Wedge-tailed shrike
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Wedge-tailed shrike ( Lanius sphenocercus ) |
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| Lanius sphenocercus | ||||||||||||
| Cabanis , 1873 |
The wedge-tailed shrike ( Lanius sphenocercus ) is an almost jay-sized species of bird from the genus Lanius within the family of the shrike (Laniidae). Together with the closely related, slightly larger Sichuan shrike ( L. giganteus ), which was only separated from L. sphenocercus in 2010 and placed in species rank, it is the largest species of this bird genus. Males and females of this mighty, sharply contrasting black-white-gray songbird are identical in appearance and cannot be distinguished from one another by field ornithology. Both the German common name and the scientific epithet give the name to the long, stepped tail.
The wedge-tailed shrike breeds on the Korean peninsula and inhabits an extensive area in northern and eastern China , with parts of the Korean breeding areas apparently not being occupied until the second half of the 20th century. Except for a few resident populations, most of the wedge-tailed shrike are short-range and medium-range migrants with wintering areas south of the breeding area in south-east and south China as well as in Korea.
The wedge-tailed shrike is like many of its conspecifics an opportunistic ambulance hunter . It feeds on large insects as well as various vertebrates such as small rodents , songbirds , amphibians and reptiles .
L. sphenocercus belongs to the species group of the Great Gray Shrike; the species is monotypical . Although the species has been scientifically recorded in great detail by Russian ornithologists, all studies only concern the Far Eastern Russian populations; in its wide distribution area in central and southern China, the wedge-tailed shrike is almost completely unexplored. Supra-regional studies on population dynamics are also pending. Nevertheless, the IUCN currently (end of 2018) assesses the population of the species with LC (= least concern).
Appearance
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The wedge-tailed shrike measures between 29 and 31 centimeters; his body weight fluctuates between 87.2 and 100.0 grams, depending on nutritional status and the time of year. There is no color dimorphism , but Panov doubts whether females are on average slightly larger and heavier than males, as has been stated many times. The long tail and the contrasting black-white-gray plumage are characteristic; Particularly in flight, the white wing markings that extend over the hand and arm wings , as well as the white outer control feathers are noticeable. Compared to other gray stranglers, the species shows a lot of white in the black wing even when sitting.
The parting, nape of the neck, mantle, upper tail-coverts and rump are light slate gray; the shoulder plumage is pure white. The black face mask begins narrowly at the base of the beak and runs - widening slightly - to behind the ear covers . It has a relatively wide white border on the top; this white band can also be seen above the frontal base of the beak. The wings are black, white at the base of the hand and arm wings; When the bird is sitting, this produces wide white wing mirrors , when it is in flight a white band of different widths extending over the entire wing. The central two control feathers of the strongly stepped tail are black, the rest are white. The underside is washed-out white, often tinged a bit beige or light pink in the side chest area. The mighty hooked bill is black except for the light base of the lower mandible, the legs and the iris of the eyes are also dark brown to black .
Young birds have a very similar color distribution. It is characterized by a slight undulation of the head plumage, as well as the brownish tone of the large elytra. The white shoulder plumage of the adults is rather gray in the juvenile , the face mask begins behind the eyes. Overall, the sharp contrasts of the adult plumage are missing in the youth dress.
The very similar Sichuan shrike , possibly in the southwest of the distribution area sympatric with the wedge-tailed shrike, is slightly larger and clearly darker; it shows much less white overall; the white drawings in the wing of the flying bird are mainly concentrated on the wings of the hand, the wings of the arm show only a few white spots, but no continuous white band. The inner four of the control springs are usually black.
Mauser
After flying out, the young birds begin to switch to their first juvenile plumage at around 50 days of age. In doing so, they molt all body and contour springs, most control springs, and occasionally also some wings. Yearlings then moult into their first adult dress in June of the next year. This moult roughly corresponds to the complete moult that adults start every year at this time and complete by mid-October. Freshly molted wedge-tailed shrike show a slightly pink tint on the chest.
