Sedge wren

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Sedge wren
Sedge wren (Cistothorus platensis)

Sedge wren ( Cistothorus platensis )

Systematics
Order : Passerines (Passeriformes)
Subordination : Songbirds (passeri)
Superfamily : Certhioidea
Family : Wrens (Troglodytidae)
Genre : Cistothorus
Type : Sedge wren
Scientific name
Cistothorus platensis
( Latham , 1790)

The sedge wren ( Cistothorus platensis ) is a small songbird belonging to the wren family . The distribution ranges from the largest sub-area in the temperate latitudes of North America through numerous scattered occurrences in Central and South America southwards to Tierra del Fuego . The species is also found on the Falkland Islands .

In December 2014, a genetic test revealed that the species in its current composition is paraphyletic . It should also include the Meridae wren ( Cistothorus meridae ) and the Apolinarus wren ( Cistothorus apolinari ). The authors of the study suggest dividing the entire complex from three into eleven types. The North American populations would then be called, for example, Cistothorus stellaris ( JF Naumann , 1823) as “Sedge Wren”, the nominate form Cistothorus platensis with the subspecies polyglottos form another species (“Pampas Wren”).

description

With a body length of 9–12 cm and 7–10 g, the sedge wren is one of the small species in the family and is slightly larger than a wren . There is no sexual dimorphism . The rather short beak is brown on the top, lighter yellowish brown on the underside with a lightened tip. The iris is brown. Legs and feet are flesh-colored.

In adult birds, the upper side is dashed in black and white on a beige-brown background. The dotted lines are created by whitish shaft lines and / or points as well as black centers and / or hems. The stripes are finer on the head and much wider on the back. The striations can continue on the rump and tail-tail-coverts, in some populations and subspecies it can be only partially or weakly pronounced, just as it is absent on the apex. The outer eye stripe is beige and bordered by dark brown ear covers. The chin, throat and front breast are whitish, the rest of the underside is tinted sand beige to cinnamon, especially towards the flanks and the under tail coverts. This tint can condense into an implied band on the chest. The rudder feathers are darkly striped on a light brown background, in some populations the inner flags of the central rudder feathers are completely black. The wings are broadly banded light brown to light beige on a dark background, the banding becomes lighter towards the inner arm wings and arm covers.

voice

The singing is performed exclusively by males. It is somewhat reminiscent of that of the gray bunting and consists of stanzas 1.5 to 2 seconds long, which are repeated at intervals similar or in the same form. These are introduced with three to four short, staccato-like syllables and end in quite variable, jingling trills.

Males and females utter a number of different calls, including a high, short chid , which can resemble the first syllables of the chant.

Distribution and existence

The brood distribution of the sedge wren extends in numerous disjoint sub-areas from temperate North America through Central and South America to Tierra del Fuego. It also includes the Falkland Islands.

The North American distribution area extends in Canada from the eastern center of Alberta and the southern half of Saskatchewan , the southern part of Manitoba and Ontario to the extreme south of Québec . In the USA , the western border of the area runs roughly through the middle of the states of North and South Dakota and Nebraska , the southern border through the extreme northeast of Kansas , central Missouri , southern Illinois and the extreme north of Kentucky . Eastward, the species is found in all of Ohio , to the extreme northwest of Pennsylvania , in the middle and north of New York and in the extreme northwest of Vermont . There are also scattered occurrences eastward to New Brunswick and south of the closed distribution in an area at the level of Chesapeake Bay .

In Central America the species occurs locally from central Mexico to Costa Rica . Deposits that reached into western Panama became extinct at the beginning of the 20th century. In Mexico, the area extends over southeastern San Luis Potosí and southern Nayarit eastwards through southern Michoacán to Puebla and the western center of Veracruz and from the south of the same state to western Campeche and the southeast of Chiapas . Furthermore, the species occurs in southern Guatemala , northeast El Salvador , western Honduras and the eastern center of Costa Rica.

In South America the occurrences are very dispersed. In Colombia and Venezuela , the species is found in several regions along the Andes . It also occurs locally in the Colombian Llanos , the Sierra Nevada de Santa Marta , the Sierra de Perijá and the Roraima-Tepui on the border with Guyana . There are other large sub-areas in the Andes in Ecuador , Peru , Bolivia , Chile and Argentina south to Tierra del Fuego. Furthermore, a large sub-area extends eastward in the plains of central Argentina to the province of Buenos Aires , in southeastern Brazil from southern Goiás and Minas Gerais southward to Paraná and another over the extreme south of Paraguay and part of Argentina to Rio Grande do Sul .

The species is not endangered and the population trend is predominantly positive.

