Rush claws
| Rush claws | ||||||||
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Mask Finfoot ( Heliopais personata ), female |
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| Systematics | ||||||||
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| Scientific name | ||||||||
| Heliornithidae | ||||||||
| Gray , 1840 | ||||||||
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The rush claws (Heliornithidae), also called rush fowl , are a pantropically widespread family in the order of the crane birds (Gruiformes). The little researched family consists of three genera , each with one species . All species are about the size of a duck and live mainly aquatic along inaccessible, densely overgrown bodies of water.
features
anatomy
The physique of the three species is strongly adapted to a predominantly aquatic way of life. The body length ranges from 26 cm in the case of the female dwarf rush claw to 59 cm in the case of the male African rush claw . Rush claws have a long neck and a slender, streamlined body, the beak reaches about the length of the head, is only imperceptibly bent downwards and ends in a point. Unlike many other waterfowl, the toes do not have webbed feet , but rather swim flaps and have sharp claws . The control springs of all rush claws are fanned out and seem to form a plate. The African rush claw has another special feature: It has a claw on the wing that attaches to the first finger and reaches 12 to 18 mm in length. This claw makes climbing in the branches easier. Rush rims show a partly clear difference in weight depending on the species, subspecies and gender. For example, African rush rushes from South Africa weigh twice as much as animals of the same species from western Africa. In addition, males weigh up to 25% more than females. Masked rush claws and dwarf rush claws also show differences in weight between the sexes, but these are not as clear as in the African rush claws.
Coloration and plumage
The plumage of the rush claws is brown or gray-brown in all species on the neck and neck, as well as on the wings and back, and the breast and belly are always light ocher or white. All three types of rush rims have a characteristic feature of a white stripe along the neck, which starts behind or under the eye and runs along the side of the neck down to the nape of the neck. The head is always darker in color than the rest of the body, but some subspecies of the African rush claw, the dwarf rush claw and the female masked rush claw show a white throat spot or a white fore neck. The African rush rail is the only rush rail to have white dots on the neck and arm covers, and the flanks and chest are provided with brown transverse bands. The control feathers are colored dark brown to black in each of the three types. Only one subspecies of the African rush claw ( ssp. Camerunensis ) differs from this color, it is completely black except for the rump and belly. The beaks are brightly colored. All rush claws show a partly clear sexual dimorphism with regard to the fletching. Males of the African and masked rush claw are generally darker in color than females, the males always have clearly more strongly colored throats and necks, often they lack the white throat spot. Female dwarf rush claws have a white front neck, but a reddish-brown, broad stripe on the side of the head. The beak of the African rush rail is bright red, that of the masked rush rail is bright yellow and that of the dwarf rush rail is two-colored. Females of this species have a red or orange upper bill and a yellow-green lower bill, in males the upper bill is gray-black in color. The African rush claw has bright orange or salmon-colored legs with yellow claws on the toes, the masked rush claw greenish legs and the legs of the dwarf rush claw have a striking black and yellow ringing. During the breeding season , males of the African rush rail show a slightly gray fletching on the throat, the upper chest area and the neck, which are white outside the breeding season. Female dwarf rush claws develop a scarlet upper beak during the breeding season, the brown feathers above the eye turn red, and the feathers on the neck and side neck turn cinnamon-colored.
The tail feathers of the African rush rail are strongly stiffened, those of the other two species show only a slight stiffening.
Move
The toes, which are provided with swimming flaps, allow the rushes to swim quickly, while at the same time they do not hinder the birds when walking on land. There rush claws carry the body slightly upright and can reach considerable speeds when running. The strong claws also enable the birds to move about in the branches of trees.
While swimming, the neck and head move back and forth, nodding strongly, similar to darters . Rush claws are also able to keep their bodies very deep in the water, occasionally only the neck and head protrude above the surface of the water. Rush claws are capable of diving, but they rarely make use of this ability. Likewise , the birds rarely fly , although they are good fliers and able to cover long distances. The flight resembles that of ducks with rapid wing flapping . To fly up, the animals need a run-up stretch on the water and, like other waterfowl, run across the surface of the water with flapping wings before they rise into the air. Water is also preferred for landing, the birds rarely land directly in the branches of trees.
voice
Rush claws are capable of a multitude of different vocalizations, but only use them relatively rarely. The African rush rail has a dull, deep hum, especially during the breeding season, but harsh croaks, barks and a gossiping call are also known to be emitted in quick succession. The call known from the mask rush claw is a bubbling gurgling. The dwarf rush rail emits a territorial call that can be heard from afar and sounds like "iiijooo, iijoo, iijooo-iijaaa, iijaa" . Rush claws in distress occasionally make squeaky and growling noises.
distribution and habitat
dwarf rush claw : green;
African rush rail : red;
Mask rush claw : orange
The rush claws are a pantropical family. In their area of distribution, they always inhabit larger bodies of water , mostly rivers that have to be densely overgrown on the bank and inaccessible. Waters near the mouth of the sea are populated as well as large wetlands and waters up to 2000 meters above sea level. Only the heavily overgrown banks of the water are settled. Where available, densely overgrown, large wetlands such as mangrove forests are preferred .
