European roller
| European roller | ||||||||||
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European roller |
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| Coracias garrulus | ||||||||||
| Linnaeus , 1758 |
The European Roller ( Coracias garrulus ) is an approximately hähergroßer representatives of Racken . In the German-speaking world, the species is also called almond crow . The bird, which is very strikingly colored with turquoise and azure blue plumage areas, is the only representative of this family in Europe . Bluebirds migrate long distances , which means that they all leave their breeding areas in the western, southern and central Palearctic in late summer and early autumn , mainly to overwinter in southern Africa.
Blue rags breed in natural tree hollows, in spacious woodpecker hollows or dig brood tubes in sand or loess cuttings. They feed on large insects, especially beetles, which can be spotted from a hide and preyed on the ground.
Two subspecies are recognized: By far the largest area of the distribution area is the nominate form C. g. garrulus ingested. In the southeastern part is the slightly larger and less contrasting subspecies C. g. semenowi spread.
The main call of the bird is a rough, croaking rack . The specific epithet garrulus means loud , babbling .
The total population of European roller is currently rated as almost endangered (NT = Near Threatened - warning level). The European roller was not common in Central Europe until the middle of the 19th century, but it was widespread. Today it has become extinct here, with the exception of a few remaining occurrences, and significant population declines have been recorded in northeastern Europe and, more recently, in southeastern Europe and Turkey.
features
Blue racks reach a size of 31–32 centimeters; their weight is between 130 and 160 grams. This makes them slightly smaller and lighter than a jay. There is no size or weight dimorphism . Females and males are similar in color distribution, but females are generally paler in color. As the only rocket birds they are unmistakable in their Palearctic range, only in the extreme south-east do the ranges of the Hindu roller and the blue roller slightly overlap . However, the Hindu racket is easy to distinguish by the predominance of green tones and the brownish breast.
Blue racks appear large-headed and short-necked. They resemble a small crow in habit , this appearance is emphasized by the powerful, clearly rounded and slightly hooked beak. Turquoise, azure brown and deep blue color elements predominate, with the turquoise ones facing the sun appearing light blue, while in the shade turquoise green.
The head, neck and the entire underside are turquoise. Forehead and chin are whitish-gray, behind the eyes there is a small, featherless black region. The upper back and shoulders are reddish-cinnamon-colored, the lower back violet-blue, the upper tail covers ultramarine blue . The two central control springs are dark olive green, the other turquoise azure blue with darker bases. The two outermost control springs are slightly elongated and have dark edges. The hand wings are mostly brown-black, towards the arm wings in the basal area turquoise; 3/5 of the arm wings are brown-black and the basal area is turquoise. The turquoise areas are more intense in color on the top; on the underside, the dark wings can shimmer purple depending on the incidence of light. The lesser upper wing coverts are intensely purple-blue, the rest and the under wing coverts are mostly turquoise. The short and weak feet are dull ocher yellow, the iris is hazelnut brown, the beak black-brown.
Fledglings resemble adults in simple dress. Washed out brown tones predominate, the turquoise and blue color elements are less contrasting and paler.
Mauser
Shortly after flying out, the young birds molt the small plumage and some or all of the tail feathers. The swing moult takes place in the wintering area. Annuals and older blue rascals change their small plumage and the four inner wings of the hand in the breeding area after they have brooded. The moulting of the remaining wings as well as that of the control springs takes place very slowly in the wintering area and is only completed shortly before the home migration.
