Dippers
| Dippers | ||||||||||||
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Dipper hunting ( Cinclus cinclus ) |
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Cinclidae | ||||||||||||
| Sundevall , 1836 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Cinclus | ||||||||||||
| Borkhausen , 1797 |
The dipper ( Cinclus ) form the only genus of the Cinclidae family with five species . They are assigned to the order of the passerine birds (Passeriformes) and the subordination of the songbirds (Passeri). The rounded-looking, finch - sized to starling - sized birds occur in Europe and Asia as well as in North, Central and South America. The Eurasian dipper or short dippers ( Cinclus cinclus ) also breeds in northwest Africa. All species live along fast-flowing, oxygen-rich waters, where they mostly feed on aquatic insects and other aquatic invertebrates , some of which are preyed by diving and swimming. Dippers build extensive spherical nests in caves, half-caves or niches, usually very close to the water's edge. The majority of them are resident birds that can stay near the breeding water even in harsh winters as long as it does not freeze over. Only the northernmost populations of the Eurasian dipper and the Pallas dipper (also river dipper, Cinclus pallasii ) are migratory birds. Except for the Rostkehl dipper ( Cinclus schulzi ), no species is endangered.
Appearance
Dipper are compact, large-headed and short-tailed birds with mostly little contrasting brown, gray-black or black plumage. The largest species, the Pallas dipper ( Cinclus pallasii ), measures a maximum of about 23 centimeters, the smallest, the South American Rostkehl dipper, only 15 centimeters. The Pallas's dipper is largely uniformly brown, the gray-water dipper ( Cinclus mexicanus ) is dark, slate-gray, almost without any drawing. The Eurasian dipper and the two South American species are more conspicuous in color. The throat and breast of the Eurasian dipper are pure white, often raised from a reddish-brown edge to the rest of the plumage, the white-headed dipper ( Cinclus leucocephalus ) has a white and black streaked head plumage and a white throat and breast, and are in the rust-throated dipper Throat and chest orange-rust red. In her the bases of the hand wings form a bright wing field, a feature that is also indicated in the white-headed dipper, but is missing in the other species.
The dark brown or dark gray legs and toes are relatively long and strong; the irises of the eyes are inconspicuously dark brown. In the Eurasian dipper and the gray water dipper, the edges of the eyelids are white, which gives the blinking an increased signal effect.
The sexes differ neither in size nor in color. Young birds are usually pale in color and often quite conspicuously spotted with whitish spots.
The dipper's flight is quick and straightforward; mostly it runs close to the water; A clearly purring flight noise can be heard up close. However, the control effect of the short tail does not allow tight flight maneuvers and turns.
voice
Dippers have a rich voice repertoire. The main calls for all species are short, sharp ziit sequences that are quite loud, but are often drowned out by the background noise in their habitat. Therefore, the optical signals, such as the kinking and blinking, or the spreading wings of the South American species, are of particular importance. In a quiet environment, for example, the singing of the gray-water blackbird can be heard over a kilometer away. The singing is often a melodious chirping, interspersed with whistling tones and gossiping, often pressed elements.
distribution and habitat
Although the Cinclidae family consists of only one genus and only five species, the dipper are common on five continents.
The distribution areas of the species are clearly separated except for the Eurasian dipper and the Pallas dipper. These two species inhabit an extensive area in Central and East Asia together without any hybridization being known. In the jointly inhabited areas, the Pallas's dipper mostly, but not exclusively, prefers slow-flowing, larger rivers in lower elevations.
The North American gray-water dipper can be found in the mountains of Panama , but does not reach the Santa Marta Mountains , where the northernmost breeding population of the white-headed dipper is located. Also between this and the Rostkehl dipper in the south of Bolivia there is a striking dividing belt, which also separates the distribution of a number of bird species in South America. In 1995, several sightings of dipper in the Venezuelan state of Carabobo that resembled the gray-water dipper became public. So far, these reports have not been confirmed, so it remains uncertain whether it is a new species, a subspecies or a miscarriage.