Way of life
Territory and migration behavior
As loners , all rushes defend territories all year round outside the breeding season , which usually consist of a section of water several hundred meters long.
All rushes are largely true to their location and do not leave their territory. However, some individuals, presumably mainly young birds, always seem to cover longer distances in order to find suitable areas unoccupied by conspecifics. Occasionally, dwarf rush claws appear in Trinidad and masked rush claws in western Java , where they do not breed.
Activity and comfort behavior
Rush rushes show the greatest activity in the early morning and in the evening . The animals spend the time between about 9:00 a.m. and 4:00 p.m., floating on the water or sitting on a branch protruding above the water. To sleep , rush rushes usually climb up higher branches in the immediate vicinity of or above the water. The well-known comfort behavior consists of spreading a leg and a wing, fluffing the plumage and bathing in water.
Social and antagonistic behavior
Rush claws are strictly loners outside of the breeding season, who will not tolerate any other individual in the defended territory. Only during the breeding season are pairs and any young birds that may be found together. If individuals from neighboring territories invade, they are attacked instantly by the animal occupying the area and driven away with flaps of their wings and bills.
If rushes feel threatened by predators , they always flee into the dense bank vegetation and hide there by looking for privacy behind branches and low vegetation and remaining motionless. Occasionally, rush rushes dive to escape predators and then hide between floating vegetation by just lifting their heads out of the water. Rare claws flee in flight, rarely and only when there is immediate danger. In general, rush rushes are extremely cautious animals, which immediately withdraw and remain motionless when unfamiliar noises and processes occur.
nutrition
The rushes' diet consists mainly of insects and snails , which the birds look for in the bank vegetation and between floating plants or collect them directly from the surface of the water. Insects flying close to the surface of the water are often caught by the water with a quick flutter. Occasionally larger animals such as frogs are also eaten, and small fish are also captured when the opportunity arises. Rush rushes also consume a small proportion of plant-based food, which mainly consists of seeds and leaves . Rush claws rarely hunt for food by diving for a short time.
Reproduction
Rush claws breed during or shortly after the water peak in the rainy season . In the case of the African rush rushes living in southern Africa, this period falls roughly in the months of September to December, while birds in eastern Africa nest in the months of March to June. Shortly before the start of the breeding season, moulting into the magnificent plumage takes place, and male masked rush claws develop a hump at the base of their beak during this time.
Pair formation
Little is known about the courtship behavior of the rush claws. Male African rush rushes courtship by repeatedly swimming out of a hiding place on the bank and alternately stretching their wings in the air. The female observes the spectacle from the bank, occasionally makes a snapping sound and after a while leads the male back to the bank, where the ritual begins again. In the courtship ritual of the dwarf rush rail, the partners swim around each other in opposing circles, keeping the neck and head flat above the water and lifting the wings slightly.
Nest building and nest location
The nests of the rush claws are tub-shaped and consist of untidily stuck together branches and water plants. Dead leaves are used for lining. The nest is created jointly by males and females.
The nest location is usually a stable branch that protrudes over the water, occasionally nests are also built in dense bank vegetation. If the flood has carried uprooted trees or a lot of branches that have caught on the bank, a nest is often made there.
Clutch and brood
Clutches of the African rush claw and the dwarf rush claw usually consist of two, more rarely three eggs , while the masked rush claw lays five to seven eggs.
Both males and females incubate the clutch. Males of the dwarf rush claw sit on the clutch from late morning to late afternoon and are then released by the female, while males of the other two species breed much less frequently and for a shorter time.
The young birds of rush claws hatch after an extremely short breeding period, which in the case of the dwarf rush claw only lasts ten to eleven days and for the African rush claw only a little more than twelve days. Young birds of the African rush rail and masked rush rush flee the nest and leave the nest at the latest one day after hatching . Young dwarf rush claws, on the other hand, are pronounced nests , initially completely naked, with a short, barely developed beak and still poorly developed legs. The ability of the male dwarf rush claw to transport the young birds by means of a skin pocket under each wing is remarkable, even during the flight. The pocket is formed by a fold of skin that sits at the base of the wing and is closed by the surrounding feathers. The dwarf rush claw is the only bird known to have this ability; no other bird species is capable of transporting young birds in this way.