Vocalizations
Wedge-tailed shrike are rather silent birds. Acoustically they are comparatively noticeable after arrival in the breeding area and in the early pairing period. Most frequently, polyphonic doubles emphasized on the second element can be heard in a row, which are often ended with a jay-like screeching when they are blown up. In addition, the vocal repertoire diverse whistles, pressed, avokale sounds hoarse croaking calls and instrumental sounds, especially contains Schnabel miners . The singing, which is seldom heard, is a rather low warbling and chirping, with differently built-in whistles and pressed phrases. Nothing is known about song imitations, such as those very common in the closely related gray shrike .
distribution and habitat
The distribution area of the wedge-tailed shrike stretches in a south-westerly direction from the Amur - Ussuri region in the extreme southeast of Russia over the Korean Peninsula, Inner Mongolia , northeast Liaoning , parts of Heilongjiang and Jilin to Gansu , Shaanxi and Shanxi . The breeding area of the Sichuan shrike begins further to the southwest; to what extent it overlaps with that of the wedge-tailed shrike or is topographically separated from it has not yet been clearly clarified. The wintering areas of both species connect to the southeast and south. They reach the East China Sea in the southeast and extend to about Hong Kong in the south .
Detailed information about the preferred habitat of the species is only available from the north-easternmost areas of the Russian breeding areas in the Amur- Saya - Bureja plains and areas bordering south-west towards Inner Mongolia. This region is today partly strongly agricultural and comparatively densely populated by East Siberian standards; it is relatively humid with annual rainfall of up to 700 mm / m² in contrast to the largely arid areas of the southwest. Here the species breeds preferentially in loosened river valleys interspersed with meadows, on the edge of traditionally agricultural areas, in loosened birch stands, on pastures with bushes and trees, in reed areas with isolated pastures and on tree-lined roadsides, as long as such areas are on low-grass or low-vegetation Adjacent areas with isolated seats, or contain such areas. The wedge-tailed shrike often appears in extensive clearings after clear cuts or in secondary vegetation after forest fires. He avoids contiguous forests and densely bushy landscapes; also areas with tall grass, which are not interspersed with sections with little vegetation, are unattractive for the species. As far as is known, L. sphenocercus penetrates further in the southwest to sparsely with Caragana sp. and other xerophytes existed in semi-arid and arid landscapes. Vertically, the wedge-tailed shrike is more of a type of plains and low mountain ranges. The highest breeding occurrences in China were found at 1,800 meters.
The species takes up a lot of space. The highest settlement density with a breeding pair on 3 km² was found in areas with traditional agriculture near the Amur; mostly, however, lower densities were recorded with one breeding pair per 10 km². The breeding territories are also very extensive with at least one km², although the actual, vehemently claimed nesting territory, in which, in addition to the nesting trees, there are resting places, hiding places and at least one skewer area, is surprisingly small with about 4 hectares . The smallest distance between two flown nests was only 25 meters.
hikes
The migration behavior of the species is inconsistent. Large parts of the populations of the Amur-Ussuri region leave their breeding grounds as early as mid-July and move south, south-west and south-east. Their wintering areas are partly in Korea, but mostly in the southeast Chinese provinces of Hubei , Anhui , Hunan , Jiangxi , Zhejiang , Fujian and in eastern Guangdong . Some birds of the Siberian occurrences try to stay in the breeding area in winter and only pass in extremely unfavorable weather conditions. As far as is known, the wedge-tailed shrike of the Chinese breeding areas are medium-range or short-range migrants with winter quarters in the western area of the above-mentioned provinces. The withdrawal begins in early March. The northernmost breeding territories are occupied from mid-March, but most of them only in the course of April. Outside the breeding season, wedge-tailed shrike have been observed in Japan and the Baikal region .