The habitats of all five species are very uniform. Everywhere they populate shoreline along fast flowing, clear streams and rivers from sea level to heights of over 4500 meters. They need tree-lined river banks, but avoid rivers in closed, dense forests, especially in coniferous forests. Important characteristics of a good dipper habitat are a high water quality with the water levels remaining as constant as possible, smaller waterfalls, stones and rocks in the river beds as well as unobstructed banks that offer the opportunity to build nests. In winter, the Eurasian dipper, the gray-water dipper and the Pallas dipper can also be found looking for food on the coast of the sea, mostly in the area of the confluences of small rivers or streams.
Most dippers are resident birds that only leave their breeding area in small areas in very unfavorable weather conditions. Regular migratory movements of 1000 kilometers and more are only carried out by northern populations of the Eurasian dipper and the Pallas dipper; Smaller regular migratory movements were also observed in some areas of distribution of the gray-water dipper.
Dippers occupy breeding and winter territories, which are vigorously defended. They encompass the water itself and usually a fringe along both banks. The length of the territorial sections depends on the width of the watercourse and its creditworthiness; it ranges from a few 100 meters to more than two kilometers.
Food and subsistence
All five species of dipper are carnivores . They feed mainly on living in and around the water invertebrates that diving species (Eurasian dipper, Pallas dippers and Dipper) mainly by larvae of caddis flies , mayflies , stoneflies , blephariceridae and blackflies . In the South American species, small animals predominate on stones and in the bank. In addition, various other invertebrates living on the water, mosquitoes , worms and snails, daphnia and hippopotamus , small fish and fish spawn, and occasionally tadpoles are also eaten. Vegetarian material is only picked up by chance; the indigestible parts of the food are excreted in small balls of speech.
The three diving species prey largely on their food under and on the water, either by wading in shallow water, swimming on the surface or by diving. The two South American species do not appear to be diving or swimming. They peck their prey from stones in the river bed or on the banks of the water. Air hunts occur when there are large numbers of flying insects.
behavior
In addition to diving and swimming, which distinguish the dipper among songbirds, two other behaviors are characteristic of them: kinking and blinking. When kinking, which the three Holarctic species show intensely, the white-headed dipper less strongly and the Rostkopf dipper almost not practiced at all, the birds briefly buckle in the heel joint so that the entire bird appears to crouch. The kink intervals shorten with increasing excitement. Dipper , the English name for the dipper , is derived from this movement. The South American species have a white markings in the wing, which is not visible when the wing is on; in order to present these, the arm wings are fanned out slightly at short intervals. Both behaviors are likely to be of communicative importance.
The blinking of dippers is no more common than in other songbirds, but it is more noticeable because some species have white-rimmed eyelids. Here, too, a communicative function is assumed in addition to the purely physiological one.
Three types of dippers dive and swim. The two South American representatives do not seem to do this, or only rarely. When swimming the birds paddle with their legs; they can also navigate skillfully in current-rich stretches of water and immediately fly out of the swimming position. Dippers that have not yet fully fledged can swim. When diving, dippers plunge headfirst into the river bed from stones or dive in from the swimming position. Occasionally, especially when trying to evade a bird of prey attack, they also disappear from flight. Underwater the birds row their wings, especially the arm wings serve as paddles. On the bottom of the water they run against the direction of the current with their tails raised; with the claws of their big toes they can hold on securely on slippery ground. The dives last an average of 5–10 seconds, but occasionally up to thirty seconds. Sometimes nests that were temporarily inundated by floods and in which the young could survive in an air bubble are reached by diving.
Breeding biology
Dippers have a seasonal marriage; Reparations from last year's partners are common in some species; Polygyny is also likely to be not uncommon. All species build extensive spherical nests, which are used several times, at least in the Holarctic species, and can thus grow over the years to form extensive structures with a diameter of almost half a meter. Both partners are involved in nest building; it is noticeable that the materials are often installed wet. The nests consist of at least two, sometimes three layers: an outer layer is tightly woven from moss, the inner bowl consists of grass, leaves, animal wool and other soft materials. The side entrance, sloping downwards, is located directly above the flowing water. Often the nest lies in a crevice in a rock, in a niche in the bank scree or in crevices and caves of block structures, often under the roots that have been washed out. Cornices and niches on structures such as bridges or mills are also used as nesting sites. The Eurasian dipper also gladly accepts nesting aids. Completely exposed nests were not found in any species. Due to the proximity of the water, flood events are the most common cause of egg loss. The Eurasian dipper and the gray-water dipper often breed twice a year, with the other species nothing is known about second broods.
