Red backs

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Red backs
Red-backed Red-backed Shrike (Lanius collurio), male

Red- backed Red-backed Shrike ( Lanius collurio ), male

Systematics
Order : Passerines (Passeriformes)
Subordination : Songbirds (passeri)
Superfamily : Corvoidea
Family : Shrike (Laniidae)
Genre : Real strangler ( Lanius )
Type : Red backs
Scientific name
Lanius collurio
Linnaeus , 1758

The Red-backed Shrike ( Lanius collurio ) or Rotrückenwürger (also Rotrückiger strangler ) is a species of bird from the family of the Strangler (Laniidae) and in Central Europe, the most common shrikes. He is best known for his behavior in impaling prey on thorns.

Its diet mainly includes large insects, but also small mammals and birds. Native to large parts of Europe and western Asia, it breeds in semi-open landscapes with a good supply of hedges and shrubs. The nests are preferably created in thorn bushes. Due to the intensification of agriculture, the red-backed killer suffered great population losses in Central Europe in the second half of the 20th century. The migratory bird overwinters in the southern part of Africa.

Red-backed song

Naming

The name red-backed shrimp refers to the erroneous popular belief that it would first impale nine prey before eating it. Or as the Zedler put it in the 18th century: “ ... and want to keep a number of them, albeit for no good reason, from the fact that this bird is enjoying nothing, because it has made nineerley dead, as from which it is said to have received the name Neuntödter. “This also gave rise to similar names such as Neunmorders ( Negenmorders in Low German ) or Neunwürger . The name Dorndreher ( Dorndreier in Low German ), Dornreich , Dornkreul or Dorntreter also refers to the “ skewer” . The name falcon singer seems to indicate its falcon-like beak. The name Dickkopp is also known in Low German , which describes the typical proportions succinctly but aptly.

Since even in the 18th century there was not a clear distinction between the species (or sexes), but sometimes all native stranglers were referred to as “ ninth killer ”, not all popular names can be clearly assigned to Lanius collurio . This species was apparently also referred to as the " small nine-killer ". Names related to the Elster such as B. mountain , wild or Kruck Elster designate probably because they probably relate to the black-and-white coloration, rather the Shrike . Other names that can be found in old reference works are Quargringel (or Quarkringel , perhaps referring to Ruf und Bandung ) or Rabraker .

description

Red backed male
Red-backed shrimp (female) with clearly recognizable teeth behind the tip of the beak

The red-backed shrike is the smallest Central European shrike species with a length of 16-18 cm. It shows a very pronounced sexual dimorphism - males and females clearly differ in color.

The wing length averages 93 (91–95) mm, in the male it is between 88 and 100 mm, in the female between 82 and 98 mm. The length of the tail is between 71 and 90 mm for the male and between 68 and 85 mm for the female. The average weight of the males is around 28 grams. In females, it can increase to 32.8 grams during the breeding season and is around 28.5 grams outside the breeding season. Before the pull, fat deposits can be formed and the weight increased to a maximum of 37 g. Apparently this is not the rule.

male

The male has, as the name "red-backed shrike" indicates, a rust-red-brown to chestnut-brown back and shoulder plumage. The top of the head and neck stand out clearly with their light blue-gray. Like other Lanius species, red- backed shrimp have a narrow, black face mask in which the dark eye often disappears visually from a distance. The mask is sometimes delimited by the gray top of the head by an indistinct, faded white stripe over the eyes, which is often more pronounced behind the eye. The feather feathers of the wings are reddish-brown with a distinctly lighter and more reddish border; the hand wings are chestnut brown with a lighter border and the arm wings are dark brown with no border. In rare cases, a white hand swing mirror occurs. This is formed by a more or less pronounced white drawing at the base of the hand wings. The rump is colored gray - partly except for the lower back. The tail shows a contrasting black and white, spoon-shaped drawing: the middle control feathers are mostly black, followed by feathers with a lot of white in the upper area, which increases towards the outer tail feathers. The control springs are narrowly lined with white at the tips. The underside is usually whitish to cream-colored, often the flanks and chest are tinted slightly salmon to pink.

female

Red-backed female, the scaling of the breast is easy to see

In contrast to the male, the female does not show a gray skull. In the female, the entire upper side is a single color, reddish brown, usually a little less vivid than in the male. The face mask is more indistinct, mostly dark brown to blackish, the eye stands out more clearly. On the other hand, the light stripe above the eyes is more evident. The tail is usually monochrome brown with white edges. The underside is cream-colored to beige and shows on the chest and flanks a partly only hinted, partly strong dark scaling (" sparrowing "). This is sometimes very pale on the back. The scaling can fade with age, and the color of the female becomes closer and closer to the male.

variation

The red-backed killer shows great variation in plumage coloring even within local populations in Central Europe. In addition to the normal type described above, males often have significantly grayer individuals, in whom the gray of the head and rump can extend far to the back and also into the shoulder area. The wings of the hand and arm are often slate gray in this morph , so a wing mirror that may be present is particularly noticeable. In a second color variant that deviates from the normal type, the reddish areas dominate and extend far into the neck and back. On the wing, the reddish plumage is not limited to the seams, as is usually the case, but extends to large parts of the flags of the cover plumage and the wings. There is also a wide range of variation in the females, from particularly gray, intensely red-brown and “normal” (rust) brown color types on top.

Fledglings

Young bird

The dark scaling, sometimes only hinted at in females, is much more pronounced in juvenile plumage, extends over the head and back and covers the entire underside. In addition, the back usually has a darker basic color.

