Isabel Shrike

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Isabel Shrike
Lanius isabellinus GRK.jpg

Isabellus Shrike ( Lanius isabellinus )

Systematics
Order : Passerines (Passeriformes)
Subordination : Songbirds (passeri)
Superfamily : Corvoidea
Family : Shrike (Laniidae)
Genre : Real strangler ( Lanius )
Type : Isabel Shrike
Scientific name
Lanius isabellinus
Hemprich & Ehrenberg , 1833

The Isabelline Shrike ( lanius isabellinus ) is a singing bird from the genus of Real Würger ( lanius ) within the family of Würger (Laniidae). The rather small shrike with a sand-colored or gray-brown appearance inhabits an extensive area between the Caspian Sea and north and central China, southeast to the Qaidam basin . Among the Palearctic stranglers it is the species with the least color contrast.

All Isabellus are migratory birds, especially the western subspecies long-distance migrants with wintering areas in Arabia , East Africa , the Nile Valley , westward to the African Atlantic coast . The eastern populations overwinter mostly south of their breeding areas in northwest and central India and in Pakistan .

Isabellus shrike breed in arid areas, steppes and semi-deserts , where they feed primarily on insects and , more rarely, small vertebrates, as hunters from the hide .

Isabellus' taxonomy is complicated and controversial. The HBW and other authorities distinguish three other subspecies in addition to the nominate form , Russian ornithologists, but also the IOC and Avibase separate the Turkestan shrike ( Lanius phoenicuroides ) from this complex as an independent species. The sister species is the red-backed shrike , with which the Isabel shrike hybridizes and produces fertile offspring. The brown shrike is also in close relatives .

In Europe, the species is a rare, but observed in increasing frequency Irrgast ; most of the evidence comes from Great Britain and Heligoland . Isabellus strangles have been found several times in Central Europe at longer intervals .

The IUCN does not currently see any of the subspecies as endangered.

Appearance

Lanius (Isabellinus) phoenicuroides , female
A likely due to a reversal train to Northumberland verflogener juvenile Isabelline Shrike

Isabellus shrike are 17–19 centimeters tall and weigh around 30 grams as heavy as the red backed shrike, with which the species occurs sympatric in the western part of its range . While colored males can generally be reliably identified using the field ornithological method, it is difficult to differentiate between juveniles and immatures , but also between females with those from red-backed shrike and brown shrike. There is no size or weight dimorphism , the color dimorphism is not as conspicuous as in the red-backed shrike due to the rather pale, faded basic coloration of the males, but it is still clearly recognizable.

The Isabellus shrike is a polytypic species, from which two color groups can be distinguished: The nominate form and L. (i). phoenicuroides are more saturated, more brownish in color on the upper side, while the plumage of L. i. arenarius and L. i. tsaidamensis is paler and has predominantly gray-brownish tones on the upper side. In the second group, the color dimorphism is less clear.

The parting is light gray, the forehead slightly isabel-colored ; towards the neck and upper coat the gray becomes more intense and takes on a brownish tone on the back. The black mask typical of a strangler begins above the cleft of the beak, usually covers only the lower half of the eyes and runs - widening significantly - far behind the ear covers . At the upper edge it is bordered by a pure white stripe above the eyes. The rump is light rust-red, the top of the tail a little darker red-brown. The wings are dark brown-black. The large cover feathers and the arm wings are edged in cream color. The base of the inner hand wings is white, which creates a small, often covered wing mirror when the bird is sitting , and a narrow, sickle-shaped wing field when it is in flight. The throat is white, the underside sand or isabel colored, with a more intense color tint on the flanks and on the underside of the abdomen. The beak is dark brown to black, the legs and toes are dark gray, the iris is dark brown.

Females show a similar color distribution as the males, but they are significantly less contrasting, washed out, and overall more uniformly sand-colored. The throat is matt white to cream-colored, the mask is brown-gray, shorter and narrower than that of the males, the underside on a creamy-white background is sparged and flaked in differently rust-brown colors. The wing field is smaller and only slightly brighter than the other hand wings. The lower beak is tinted pink.

