Yellow bale

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Yellow bale
Yellow Rail.jpg

Yellow jelly ( Coturnicops noveboracensis )

Systematics
Sub-stem : Vertebrates (vertebrata)
Class : Birds (aves)
Order : Crane birds (Gruiformes)
Family : Rallen (Rallidae)
Genre : Coturnicops
Type : Yellow bale
Scientific name
Coturnicops noveboracensis
( Gmelin , 1789)

The yellow beak ( Coturnicops noveboracensis ) is a relatively small species of bird in the bail family . Its distribution extends mainly over the northern parts of temperate North America east of the Rocky Mountains , where it breeds in swamps, sedge beds and wet meadows. Like many rails, the species lives very hidden, but is noticeable during the breeding season by the nocturnal, clicking courtship calls of the males, which sound like the rhythmic clashing of small stones. It winters on the Atlantic coast and the northern Gulf of Mexico from North Carolina to Texas . The locally restricted occurrence of its own subspecies in Mexico has not been confirmed since 1964.

description

With a length of 16–19 cm, the yellow jelly is roughly the size of a star . The wing length is between 73 and 93 mm in males and between 78 and 91 mm in females. Males weigh 52–68 g, females 41–61 g. Outwardly, the sexes hardly differ. In the male in the breeding plumage, the approximately 12-15 mm long beak is yellow and turns olive-green to blackish olive-colored after the breeding season, in the female the yellow coloration occurs only in exceptional cases. The iris is brown to red-brown, the legs and feet are reddish gray-brown, brownish or greenish.

Adult birds are predominantly blackish-brown on the forehead, crown and neck, reddish black-brown on the lower neck and upper back, and black on the back, shoulders, rump, tail and umbrella feathers . The individual feathers are lined with a wide, warm yellow-brown, with the feather hems on the top forming a pattern of longitudinal stripes. Each feather has at least two narrow, white cross bands. The pattern is fine on the head and neck, and much coarser on the rest of the top. Like the sides of the head, the broad stripe above the eyes is light yellowish-brown in spots. The black rein and a dark field that extends from the eye over the upper ear covers stand out. The chin and throat are whitish with a yellowish beige tint. Front neck and chest are yellow-brown, chest and flanks a little pale yellow-brown. The individual feathers have a very variable, diffuse dark brown end hem. The lower middle of the chest and the lower abdomen are whitish to creamy white. The wings of the hand are dull brownish; the inner ones often with a whitish lace border, the outer one on the outer flag white except for the distal part. The wings of the arm are predominantly white and only in the basal part and on the outer flags of the outer three are brownish gray - a feature that is noticeable in flying birds. Fittich and hand covers are brown-gray and sometimes have a fine, white subterminal tape. The outer flag of the outermost aluminum spring is white. The arm covers correspond in color to the back. Axillary feathers and under wing coverts are white except for gray-brown bases.

There is a lack of clarity in the literature about the correct description of the first simple dress. According to some authors, immature birds are overall darker than adult birds, others describe them - conversely - as paler and lighter. The youth dress has not yet been described. Downy young are completely black with a greenish sheen on the crown and throat, a light pink beak that turns whitish after about 16 days and greenish after 24 days. Legs and feet are gray-brown. It has a small wing claw.

Mauser

The pre-juvenile moult begins at 12 days of age when the first beige feathers can be seen between the black dunes. After 18 days, the feathers of the youth dress predominate. The growth of the swing and control springs is completed after about 35 days. The juvenile moult only affects the body plumage. In the nominated form, it begins in late summer or autumn and is completed between September and October.

The postnuptial moult is a full moult in which the wings are thrown off at the same time. The birds are therefore incapable of flight for about two weeks in August. Nothing is known about a possible prenuptial molt.

voice

The call of the males during the breeding season (audio sample) is a noticeable click that sounds like striking two pebbles together. However, it is so loud that it can be heard up to a kilometer away. It is usually performed at night, less often during the day and sometimes for a long time (up to 17 minutes continuously). The individual stanzas are about a second long and usually consist of five ( click-click ... click-click-click ), but sometimes four syllables ( click-click ... click-click ). The calling period usually ends in mid-July, but locally also extends through August.

In connection with couple activities in the nest area, descending cackles, knocking and dull frog-like sounds were noted. A squeak could be heard from a bird that had lost in an argument, panting calls from females in an aggressive mood. With whimpering sounds attracts the female approach the young birds and the Hudern a groaning noise was heard.

behavior

The yellow bar behaves like many bars very secretly. It usually hides in dense vegetation, through which it skilfully slips and looks more like a mammal than a bird. She moves forward walking or walking. When walking, the feet are placed exactly in front of each other in a line. When running fast, the head is stretched out and the plumage is put on; sometimes the wings are used for balancing. If the bird is frightened, it usually only flies a short distance and then falls back into the vegetation, where it often remains motionless. In flight, the white arm wings are noticeable, and for short distances the legs hang loosely with the long toes; the bird barely rises above the vegetation. On longer journeys, such as on a train, the legs are stretched backwards. The species can swim and dive well, but rarely uses these skills. It has been observed, however, that yellow balls pursued by predators escaped by diving.

