Storks
| Storks | ||||||||||||
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White stork ( Ciconia ciconia ) |
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| Systematics | ||||||||||||
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| Scientific name of the order | ||||||||||||
| Ciconiiformes | ||||||||||||
| Bonaparte , 1854 | ||||||||||||
| Scientific name of the family | ||||||||||||
| Ciconiidae | ||||||||||||
| Sundevall , 1836 |
The storks (Ciconiidae) are the only family of the Ciconiiformes and with six genera and 19 species distributed in all continents except Antarctica . These birds are characterized by their long neck, long legs and large, often elongated beak. All storks are carnivores, but the diet varies depending on the species. The most famous stork in Europe is the white stork ( Ciconia ciconia ), other well-known representatives of this group are, for example, the marabou ( Leptoptilos ) and the very hungry ( Mycteria ibis ).
features
Storks are medium to very large birds. The size ranges from 75 cm ( Abdimstorch ) to 150 cm ( saddle stork , marabous), the weight from 1 kg ( gaping beaks ) to 9 kg (marabous). Characteristic are the long legs and the long neck, while the tail is very short. Outwardly, they resemble the related herons , but usually appear larger and heavier.
The beak is always large, but very different in shape. A long, slender beak is only found in the main genus Ciconia . In contrast, in the saddle stork , giant stork and Jabiru it is powerful and slightly curved upwards, but especially large and voluminous in the marabous, where it grows throughout its life and can reach 35 cm in length; it appears that this beak is mainly used to drive food competitors away from cadavers. The very hungry beak and its relatives have a slightly downwardly curved beak, at the tip of which are sensory cells that are helpful in tracking down food in murky water. The gaping beaks have a gap on both sides between the upper and lower beak; this beak is used to open snail shells.
In the stork's foot, the first toe points backwards and the other three forwards (anisodactyl). Webbed found only stunted toes on the base. The long legs allow you to walk slowly. Storks rarely move over short distances with quick steps.
The wings are big and wide. They are well suited for gliding, which is only occasionally interrupted by slow wing beats. With a wingspan of 320 cm, the marabous in the bird kingdom are only surpassed by a few albatrosses and pelicans . Maraboos fly like herons with their necks drawn in, while for all other storks a flight pattern with a stretched neck is typical, which can also serve as a reliable distinguishing feature to the herons. When storks fly in groups, they do not form formations.
The plumage consists of black and white tones, which are distributed differently depending on the species. The black parts of the plumage often have a metallic sheen. This intensifies during the breeding season, when white plumage also looks brighter. This is all the more true for the featherless parts. Many species have a completely featherless face, with the marabou these bare parts reach far down the neck. The very hungry and his relatives protect themselves from contamination of the plumage when they look for food in the mud; the marabous can bury their heads deep in carcasses without damaging the plumage.
A slight size dimorphism in favor of the males exists in all species, this is only noticeable in the saddle stork and giant stork.
Contrary to what is often claimed, storks are not voiceless. There are croaking, squeaking and mooing sounds. The species of the genus Ciconia emit whistling sounds; these are particularly pronounced in the black stork, much less so in the white stork. Better known than these sounds is the clatter of bills, which is most developed in the white stork.
distribution and habitat
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Storks are common in large parts of Eurasia, Africa , Australia and South America ; in North America , however, they only inhabit the extreme south. Most species are native to the tropics ; only three species live in the temperate zones.
Storks are bound to water and temporarily damp habitats to very different degrees. The very hungry and the gypsies can be found near the shore for life, while marabous and Abdim storks often stay far away from the water in the open savannah . Most species, however, live at least near swamps, lakes, or river banks.
