Marsh Wren

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Marsh Wren
Marsh wren (Cistothorus palustris)

Marsh wren ( Cistothorus palustris )

Systematics
Order : Passerines (Passeriformes)
Subordination : Songbirds (passeri)
Superfamily : Certhioidea
Family : Wrens (Troglodytidae)
Genre : Cistothorus
Type : Marsh Wren
Scientific name
Cistothorus palustris
( Wilson , 1810)
Bog wren clinging between stalks of sedge

The marsh wren ( Cistothorus palustris ) is a small songbirds from the family of Wrens (Troglodytidae). It is common in large parts of North America, where it breeds in swamps with stocks of cattails and pond cornices. He is particularly noticeable because of his mechanical creaking, rattling, but sometimes also melodic singing. A male often mates with two, sometimes three females. During the breeding season, the male builds numerous nests. The average number varies locally and from year to year between 7 and 22 nests, of which the females choose one to lay their eggs.

description

The marsh wren is 10.4 to 14 cm long and is between the blue and great tit . The weight is between 9 and 14 g. The sexes do not differ in color, but the male is significantly larger than the female. The relatively long beak is brown on the top, yellowish horn-colored underneath and lightened towards the base. The iris is brown. Legs and feet are pale brown.

In the adult dress , the parting is matt black and stands out from the whitish stripe over the eyes that extends almost to the neck . The top is cinnamon brown with a black, whitish dashed triangle on the front back. The underside is whitish beige with a yellowish brown tint on the flanks, which sometimes extends across the chest. The control feathers, like parts of the wing plumage, are cross-banded in black.

The youth dress is similar to the adult dress. However, the whitish stripes on the back are missing. An eye stripe is at best weakly developed and the wing plumage is less banded.

The species can be distinguished from the very similar, somewhat smaller sedge wren by the longer beak, the unstreaked crown and rump, the less pronounced over-eye stripe and the lighter underside.

voice

The very unmistakable singing of the male (audio sample) consists of 1–2 second long stanzas that are repeated or varied up to twenty times per minute. They are each introduced by two chuckling syllables and vary in expression between mechanical noises and melodic sounds. Some phrases are creaking like a cane-singer , some like whirling , some are reminiscent of the “castanets phrase” of the sprout . In terms of onomatopoeia, they can be described as tek-tak-ji-ji-ji-ji-ji-ji . There is a striking geographic variation in singing, with the transition between an eastern and a western type running roughly through the Great Plains . Birds of the western populations bring very loud phrases, some of which are perceived as disharmonious, which encompass a broad spectrum of pitches and are often very variable; the singing of the eastern populations sounds more flowing and melodic and is less varied.

The call repertoire is similar in quality to the components of singing. In the male, a nasal snarling, relatively loud series of calls such as choo choo choo or trills like trr trr trrr are described. Both sexes utter a short click or chack as a call for excitement or contact, and when you meet at the nest you can hear a soft, melodic trill.

distribution

The breeding distribution of the swamp wren extends over large parts of temperate North America, the species being absent in the Rocky Mountains and in the area of ​​the Pacific coastal mountains .

The northern border runs from northeast British Columbia southeast through Alberta and through the middle of Saskatchewan , includes southern Manitoba and the extreme southwest of Ontario , and then cuts through the Great Lakes area at the level of northern Minnesota , touching southernmost Québec and then each other move in an arc through the New England states to the east coast. There are scattered occurrences in New Brunswick and Nova Scotia .

Along the east coast, the distribution extends to northeast Florida and in a further subarea along the Gulf Coast from northwest Florida to southeast Texas . On the rest of the continent, the southern limit of the distribution extends from the District of Columbia westward through north west Virginia , the southern center of Ohio , south of Indiana and Illinois , north of Missouri and Kansas and from there diagonally southwest through Colorado , New Mexico and Arizona to the Gulf of California . The species is absent in the Colorado Plateau and Mojave Desert . There is a disjoint occurrence in central Mexico (see subspecies C. p. Tolucensis ).

On the west coast, the distribution extends northward to the east of Vancouver Island and in a branch to central British Columbia.