The yellow trap is mostly diurnal, but during the breeding season the males often call all night long. It has been observed that birds in captivity, if they did not call, spent most of the night sleeping. The birds stood on one leg with their head resting on their shoulder, their beak often hidden in their plumage.

distribution

The breeding distribution of the yellow trumpet extends mainly east of the Rocky Mountains over central and southeastern Canada and the northeastern United States. The species occurs only very scattered within its range. A small, disjoint deposit was rediscovered in southern Oregon in 1982 , and possibly another in eastern California in 1985 . A local occurrence in the upper valley of the Río Lerma in Mexico could not be confirmed again since 1964.

The main area extends from Great Slave Lake over large parts of Alberta , Saskatchewan and Manitoba to the west of James Bay and eastern Québec , New Brunswick and possibly Nova Scotia . To the south it extends to the extreme northeast of Montana , North Dakota , northern Minnesota , Wisconsin , the lower peninsula of Michigan , southern Ontario and Maine .

hikes

The yellow trumpet winters in coastal swamps along the Atlantic coast and the Gulf of Mexico, where it occurs from North Carolina southwest to southern Texas. Isolated winter evidence comes from California, one bird was found on Grand Bahama . Little is known about migration behavior; Dead finds on television towers suggest that the species migrates at night. In addition, there are some observations that suggest that it is moving across the continent at least partially in troops and on a broad front.

The arrival dates in the breeding areas are between the end of April and the end of May; the birds leave the breeding grounds in September. Sometimes the species is still found until October. In the winter quarters, yellow bales could be observed on October 6th at the earliest and May 1st at the latest.

Systematics and fossils

The yellow troll is closely related to the smaller Manchur troll ( Coturnicops exquisitus ) native to East Asia , about which very little is known. Some authors regard them as a subspecies of the yellow bale, but mostly both are now combined as separate species in a superspecies .

Fossils of the yellow bale come from the late Pleistocene ( Ranchola Treum ) and are almost 400,000 years old. The species was found in Florida, Missouri and Tennessee. In Mohave County , Arizona , remains of a bird of the same genus from the late Hemphillium , indistinguishable from today's species, have been discovered. A presumed ancestor was found with Coturnicops avita in Idaho ; he lived about 3.5 million years ago (late Blancum ).

Geographic variation

The geographic variation of the yellow bale includes the size, the plumage color of adult birds and the extent of the spotting in birds in their first resting plumage. Two subspecies are recognized, two more ( richii and emersoni ) are incorporated into the nominate form . The subspecies goldmani , which occurs locally in Mexico, is believed to be extinct - the occurrence has not been confirmed since 1964. Birds of this subspecies are larger, darker on top with blacker logs and black-streaked necks. The immature birds lack the whitish spots on the head and flanks.

  • C. n. Noveboracensis (Gmelin, 1789) - central and southeastern Canada, northern central and northeastern United States
  • C. n. Goldmani ( Nelson , 1904) - Marshes of the Río Lerma near Lerma and San Pedro Techuchulco in central Mexico (probably extinct)

habitat

The nominate form of the yellow bale colonizes the drier edge areas of swamps, which are dominated by dense stands of relatively low sedges and other grasses or rushes . It is often found in pure stands of the thread sedge , or where it is associated with other sedges, ledges , rushes, riding grasses , swamp rushes or Dulichium arundinaceum . It also occurs in wet meadows, but only very rarely in cattail stocks . In Canada it also breeds in brackish swamps. The water level at the nesting sites is between 0 and 12 cm; the floor should at least be waterlogged; a maximum of 46 cm deep water was found at a point where a male called. Larger areas that offer space for several breeding pairs are preferred. The quality of the habitat declines as bush cover grows. Settlement density decreases in drier years.

On the train and in autumn, the yellow bale also occurs on the prairie and in wet grassland, in hay meadows and grain fields. In winter quarters, it can be found in salt marshes and coastal swamps. There it prefers the drier sections of silt grass and rice fields.

The habitats of the presumably extinct Mexican subspecies C. n. Goldmani were described as extensively widened wet grassland with clump-like grasses, sedges and cattail swamps at an altitude of over 2500 m. The height of the vegetation was less than 50 cm.

nutrition

The yellow jelly feeds on earthworms , small water snails , insects and other arthropods that live in and around water , as well as seeds. Food is sought in areas with shallow water within dense vegetation and is read from the ground, from plants and from the 3–4 cm deep water. The search for food takes place during the day.