Vocalizations
During courtship and the demarcation of the territory, blue ruff is acoustically quite noticeable, but hardly audible during the breeding season and afterwards. The cry of excitement and disturbance of the European roller is a rough rak , which is often repeated several times and has creaky or croaky sound properties. During the ascent phase, the courtship flight is accompanied by individual rak calls, which in the swoop turn into a rattling Rärrärrärrärrärr… Screeching sound is a crow- like kraah , with a glaring, loud anrrrr warning blue racks . Also percussion sounds belong to their vocalizations, such as beak hitting against a swinging branch.
distribution and habitat
The European roller is a heat-loving species that needs dry and warm weather conditions as possible during the breeding months of May, June and July. The nominate form is particularly common in eastern, southern and south-eastern Europe. The species is also represented in western North Africa ( Maghreb ), in large parts of Spain as well as on the French Mediterranean coast and some of the large Mediterranean islands. In Corsica and Crete , however, it only appears as a pull-through. In north-eastern Europe, the European roller breed in eastern Poland and occasionally in the Baltic states and in European Russia. In the area of Lake Ladoga it reaches its northernmost distribution at about 60 ° nB. Further east, the distribution limit gives way to the south and essentially follows the northern distribution limit of the pedunculate oak . In Asia , the deposits reach the south-central Siberia and , if the Central Asian steppe areas are omitted, the north-west of Iran . The semenowi subspecies breeds in the southwest and southern parts of Central Asia, to the east as far as Xinjiang .
The European roller nests primarily on the edge of very light forest stands, preferably in old oak forests and light pine stands that border on insect-rich heather stands or meadows , pastures and other extensively used areas. Sometimes she also uses orchards and larger park areas. Breeding sites near the water are preferred. Further south it breeds in woody trees that accompany the river and in woody islands in otherwise largely treeless regions. As a cave breeder it is dependent on the existence of natural breeding caves or old woodpecker caves or has to find sand , clay or loess fragments in order to be able to dig the breeding caves itself. In order to be able to hunt successfully, it needs hides from which it searches the open spaces for prey. If not persecuted, it will not avoid the proximity of humans and human settlements.
The European roller lives in the lowlands and in the hilly landscape. The highest known breeding areas to date are located at around 2000 meters in the Atlas .
Their space requirements are relatively large in average habitats with 15 breeding pairs per 100 km² (= 0.15 pairs / km²). However, breeding densities of up to 9 pairs / km² have been found in optimal habitats. In the last remaining Austrian breeding area in south-eastern Styria , up to 18 breeding pairs (= 0.67 pairs / km²) brooded on about 27 km².
hikes
All populations and both subspecies are migratory birds, most of them obligatory long- distance migrants with pure migratory distances between about 4,000 and 8,000 kilometers. The wintering areas are in the thorn bush and acacia savannah, especially in southern Africa, primarily between 20 ° and 25 ° south. In a significantly lower density, blue rock overwinter in suitable habitats further north. Pure deserts, treeless semi-deserts and closed tropical forest areas are not visited permanently. Depending on the food supply, blue ruff roam small areas in the wintering areas. During the autumn migration, which usually begins in full after a small intermediate migration in mid-August, the western populations on the southern edge of the northern savannah belt take longer breaks, while the birds migrating east over the Mediterranean mainly in Sudan, in the area of Lake Chad but also on the southern Mediterranean coast take longer breaks. The spring migration , which begins at the beginning of March, is also interrupted several times, but only for short stopovers ; the northern savannah belt, partly also the southern Mediterranean coast, are the main resting areas.
Most European crustaceans pull in a broad front . The brooding racks in southwestern Spain follow the African Atlantic coast to the south for a long time, until the migratory front in the savannah belt fans out to the east. The remaining Spanish and French Racken cross the Sahara on a broad front, most of them in an approximately straight north-south direction; however, a few immediately choose a southeast direction; they meet the Ostzieher in the lower Nile valley. The eastern populations cross both the Mediterranean and the Sahara on a broad front, but at narrow points such as the Nile Valley or the Somali northeast coast, migration densities of tens of thousands of migrants have been observed on individual days. The homeward migration of the western breeders follows the same routes as the departure, but the migration distance is more straightforward and covered with shorter breaks. However, most eastern breeders pull in a loop , with birds breeding in northeastern Europe moving far to the east and returning to the breeding areas across the Arabian Peninsula . This counterclockwise loop was also observed in various types of shrike, for example the red-headed shrike . With an average daily distance of around 67 kilometers, the journey is a little slower than the return home, which covers an average of 110 kilometers.
