northern Germany: Basics for the use of ornithological data in landscape planning", IHW-Verlag, Eching 1994, ISBN 3-930167-00-X
- ↑ a b c d Sorjonen in Glutz v. Blotzheim (see literature)
- ↑ a b Sorjonen (1980), see literature
- ↑ Bauer / Glutz v. Blotzheim (see literature)
- ↑ simplified according to R. Emmrich: "On food and nutritional biology of the sprout", Dresden 1971 in Bauer / Glutz v. Blotzheim, "Handbook of the Birds of Central Europe" Volume 11-I, 1988
- ↑ Glutz v. Blotzheim, p. 134ff, s. literature
- ↑ Steinfatt in Hilprecht (1965), see literature
- ↑ Hilprecht, p. 63, s. literature
- ↑ Steinfatt (1939), cited in Hilprecht and Glutz v. Blotzheim, s. literature
- ↑ Glutz v. Blotzheim, p. 131, p. literature
- ↑ a b Glutz v. Blotzheim, p. 121 f., S. literature
- ↑ F. Zivsa, 1877 in "Gefiederte Welt" about sprout catching, in Hilprecht, p. 86, s. literature
- ↑ Hilprecht, pp. 87 f., S. literature
- ^ Bogucki / Sorjonen, s. literature
- ↑ M. Flade, J. Jebram et al .: The birds of the Wolfsburg area in the field of tension between industrial city and nature , Ed. NABU, Wolfsburg 1995, ISBN 3-00-000113-1
- ↑ J. Seitz, K. Dallmann: The birds of Bremen and the adjacent river lowlands , BUND Bremen (ed.), 1992, ISBN 3-9802876-0-2
- ↑ Glutz v. Blotzheim, p. 116 ff. And p. 122 f., S. literature
- ↑ http://datazone.birdlife.org/userfiles/file/Species/BirdsInEuropeII/BiE2004Sp6592.pdf
- ↑ J. Birk (1937) on "Ornithology and bird lovers around the year 1752" in Hilprecht (1965), s. literature
- ^ Zipp, quoted in Hilprecht (1965), s. literature
- ^ Rausch (1894 and 1898) in Hilprecht 1965, s. literature