Food and subsistence
Like most species of this bird genus, the wedge-tailed shrike is also an opportunistic hunter who tries to capture living things with the most favorable ratio of energy gain and effort. Its food spectrum is correspondingly diverse in its species composition, but it is always made up of invertebrates , mainly large insects and vertebrates , especially birds and rodents , in different proportions depending on the season.
In an extensive analysis of dumps, 129 different species of invertebrates were identified, including, in particular, mole crickets , long-feeler terrors , migratory locusts , ground beetles , gravedigger and bumblebees . Obviously the wedge-tailed shrike prefers large species. During the summer months, insects seem to be the main food and also an essential part of the nestling food. The same investigation found remains of 45 vertebrates in the strangler's ridges. Shrews , mice and voles make up the main part of the biomass in addition to birds, of which 20 different species were found in the prey remains. The wedge-tailed shrike can prey on birds as large as reversible necks or pheasant chicks and mammals up to the size of a Burunduk , and can carry animals up to its own body weight. After all, frogs and toads are also regularly caught. Vertebrates play a special role with regard to the consumed biomass, especially in the winter months.
The hunting strategies of the wedge-tailed shrike are more diverse than those of most other representatives of the genus. He is primarily a hide hunter who observes the surroundings from an elevated viewing point in a relatively narrow radius and beats suitable prey on the ground. He kills vertebrates by biting the neck. He consumes smaller prey on the spot, he carries larger prey in the claws to one of his feeding places, where he divides them by fixing them to the base with a catch. If there is an excess of food, he deposits them in one of his skewers' places. Real aerial hunts in the manner of a small hawk are observed relatively often, in which it pursues small birds over distances of 50–100 meters and tries to hit them in the air. It also shakes much more frequently than other stranglers in search of suitable prey at a height of around 10–20 meters. He mainly uses this energy-intensive hunting method where there is too dense ground vegetation that does not allow high seat hunting.
Breeding biology
Sedentary populations begin courtship as early as the beginning of March, while dragging wedge-tailed shrike a month later. There are indications that the breeding site fidelity is high, so that last year's partners often mate again. The territoriality of the species is very moderate compared to other species; only a relatively small area, covering a few hectares, is also vigorously defended against other wedge-tailed shrugs: it includes the actual nesting trees, some resting places and perches and at least one spit hole. The couple tries to drive away food competitors and potential predators such as oriental turtle doves , magpies , other crows , as well as various birds of prey and owls from this narrow breeding territory and also attacks people if they get too close to the nest. Even Brown Shrike will not be tolerated in this area. Large areas of the district are only vaguely defined and can largely overlap with neighboring districts. The courtship itself is relatively inconspicuous; it consists of bowing to one another, gentle duet singing, nesting and ritualized nesting; at first the female dominates while later adopting regressive behaviors.
The nest is a very solid, mostly three-layer construction. A coarsely woven base of twigs and twigs, usually positioned in a fork near the main trunk, carries the actual, deep bowl, which consists mainly of dry grasses, wormwood stalks and bark, which are very neatly intertwined; inside it is embedded with various soft materials such as animal and plant wool and with feathers. It is erected in different woods such as willow, birch , elm or pea bushes at heights between 2 and 5 meters. The outer diameter is on average 215 millimeters, the inner cup width is 108 millimeters. Nothing is known about the participation of the sexes in nest building.
A full clutch consists on average of 7 (5–9) eggs with gray or brown speckles on a dirty white background, which are laid every day. They measure an average of 28.16 × 20.72 millimeters. The laying period begins in mid-April and lasts until the beginning of June. Most wedge-tailed shrike breed only once a year, very rarely twice. Replacement clutches in the event of an early clutch loss are the rule. During the brood, which lasts about 19 days, the female is provided with food by the male. In large clutches, the hatching process can extend over four days, so that the developmental difference of the nestlings is large at the beginning and the chicks that hatch last often do not fly out. During the first 10 nestling days, the male feeds almost exclusively, later both parents. After 19-21 days, the young birds leave the nest; at this point in time they weigh between 44 and 54 grams. In the next few weeks they move more and more away from the nest and nesting trees, but are still looked after by their parents. They are only able to hunt themselves when they are around 60 days old; at this point, usually at the end of July, they also leave the breeding area. Nothing is known about the type of dismigration and the average distances of the scattered migrations.