The Central European adult birds begin their departure in mid-August and are completed in mid-September. They migrate home from the beginning of March, and most of the Central European blue rags come back to their breeding area in the first decade of May.
Food and subsistence
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The food of the European roller consists mostly of insects and other arthropods , preferring those prey that are easiest to reach and are at least one centimeter in size. Only on the train does she eat plant-based food ( grapes , figs ). Large beetles dominate, but other insects such as grasshoppers , dragonflies , crickets , cicadas , butterflies and caterpillars are also prey. It also consumes species that protect themselves with antibodies, apparently without harm ( bed bugs , ground beetles ). In addition, smaller mammals , amphibians and reptiles are also preyed on, but not quantitatively significant .
As a waiting hunter , the European roller sits on its hide (stake, wire). If it sees a worthwhile prey, it drops in gliding flight, grabs the prey on the ground and returns to its control room. There the prey is often hit against a hard surface and sometimes thrown into the air before it is swallowed. Fleeing prey animals are not pursued at all or only briefly hopping. Air hunts do occur, but can only be observed more frequently when there are large numbers of flying insects, such as swarms of termites.
behavior
The European roller is diurnal with two distinct activity peaks in the early morning and late afternoon. In between, she usually sits quietly on her hide . Their presence is not noticeable outside of the breeding and courtship period. Your flight is a fast-paced, crow-like rowing flight . Bluebirds hardly move on foot. They bathe by diving briefly into the water while in flight.
Blue ruff are moderately gregarious, but can breed in loosened colonies. On the migration and in the wintering area there are higher concentrations, but the individual distances of 100-200 meters are observed. They claim a territory in the breeding area that is vigorously defended against other conspecifics, especially around the cave tree. This can also lead to contact fights. The European roller is often inferior to its cave competitors.
Young birds lay their droppings in the breeding cave without, however, often very heavily polluted caves being observed. When in danger, they vomit a very foul-smelling gastric secretion into the brood cavity, which may make them less attractive to potential predators as prey.
Courtship and brood
The exact breeding age is not known, but due to the regular presence of non-breeding annuals in the breeding area it should be two years. Blauracken lead a monogamous seasonal marriage. It is possible that the pair bond does not end outside of the breeding season, so that long-term partnerships occur. The great loyalty of both sexes to breeding sites should also lead to frequent re-breeding of last year's breeding partners. The courtship and pairing already takes place in the wintering area or on the home migration. The most important courtship elements are sustained mutual bows accompanied by long rows of calls, handing over of prey and pursuit flights with cave points. The spectacular dives of the males in the breeding area serve above all to delimit the area.
Blauracke are cave breeders, i.e. they rely on the existence of woodpecker holes (mostly black woodpecker or green woodpecker ) or natural hollows in trees. They also dig 50–60 centimeters deep nesting tubes in sandstone, clay or loess cuttings. Occasionally, building broods occur, in largely treeless areas such as in Central Anatolia, blue rock breeds in burrows. Nest boxes are accepted. Nesting material is not entered, existing ones are even removed.
All tree species in the lowlands can be used as cave trees; in Europe there is a certain preference for pine and oak. The remaining blue racks in eastern Austria breed in beeches, old fruit trees and increasingly in nesting boxes. The caves are usually quite high, on average around 8 meters.
Blue ruff breed once a year. There is no information available on re-laying in the event of a loss of clutch. Laying begins in southern Europe in mid-May at the earliest with a peak in the first half of June; one to two weeks later in more northerly breeding areas. A clutch consists of 4–6 (2–7) shiny, pure white, short oval eggs with an average size of 35.80 × 28.26 millimeters. They are laid 48 hours apart and are firmly incubated from the last egg. Both partners breed, but mostly the female who also breeds the chicks at the beginning and is supplied with food by the male during this time. The incubation period varies between 18 and 19 (17–20) days. The chicks hatch naked and blind. After 26–28 (25–30) days, the nestlings leave the den and are led by their parents for a while. No data are available on dismigration . The young birds begin their first migration 1–2 weeks after the adult birds have left the breeding area.