Systematics and geographic variation

As early as 1809, Louis Pierre Vieillot described a species called Troglodytes arundinaceus , which corresponded to the marsh wren in behavior, habitat and nest description, but corresponded to the Carolina wren ( Thryothorus ludovicianus ) in its plumage description . It could therefore be doubted that the generally recognized specific epithet palustris chosen by Wilson in 1810 is compatible with the principle of priority .

The internal systematics is complicated and up to 17 subspecies are described due to different characteristics. These include the coloring, the drawing of the top, different body measurements and differences in moulting. The most important geographically varying feature is the singing (see also voice ). Then the total population can be divided into an eastern and a western group. In the Great Plains there is an intergradation zone with mixed singers. In investigations that also include genetic findings, the choice of partner in these areas is made relatively strictly according to the singing - so there are either pairs with partners from the eastern group or from the western group. Mixed singers also usually stay among themselves. Although about 40% intermingling can be identified genetically in the areas examined, the degree of sexual selection for the eastern and western populations could justify species status.

Eastern subspecies group

Western subspecies group

More subspecies

Two of the subspecies described cannot be clearly assigned. Their areas border on the north to the overlap zone between western and eastern subspecies. Little is known about a third, which occurs in a disjoint area in central Mexico.

  • C. p. laingi ( Harper , 1926) - from northern Alberta and central Saskatchewan eastward to southeastern Manitoba, northeastern Montana .
  • C. p. iliacus ( Ridgway , 1903) - from Manitoba and southwestern Ontario southward to eastern Kansas and Missouri.
  • C. p. tolucensis ( Nelson , 1904) - Central Mexico ( Hidalgo and México south to Puebla )

The status of three other subspecies is controversial. According to Kroodsma and Verner, C. p. deserticola to C. p. aestuarinus , C. p. thryophilus to C. p. marianae and C. p. canniphonus to C. p. dissaeptus to be expected.

hikes

The migratory behavior of the marsh wren varies depending on the geographical location of the breeding areas. The southern coastal populations, the birds of the enclave in central Mexico and many populations in western and southwestern North America are resident birds , the rest are part migrants or migratory birds , for which the winter temperatures determine whether and how far they migrate. In addition, this year's birds tend to migrate more than older ones.

The eastern subspecies group winters on the southern Atlantic coast and the Gulf of Mexico, the migratory birds of the western from central Texas and Mexico westward.

The autumn migration begins in August and continues into October, in some places until the end of November. The peak of the arrival in the winter quarters is in Florida around mid-October. After winter, the singing males usually arrive in the breeding areas in the first weeks of May, the females follow 7-10 days later.

habitat

The swamp wren inhabits swamp landscapes of all kinds and breeds there in reed beds and high stands of sour grasses or rushes . Waterlogged mixed stands of bulrushes and pond rushes are preferred (especially Schoenoplectus tabernaemontani and Schoenoplectus acutus ), but the species occasionally also breeds in scattered spar shrubs (e.g. Spiraea douglasii ). Breeding success is greater in wet locations. If the districts dry out in late spring, a biotope change can occur on a small scale. In later broods from mid-July onwards, the nests are generally in pond rush stocks.

The species is also found in silt grass in salt marshes . It breeds on the coast in very high reed beds along estuary arms that reach more than 2 m in height, in the area of ​​dams in medium-high grass stands of 1–1.5 m in height.

In contrast to the closely related sedge wren, which breeds in wet meadows and on the edge of swamps, the swamp wren occurs in wetter locations.

nutrition

The marsh wren feeds on various invertebrates such as insects and spiders in particular . Insects that live in the water make up a large part of it. Most of the food is sought at the bottom of reed beds, close to the water surface or the swamp floor. Sometimes reeds or sedge stalks as well as cattails are searched; occasional short fishing flights are undertaken.

Reproduction

Two marsh wren females and one male at the nest, engraving after John James Audubon
Bog wren's eggs

The swamp wren is polygynous ; many males mate with two or more females. The number of polygynous males in a population, however, varies greatly from region to region. Only 5% were found in Georgia, 25–35% in New York, 41–54% in Manitoba, and 50% in Washington. In a population in Washington where the sex ratio was 80:87, there were 13 unmated males, 47 monogamous, and 20 bigame males. A study in two areas in Manitoba showed a sex ratio of 120: 186, here 10 unpaired, 53 monogamists, 48 ​​bigamists and 9 males with three females each were found.