The clutches of the well-researched Holarctic species consist of 3–6 elongated oval, pure white, matt-glossy eggs. Little is known about the clutch size of the two South American species, mostly clutches were found with two, also white eggs. The incubation period varies between 14 days and almost three weeks; the nestling period is twenty to 25 days. Apparently only the female breeds; Both partners take care of the rearing of the young and the care during the subsequent tour.
Adjustments to the habitat
Dippers among the songbirds have adapted most strongly to their aquatic habitat and show a number of adaptations to this ecological niche . In addition, at least three of the five Cinclus TYPES there are few songbirds that dive for food assistance, including pottery birds of the genus Cinclodes and the six types of scissors tails of the genus Enicurus . The following information applies in particular to the swimming and diving species Cinclus cinclus , C. pallasii and C. mexicanus .
- The plumage is particularly rich in fur down and is therefore an excellent thermal insulator.
- The price gland is 6 to 10 times larger than that of songbirds of comparable size. The Eurasian dipper and the gray-water dipper are the only representatives of the songbirds to have functional salt glands .
- The nose and ears are reflexively closed by a membrane or skin folds when submerged.
- The eyes' ability to accommodate is very great. The eyes of less specialized land-dwelling songbirds accommodate up to 12 dioptres, those of dippers over 50 dioptres. This enables the different refractive indices of water and air to be compensated and thus enables sharp vision both above and below water.
- The short wings, which are very flexible at the tips, are specially adapted to rowing underwater, but also enable fast, straight flight.
- The tail is short and strong and ends in a straight edge; Set up against the direction of flow, the flow of water pushes the bird onto the bottom of the water; this ensures an energy-saving search of the water bed; However, its control effect is not sufficient for tight flight maneuvers.
- The arm-swinging moult is very quick and not progressive, as with most songbirds, but in three successive phases; this means that there is no instability during the swing moult when diving.
- The particularly strong chest muscles enable rowing movements with the wings under water. This also results in the rounded body shape of the dipper.
- The legs are sturdy and strong to hold on to the current underwater and to be able to walk underwater.
- As with many diving birds, the bones are not very pneumatized and thus increase the specific weight.
Systematics
Due to their morphological and behavioral similarities, the dippers were until recently placed in close relatives of the wrens . It was only the DNA-DNA hybridizations carried out by Sibley and Ahlquist that cast doubt on this assessment. Sibley and Ahlquist placed the dipper between the thrushes (Turdidae) and the waxwings (Bombycillidae). A new study, which is based primarily on sequencing the mitochondrial cytochrome b gene , confirms that the dippers are related to the waxwings and wrens, but clearly shows that the thrushes (Turdidae) are most closely related to the dippers. However, the mockingbirds (Mimidae), which are also suspected to be closely related, were not taken into account in this series of studies . The most recent biogenetic analyzes place the dipper in the close relationship of both thrushes and starlings (Sturnidae). Voelker suspects that the immediate ancestors of today's Cinclidae developed a little more than 4 million years ago in Eurasia and that North and a little later South America were settled around 3.5 million years ago. His opinion is in contrast to other authors who suspect the ancestors of the dipper in North America. However, the assumption of a Eurasian origin seems to be increasingly favored. A relationship with the thrush was already obvious for Buffon , who referred to the dipper in 1775 as the "swamp thrush" ( Turdus palustris ).
The genus Cinclus as the only genus of the Cinclidae family comprises five species, of which the two Old World species and the two South American representatives are sister species .
- Eurasia and Northwest Africa
- Dipper , also Eurasian dipper C. cinclus ( Linnaeus , 1758 ) - 13 generally recognized subspecies
- Pallas dipper C. pallasii Temminck , 1820 - 4 recognized subspecies - is also often called river dipper.
- North and Central America
- Gray-water blackbird C. mexicanus swainson , 1827 - 5 recognized subspecies
- South America (Northern Colombian Andes to Northern Argentina)
- Rostkehl dipper C. schulzi Cabanis , 1882 - monotype
- White-headed dipper C. leucocephalus Tschudi , 1844 - 3 recognized subspecies
Life expectancy, existence and exposure
Very little data is available on life expectancy. Overall, youth mortality appears to be very high. For C. cinclus the maximum age determined so far is 8.5 years, for C. mexicanus almost 7 years.