Systematics
The rush rushes are among the least researched birds, which is why their position within the system has not been conclusively clarified and is the subject of scientific discussion. Traditionally, the rush claws are placed on the basis of comparative studies on muscles and skeleton as well as phylogenetic studies on the crane birds , but their exact position within this order is controversial. In the past, the rush claws were sometimes regarded as the sister taxon of the clawed crane and at times the cranial crane was classified in the rush claw family. However, based on phylogenetic studies , the rails are currently regarded as the closest relatives of the rush rails.
The three species are each placed in their own genera. Since the masked rush claw and African rush claw differ quite clearly from the dwarf rush claw in terms of anatomy and behavior , it was proposed to subdivide the rush claws into the families Podicinae (African and masked rush claw) and Heliornithinae (dwarf rush claw), but this view did not prevail.
- Genus Podica Lesson , 1831
- African rush rail ( P. senegalensis ) ( Vieillot , 1817)
- Genus Heliopais Sharpe , 1893
- Masked rush claw ( H. personatus ) ( GR Gray , 1849)
- Genus Heliornis Bonnaterre , 1790
- Dwarf rush claw ( H. fulica ) ( Boddaert , 1783)
Rush claws and man
Because the habitats of all three types of humans are viewed as hostile to life and are hardly populated, the birds rarely come into contact with humans. Added to this is their long escape distance and inconspicuous behavior. Rush claws do not play a major role as hunting prey for the local population and are only viewed as random prey , which is, however, considered tasty. Due to their predominantly invertebrate diet, the birds are nowhere seen by the population as competition and are therefore not specifically pursued. Rush rushes are not currently used in zoos . The name Heliornithidae is derived from the Greek Helios ( sun ) and Ornis (bird). The reason why the rush rushes are called sunbirds despite their hidden way of life is unclear.
Danger
Although rush rushes live in remote and extremely sparsely populated regions, they will suffer from the loss of their habitat in the long term. Tropical wetlands are being populated and drained by more and more people, and mangrove forests are being cleared. Another danger is the increasing pollution of the waters. The expansion of bodies of water into waterways also poses a threat, as dense vegetation on the banks of the river is particularly important for the birds. Rush rushes occur only in low population densities in the entire distribution area. This fact makes them sensitive to the increasing fragmentation of habitats, which gives rise to small fragment populations, each with a few individuals, which can subsequently suffer from genetic impoverishment . BirdLife International lists the masked rush claw as endangered due to the increasing destruction of the habitat and the associated decrease in the population in recent years, the population is estimated at less than 10,000 remaining animals, and the trend is decreasing. African and dwarf rush claws are currently listed as not endangered, but the habitats of these species are also increasingly being destroyed.
swell
Much of the information in this article is taken from:
- Josep del Hoyo , Andrew Elliot, Jordi Sargatal: Handbook of the birds of the world. Volume 3: Hoatzin to Auks. Lynx Edicions, Barcelona 1996, ISBN 84-87334-20-2 .
The following sources are also cited:
- ↑ CG Sibley, JE Ahlquist. 1990. Phylogeny and Classification of Birds . In: Yale University Press , New Haven, CT.
- ^ CG Sibley, BL Monroe Jr., 1990. Distribution and Taxonomy of Birds of the World. In: Yale University Press , New Haven, CT.
- ↑ Per GP Ericson, Cajsa L. Anderson. Diversification of Neoaves: integration of molecular sequence data and fossils In: Biology Letters doi : 10.1098 / rsbl.2006.0523 .
- ^ MG Faina, C. Krajewskib, P. Houde. Phylogeny of "core Gruiformes" (Aves: Grues) and resolution of the Limpkin-Sungrebe problem . In: Molecular Phylogenetics and Evolution 2007, Vol. 43, No. 2, pp. 515-529.
- ^ RK Brooke, 1984. Taxonomic subdivisions within the Heliornithidae. In: Ostrich Vol. 55, pp.171-173
- ^ [1] BirdLife International (2008) Species factsheet: Heliopais personatus. Downloaded from http://www.birdlife.org on 29/6/2008
Web links
- Rush claws in the Internet Bird Collection
- Birdlife International factsheet, 2008
- xeno-canto: sound recordings - Sungrebe ( Heliornis fulica )
- xeno-canto: Sound recordings - Masked Finfoot ( Heliopais personatus )
- xeno-canto: sound recordings - African Finfoot ( Podica senegalensis )