Young birds are even paler, more uniformly colored. The top is gray-brown and has very dense, but not always clear, banding. The face mask is reduced to a brown spot on the ear covers. The underside is cream-colored and usually more clearly pitted and flocked. The tail is maroon on top.

Mauser

Two different moulting strategies were observed: Most of the southwest migrants, i.e. birds of the subspecies L. i. phoenicuroides , and some of those of the nominate form, moult most of the small plumage, the control feathers and some of the wings after the breeding season. In the wintering areas they change their entire plumage again before they move home. South and southeast migrants as well as short-distance migrants , mainly birds of the subspecies L. i. arenarius and L. i. tsaidamensis , change their entire plumage before they move away and have no further plumage changes in the wintering areas.

Vocalizations

Overall, the calls and the singing of the red-backed shrike and Isabellus are very similar. The singing is a relatively quiet, mostly melodious murmuring and chattering, interspersed with imitations of other bird songs and sounds. The singing serves exclusively to form pairs and to strengthen the bond, it has no territorial function. The repertoire of calls is diverse. The most common territorial call is a loud, sharp kschä-kschä , which can be modified in many ways. Tseä… tseä calls, which are also sharp in the sound quality, are also placed in a territorial context. More sexually motivated are somewhat softer two-syllable zotsät and kou-ig series of calls and a low, high - pitched trill. The alarm call is a jarring screeching as well as a quickly repeated Tscheck… Tscheck… Tscheck . In addition to the alarm calls, which are also used by the females, the most frequent contact call to be heard from them is a Zschä… zschä .

distribution and habitat

Distribution of the Isabellian shrike and the red-tailed shrike ocher: breeding area of ​​the Isabellian shrike light brown: breeding area of ​​the red-tailed shrike striped ocher: wintering area of ​​the Isabellian shrike striped green: wintering area of ​​both species dark net: migration corridor of both species

The Isabellus shrike is primarily a Central Asian shrike species. Its occurrences are east of the Caspian Sea and extend in a wide belt that narrows towards the east to around 120 ° East, although the actual eastern limit of distribution is not precisely known.

The northern limit of the distribution area lies in landscapes like this one on Lake Gussinojesee .
In Saxaul, like here in the southwest of Mongolia on the edge of the Gobi , the Isabellus shrike finds breeding opportunities.

To the north, its distribution area extends to the southern edge of the taiga . The southern borders are formed by the Nan Shan mountain range or the Qaidam basin in the east, and the areas of distribution extend into Inner Mongolia and Níngxià to the east . In the west there is a large island in southern and eastern Iran, separated from the closed range of L. (i.) Phoenicuroides . The eastern border of the range of this species / subspecies is difficult to determine. Certainly it extends in the southeast to close to the foothills of the Tian Shan and in the north it touches the western border region of the Altai .

The wintering areas of the south-south-east and south-west migrants from the eastern distribution areas of the species are located in southernmost Pakistan as well as in north and central India, those of the south-west and west migrants of the nominate form mainly on the Arabian Peninsula, in the Nile Valley and in northeast and east Africa . However, some populations also overwinter in the Sahel region of northern Central Africa westwards to the semi-desert regions of Mauritania on the Atlantic coast. In Africa the wintering areas of the Isabellus shrike are north of those of the red killer. They are mostly widely separated from them, only in northern Uganda there could be an overlap zone.

Isabellus shrike mainly inhabit dry habitats, such as steppes and semi-deserts, but also occur in slightly more humid areas, such as on the edge of the large steppe lakes, as well as in moderately dry mountain areas. The most important habitat requisites are, in addition to a sufficient supply of prey, bushes and low trees as hides and nest carriers. Isabellus shrikes are often found in areas with tamarisks , saxaul and senna , in the southwest with pistachio bushes , on small rivers in willow or acacia stands and in the edge areas of the reed zones of the steppe lakes, such as Lake Balchasch or Lake Tengiz . At higher altitudes, short lawns with isolated juniper bushes and open areas covered with rose bushes on the edge of light coniferous forests are particularly suitable habitats. Isabellus shrike occasionally breed in suitable habitats on the edge of small settlements, more rarely in parks, orchards and other strongly anthropogenic landscapes. Vertically, the species is represented from levels around 200 meters to heights of 2500 meters. L. (i.) Phoenicuroides was found as a breeding bird up to an altitude of 3500 meters.