Geographic variation

The geographical variation is quite pronounced and complicated. It relates to body measurements and proportions, stripes on the top and coloring of the bottom. There are up to 20 subspecies, which can be divided into three groups. Two of them are common in South America, one mainly in the Andes, the other in subtropical mountain regions and in the lowlands in regions to the east. There are intermediate populations in the north of Argentina and in the south-east of Brazil, so it can be assumed that the two groups mix in these areas. Traylor (1988) suspects that the first group spread in South America along the Andes a very long time ago, because today there is a noticeable geographic variation within the group, some of which is clinical. The other has only recently colonized South America and still has fairly constant characteristics. The closely related species Méridazaunig ( Cistothorus meridae ) and Apolinarzwönig ( Cistothorus apolinari ) could also be incorporated into this development scenario .

Stellaris group

The distribution of this group ranges from North to Central America. It is characterized by a missing or only hinted stripe on the rump and under tail-coverts. This plumage is common in C. p. stellaris reddish cinnamon. Birds of this subspecies are migratory birds and have, on average, quite long wings.

  • C. p. stellaris ( JF Naumann , 1823) - Breeds in southern Canada to northern Kentucky , eastern Pennsylvania and New York in the US, non-breeding from Virginia to the south coast of Texas and northeast Mexico .
  • C. p. tinnulus R. T. Moore , 1941 - Michoacán , Central Mexico, only known from the type specimen.
  • C. p. elegans P. L. Sclater & Salvin , 1859 - Highlands of southeastern Mexico, Guatemala, and western Belize.
  • C. p. lucidus Ridgway , 1903 - Central Costa Rica southwards to western Panama .
  • C. p. potosinus Dickerman , 1975 - North and Central Mexico.
  • C. p. jalapensis Dickerman , 1975 - Eastern Mexico.
  • C. p. Warneri Dickerman , 1975 - East Mexican Lowlands.
  • C. p. russelli Dickerman , 1975 - Belize .
  • C. p. graberi Dickerman , 1975 - Inner and Eastern Honduras and Northeast Nicaragua .

Platensis group

This South American subspecies group differs from the polyglottus group by the continuously streaky tail and an average longer wing length. It is quite variable in body size and plumage color with several clinically distinctive subgroups and some distinct breaks. Traylor (1988) does not consider the separation of the subspecies tolimae and tamae to be justified. He considers them to be clinical manifestations of aeqatorialis .

  • C. p. aequatorialis Lawrence , 1871 - Southern end of the Andes in Colombia to the south of central Peru.
  • C. p. Tolimae Meyer de Schauensee , 1946 - Northern part of the Andes in Colombia.
  • C. p. tamae Cory, 1916 - Southwest Venezuela and Eastern Colombia.
  • C. p. graminicola Taczanowski , 1874 - South and Central Peru.
  • C. p. tucumanus Hartert , 1909 - Northwest Argentina .
  • C. p. platensis ( Latham , 1790) - Eastern Argentina.
  • C. p. hornensis ( Lesson , 1834) - Central Chile and southern Argentina to Cape Horn .
  • C. p. falklandicus Chapman , 1934 - Falkland Islands.

Polyglottus group

In contrast to the Platensis group, these subspecies show very little variation among each other. The rump is mostly unstriped, the wing length is relatively short and the central control feathers have completely black inside flags.

  • C. p. polyglottus ( Vieillot , 1819) - Paraguay and southeastern Brazil.
  • C. p. alticola Salvin & Godman , 1883 - Mountains of Northern Colombia, Western, Northern and Eastern Venezuela, and Western Guyana.
  • C. p. minimus Carriker , 1935 - South Peru to South Bolivia.

hikes

The northern subspecies C. p. stellaris is a short-range migrant that winters along the southern Atlantic coast of North America and the Gulf of Mexico in the United States and northeastern Mexico. The wintering areas there extend very far inland. The spring migration takes place from the end of April to June, the autumn migration between the beginning of August and the end of October. All other populations are resident birds .

habitat

The sedge wren breeds in sedge meadows and other high grass stocks in wet meadows and hay meadows, wet fallow land, reed beds on bodies of water, salt marshes and raised bogs . It avoids short-grass, open, flooded or cattail- dominated habitats. Optimal habitats are not interspersed with too many bushes and tall perennials and have an average height of 1.1 m.

Reproduction

Pair of Sedge Wren at Nest, Engraving after John James Audubon

In addition to monogamous brood marriages, bigyny often occurs in the sedge wren . Although the sex ratio is mostly almost the same, it is not uncommon for two females to breed in the territory of a male with a promising territory, so that other males - often those with marginal or less suitable territories - remain unmated. The proportion of polygyny can be between 30 and 50%.

Sedge wrens breed once or possibly twice a year. The breeding season in North America is between May and September, with regional differences. West of the Great Lakes , most broods take place between May and June, in southern and eastern regions often between July and August, sometimes even in September. Late broods can be secondary clutches; however, this may also be an adaptation to breeding areas in which the water levels do not fall until late in the year, so that the required moist, but not flooded habitats are only then available.