Beak and feet

The beak of the red killer is - as with all stranglers of the genus Lanius - strong, laterally flattened and has a pronounced hook as well as a slight perforation just before the tip of the upper bill, which engages in a corresponding recess in the lower bill. At the base it is provided with pronounced beak bristles. In the young birds it is horn-colored with a dark tip, in the adult birds it is black. The black color fades over the course of the year and renews itself annually on the move home. The strong feet are gray-brown in juveniles, blackish in adults.

Mauser

During the juvenile moult, on average between the 28th and 45th day, the small plumage and the middle arm and edge covers are renewed. This dress, which is much more durable and therefore better suited for migration than the first youth plumage, will be worn by this year's birds for about four months. In the winter quarters they change into the dress of the adult birds in a full moult.

In some adult birds, a partial moult takes place towards the end of the breeding season, during which parts of the small plumage and some of the outer arm wings can be replaced. Missing control springs or rockers are often replaced. In any case - both adult birds and this year's birds - a full moult sets in towards the end of the autumn migration, the peak of which is in January and is sometimes only completed at the beginning of the migration in April. If this has not already happened, the entire large and small plumage is renewed. The large feathered moult lasts between 80 and 85 days. In the adult birds, this molt usually starts earlier than in this year's.

voice

singing

Red backs on hold

The singing is a pure courtship song that does not serve to delimit the territory. It often begins and ends with the typical, rough "Jää" sounds and consists of softly chattering rows of pressed, rough tones. These are often alternated with imitations of other species (numerous songbird species, but also non-passeriformes such as partridge , little grebe or snipe ), whereby the imitations are usually much quieter and more pressed than the original. Parts that cause difficulties for the bird can also be left out or replaced by sounds typical of the species. According to reports, an apparently particularly talented male mastered longer passages of the skylark song as well as several variants of the chaffinch strike .

Singing activity

At best, very restrained singing can be heard on the train. The first clear vocal activity starts immediately after occupation of the breeding grounds. Later, the singing can be heard mainly in the presence of females during courtship, after mating only occasionally (e.g. when the female is prompted by her rhythmic tail beating) and not at all after the nest is built. Only after the young have fledged, around July, does the male begin to sing again. The singing of non-breeding males can be heard throughout the breeding season.

The song is usually performed in an upright sitting position with the beak barely open. It can take up to ten minutes or even more. The male often sits high in the trees. The singing activity begins about half an hour after sunrise.

Calls

A harsh “Gwää” or “Gää” can be heard particularly frequently among the calls. It is used to establish contact and is therefore often expressed to young birds in the phase after they have fled the country. A sharper and shorter version of this call is given when aroused - a "Tschä" or "Tschäck". The excitement or alarm call is a stringed, drawn out "Dschrä dschrä dschrä". A loud, hard "Teck-teck" serves as a warning sound in the presence of enemies.

The male's imposing call is a “Tschock”, “Chee-uk” or “Ko-ick”, which instead of a chant of the area is usually uttered while waiting or when flying over the area and responds to the other male or even reacts aggressively.

behavior

The male, in particular, likes to sit - often visible from afar - in waiting areas from which the area can be viewed. These can be shrubs, young trees, fence posts, hay bales , stump walls or other exposed locations. Before the clutch is incubated, the female can usually be found near the male. As a rule, without changing location, people spend a long time in the same control room where the bird rests for a long time, cleans itself or sunbathes. If it gets too hot for it, the red-backed killer looks for shade for a short time. In between, hunting flights, z. B. undertaken on large insects, sometimes these are associated with a change of location. The area owner's favorite control room can change depending on the time of day and the position of the sun. The characteristic approach to waiting is targeted and fast, then the bird brakes briefly and lets itself glide up the last, short stretch.

The flight is mostly straight with irregular wing deflections and - in contrast to other stranglers - without arches. During flights in the area, an average speed of 33.4 km / h was determined.

When danger is imminent at the nest, the body is often bent down, the tail raised and the wing tips flapped sideways. With less excitement, the erect tail is often turned slightly sideways and spread apart.

Overnight stays in bushes with fluffed plumage, the head is not tucked under the wing. Before incubating the clutch, couples spend the night in close proximity to each other.

Red-backed red backs behave territorially all year round. There are no mergers on the train either. Larger gatherings, for example at popular rest areas, only arise by chance. Only at the end of the breeding season, after the young birds have fled out, do non-breeding males sometimes join the families, take part in feeding the young or act as "singers". Sometimes after the dissolution of the families, young birds of different broods socialize with non-breeding bachelors or males whose breeding business has been concluded. With the move, these groups quickly dissolve again. Such loose socializations can sometimes also occur in the winter quarters.

distribution

Brood distribution, winter roosts and migratory movements (schematized)

The breeding area of ​​the red killer is limited to the western Palearctic . In the west its distribution extends to northern Portugal , on the Iberian Peninsula it occurs only in the northern part. In France, it is absent in Brittany , Normandy and the coast of the English Channel . An extensive breeding population on the British Isles has died out (see population development ). In Scandinavia he populates southern Norway and the Baltic Sea region. In the Mediterranean area it occurs in Corsica and Sardinia , in Italy, on the Balkan Peninsula and in Asia Minor, and it also inhabits a narrow coastal strip on the eastern edge of the Mediterranean as far as Israel .

It is largely absent in Sicily , Crete and Cyprus (only 1–2 breeding pairs). South of the Caspian Sea it also occurs in a narrow strip, east of which its distribution ends. To the north of it, however, it extends to about 90 ° east into the Altai . The northern limit of the distribution runs in an arc northeast of the Volga approximately between 48 ° and 64 ° north.

The natural distribution of the species seems to be limited in the northwest by frequent rainfall, in the north by very low minimum temperatures and in the south by very dry summer weather along the 26 ° C July isotherm .