Information on breeding success is scarce. Apparently the reproduction rate of the populations breeding on the northern edge of the distribution area with 1.5–1.8 fledgling young birds is too low to be able to secure the population in the long term. This contrasts with an average escape rate of 5.4 young birds in the expanding Mediterranean breeding areas of France.
Life expectancy
There are only 126 re-finds of ringed birds for the European roller. As with all birds, and especially with long-distance migrants, losses will be particularly large in the first year of life, but detailed data are not available. A bird that was ringed when it was young was read in Hungary at 6 years and 11 months, in Poland a 9 year and 2 month old bird was shot.
Systematics
Coracias garrulus is one of seven representatives of the genus Coracias , which is represented with five species in the Afrotropic and one each in the Palearctic and the Oriental . Together with the small genus Eurystomus , it forms the family Coraciidae. At the moment two only weakly differentiated subspecies are described, which are spatially relatively well separated from one another, because C. g. garrulus occurs only in small numbers on the southern edge of its distribution area (see distribution map).
- Coracias garrulus garrulus Linnaeus , 1758 : described above; occurs in by far the largest part of the distribution area.
- C. g. semenowi Loudon & Tschusi , 1902 : From the southern Jordan Valley eastwards via Iraq and Iran to the Kashmir region and Xinjiang. The racks of this subspecies are slightly larger, the green and blue tones are paler overall, the back is more maroon.
Existence and endangerment
The endangered status of the species was upgraded in 2005 by BirdLife International from LC (= least concern - no endangerment ) to NT ( near threatened - warning level ). The main reasons for this are the strong declines in north-eastern Europe and the emerging population decline in south-eastern Europe and Turkey, as well as the continuing danger of migrating blue rags. This contrasts with the almost stable or only slightly declining population in Spain and an expansion in Mediterranean France and Italy, as well as - as far as the sparse data allow conclusions - an equally only slightly declining breeding population in Central Eastern Europe and Central Asia. In Portugal , the population appears to be declining more than in Spain and is currently not likely to exceed 100 breeding pairs.
The population of the nominate form in Europe was estimated at a minimum of 55,000 and a maximum of 117,000 breeding pairs in 2009, of which a maximum of 25,000 breed in EU countries. This corresponds to at least 50% of the total population of birds of subspecies C. g. garrulus in Europe. About C. g. semenowi are not available. Fry & Fry (1999), on the other hand, vaguely put the total population at millions and state that 500,000–700,000 individuals overwinter in the area of the two Tsavo National Parks alone. Spain , Romania , Ukraine , Russia , Cyprus and Turkey are now home to the best blue racks . In Central Europe, around 1000 pairs, only a significant number of these birds breed in Hungary .
In addition to the increasingly Atlantic-influenced climatic conditions in the abandoned former breeding areas of Central Europe, the decline in the population is primarily due to the biocide input and the associated decline in prey, the conversion of previously extensively used landscape areas into intensively built, cleared " agricultural factories " and the merging of small, richly structured ones Agricultural areas in large monocultures and the associated loss of the ecologically particularly valuable peripheral zones. Forestry measures, in particular large-scale pest control and removal of dead wood, deteriorate the biotope quality for the species. In addition, there are considerable impairments to living conditions in the wintering areas. The shooting down of pulling blue rags also has a serious effect in many states. Hundreds of European crests are killed every year, especially in Oman . The losses suffered by the species in traffic and through collisions with power lines and wind turbines are also not inconsiderable. Above all, various birds of prey and martens come into question as natural predators .
In addition to maintaining suitable landscape structures, the most effective protective measures have proven to be the attachment of nest boxes and the use of sitting crutches. In agricultural areas, differentiated land use and staggered mowing dates make a significant contribution to maintaining the quality of the habitat.