In addition to the numerous natural enemies such as martens , rats and birds of prey , meteorological events also influence the population; these are above all floods during the breeding season and the widespread freezing of the breeding waters. Influences that endanger the existence of the population at least regionally were and are of an anthropogenic nature: These include, above all, water barriers, removal of wood on the banks, introduction of pollutants into the breeding waters, the construction of hydropower plants and leisure activities. For a long time, dippers were also directly pursued as supposed fish spawn robbers. Except for the Rostkehl dipper, no species is endangered. However, reliable data on the population is only available for the European dipper, the Japanese dipper and the North American dipper. The population of the gray-water dipper is stable, that of the Eurasian dipper has recovered in the last twenty years after significant declines from the 1960s, so that suitable areas are occupied at a high level in most of their range.
literature
- Hans-Günther Bauer, Peter Berthold : The breeding birds of Central Europe. Existence and endangerment. 2nd Edition. AULA-Verlag, Wiesbaden 1997, ISBN 3-89104-613-8 , pp. 322-323.
- Einhard Bezzel, Roland Prinzinger: Ornithology. Ulmer, Stuttgart 1990, ISBN 3-8001-2597-8 .
- Urs N. Glutz von Blotzheim (Hrsg.): Handbook of the birds of Central Europe. Edited by Kurt M. Bauer and Urs N. Glutz von Blotzheim, among others. 17 vols. In 23 parts. Academ. Verlagsges., Frankfurt am Main 1966ff., Aula-Verlag, Wiesbaden 1985ff. (2nd Edition). Vol. 10, Part 2, ISBN 3-89104-435-6 , pp. 958-1020.
- David Brewer, Barry Kent MacKay: Wrens, Dippers and Thrashers . Yale University Press, New Haven / London 2001, ISBN 0-300-09059-5 , pp. 19, 62-63 and 199-202.
- Gerhard Creutz: The dipper . (= Neue Brehm Library. 364). A. Ziemsen Verlag, Wittenberg 1986, ISBN 3-7403-0008-6 .
- Jochen Hölzinger (Ed.): The birds of Baden-Württemberg. Singvögel 1. Ulmer, Stuttgart 1999, ISBN 3-8001-3493-4 , pp. 244-264.
- Hugh E. Kingery: American Dipper (Cinclus mexicanus). In: The Birds of North America Online. (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca 1996.
- Gary Voelker: Molecular phylogenetics and the historical biogeography of dippers ( Cinclus ). In: Ibis. Volume 4, Issue 3, 2002, pp. 577-584.
Web links
- Summary of the dipper, illustrations and singing example
- Cinclus on the IUCN Red List of Threatened Species.
- Videos, photos, and sound recordings of Cinclidae in the Internet Bird Collection
Individual evidence
- ↑ Brewer (2001) pp. 199-202.
- ↑ Brewer (2001) p. 204.
- ↑ Voelker (2002) pp. 581-582.
- ↑ Brewer (2001) p. 204.
- ↑ Brewer (2001) pp. 199-202.
- ↑ Creutz (1986) p. 127.
- ↑ HBV (1985) Volume 10/2, p. 957.
- ↑ Bezzel & Prinzinger (1990) p. 44, p. 153.
- ↑ cit. according to Voelker (2002) p. 577.
- ↑ Voelker (2002) p. 577ff.
- ↑ Brewer (2001) p. 19.
- ↑ Ormerod, S. & Tyler, S. (2016). Dippers (Cinclidae). 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. (retrieved from http://www.hbw.com/node/52314 on October 29, 2016).
- ↑ Voelker (2002) p. 577.
- ↑ Histoire naturelle, générale et particulière, avec la description du Cabinet du Roi, eighteenth volume (1775) ( Memento of the original of November 27, 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.
- ↑ Creutz (1986) p. 130.
- ^ Kingery (1996) Life Span And Survivorship
- ↑ HBV (1985) Volume 10/2, p. 999.
- ^ Kingery (1996) Life Span And Survivorship
- ↑ Cinclus schulzii in the IUCN Red List of Threatened Species .