The popular claim that water snails are the main diet of this species has not been confirmed by quantitative studies. The food spectrum, however, seems to be very broad. In addition to earthworms and small snails , the prey includes woodlice , millipedes , spiders , beetles , cockroaches , bed bugs , grasshoppers and crickets , ants and diptera larvae . Especially in autumn and winter, seeds make up between 2 and 10% of the diet, including seeds from sedges and other sourgrasses , millet and knotweed .

Reproduction

The yellow allele is presumably monogamous , but in captivity successive polygyny was found and two brooding females were found in one male's territory in the wild. Young yellow balls probably breed in the second calendar year.

Pair formation probably takes place in the breeding area where the birds arrive between the end of April and the end of May. The males occupy territories and begin to call persistently and to patrol within the territory. The districts are 5.8–10.5 hectares in size and can overlap somewhat, which suggests a certain sociability. The males show only little loyalty to their territory, so that the same territory can be occupied by different males in successive years.

Nest building activities begin up to a month before the eggs are laid. Both partners create nest hollows, but nests are only built by females. In addition to the brood nest, there can be several others that are used for huddling. The nest is well hidden in sedge or other sour grass stocks in places with up to 15 cm water depth or waterlogged soil. It is a 3–8 cm high bowl with 7–10 cm diameter and 2.5–4 cm wall thickness, which consists of fine blades of sedge and grass and is covered by the vegetation above. If this is pushed aside, the female tries to restore the old condition as quickly as possible.

After the nest is ready, the female starts laying eggs and lays one egg every day. The clutch consists of 5–10 oval, sometimes somewhat elongated eggs of about 29 × 20 mm in size, which are brightly reddish-brown spotted on a cream-colored background, with the spots condensing in a wreath-like shape at the blunt end. It is incubated by the female for around 17-18 days. It stays on the eggs all the time at night, and during the day it takes short breaks that it uses to bathe, clean and eat.

The young are fleeing nests, some of which leave the nest around 15 hours after hatching, but sometimes only after two days and follow the female. They use the wing claw to climb in the vegetation or to get back into the nest. After about five days they are able to look for food independently, but are still fed and flocked by the female for about three weeks before they are completely independent. They are completely feathered after 18 days and fledged after 35 days.

literature

  • Theodore A. Bookhout: Yellow Rail (Coturnicops noveboracensis) , in A. Poole (Ed.): The Birds of North America Online , Cornell Lab of Ornithology, Ithaca, 1995, doi : 10.2173 / bna.139
  • Barry Taylor, Ber van Perlo: Rails - A Guide to the Rails, Crakes, Gallinules and Coots of the World , Pica Press, The Banks, Mountfield 1998, ISBN 1-873403-59-3
  • Michel Robert, Pierre Laporte: Field techniques for studying breeding Yellow Rails , Journal of Field Ornithology 68 (1) / 1997, pp. 56–63, ( PDF Download )
  • Michel Robert, Benoît Jobin, François Shaffer, Luc Robillard, Benoit Gagnon: Yellow Rail Distribution and Numbers in Southern James Bay, Québec, Canada , Waterbirds 27 (3) / 2004, pp. 282–288, doi : 10.1675 / 1524-4695 (2004) 027 [0282: YRDANI] 2.0.CO; 2

Individual evidence

  1. ↑ a b Bookhout (1995), section Introduction , see literature
  2. ↑ a b c Taylor (1998), p. 184f, see literature
  3. ↑ a b Bookhout (1995), section Appearance , see literature
  4. ↑ audio sample
  5. ↑ a b Bookhout (1995), section Sounds , see literature
  6. ↑ a b Taylor (1998), p. 187, see literature
  7. ↑ a b c d Bookhout (1995), Behavior section , see literature
  8. ↑ a b c d Bookhout (1995), section Distribution , see literature
  9. ↑ a b Bookhout (1995), section Migration , see literature
  10. ↑ Taylor (1998), p. 185, see literature
  11. ↑ a b Bookhout (1995), Habitat section , see literature
  12. ↑ a b c Taylor (1998), p. 186, see literature
  13. ↑ a b Taylor (1998), p. 186 f, see literature
  14. ↑ a b Bookhout (1995), section Food Habits , see literature
  15. ↑ a b c d Bookhout (1995), section breeding , see literature
  16. ↑ Taylor (1998), p. 187, see literature

Web links

Commons : Gelbralle ( Coturnicops noveboracensis )  - Collection of images, videos, and audio files