In the east its distribution area overlaps with that of the closely related Isabellus shrike ( Lanius isabellinus ) and that of the red-tailed shrike ( Lanius cristatus ).

hikes

Dry savannah in Tanzania
The Kalahari on the Namibia-Botswana border

The red-backed shrike is a long-distance migrant that overwinters in the southern part of Africa. The main wintering area lies south of the equator and extends, excluding the rainforest zone with the Congo basin, to the north and east of South Africa . Sporadic hibernators have been observed in more northerly areas as far as South Sudan or in more southerly areas as far as the Cape . Most birds winter in Mozambique , Zimbabwe , Botswana and Namibia . Particularly dry areas, such as the interior of the Kalahari , are largely avoided.

In winter quarters, the red-backed killer occupies suitable locations in the thorn bush and dry savannah . It sometimes shares its habitat here with up to 12 native shrike species and the black- fronted shrike , behaves territorially and partially defends its territory against other species. In favorable habitats there is up to one area per hectare.

The migration begins in August and is initiated by the adult birds. The young birds follow 1–2 weeks later. The first red-backed shrimp reach northeast Africa in August and South Africa in September. The withdrawal is usually completed at the end of September. Rare evidence from the breeding areas comes from October. These are mostly young birds from very late broods.

Using the day to eat, the red-backed shrike presumably only migrates at night. There is rest at lunchtime. An investigation on Karpathos revealed a train speed of 70–75 km / h.

In terms of migratory movements, a rough distinction can be made between the European populations and those breeding further east. Those birds that colonize the eastern part of Russia and western Siberia migrate south-southwest across the Arabian Peninsula to winter quarters. To the east there are individual records at migration times as far as the west of the Indian subcontinent . The withdrawal takes place on roughly the same routes: After the flight over the Iranian highlands , the Caspian Sea is circled in the south and the Pamir and Altai are flown around west.

The western populations, on the other hand, show a pronounced loop formation ; the spring migration runs on a route much further to the east than the autumn migration. In autumn, the southern Mediterranean coast is crossed in an area that lies roughly between the Libyan Cyrenaica and the Suez Canal . To reach this area, the populations of Spain or France must first move eastwards and then move south-east across the eastern Mediterranean. The breeding birds of Scandinavia move southeast to south across the Balkan Peninsula and the Aegean Sea . From the edge of the African continent, the train then moves south in a narrow corridor between 25 ° –35 ° east and only fans out again after the rainforest belt. However, individual birds also make their way further west into Chad .

In spring, the European red-backed red-backed birds migrate northwards on more easterly routes south of the equator. These lead over Ethiopia , Northern Somalia and Eritrea , along the coast of the Red Sea to the eastern edge of the Mediterranean and over the Sinai . The Mediterranean is essentially crossed to the east by Cyprus , while the Aegean is flown around by land via Anatolia . The first migrants arrive in the breeding areas in early May.

Based on the migration routes, it was assumed that the evolutionary origin of the species lies in the area around the Caspian Sea and that it spread from there.

Systematics

Geographic variation

The closely related Isabellus shrike forms a super species with the red backed shrike

Some authors treat the species as monotypical, others provide for a subdivision (among other things on the basis of dimensions and plumage characteristics):

External system

Occasionally the Isabel shrike ( Lanius isabellinus ), which occurs in Central and Central Asia , or its subspecies isabellinus, phoenicuroides, speculigerus and tsaidamentis have been described as subspecies of the red killer. Mostly, however, the Isabel Shrike is viewed as a separate species, which forms a superspecies because of its close relationship with the red backed shrike.

Within the so-called “red-backed shrike group” ( L. collurio , L. cristatus , L. isabellinus and subspecies, or L. phoenicuroides and L. speculigerus ), the species status of the red-tailed shrike ( L. cristatus ) is largely undisputed. Hybrids with L. collurio are only known in two cases.

Hybrids

In the overlapping areas of their distribution, there is often a hybridization between red-backed shrike and Isabel shrike (or Turkestan and white-fronted shrike). Numerous types of hybrids have been described and given their own names (e.g. bogdanowi, karelini, darwini, raddei, pseudocollurio, dichraus, elaeagni, infuscatus, zarudnii ), but mainly there seem to be two types of hybrids: In a narrow one Zone in East Kazakhstan and north of the Aral Sea to the northeast of Iran , the red-backed shrike crosses with Isabel shrike of the subspecies phoenicuroides ( L. collurio X L. (i.) Phoenicuroides ), in the southeastern Altai (Kurai Mountains) in Central Asia it mixes with the subspecies speculigerus ( L collurio X L. (i.) speculigerus ), which usually results in fertile offspring.

In seven cases there were also mixed broods with the red-headed shrike , with the female being a red-backed shrike in only one case. In addition, male red-backed male breeds with females of the black-fronted shrike .

habitat

A typical red-backed habitat offers - in addition to thorn bushes - open, insect-rich areas and exposed waiting areas
A farm road, which is lined on both sides by richly structured hedges, offers the red backed an ideal habitat

The red-backed shrimp populates well-manageable, sunny terrain, which has open areas with low or sparse vegetation (e.g. perennial corridors , meadows , dry grassland ) alternating with scattered hedges or woody plants with less than 50 percent coverage. It needs bushes one to three meters high as a waiting area for hunted hunts and territory observation and as a nest location. Thorn bushes such as sloes , hawthorns or dog roses are preferred (see nest and nest location ), but under otherwise favorable conditions they do not have to be present in large numbers.

Accordingly, the red-backed shrike likes to colonize hedge-rich green and pasture land , fallow land , partially drained bogs with dam cultures, orchards and clearings, windthrow and clear-cut areas or young plantings within forests. In natural regions, forest edges or clearings, especially moist locations, e.g. B. Edges of alder quarries or willow forests are important.