The European roller may have been most widespread in the years 1774–1824, which were characterized by particularly hot summers. At that time, their breeding area reached as far as northern southern Sweden and reached Finland . It appears to have been a frequent breeding bird in central and southern Germany , western France and eastern Austria . In the 1950s, the breeding population of the species in Styria was 500 breeding pairs. Only in Switzerland , Liechtenstein , Belgium and the Netherlands has the European roller apparently never brood or only in exceptional cases. The decline in the population and shrinkage of land that began soon after is attributed primarily to climatic changes, to increasingly stronger Atlantic weather influences, but above all to pesticide inputs and large-scale changes in agricultural use.
First, the species gradually cleared its Scandinavian breeding grounds until the last occurrence on Fårö died out in 1967 .
In Germany, the European roller first disappeared from its northern and northwestern breeding areas, while in eastern Lower Saxony , Baden-Wuerttemberg and Bavaria small populations were able to survive until the 1940s and 1950s. In 1976, a maximum of 27 pairs were breeding in the former GDR . The last deposits in the Colbitz-Letzlinger Heide became extinct in 1989, those in Niederlausitz a year later. In 1994 there was a successful brood in Baden-Württemberg.
In Austria, the European roller first disappeared from its breeding areas in Lower Austria , then within a few years it cleared the previously well-occupied territories in the Klagenfurt Basin . In the 1970s and 1980s, the breeding grounds in the Graz Basin , as well as in western and northern eastern Styria, were completely abandoned. This development was triggered by the almost complete conversion of differently agriculturally used and structured areas into maize monocultures. In the Vorarlberg Lake Constance area in 1965 a breeding attempt failed because the adult birds were killed. The species is still occasionally observed as a migrant in the Rhine delta and the adjacent reed areas . Today Austria’s last blue racks breed in a small area near Straden / Southeast Styria. In 2011 two successful broods were found there. In 2013, 5 pairs successfully hatched and 16 fledglings flew out. This last population of Central Europe is limited to an area of about 30 km². Despite the most intensive protective measures under scientific supervision, their future is uncertain, especially because no gene exchange with other populations can take place.
A breeding attempt from 1896 in the area of Meyrin has become known from Switzerland . That also failed because the feeding adult bird was shot down. The meager migration time observations (on average <3 per year) mainly concern the homeward movement and originate in particular from the Upper Engadin , Ticino and the area around Lake Thun .
In Hungary, too, the European roller cleared many breeding areas after the 1960s, especially in the west and south-west of the country and in the northern peripheral areas of the low mountain range. In the key zones between the Danube and the Tisza , on the Tisza and to the east of it, the species was able to survive. Today in these areas hatch about 1000 pairs, about 50% of them in special areas (SPA = Special Protected Area ); the stock is considered stable.
Successful broods were not found in Slovenia between 2005 and 2011. The species disappeared from the Czech Republic by the beginning of the 21st century at the latest and it does not seem to be able to survive in Slovakia either. In north-eastern Poland and the Baltic States, the blue ridge stocks were relatively stable until the last quarter of the 20th century. In Poland the population decreased from more than 1000 to around 100 breeding pairs in the years 1980–2000. In 1970 1000–2000 breeding blue rock in Lithuania were suspected, in 2004 20 pairs could be detected. The trend is similar in Estonia , where thousands of breeding pairs were still found in the 1950s and early 1960s. Then the very rapid decline began, so that by 2000 fewer than 15 pairs were breeding regularly, especially in the south of the country. In 2010 the last successful brood with two fledged young birds was found.
literature
- Hans-Günther Bauer, Peter Berthold : The breeding birds of Central Europe. Existence and endangerment. 2nd, revised edition. AULA Verlag, Wiesbaden 1997, ISBN 3-89104-613-8 , p. 294, p. 277 f.
- Urs N. Glutz von Blotzheim (Hrsg.): Handbook of the birds of Central Europe . Edited u. a. by Kurt M. Bauer and Urs N. Glutz von Blotzheim. Volume 9. Columbiformes-Piciformes. 2nd, revised edition. AULA Verlag, Wiesbaden 1994, ISBN 3-89104-562-X , pp. 1095-1115 (HBV). 831-851
- C. Hilary Fry and Kathie Fry: Kingfishers, Bee-Eaters & Rollers. Princeton University Press, Princeton 1999, ISBN 0-691-04879-7 . Pp. 100-101 and 298-300.