Males arrive in the breeding areas up to two weeks before the females arrive and establish their territories there. At about the same time as the females arrive, they start building several nests, one of which is then selected by the female and lined with finer nesting material for the brood. In twelve Minnesota districts studied, the average number of nests per territory was 7.4. Most of the exterior construction was completed. The high number of nests may serve to distract predators , and some of them are also used as sleeping nests .

The nest is built in dense stands of upright sedges or other grasses at heights between 10 cm and 1 m. Sometimes it stands low in bushes or bulbs . It is a spherical, finely woven structure with a side entrance, which consists of sedge or other fine blades of grass and - if it is selected as a brood nest - is lined with fine blades, feathers and hair. Construction takes 7–8 days. In contrast to the elongated nest of the marsh wren , it is spherical and does not contain any components of cattails.

The outside diameter is between 8 and 13 cm, the diameter of the interior between 4.5 and 7 cm. The entrance hole is 1.5–2.5 cm.

The clutch usually consists of 7, less often 3–8 eggs. Additional gears are often smaller. The white, slightly shiny eggs are oval to pointed-oval and 16 × 12 mm in size. The female lays 1 egg per day and incubates it before the last egg is laid. The incubation period is between 13 and 16 days.

The young hatch over two to three days. They are mainly cared for by the female, but the male also occasionally feeds them. They leave the nest after 12 to 14 days.

nutrition

The diet consists mainly of insects, but also arachnids .

Individual evidence

  1. ↑ Mark B. Robbins, Árpás S. Nyári: Canada to Tierra del Fuego: Species Limits and Historical Biogeography of the Sedge Wren (Cistothorus platensis) , The Wilson Journal of Ornithology 126/4, pp. 649-662, 2014, doi : 10.1676 / 13-162.1
  2. ↑ a b c Herkert et al. (2001), Birds of North America Online, Distinguishing Characteristics and Appearance Sections
  3. ↑ Traylor (1988), p. 8f, see literature
  4. ↑ Traylor (1988), p. 13f and Dickerman (1975), see literature
  5. ↑ Traylor (1988), p. 13f, see literature
  6. ^ A b D. A. Sibley: The Sibley Field Guide to Birds of Eastern North America. AA Knopf, New York 2003, ISBN 0-679-45120-X , p. 304
  7. ↑ Singing of the sedge wren audio sample ; MP3
  8. ↑ Herkert et al. (2001), Birds of North America Online, Sounds Section
  9. ↑ Kurzruf ( tschid ) des sedge wren audio sample ; MP3; 390 kB
  10. ↑ a b c Herkert et al. (2001), Birds of North America Online, Distribution Section
  11. ↑ Traylor (1988), see literature
  12. ↑ BirdLife International: Species Factsheet - Sedge Wren ( Cistothorus platensis ) . Retrieved October 7, 2011.
  13. ↑ Traylor (1988), see literature
  14. ↑ Traylor (1988), p. 27f, see literature
  15. ↑ Herkert et al. (2001), Birds of North America Online, Habitat Section
  16. ↑ Crawford (1977), see literature and Jared Verner: Evolution of Polygamy in the Long-Billed Marsh Wren , Evolution Vol. 18, No. 2 (1964), pp. 252-261
  17. ↑ a b c J. T. Burns: Nests, territories, and reproduction of Sedge Wrens (Cistothorus platensis) , Wilson Bulletin 94, 1982, pp. 338-349.
  18. ↑ a b c d e f g Herkert et al. (2001), Birds of North America Online, Breeding Section
  19. ↑ Michael K. Rylander: The behavior of Texas birds. Audio Forum, 2002, ISBN 978-0292771208 , p. 280.

literature

  • James R. Herkert, Donald E. Kroodsma, James P. Gibbs: Sedge Wren (Cistothorus platensis) in The Birds of North America Online (A. Poole, Ed.), Cornell Lab of Ornithology, Ithaca 2001
  • Melvin A. Traylor: Geographic variation and evolution in South American Cistothorus platensis (Aves: Troglodytidae) . Fieldiana Zoology, New Series No. 48, Field Museum of Natural History, 1988, pp. 1-35
  • Robert D. Dickerman: Revision of the Short-billed Marsh Wren (Cistothorus platensis) of Mexico and Central America. American Museum Novitates, No. 2569, pp. 1-8, New York 1975, ISSN  0003-0082
  • JT Burns: Nests, territories, and reproduction of Sedge Wrens (Cistothorus platensis) , Wilson Bulletin 94, 1982, pp. 338-349
  • Crawford RD: Polygynous breeding of Short-billed Marsh Wrens , The Auk , 94 (1977), pp. 359-362

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