The brood density varies greatly from region to region. In some areas, all subspecies, but especially L. (i.) Phoenicuroides, can reach high population densities. In the bush zones of the Kazakh steppe, where the species nests mainly in stands of horned horn, the nest distance was around 100–150 meters. Even higher densities with nest spacings of around 60 meters were found in individual river valleys on the edge of the Altai. There the activity centers of courting males are relatively small at around 0.3  hectares . Detailed information on the settlement densities of L. i. arenarius and L. i. tsaidamensis are not available.

hikes

The Isabellus shrike is a migratory bird whose migratory behavior has not yet been adequately researched. Some early breeders begin to move out at the end of July. All breeding areas have been largely cleared by mid-September.

The wintering areas and the direction of migration depend on the breeding area of ​​the respective subspecies. L. (i.) Phoenicuroides and some of the shrikers of the nominate form migrate in a south-westerly direction and overwinter for the most part in the Nile Valley and in the arid regions of northern and central East Africa. However, some of them are already staying on the Arabian Peninsula, while others are moving westward to northern Nigeria and the Atlantic coast of Mauritania. Birds of the subspecies L. i. arenarius and L. i. tsaidamensis spend the winter months in southern Pakistan, southern and eastern Iran, easternmost Iraq and northern and central India. Since the Himalayan range is flown around, some of these birds first depart in a south-easterly direction and later turn to the south or south-west. A small percentage of first-time migrants spend the first summer in the wintering areas.

The migration home begins in February, mostly with birds that wintered in Iraq and Iran. Most shrikes of the nominate form and L. (i.) Phoenicuroides return by the end of April, those of the other two subspecies a little later. By the end of May, the breeding grounds for these subspecies will also be occupied again.

Food and subsistence

Isabellas feed themselves and their young almost exclusively on insects. Like most shrikes, they prefer large individuals, but small species are also collected when they occur in large numbers. Among the insects outweigh beetles (especially beetles , darkling beetles and scarab beetles ), crickets , mole crickets , cicadas , grasshoppers , mantis , butterflies and their caterpillars , ants , dragonflies and Hymenoptera , including stinging species. Other invertebrates, such as arachnids and worms, are rarer prey. Occasionally, especially in the spring after arriving in the breeding area, the species preyes on small reptiles such as steppe runners , small rodents, especially gerbils , and small passerines , mainly nestlings and young birds that have just fled. In the wintering areas, however, nestlings of colony-breeding small birds are frequent prey of this shrike species, in Africa especially those of the bloodbeak weaver .

The Isabellus is above all a waiting hunter. The majority of the prey is of a 1-3 meters above ground level lying Ansitz spied out and hit the ground. To a much lesser extent, it obtains its food by searching the ground, reading the food animals from substrate surfaces, or by flying hunting. Large prey animals that are not eaten or fed are impaled in thorny bushes or clamped in branch forks.

behavior

Detailed information on the general and territorial behavior of the species is only available for L. (i.) Phoenicuroides and to a lesser extent for the nominate form. The main behaviors are largely similar to those of the nine-killer. Isabel Shrike are diurnal; they live in a seasonal pair bond during the breeding season, and are largely solitary outside the breeding season. The pair formation takes place in the first days after the arrival of the females in the breeding area, less often already when resting during the migration home. Isabellus shrike build breeding territories and are also territorial outside the breeding season. Neighboring territories can overlap extensively without the first conflict between neighboring couples. Contact fights were never observed. Only the immediate vicinity of the nesting area, the spit areas and some perches within the area are asserted and defended more intensively. The territory is marked by low, slow sightseeing flights and rows of calls in an upright position at prominent places. The threatening gestures include the typical strangler repertoire, such as nodding the head, hump position, spreading the tail and wings, and pointing the beak. They are always accompanied by loud calls.