The original habitat of the red killer is probably in the transition from closed forests to grass steppes or similar open habitats (e.g. fens or silting zones), i. H. in forest steppes, scrubland and at forest edges as well as various early stages in the succession of forests or regeneration stages after forest fires or storm damage. The preferred thorn bushes are often found in primary habitats in locations that are regularly exposed to browsing by various ungulates .

These habitat requirements predestine the red-backed killer for the extensively used cultural landscape - that is, small-scale habitats divided by hedges and woody plants and characterized by extensive pasture farming. In the course of the Neolithic , when agriculture and cattle breeding developed on a large scale, it is likely to have exhausted the newly emerging settlement possibilities considerably. So it will not only have increased significantly in population numbers and settlement density, but also a significant expansion of its distribution area. The positive effects of small-scale cultivation such as wind protection, drainage or clearing and the cultivation of sunny locations made it possible for the red-backed shrimp to spread to cooler or climatically exposed areas.

With the arrival of intensive agriculture in the second half of the 20th century, this development was reversed: As part of the land consolidation, hedges and trees were removed to enable cultivation with large harvesting machines. The extensive pasture management gave way to intensive grazing or stable keeping , orchards were converted into plantations, natural vineyards were replaced by monoculture-like terraces . Meadows were cultivated more intensively and with high use of pesticides, which u. a. the supply of large insects became scarce and, as a result, led to major population losses across Europe from the 1950s onwards (see population development ).

Today the red-backed shrike can often only be found in suitable peripheral areas in the cultivated landscape, for example on fallow, bushy land, on clear-cut areas and young plantings, also within closed forests, on landfills, gravel pits or motorway embankments and railway embankments.

Settlement density

In densely populated, optimal habitats, the area size is between 0.08 and 1.52 ha, with an average of 0.48 ha. The area size can vary greatly during the breeding season; clear boundaries can often not be determined (see area and pair formation ). Areas are often linear along hedges or borders and have a correspondingly tiny area. In sparsely populated areas such as B. observed in southern Sweden, there can also be territory sizes of up to 3.38 ha.

Normal settlement densities vary, depending on the habitat, between 0.2 (e.g. in open fields) and around 4 territories per 10 ha with favorable habitats such as wet grassland rich in hedges or damp forest fringes. In exceptional cases, however, higher settlement densities are achieved, such as 5.4 breeding pairs / 10 ha on a pasture with a lot of thorn bushes, 6.7 breeding pairs / 10 ha on a landfill at Lake Wannsee or even 15 areas on 10 ha in Slovakia.

nutrition

The red-backed shrike has a wide range of prey for small animals and has a corresponding repertoire of hunting techniques. Insect hunting makes up most of his diet, but he is very effective at expanding it by hunting small vertebrates.

Food spectrum

Large insects, such as beetles or this darter , are the main food of the red killer
Small mammals such as mice expand the food spectrum

When it comes to food for insects, large beetles predominate , and hymenoptera ( bumblebees , bees and wasps ), but also larger two-winged animals , are often represented. These are mainly adults , larvae (for example butterfly caterpillars ) play a role as nestling food. Occasionally, other arthropods such as spiders , woodlice or millipedes , but also earthworms, are added. Snails play a rather subordinate role and are only included in the food spectrum by a few individuals.

In years of field or field vole - gradations they can account for the largest share of the spoils. Otherwise, small mammals ( shrews , wood mice ,  house mice or bank voles ), although they often make up a large proportion of the prey in terms of weight, are more of a food supplement in bad weather. Amphibians can make up a large part of wetlands, and reptiles ( lizards , blindworms and young grass snakes ) are also captured.

Small birds also fall into the range of prey. It rarely is more of adult birds - in which case types to the size of a Goldammer be hunted - and mostly nestlings or fledglings. Above all, young songbirds, especially warblers and finches , but also chicks of larger species such as railings and chicken birds were found . It is possible that these were not hunted, but found dead. On the migration, birds seem to be of greater importance as prey - partly due to the lack of other food, partly because of its good availability. Red-backed shrike have been observed hunting small birds that have been exhausted by migration. At an oasis in Sudan, several species of stranglers, including the red-backed shrike, mainly fed on dead or perishing birds.

Vegetable food only plays a role in the form of berries (for example elderberries , raspberries , rowanberries ) in late summer and autumn. Fruits that ripen early enough, such as hedge or sour cherries, are also fed to the nestlings.

Hunting techniques

The Lauer hunting is mainly used for small mammals are used, but also in insects such as beetles and grasshoppers. From a control room, prey animals on the ground within a radius of about 10 m are attacked. The target flight is straight and can be accelerated with short wing beats. Towards the end there is usually a short gliding flight. Either the prey is flown to directly or the course is corrected again by briefly braking with the wings.

Some of the insects are hunted by air. When hunting insects from a control room, the hunting radius is around 30 m larger than when hunting small mammals. The attempt is made to throw the prey out of the path with a targeted approach and then to grab it. The more straightforward the insect's flight, the higher the hit rate. Bumblebees or butterflies are therefore more often missed. Often insects are pursued at high speed, swarming insects even up to great heights.

Small birds or grasshoppers are sometimes captured on a kind of stalking hunt, whereby the bird approaches in small stages and appears disinterested, only to strike surprisingly. The hunt for other birds is rarely crowned with success, but individuals have been observed who have achieved a high degree of specialization and a corresponding success rate. The red-backed shrike also acts as a nest robber on occasion, a systematic search for nests has been observed less often.

Hunting is sometimes done on foot in hay meadows, which has often been observed in young birds or females, which were impaired by their heavy weight before laying eggs.