Females arrive in the breeding areas in spring 7-10 days after the males, pair formation takes place in the days after, when the females inspect several territories of the males in a relatively short time. The criteria according to which the election is made is also very different from region to region. While the females in some populations prefer males with good territories, even if these are already mated with other females, elsewhere they tend to choose unmated males as partners.

The main breeding season lies between mid-April and June, with slight regional differences. Second broods are not uncommon.

Males build numerous nests during the breeding season. The number can vary from year to year or regionally, the average is between 7 and 22 nests per male. Only a few nests are actually used for laying eggs; many of them serve as a place to sleep, especially in winter, as a refuge for fledgling youngsters or as an alternative nest when they lose their clutch. Apparently the nests also play a role in distracting enemies. The number of nests built may also be a criterion for choosing a partner, according to which the females choose the most vital males with the best territories. In experiments in which a large number of the nests were removed, the affected males were unable to bind a female to themselves.

The nests are mostly in rushes or rush stands at a height of 75–95 cm, and higher as the vegetation grows. They are complex, round oval structures that are about 18 cm high and 13 cm wide. The walls are about 2 cm thick, the nest cavity measures about 8 cm × 13 cm. The brood nest consists of an exterior of interwoven stalks of sedges or riding grasses and a finer padding of fine stalks, rootlets or woolly airborne seeds of bulrush. The outer structure is erected by the male in the course of up to 3 days in a total of around nine hours. To do this, it first forms a bowl, then later it pulls up the walls. These consist of supporting stalks that are woven into a dome at the top and serve as the basis for weaving finer stalks. The approximately 3 cm wide nest opening is in the middle or in the area of ​​the upper half.

Accompanied by the male, the female inspects the nests during courtship, selects them if necessary and then pads them with fine nesting material. However, the female often starts building a new nest. How often this is the case is unclear and can also vary regionally. If the female has padded a nest for the brood, it can be recognized by the fact that fine nesting material hangs out from the nest opening or even forms a small tunnel.

The clutch usually consists of 4–6, more rarely 3–10 eggs, about 12 mm × 16 mm in size, on a brown background, finely and darkly speckled. They are laid one day apart and incubated by the female alone 1–2 days before the last egg is laid. The incubation period is between 12 and 14 days. The nestlings are about 7-8 days brooded and fly to 13 to 16 days out. After that, they are fed for about 12 days.

Existence and endangerment

The marsh wren is relatively common, although its numbers decline with the loss of wetlands . Large-scale drainage of swamps leads to local declines. In other regions, however, the inventory trend is positive. In some states, the species is on the alert list; for example in Florida, where the species is largely restricted to salt marshes, or in Pennsylvania, where about 40% of the wetlands fell victim to land use in the second half of the twentieth century. The IUCN classifies the species as LC IUCN 3 1st svg(= least concern - not endangered).

Sources and References

literature

Web links

Commons : Marsh Wren  - Collection of images, videos, and audio files

Individual evidence

  1. ↑ audio sample
  2. ↑ a b c Kroodsma / Verner (2007), section “Sounds”, s. literature
  3. ^ DA Sibley: The Sibley Field Guide to Birds of Eastern North America , AA Knopf, New York 2003, ISBN 0-679-45120-X , p. 304
  4. ↑ a b c d Kroodsma / Verner (2007), section “Distribution”, s. literature
  5. ↑ a b c Kroodsma / Verner (2007), section Migration , see literature
  6. ↑ a b c Kroodsma / Verner (2007), Habitat section , see literature
  7. ↑ Kroodsma / Verner (2007), section Food Habits , see literature
  8. ↑ a b Kroodsma / Verner (2007), section “bahaviour”, s. literature
  9. ↑ Verner / Engelsen (1970) and Leonard / Picman (1987), see literature
  10. ↑ a b c d e Kroodsma / Verner (2007), section “breeding”, s. literature
  11. ^ Roger Tory Peterson, Mada Harrison (ed.): A Field Guide to Western Birds' Nests: Of 520 Species Found Breeding in the United States West of the Mississippi River , Houghton Mifflin Harcourt, 2001. ISBN 0618164375 , p. 165.
  12. ↑ Kroodsma / Verner (2007), sections Demography and Populations / Conservation and Management , see literature