Breeding biology

The males appear first in the breeding area and occupy a territory. The courtship and pair bond takes place very quickly, often within a few hours. The most important elements are the upright sitting of the potential partner very close to each other, with the male constantly calling and singing. Then it bows rhythmically and turns its head, the wings and tail feathers are slightly raised. These elements can be repeated several times, interrupted by ritualized chases, showing nesting sites with indicated nesting hollows and handing over food until the first copulations end the pairing phase and nest building activities begin.

Clutch of the Isabel Shrike

The nest is usually built at heights between one and two meters. The bushes and trees in the breeding area come into question as nest carriers, but thorn-bearing species are preferred. The female does most of the construction work, while the male mainly procures material. The nest rests on a base of loosely wedged twigs and twigs. It is a very carefully and compactly built, deep bowl, which mainly consists of intertwined blades of grass and fine roots. However, all suitable materials available in the nest environment are used. Inside, the nest is lined with feathers and plant and animal wool, while the outside is occasionally covered with leaves and pieces of bark. The average outside diameter is 165, the inside diameter about 68 millimeters. The height is 82 millimeters.

The first clutch of the subspecies L. i. arenarius were found at the end of March. Birds of this subspecies often appear to breed twice a year, with the others, replacement clutches are the rule if the clutch is lost early. The breeding season of the other subspecies begins at the end of April at the earliest and ends around mid-June. The clutch size varies between three and eight eggs, usually five or six. The eggs are on a variable background (whitish, cream-colored, greenish, pale reddish) towards the blunt end with different intensities of gray, ocher or reddish dots and speckles. L. (i.) Phoenicuroides eggs measure 22.2 × 16.7 millimeters on average. The female lays at a daily interval, usually in the morning hours. Only the female breeds. It is supplied with food by the male during the breeding season and in the first days of the nestling. The breeding season varies, depending on the weather conditions, between 13 and 17 days. The young hatch naked and blind, but develop very quickly and leave the nest after 13-16 days. The last hatched young often wither and die. Freshly fledgled Isabellus shrike remain in the nest environment for a long time and are fed by their parents for up to one month after leaving the nest. Isabellus shrubs are mainly parasitized by the cuckoo .

No data are available on the breeding success of the species.

Systematics

The systematics of the Isabellus shrike species complex is difficult and controversial because of the polytypic appearance as well as due to the mixing zones between the subspecies as well as between the red-backed shrike and the brown shrike; the Dutch ornithologist Karel Voous described it in 1979 as capricious (unpredictable, difficult to assess).

The type specimen was first determined in 1833 by Christian Gottfried Ehrenberg as Lanius isabellinus . It comes from a collection of bellows that Friedrich Wilhelm Hemprich , who died in 1825, collected or that Hemprich and Ehrenberg brought back from trips together to Arabia and Northeast Africa. The place of origin of the bellows is in the south of the province of Mecca . Later this species was considered to be the nominate form of a series of similarly colored stranglers found mainly in Central Asia east to northwest China. According to very different taxonomic assessments, the Russian ornithologist Boris Karlowitsch Stegmann split the entire isabellinus complex into four species in 1930 . Between 1960 and 1980, Panov in particular , but also other Russian ornithologists, revised this taxonomic assessment: They confirmed the species rank of the most widespread species / subspecies, L. phoenicuroides , but summarized the remaining three stranglers from this complex in a species with the Nominate form L. isabellinus together.