Food processing

Defensive hymenoptera such as this wasp are often "unstinged" in a complex process

After a successful hunt, the prey is usually more or less laboriously prepared for consumption and freed from poorly digestible components. In acute hunger, the prey is devoured in large parts or, if possible, in whole. Indigestible components are choked out as spittle balls. With an approximate length of 25 mm, these usually have a diameter of 8–9 mm and disintegrate easily when dry. Vaults with mouse components are usually more compact and can be larger.

Food preparation can take up to ten minutes. In the case of insects, for example, antennae, wings and legs are neatly separated. Caterpillars are hit against branches and worked through from head to end . Snail shells are smashed on stones. Larger fruits or berries are often cut up and skewered on thorns for this purpose.

Spiked insects such as wasps or hornets are usually thrown away immediately after being grabbed by the thorax and picked up again, which is repeated until the prey stops moving. Then an attempt is made to remove the sting by squeezing it out by rubbing it on a firm surface. Using mock-up tests on hand-reared red-backed red-backed birds, it was found that the bird instinctively recognizes the danger from the elasticity and size of the insect's body. In some individuals, however, it was also observed that larger hymenoptera were devoured together with their prickles. The red-backed killer also proves to be insensitive to other defense mechanisms, such as smelly or caustic secretions from some species of beetle.

Vertebrates are killed by a bite in the neck and then cut and eaten from the head. Often the skull is opened first and the brain is eaten. In attempts at dummies, alleged rivals were also attacked with bites in the neck. Insects are also grabbed and crushed behind the head on the thorax, if possible. When holding, the bird never lets itself down on the prey, but only holds it with one foot, whereby it gains stability by placing the walking leg . The feet are also often and skillfully used to carry the prey as well as to "eat out of the fist".

"Skewers"

In general, the red backed hunted insects. In bad weather, however, this can not be very profitable. In order to bridge several rainy days or damp, cold morning hours, for example, he tends to build up supplies by spearing larger prey - mostly small vertebrates, but also larger insects - on thorns or spikes and on barbed wire from pasture fences. Hanging the prey in forks of branches or branches is less common.

The innate behavior of "spitting" is refined through experience in skill. Sometimes the impaling is only used to cut up larger pieces of prey. In this form it can also be observed from time to time in the winter quarters. Mostly (and only during the breeding season) the skewers are used for storage purposes. Storage spaces are usually filled by the male, less often by the female, but both of them make use of it. Storage places are never in the nest bush, but mostly concentrated in the immediate vicinity at one or two places in the area. Decaying loot is removed regularly.

In some cases very extensive storage spaces were found, for example with up to seven mice, as many young warblers or 30 cockchafer .

Reproduction

Territory and pair formation

The males usually arrive in the breeding area first

Red-backed red-backed mates usually only mate for one breeding season. If both males and females return to the same area, re-breeding is possible in the following year. However, this is rare due to the low loyalty of the females to their territory. After the loss of a brood, mating can occur later.

The birds are sexually mature in the first year and usually breed. To do this, however, they rarely go to their place of birth. First breeders without breeding success also very rarely return to the previous year’s territory. Territorial loyalty seems to increase with the age of the birds.

Arrival in the breeding area

Occasionally pair bonds are already formed on the move, but mostly red-backed red backs arrive unpaired in the breeding grounds. The males are usually the first, the females follow up to five days later. If a male does not find a partner within this period, it usually looks for a new territory. For the same reason, females often change their location after minutes.

Shortly after arriving in the breeding area, the males behave rather cautiously, as the arrival of the females approaches, the area behavior becomes more conspicuous. Often the territories are initially very extensive, but can shrink massively under increasing pressure from other arriving males. At the beginning of the breeding process, there can also be another loss of space, as the pair at this point very limited its range of action and the male, instead of defending territory, is primarily concerned with defending the female against rivals willing to mate. The exact dimensions of the territory can hardly be determined, since a defense against intruders usually does not take place at the borders, but only when a rival penetrates the center.

Courtship behavior

Courtship behavior of the nine-killers, below the so-called Nickbalz

As soon as a female comes into the territory of an unpaired male, its singing volume increases and it begins to woo the female with conspicuous flights of praise before it goes to its immediate vicinity, which can be interrupted again and again by the female flying off.

If the male succeeds in staying close to the female, it begins to take it for itself - with constant turning of the head with alternating turning of the white throat and gray skull. After a long period of successful recruiting, the female is ritually fed, which reacts with a slight tremor of wings and spreading the control springs . The feeding intervals are quite short with around 8 feedings per hour on the first day, but they get longer later. Only before the eggs are laid does feeding become more intensive again.

After the first feedings, the so-called "Nickbalz" follows again and again, in which the male, while singing intensely in a rhythmic sequence, alternately lays his head back in an upright posture and stretches his beak vertically upwards and then with his back straight bow away from the female. After initially evading, the female also reacts with a rhythmic nod. After about a quarter of an hour of courting, the female approaches the male of her own accord, followed by small pursuit flights through the branches and a ritualized search for a nesting place.

After the pair formation, the female is hardly left out of sight and is intensely defended against rivals. This is obviously necessary because unpaired males - whose radius of action is usually larger than that of the pairs - try very intrusively to woo already mated females. The phase of disturbance by rivals that are still alone, the proportion of which in Central Europe is mostly constant between 5 and 16%, can extend over several days, as the females usually arrive at the breeding areas extremely delayed.

copulation

The first copulations occur about three days before the egg is laid , and these are repeated until about the end of the laying activity. Copulation is initiated by the male with trembling wings and begging cries, to which the female reacts similarly. This “foreplay” can last 3–10 seconds, copulation lasts between 2 and 4 seconds.

Nest building and nest location

Female red-backed shrub in a dog rose bush

When looking for a nesting site, the male shows various options; the final decision is made by the female.