Since the migration of white storks is so famous, it may come as a surprise that most storks are not migratory birds . They stay close to their breeding grounds and move around relatively small areas outside of the breeding season. The white stork, on the other hand, is one of the pronounced long-distance migrants . Representatives of some northern European populations travel 20,000 km annually to reach the African winter quarters and return to the breeding areas. The black stork and black- billed stork also breed in the temperate zone and migrate to tropical regions in winter. With the Abdim stork, a tropical species is also a real migratory bird: It breeds in the steppes and semi-deserts north of the equator and winters in the East and South African savannas.
Way of life
activity
Storks are diurnal birds. Only the forest stork has been observed fishing at night, the other species are dormant at night. In the tropics, storks are particularly active in the morning and evening hours, while in the temperate latitudes the activity is spread over the whole day.
Many storks are very vulnerable to changeable weather conditions. For example, rain and cold can cause the white stork to give up its brood. Standing on one leg is interpreted as a remedy for heat loss, in which one leg is warmed by the plumage and so less feathered skin is less exposed to the cold. The sticking of the beak into the plumage of the neck could serve a similar purpose.
However, in most stork habitats, heat is a bigger problem than cold. Spreading your wings, straightening your feathers, and defecating on your own feet are all means against the heat.
nutrition
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Storks are carnivores . Although there are great differences in the food spectrum of the individual species, fish , frogs and rodents, along with insects, are the main food for most storks.
The white stork and the woolly stork and their relatives of the genus Ciconia , with the exception of the Abdim stork , are food opportunists. Even if, according to popular belief, frogs seem to be the most important food for a white stork, in reality they form only a small part of the diet. The larger share is made up of fish, tadpoles, snakes, lizards, voles, moles and hamsters, as well as large insects - white storks are known for eating grasshoppers in African winter quarters. The capture of weasels, young goats and cats is documented, but occurs only in rare cases. These real storks usually sneak up to their prey with slow steps and then strike with lightning speed with their beak.
Similarly, the feed ephippiorhynchus and Jabiru , but mainly by larger prey. A jabiru's prey is the size of a young caiman . The Little Adjutant (Sunda Marabou) is also primarily a fish eater.
The Abdim stork, a close relative of the white stork, has a different diet. He is a bird of the open savannah with no ties to the water. Its diet consists almost entirely of insects, especially grasshoppers and caterpillars. Instead of sneaking up on prey, it moves very quickly when it snaps and eats.
The Glutton specialize in hunting in very shallow water, which is often muddy and cloudy. Since their eyes cannot see anything in this water, they move through the water with their beak submerged. They stir up the mud with their feet to scare away prey. If a prey comes into contact with the beak, the stork grabs immediately. Food is small fish, crustaceans and aquatic insects. A special feature in this kind of milky stork , which has specialized in the mangrove mud Springer dig.
Gypsies have specialized entirely in water snails , especially apple snails . They hardly ever take any other food. The screw housing is loosened under water. With the upper beak, the snail is pressed against the base, while the sharp lower beak penetrates the operculum and separates the muscle that holds the snail in the shell. Then the snail is pulled out of the housing and eaten. However , it is a myth that the snail is cracked open in the eponymous opening of the beak like a nutcracker .
The marabou and the great adjutant (Argala-Marabu), who work as scavengers, follow a different diet . Their beak is unsuitable for opening a carcass, so this task has to be taken over by other animals. Then the meat is pulled from the carcass, pieces weighing up to 1 kg are devoured in one piece. On the carcass, maraboos compete with vultures , hyenas and jackals . Their powerful beak serves primarily as a weapon to assert themselves against the competition. But marabous are not exclusively scavengers - like other storks, they also prey on fish, amphibians and rodents. In Africa, maraboos sometimes attack flamingo colonies to prey on eggs and young, but also adult birds. These are drowned by pushing the head under water. A permanent presence of marabous can cause an entire colony of flamingos to give up the brood and flee.
Reproduction
Several species of storks breed in colonies that can contain up to a few thousand individuals. This is especially true for the gape bills, the insatiable, marabous and the Abdim stork. The white stork and some other species of the genus Ciconia also breed in loose colonies, in which the neighbors largely ignore each other. Sometimes there are mixed colonies in which storks breed together with pelicans, ibises , herons or other stork species. In addition to these colony breeders, there are also strictly solitary storks, for example the black stork and the saddle stork.