- International Species Action Plan for the European Roller Coracias garrulus garrulus. 2008. pdf engl.
- Michael Tiefenbach: Habitat selection in foraging European Rollers (Coracias garrulus L.) in Eastern Austria Diploma thesis University of Vienna 2009. pdf engl.
Web links
- Coracias garrulus in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on December 18 of 2008.
- Videos, photos and sound recordings of Coracias garrulus in the Internet Bird Collection
- Age and gender characteristics (PDF; 4.5 MB) by J. Blasco-Zumeta and G.-M. Heinze (Eng.)
- Feathers of the European roller
Individual evidence
- ↑ a b BirdLife data sheet C. garrulus (pdf engl.)
- ↑ a b c Action Plan (2008), p. 11.
- ↑ Fry & Fry (1999), p. 300.
- ↑ HBV (1994), p. 834.
- ↑ HBV (1994), p. 835.
- ↑ Audio sample: Territorial dispute between three couples - Italy. Retrieved June 24, 2018 .
- ↑ a b c d Fry & Fry (1999), p. 299.
- ↑ Tom Finch et al. a .: A pan-European, multipopulation assessment of migratory connectivity in a near-threatened migrant bird In: Diversity and Distributions 2015.
- ↑ HBV (1994), p. 836.
- ↑ Tiefenbach (2009), p. 5.
- ↑ Tom Finch et al .: A pan-European, multipopulation assessment of migratory connectivity in a near-threatened migrant bird In: Diversity and Distributions 2015. HTML engl. oS
- ↑ Tom Finch et al .: A pan-European, multipopulation assessment of migratory connectivity in a near-threatened migrant bird In: Diversity and Distributions 2015. HTML engl. oS
- ↑ a b HBV (1994), p. 849.
- ↑ HBV (1994), p. 847.
- ↑ Guy M. Kirwan et al .: The Birds of Turkey . Helm, London 2008, ISBN 978-1-4081-0475-0 , p. 268.
- ↑ a b Tiefenbach (2009), p. 7.
- ↑ HBV (1994), p. 844.
- ↑ a b HBV (1994), p. 845.
- ↑ Euring database
- ^ Ana Teresa Marques, Inês Henriques, Inês Catry and Maria Inês Moreira: Distribution of the Roller Coracias garrulus in Portugal. An historical approach . In: Ardeola , Vol. 52 (2005), Issue 1, pp. 173-176, ISSN 0570-7358
- ^ Action Plan (2008), p. 13.
- ^ Action Plan (2008), pp. 13-14.
- ^ Report by Michael Tiefenbach, one of the leaders of the protection project
- ↑ a b HBV (1994), p. 840.
- ↑ a b Hans-Günther Bauer, Wolfgang Fiedler and Einhard Bezzel : Compendium of the birds of Central Europe , Ulmer, Stuttgart 2012, ISBN 978-3-89104-758-3 , p. 751.
- ↑ Jochen Hölzinger and Ulrich Mahler: The birds of Baden.Württembergs. Non-songbirds 3 . Ulmer, Stuttgart 2001, ISBN 3-8001-3908-1 , p. 351.
- ^ Report by Michael Tiefenbach, one of the leaders of the protection project
- ↑ a b Lyonel Maumary, Laurent Valloton and Peter Knaus: The birds of Switzerland . Swiss Ornithological Institute, Sempach and Nos Oiseaux, Montmollin 2007, ISBN 978-3-9523006-2-6 , p. 472.
- ^ Blauracke Straden / Styria
- ^ Report by Michael Tiefenbach, one of the leaders of the protection project
- ↑ Action Plan (2008), p. 12.
- ↑ Grete Lüütsepp, Andres Kalamees and Olev Lüütsepp: European Roller Coracias garrulus in Estonia 2000-2011 In: Hirundo , Vol. 24 (2011), pp. 61-72, ISSN 1406-2062 .