Thorn bushes 1.5–2.5 m high are preferred as nesting locations. Black and hawthorns , dog roses and blackberries are the most common in Central Europe . In other regions this may be the case. a. Be gorse , holly, or barberry . In the absence of thorn bushes, conifers such as spruce (e.g. on young plantings) or junipers are also accepted. More rarely, but quite often in some regions, the nest is in deciduous trees. Shrubs or trees that offer good cover through dense vegetation with climbing plants such as clematis or hops are particularly popular . Here the nest can also be found near the ground. The height of the nest location usually depends on the height of the vegetation chosen. In bushes it is usually between 80 and 160 cm on average, in trees around 3.5 m in height. In exceptional cases, e.g. In old fruit trees, for example, nests were found at heights of 12 or even 25 m. In response to the loss of the first brood, nests of replacement broods are built at a greater height, i.e. less easily accessible.

The nest is built by both partners within 4 to 6 days. It is cup-shaped and measures around 120 × 140 mm in diameter with an average height of 95 mm. The nesting trough has an average diameter of 70 × 80 mm and is about 50 mm deep.

It usually consists of three different layers: The loose exterior consists of loosely interwoven, coarse stalks of herbs (e.g. clematis , bedstraw , yarrow ), blades of grass or fine branches of shrubs, sometimes coarse material such as tree bark is built in. The middle layer is responsible for the stability of the nest and consists of well-adhering, woolly, voluminous building materials that are tightly joined together, such as moss and fine stalks, plant wool (grass panicles, daisy, willow or cattail seeds), braided roots, feathers or Hair. The inner padding is made of a similar material, but the consistency of which is usually much finer and loosely processed.

In the case of a correspondingly one-sided or rich supply, the nest can also be made exclusively or for the most part from one of the building materials mentioned. For example, nests were found that were only made of chicken feathers or the filling of an old car seat.

Clutch and incubation

Eggs of the red killer
Two eggs of the red killer and one egg of the cuckoo (front left), the color of which is adapted to that of the host bird (for other examples see there )

The eggs are usually laid directly or a few days after the nest has been completed; in individual cases, building continues after the nest has been laid. In southern Germany and the Alps, the earliest laying date is around May 5th, in northern Germany around May 13th, and the main laying time falls in the third May decade. Late knocking out of the vegetation or bad weather can delay the laying activity.

During the egg-laying phase, the female lays an egg every morning in the morning. The female sometimes spends the night on the nest even before laying eggs, but incubation does not begin until the penultimate (sometimes the last) egg has been laid, so that all young birds hatch around the same day.

The clutch consists of 2 to a maximum of 8, mostly 5–6 eggs. These are oval and on average 22 × 17 mm in size. The possible basic colors - whitish (white, yellowish, light gray or beige), greenish or reddish - have a speckle that can vary between different shades of brown. Underneath there is a paler speckle in gray that is differently tinted depending on the color type. The distribution of the speckles can also be quite different.

The incubation, which is carried out exclusively by the female, takes about 14–15 days, and even longer under poor weather conditions. It is usually interrupted every hour by an average of five-minute, maximum quarter-hour breaks, during which the female does not move more than 100 meters from the nest and hunts prey on her own or takes care of the male's "skewer place" (see nutrition ). Otherwise it is fed an average of eight times an hour by the male during incubation.

Hatching of the young birds

The earliest broods hatch in Central Europe in the 3rd May decade, the latest in early August; most of the young birds hatch in the 2nd decade of July. The hatching of the young is prepared up to 10 hours in advance by scratching the egg shell with the egg tooth . During the hatching process, the shell is blown in a lengthy process by violent movements, this takes about 5-6 hours per young bird. It usually takes more than 24 hours from the hatching of the first young bird to the last. Meanwhile, the female travels around on the edge of the nest and works the eggs. After hatching, the eggshells are carried away, unfertilized eggs usually remain there.

Nestling time

The nestling period is 14–16 days, under unfavorable conditions it is 1–2 days longer. During the first three days the male provides the female with food, which hardly leaves the nest. This divides and feeds the feed to the young birds, less often it satisfies their own hunger. From the fourth day onwards, the female interrupts huddling more and more often by hunting flights. After the seventh day, huddling becomes less frequent, but depending on the weather, it can last up to the 10th or 12th day. Both partners hunt and feed, sometimes with different proportions. If a partner fails, a bird can take care of larger broods on its own.

The feeding intensity increases sharply as the young grow. Up to the end of the first week, an average of 9-10 times an hour is fed, then from about 12 to 28 times. If the supply of large insects is sparse, it is increasingly compensated by feeding larger prey, which means that the number of feedings can be significantly smaller, as the portions fed are then larger. The balls of manure are often eaten at the beginning, when the nestlings are older, they are removed and dropped at a distance of up to 90 meters.

With intense sunlight, the female can shield the nestlings with her wings. From the age of around ten days, however, the young birds leave the nest temporarily, either to seek shade or to find a hiding place in the vegetation in the event of disturbances.

Nestling development

Immediately after hatching, the nestlings are naked except for a slight down on the stomach, the eyes are still completely closed. They lie flat in the nest and stand upright when feeding with the locking jaws open. To dispose of faeces, simply lift the rear part vertically upwards.

After two days, the growth of the fletching on the head and back can be recognized by black dots. From the fourth day on the eyes open slowly and the blood kills of the wings pierce the skin. The nestlings now sit with their heads hanging on their rump and heels. When defecating, the rear part is stretched over the edge of the nest.