Storks usually nest on trees. Only the Maguaristorch breed predominantly on the ground, with all other storks high nesting sites predominate, although, for example, the roofs of buildings have now replaced trees as preferred nesting sites for the white stork. In the case of pronounced colony breeders, the male first fights for territory after arriving in the breeding area; this can also lead to serious fighting. New couples form every year. In contrast, the solitary species maintain lifelong pair bonds.
It is often not necessary to build a new nest. Solitary species usually use the same nest every year, the colony breeders occupy an existing nest within the colony, but rarely that of the previous year. Nevertheless, fresh nesting material is always added. A stork's nest consists mainly of branches and twigs. Often it also serves as a breeding ground for smaller birds; These build their own nests outside and thus strengthen the stork's nest with their own material.
Usually three to five, rarely one to seven eggs are laid. The size of an egg varies between 5.5 cm (Abdim stork) and 8.5 cm (Marabu), the weight between 58 and 146 g. The eggs are incubated by both partners for 25 to 38 days. The hatched boys usually wear a white down dress, in the Maguaristorch a black dress. The young are peaceful with one another, so that often the entire brood can be brought through. Both partners are responsible for the procurement of food. After fifty to one hundred days, the young storks fledge.
The potential life expectancy of storks is over twenty years. A ringed white stork was proven to be 33 years old. In captivity, storks can get older; the record here is 48 years.
Tribal history
Storks have been known to be fossils since the Oligocene . The oldest known species is Palaeoephippiorhynchus dietrichi , which was found in fossils in Egypt; the older Eociconia sangequanensis ( Eocene , China) has doubts as to whether it is really a stork. The recent genera of the "real" storks ( Ciconia ), the marabous ( Leptoptilos ) and the saddle and giant storks ( Ephippiorhynchus ) are already known from the Miocene .
Systematics
The most common system of storks is based on M. Philip Kahl , who established the genera that are still valid today in the 1970s and divided them into three tribes :
- Tribe Mycteriini
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Gluttonous ( Mycteria )
- Forest stork ( M. americana )
- Milk stork ( M. cinerea )
- Gluttonous ( M. ibis )
- Colored stork ( M. leucocephala )
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Gaping beaks ( anastomus )
- Moor's beak ( A. lamelligerus )
- Silver beak ( A. oscitans )
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Gluttonous ( Mycteria )
- Tribe Ciconiini
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Real storks ( Ciconia )
- Black stork ( C. nigra )
- Abdim stork ( C. abdimii )
- Woolly necked stork ( C. episcopus )
- Hump stork ( C. stormi )
- Maguaristorch ( C. maguari )
- White stork ( C. ciconia )
- Black- billed stork ( C. boyciana )
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Real storks ( Ciconia )
- Tribe Leptoptilini
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Large storks ( Ephippiorhynchus )
- Saddle Stork ( E. senegalensis )
- Giant stork ( E. asiaticus )
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Jabiru
- Jabiru ( J. mycteria )
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Marabou ( Leptoptilos )
- Sunda marabou ( L. javanicus )
- Marabou ( L. crumeniferus )
- Great adjutant ( L. dubius )
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Large storks ( Ephippiorhynchus )
In 1997, biologist Beth Slikas performed a molecular genetic analysis to verify the classification. This resulted in a broad agreement with Kahl's system. According to this, the Gluttonous and Gapbills are actually sister taxa, and a close relationship between the large storks and the Jabiru was confirmed; however, the marabou could not be accommodated in this system. A sister group relationship between the Ciconiini and the large stork Jabiru clade was considered likely. Their monophyly could be demonstrated for all genera .