Only data from small samples are available on the breeding success and escape rate. 58 chicks hatched from 74 eggs, 45 of which finally flew out. The reason for unsuccessful broods lies in the relatively high number of unfertilized eggs and is caused by predation, especially by magpies and carrion crows .
Systematics
The species was first described by Jean Louis Cabanis in 1873 . The type specimen, an adult male, was then in a Berlin museum and is said to have come from Canton to Berlin through the natural produce trade . Cabanis describes the species very precisely and emphasizes above all the enormously long, strikingly stepped tail , after which he also names the new species (Greek: κερκος = tail; σφηνος = wedge-shaped). The even larger shrike from Sichuan , described a little later by Nikolai Prschewalski , was rated as a subspecies giganteus . Diverging molecular genetic findings, different morphological details and completely different habitat requirements finally led to the HBW splitting the taxon into the two monotypical species Lanius sphenocercus and Lanius giganteus in 2016 , while other authorities such as the IOU emphasize the need for a reassessment, but they still do not implemented (as of the end of 2018).
Persistence and Threat
According to the current state of knowledge, the population density of the species is very irregular. In some places it is described as common, but in many regions it seems to be rare. There are neither quantitative nor qualitative assessments of the inventory and the development of the inventory. However, the breeding area does not seem to be exposed to any immediate threats and a drastic decline in the population has not been reported either regionally or nationally. Therefore, the IUCN assesses the current situation (status at the end of 2018) with LC (= least concern).
literature
- 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 .
- Reuven Yosef, International Shrike Working Group and GM Kirwan: Chinese Gray Shrike (Lanius sphenocercus). 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 2018 (accessed from: https://www.hbw.com/node/60484 on September 15, 2018).
- 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
- ↑ Good photos. Scroll down to the overview. Note: Lanius sphenocercus and Lanius giganteus are mixed; dark birds with little white in the wing belong to giganteus .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 308 ISBN 978-954-642-576-8 .
- ↑ a b Lanius sphenocercus in the IUCN Red List of Threatened Species 2016.1. Listed by: BirdLife International, 2016. Retrieved September 14, 2018.
- ↑ a b c d Reuven Yosef & International Shrike Working Group & GM Kirwan: Chinese Gray Shrike (Lanius sphenocercus) . In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (downloaded from http://www.hbw.com/node/60484 on September 14, 2018).
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 317 ISBN 978-954-642-576-8 .
- ↑ T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, pp. 146-147.
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, pp. 304-306 ISBN 978-954-642-576-8 .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, pp. 333-336 ISBN 978-954-642-576-8 .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 342 ISBN 978-954-642-576-8 .
- ↑ Calls - sound file from xeno-canto.org
- ^ A b T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, p. 147.
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, pp. 308-310 ISBN 978-954-642-576-8 .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, pp. 318-320 ISBN 978-954-642-576-8 .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 320 ISBN 978-954-642-576-8 .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 326 ISBN 978-954-642-576-8 .
- ^ A b c Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 327 ISBN 978-954-642-576-8 .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 337 ISBN 978-954-642-576-8 .
- ^ A b Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 328 ISBN 978-954-642-576-8 .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, pp. 337-339 ISBN 978-954-642-576-8 .
- ^ A b Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 329 ISBN 978-954-642-576-8 .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 319 ISBN 978-954-642-576-8 .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 342 ISBN 978-954-642-576-8 .
- ^ T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, p. 148.
- ^ A b Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, pp. 331-332 ISBN 978-954-642-576-8 .
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, p. 333 ISBN 978-954-642-576-8 .
- ↑ Journal for Ornithology (1873) p. 76
- ↑ IOU - Bird List Shrikes
- ^ Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, pp. 320-322 ISBN 978-954-642-576-8 .