After 5–6 days the eyes are already open and the feathers of the small plumage open on the chest. Now the nestlings crouch on the edge of the nesting trough and place their beak on the edge of the nest. After about a week the flags of the dorsal plumage open, and small feather tips form on the wings. After eight days at the latest, the eyes have opened completely and the first visual stimuli are recorded. Nevertheless, only from the 11th day onwards, the blocking jaws are purposefully extended towards the parents.

From the 12th day the fletching covers the entire body, after 15 days the small plumage growth is essentially complete. Only shield springs, swing arms and control springs are still very short. The former are fully grown after about a month (26th - 30th day), the rest of the wing needs about 10 days longer (36-40th day), and the thrust reaches a few days later (40th - 42nd day). Day) its full length.

Fly out

Even after they leave, the boys are still fed intensively and run in the family. From the 26th day of life the young birds begin to prey on food themselves, but are only released into independence after at least 37 days. Young red-backed birds are fully grown at 42 days, but families were still observed up to the 47th day where the adult birds were feeding. Such a long feeding time is mostly due to bad weather.

Brood loss and breeding success

When a brood is lost, a new nest is almost always built. The number of eggs is usually lower than on the first attempt. If the loss occurs later than the beginning of July, it is usually not incubated a second time. However, some cases of very late broods have been documented. B. the young birds flown out in September. There are usually no second broods.

The number of nests with total loss is often relatively high (up to 40%). About 70% of the eggs usually reach the hatching stage, an average of 40% of the young birds survive until they fly out. The proportion of unfertilized eggs or those with dead embryos is usually between 2.5 and 5.2%. In pairs with breeding success, an average of 4 young birds fly out. A long-term study in Baden-Württemberg showed that the average number of young birds flown out increases only very slightly with the size of the clutch.

The causes of loss are mostly predators , predominantly corvids (especially jays and magpies ), less often mammals such as domestic cats , marten- like animals or rodents ( dormice or mice ). In exceptional cases broods were also destroyed by ants . The second most common cause was bad weather, with low temperatures in the 2nd half of July having a particularly pronounced effect. Even cold and rainy weather that lasts for several days can result in high losses; the older young birds, which are no longer hacked, are usually particularly affected by this. Man-made losses (e.g. from agriculture, disruption, etc.) can also represent a high percentage.

The red-backed shrike is not infrequently a cuckoo host . The frequency varies in different regions, but there seems to be a particular frequency in Saxony and the surrounding regions.

Inventory development

The intensification of agriculture largely displaced the red-backed shrimp from the cultural landscape

In general, the stock is usually subject to greater local or regional fluctuations. This is due to the short-lived nature of some preferred habitat types: areas such as young plantings or succession stages (such as the former " death strip " on the inner-German border that grew after reunification ) only offer favorable conditions for the red-backed killer for a few years. Often, small-scale habitat losses, such as those that characterize the extensively cultivated cultural landscape (e.g. by cutting back hedges down to the cane), are compensated for by the fact that new breeding opportunities arise elsewhere due to the advancing vegetation development.

Apart from that, the population has collapsed massively in Western and Central Europe, which started in some countries as early as the beginning of the 20th century, in other countries only in the 1960 / 70s. This slump continued into the late 1980s. Since the 1990s, after the large stock losses of the previous decades, there has been a stabilization or even a slight recovery in the remaining stocks in many places.

An extensive breeding population in England and Wales , where the red-backed killer was a widespread breeding bird in the 19th century, shrank to a residual population by 1980, which was completely extinct in 1989. Only in northern Scotland was it still possible to provide evidence of breeding in the 1990s and there have been individual successful broods in Dartmoor since 2010 . Otherwise, the red-backed shrike is extinct in the British Isles.

In the Netherlands , the populations of 5,000–15,000 breeding pairs (1900) fell to 150–220 breeding pairs (1989/90) within a century. A population decline of at least 20% has been reported from other countries. Only in the center of the distribution area, i.e. eastern Central Europe, do the populations seem to have remained stable, although the species was insufficiently recorded here. In the Scandinavian region , where the red-backed killer was even increasing in spread, the population development was at times strongly positive.

In the Atlantic area, the climatic development - towards cooler, more rainy summers - has been blamed for the population decline. The causes in Central Europe, however, are most certainly to be found in the intensification of agriculture and related circumstances such as land consolidation in the 1960s and the massive use of pesticides. But also on the train and in the winter quarters are causes of population decline. Persistent drought in the Kalahari - a major wintering area - may be a cause. In Ethiopia, a significant decrease in migrants was noted in the 1970s, while in Namibia the number of overwinterers decreased.

In 1994 the populations in Europe were estimated at 6.3–13 million breeding pairs. The inventory trend is still slightly downwards. The largest population can be found in Romania, with an estimated 1.4–2.6 million breeding pairs. As in Poland (200,000–400,000 breeding pairs), the trend here seems to be a little upwards. The German population (90,000–190,000 breeding pairs) is largely stable. However, the species is still listed as endangered on some Red Lists of the federal states (e.g. Lower Saxony). In Switzerland the population is estimated at 20,000-25,000 breeding pairs.

In some areas of Central Europe, for example in Austria, the population has continued to recover in recent years. This can be related to the increased protection of the breeding habitats, but also to the positive climate development for the red-backed shrimp.

According to the IUCN , the species is not considered endangered worldwide because its population has not decreased by 30% in the last 10 years.