This results in the following cladogram :
| Storks (Ciconiidae) |
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Storks and people
Interrelationships
People have had very positive relationships with some species of stork for a long time.
In Europe, the white stork is tolerated on the roofs of buildings, the same applies in Africa to the Abdim stork and in India to the colored stork. In connection with the white stork there is a legend in Europe that it brings the babies. In the Middle Ages, the term “man's stork” was used to describe the penis . In many parts of Europe, a stork figure is placed in front of the house after a child is born.
The Abdim stork is also called the rain stork in Africa because its arrival in the breeding areas coincides with the beginning of the rainy season. The belief in a connection is so strong in some places that podiums are built in villages around Lake Chad to serve as a nesting place for the stork.
The maraboos, on the other hand, are less highly regarded. With their large areas of unfeathered, bare skin, they are considered ugly, and most of them live on carrion and go to garbage dumps near African and Asian cities to look for something to eat. In Calcutta , in the 19th century, the Argala marabou is said to have made amends on corpses that were lying in the streets.
Storks are also eaten in some places . In ancient Rome the white stork was still considered a delicacy and was by no means protected. The milk stork in Sumatra and the Maguaristorch in Venezuela are still eaten today.
Threat and protection
Various stork species are considered threatened. In Europe, Africa and America the stocks are relatively secure. In Europe and Africa this is due to the high importance of the storks, in America to their large distribution area. It is different in Asia, where the majority of stork species are at home. Many species here are endangered for various reasons.
The population of the white stork was estimated at 500,000 to 520,000 individuals in 2009. The black stork is much rarer in Central Europe, it has a population of up to 44,000 animals worldwide. Both species are therefore not considered endangered. However, the following species are considered endangered:
- Black-billed stork: Today this species breeds in the far east of Siberia and winters in eastern China. It died out in Japan in 1970 and in Korea in 1977. Even in today's area of distribution, the storks are threatened by forest clearing, draining and overfishing.
- Mute stork : This species only has a small range in Sumatra and Borneo . The destruction of the rainforest is primarily responsible for the decline of the species, whose population was estimated to be less than 300 animals in the 1990s.
- Argala marabou: This marabou has seen a particularly dramatic decline. It was extremely common in the 19th century. A colony in what is now Myanmar is said to have included millions of individuals; in Calcutta it brooded on the roofs of houses. Today the species is restricted to the Indian state of Assam . The massive felling of nesting trees played a role in the decline of the species, but overall the reasons for the extremely rapid population decline are unclear.
Sources and further information
Sources cited
Most of the information in this article has been taken from the sources given under literature; the following sources are also cited:
- ^ Walter E. Boles: A review of the Australian fossil storks of the Genus Ciconia (Aves: Ciconiidae), with the Description of a New Species . In: Records of the Australian Museum Volume 57, 2005, pp. 165-178.
- ^ M. Philip Kahl: A revision of the family Ciconiidae (Aves). In: Journal of Zoology 1972, No. 167, pp. 451-461.
- ^ M. Philip Kahl: Family Ciconiidae, storks. In: Check-list of Birds of the World. Volume 1, 1979, pp. 245-252.
- ↑ Beth Slikas: Phylogeny of the Avian family Ciconiidae (Storks) based on cytochrome b sequences and DNA-DNA hybridization distances . In: Molecular Phylogenetics and Evolution Volume 8, No. 3, 1997, pp. 275-300
- ^ Http://www.ma-gazin.de/der-storch-wars-wo-die-babys-real-herkommen/
- ↑ BirdLife International: Species Factsheet - White Stork ( Ciconia ciconia ) . Retrieved November 19, 2011.
- ↑ BirdLife International: Species Factsheet - Black Stork ( Ciconia nigra ) . Retrieved November 19, 2011.
- ^ Ciconia boyciana in the IUCN Red List of Threatened Species . Retrieved November 19, 2011.
literature
- Josep del Hoyo et al .: Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions, 1992, ISBN 84-87334-10-5 .