The taxonomy of the Isabellus Complex became particularly confusing when a work by DJ Pearson was published in the Bulletin of the British Ornithologists' Club in 2000 , in which the author took the view that the type specimen, i.e. L. i. isabellinus Hemprich & Ehrenberg , 1833 , not of this subspecies, but of the subspecies L. i. speculigerus is to be assigned, so it has to be renamed. Logically, L. i. speculigerus the nominate form isabellinus (with the synonym speculigerus mentioned in some cases ). The taxon L. i. speculigerus became obsolete and L. i. isabellinus got the oldest available name L. i. arenarius . In addition, it was proposed that L. phoenicuroides should also be removed from the species . The most important western Lanius specialists followed this view , above all Tony Harris and Reuben Yosef . Panov, on the other hand, does not consider the determination of the type specimen by Pearson to be correct, nor does he agree to a revocation of the species rank of L. phoenicuroides .

The HBW currently sees the Isabellus shrike as a polytypic species with four subspecies, as does the IUCN. IOC and Avibase separate L. phoenicuroides as an independent species from the isabellinus group, a view that Panov also favors.

Differentiated molecular genetic studies are not yet available. The not extensive work by Wei Zhang et al. , which only considers Isabellus shrike from western China (according to the current perspective, L. arenarius ), sees the Isabellus shrike as a sister species of the red killer and the brown shrike in a parallel clade .

The following presentation of the subspecies follows the HBW in the editorial office from 2008. The separation of L. i. Phoenicuroides as an independent species seems to be increasingly supported in specialist circles.

  • Lanius isabellinus isabellinus Hemprich & Ehrenberg , 1833 : Southern and Eastern Dauria , Mongolia with the exception of the northwest, as well as northwest and northern China. (Southeast Altai , northeastern foothills of Tian Shan, and northeastern Xinjiang .)
  • Lanius isabellinus arenarius Blyth , 1846 : western and northern central China, southeastern foothills of the Tian Shan to the Tarim basin ; eastward to northwestern Gānsù and western Inner Mongolia. South-east to Níngxià. Pale gray upper side, mask usually only begins behind the crack in the beak, rump and tail washed out brown.
  • Lanius isabellinus tsaidamensis Stegmann , 1930 : Qaidam Basin in northern Qinghai . Largest subspecies. Like L. i. arenarius but still paler, more washed out. The authorization of this subspecies is controversial.
(* Lanius (isabellinus) phoenicuroides ) ( Schalow , 1875) : southern and eastern Kazakhstan , northeastern Iran, Afghanistan , Pakistan eastward to the Indus , north-east to the extreme southwestern Xinjiang. More intense, more saturated brown than the nominate form, head often chestnut brown, often a rather wide white stripe above the eyes. Whitish underside with only faintly or completely undone flanks. In addition, there are also individuals who are significantly more gray; they were sometimes referred to as the subspecies L. i. karelini described. Many authors consider the subspecies L. isabellinus phoenicuroides as a separate species, Turkestan shrike ( Lanius phoenicuroides ).
In its last taxonomic revision (2017), the HBW also recognized the species status of Lanius phoenicuroides . Red-tailed shrike is mentioned as a common German name .

Persistence and Threat

There are neither quantitative assessments nor analyzes of population dynamics. For the subspecies L. i. arenarius and L. i. tsaidamensis all knowledge relevant to the population is missing. The distribution density of the nominate form and of L. (i.) Phoenicuroides varies greatly from region to region, but the species is a frequent breeding bird in some areas. The Isabel shrike lives in very barren areas that can hardly be used for agriculture. However, where irrigated agriculture is carried out, increasing insecticide input reduces the density of prey and thus the population density of the species. The IUCN assesses the population situation as LC = no risk (least concern).