Others

In many areas of the breeding area of ​​the sparrowhawk warbler , a close relationship of this species to the red-backed killer was observed. Sparrowhawks, for example, are evidently looking for the vicinity of the strangler during the formation phase and even move their territory to the vicinity of another pair if a red-backed killer does not return to its territory from the previous year. Often the nest is built in the same nesting bush. The sparrowhawk warbler does not have a pronounced hate reaction to the red-backed killer, and conversely, the male warblers in particular are aggressively driven away by the red-backed warbler. It is also striking that the breeding area of ​​the sparrowhawk warbler largely coincides with that of the red killer. Various assumptions have been made about the purpose of the bond, which is apparently quite one-sided. One theory is that the stranglers' aggressive defense against the enemy offers protection to the warbler and thus gives it reproductive advantages. It is also believed that synecia is still evolving . However, until more accurate research data is available, these assumptions remain speculation. Similar phenomena were observed in the Orpheus warbler and red headed shrike and - in the east of their distribution - in the barnacle warbler and Isabel shrike.

In Abkhazia , the red-backed killer is preferred by falconers as a decoy to catch sparrows , which in turn are used to hunt quails .

The red-backed bird of the year was 1985 in Germany . In Switzerland he was voted Bird of the Year in 2020 .

literature

Web links

Commons : Red- backed Red-backed Shrike ( Lanius collurio )  - Collection of images, videos and audio files
Wiktionary: Red-backed shrimp  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ Rotrückiger Würger, Lanius collúrio L. Accessed on April 28, 2020 .
  2. ↑ a b c H. Stern, G. Thielcke, F. Vester, R. Schreiber: Rettet die Vögel , FA Herbig Verlagbuchhandlung, Munich / Berlin 1978, ISBN 3-453-02169-X
  3. ↑ a b c ornithologie-niedersachsen.de ( Memento of the original from January 9, 2006 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.ornithologie-niedersachsen.de
  4. ↑ a b Adelung: Grammatical-critical dictionary of the High German dialect from 1793 on zeno.org
  5. ↑ a b c d Neuntödter or Dornbrecher, Dorntreter. In: Johann Heinrich Zedler : Large complete universal lexicon of all sciences and arts . Volume 24, Leipzig 1740, column 298 f.
  6. ↑ Brockhaus from 1911
  7. ↑ Glutz v. Blotzheim, p. 1152 f., S. literature
  8. ↑ a b Glutz v. Blotzheim, s. 1153, p. literature
  9. ↑ E. Stresemann: The Nomenclature Of Plumages And Molts (PDF; 409 kB) In: The Auk , Vol. 80, No. January 1, 1963
  10. ^ Sonogram by E. Tretzel (1964) in Glutz v. Blotzheim, s. literature
  11. ^ Also E. Tretzel (1964) in Glutz v. Blotzheim, s. literature
  12. ^ Sonagram in Panow, p. 53, s. literature
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  14. ↑ a b c Panow (1983), p. literature
  15. ^ Harris & Arnott (1988) in Glutz v. Blotzheim, p. 1204, p. literature
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  17. ↑ L. Fornasi, P. Kurlavičius, R. Massa 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
    Note: The information given in the source "16 ° July isotherm" is, as a comparison with an isotherm map showed, probably a sentence error. The 26 ° July isotherm runs along the southern edge of the distribution area.
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  28. ^ Steiof in 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
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  30. ↑ Drost in Glutz v. Blotzheim, s. literature
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  32. ↑ H. Jakober, W. Stauber: Dummy tests on the Neuntöter (Lanius collurio) , J. Orn. 130, 1989: pp. 247-251
  33. ↑ a b Durango (1950) in Glutz v. Blotzheim, p. 1199, p. literature
  34. ↑ Schreurs (1936) in Glutz v. Blotzheim, s. literature
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  36. ↑ Panow, pp. 55f, s. literature
  37. ↑ a b c d Jakober & Stauber in Glutz v. Blotzheim, p. 1194, p. literature
  38. ↑ a b c d e Glutz v. Blotzheim, p. 1204ff, s. literature
  39. ↑ a b c Panow, p. 52ff, s. literature
  40. ↑ a b Neuschulz (1988), s. literature
  41. ↑ Jakober & Stauber (1981), see : ↑ A very detailed study of nest bushes and nest height . literature
  42. ↑ a b Jakober & Stauber (1981), s. literature
  43. ↑ Chessex & Ribaut / Lanz & Kehrli-Zenger (1979) in Glutz v. Blotzheim, s. literature
  44. ↑ Todte (1983) in Glutz v. Blotzheim, s. literature
  45. ↑ Ash (1970) in Glutz v. Blotzheim, s. literature
  46. ↑ a b Jakober & Stauber (1983) in Glutz v. Blotzheim, pp. 1207f, s. literature
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  48. ↑ Glutz v. Blotzheim, p. 1192ff, s. literature
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  50. ↑ a b Jakober & Stauber (1983) in Glutz v. Blotzheim, p. 1192, p. literature
  51. ↑ Lefranc (1979) in Glutz v. Blotzheim, p. 1194, p. literature
  52. ↑ a b Glutz v. Blotzheim, p. 1194, p. literature
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  54. ↑ Press release of the Royal Society for the Protection of Birds and on birdwatch.co.uk ( Memento of the original from June 5, 2012 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed May 14, 2013 @1@ 2Template: Webachiv / IABot / www.birdwatch.co.uk
  55. ↑ Hustings & Bekhuis (1993), cited 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
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  57. ↑ Ash (1993), cited 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
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  59. ↑ vogelwarte.ch
  60. ↑ Lanius collurio in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on 18 November, 2008.
  61. ↑ Neuschulz (1988), p. 212ff, s. literature
  62. ↑ Panow, p. 46, p. Literature and described in more detail on lanius.ch ( Memento of the original from February 21, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 119 kB), accessed on May 14, 2013 @1@ 2Template: Webachiv / IABot / www.lanius.ch
  63. ↑ The red-backed shrike is the bird of the year 2020. In: birdlife.ch . January 30, 2020, accessed January 30, 2020 .
This article was added to the list of excellent articles on September 10, 2009 in this version .