literature

  • Hans-Günther Bauer, Einhard Bezzel and Wolfgang Fiedler (eds.): The compendium of birds in Central Europe: Everything about biology, endangerment and protection. Volume 2: Passeriformes - passerine birds. Aula-Verlag Wiebelsheim, Wiesbaden 2005, ISBN 3-89104-648-0 .
  • Tony Harris, Kim Franklin: Shrikes & Bush-Shrikes. Including wood-shrikes, helmet-shrikes, flycather-shrikes, philentomas, batises and wattle-eyes. Christopher Helm, London 2000, ISBN 0-7136-3861-3 .
  • Josep del Hoyo , Andrew Elliot, Jordi Sargatal (Eds.): Handbook of the Birds of the World. Volume 13: Penduline-Tits to Shrikes. Lynx Edicions, Barcelona 2008, ISBN 978-84-96553-45-3 .
  • Norbert Lefranc, Tim Worfolk: Shrikes. A Guide to the Shrikes of the World. Pica Press, 1997, ISBN 1-4081-3505-1 .
  • R. Yosef, E. de Juana: Isabelline Shrike (Lanius isabellinus). In: J. del Hoyo, A. Elliott, J. Sargatal, DA Christie, E. de Juana (Eds.): Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona 2013 ( online , accessed December 13, 2014).
  • Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, ISBN 978-954-642-576-8 .

Individual evidence

  1. ↑ a b c d e f g h R. Yosef, E. de Juana: Isabelline Shrike (Lanius isabellinus) In: J. del Hoyo, A. Elliott, J. Sargatal, DA Christie, E. de Juana (eds.) : Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona 2013 ( online , accessed December 12, 2014).
  2. ^ A b T. Harris, K. Franklin: Shrikes & Bush-Shrikes [...]. 2000, pp. 190-191.
  3. ↑ a b c EN Panov: The True Shrikes (Laniidae) […]. 2011, pp. 546-554.
  4. ↑ a b c EN Panov: The True Shrikes (Laniidae) […]. 2011, pp. 516-521.
  5. ^ A b International Ornithologists Union Committee on Nomenclature: IOC World Bird List 4.4 . 2014, doi : 10.14344 / IOC.ML.4.4 .
  6. ↑ a b Isabellus shrike ( Lanius isabellinus ) at Avibase; Retrieved December 12, 2014.
  7. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, pp. 568-591.
  8. ↑ Hans-Günther Bauer, Einhard Bezzel and Wolfgang Fiedler (eds.): The Compendium of Birds in Central Europe […]. 2005 pp. 37-38.
  9. ↑ a b Lanius isabellinus in the IUCN Red List of Threatened Species 2014.3. Listed by: BirdLife International, 2012. Retrieved December 13, 2014.
  10. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, p. 517.
  11. ^ A b c d T. Harris, K. Franklin: Shrikes & Bush-Shrikes […]. 2000, p. 191.
  12. ^ A b c d e T. Harris, K. Franklin: Shrikes & Bush-Shrikes […]. 2000, p. 192.
  13. ↑ xeno-canto: sound recordings - Isabellwürger ( Lanius isabellinus )
  14. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, pp. 523-524.
  15. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, p. 524.
  16. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, pp. 526-527.
  17. ↑ a b EN Panov: The True Shrikes (Laniidae) […]. 2011, p. 553.
  18. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, p. 555.
  19. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, pp. 527-528, 554 and 560.
  20. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, p. 544.
  21. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, pp. 529-535.
  22. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, p. 532.
  23. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, p. 538.
  24. ^ A b T. Harris, K. Franklin: Shrikes & Bush-Shrikes [...]. 2000, p. 193.
  25. ↑ EN Panov: The True Shrikes (Laniidae) […]. 2011, p. 556.
  26. ^ David J. Pearson, The races of the Isabelline Shrike Lanius isabellinus and their nomenclature. In: Bulletin of the British Ornithologists' Club . tape 42 , 2000, pp. 22-27 .
  27. ↑ a b EN Panov: The True Shrikes (Laniidae) […]. 2011, p. 547.
  28. ↑ Wei Zhang, Fu-Min Lei, Gang Liang, Zuo-Hua Yin, Hong-Feng Zhao, Hong-Jian Wang, Anton Krištín: Taxonomic Status of Eight Asian Shrike Species (Lanius): Phylogenetic Analysis Based on Cyt b and CoI Gene Sequences . In: Acta Ornithologica . tape 42 , no. 2 , December 1, 2007, p. 173-180 , doi : 10.3161 / 068.042.0212 .

Web links

Commons : Lanius isabellinus  - collection of images, videos and audio files