Sedge Warbler
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Sedge Warbler ( Acrocephalus paludicola ) |
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| Acrocephalus paludicola | ||||||||||||
| ( Vieillot , 1817) |
The reed warbler ( Acrocephalus paludicola ) is a very rare reed warbler species that is threatened with extinction worldwide and which is quite similar to the reed warbler ( A. schoenobaenus ). Neither geographic variations nor subspecies are distinguished.
Appearance
The reed warbler is very similar in size and appearance to the much more common reed warbler , but there are some clear differences that should almost always make a reliable determination possible: Overall, the entire plumage of the reed warbler is more contrasting than that of the reed warbler. The black markings on the back, wings and arm covers are clearer, the breasts of colored birds are finely dashed in black in contrast to the reed warbler. The pattern on the top of the head is particularly striking: two relatively wide, black (or black-brown) stripes extend from the top of the beak to the neck; they are separated by a beige to creamy yellow narrow medial stripe. The clear stripes over the eyes are also mostly beige or a little lighter, but never white. The legs of this species are orange-yellow to flesh-colored; in the reed warbler they are dark brown. The sexes are very similar to each other, but the females are more inconspicuous, less contrasting.
voice
The reed warbler and the reed warbler can be easily distinguished by their voice: The reed warbler s song verses hardly last longer than three seconds. Above all, they are performed during the first hours of the night or an hour or two before dawn, while the reed warbler is a dawn and morning singer. The singing usually consists of a monotonous snarling, which is interrupted by short whistling tones. Complete verses of the Reed Warbler, on the other hand, last over 20 seconds. In addition to the snarling and squeezing sounds as well as the whistling tones, his stanza contains various elements that are pleasant to the human ear as well as sequences from other bird strophes; the latter is almost completely absent in the reed warbler.
distribution
The distribution area lies in a narrow belt essentially between 45 ° and 60 ° north and reached in the early 20th century from the Netherlands to Siberia. The area has shrunk massively since the Second World War ; today the Oder forms the western border. The main deposits are in Poland, Ukraine and Belarus, there are also island-like deposits in Hungary and Siberia. The German and Hungarian occurrences form the western limit of distribution of the species.
In Germany there was recently a small population (1995: 34 singing males, 2000: 19 sM, 2005: at most 12 sM) in the lower Oder valley near the Polish border. A breeding population of almost 30 males near Greifswald towards the end of the 1980s has been extinct since 1998. At the last bird count in the Lower Oder Valley in 2017, no reed warblers were counted. A deposit on Lake Neusiedl in Austria that still existed around 1940 has also been extinguished . The Hungarian stocks in the Hortobágy have been decreasing again since 2002 after an increase in the 1990s.
habitat
The habitat requirements of the reed warbler are high: the habitat must be very insect-rich so that the female alone can successfully raise the young. Typical locations are fens with no more than eighty centimeters high sedge stocks and a water level in the sedge stocks of one to ten centimeters.
hikes
The reed warbler migrates long distances along the North Sea and Atlantic coasts to West Africa. Exact knowledge about the migration route and the wintering areas has not been available up to now; it was not until 2007 that an important winter quarter was discovered in West Africa south of the Sahara.
To locate the wintering areas of the reed warbler, scientists from the Aquatic Warbler Conservation Team took feathers from reed warblers ringed in Europe and isolated them for their isotopic composition. Such isotope profiles can be used to roughly determine where a bird has been. In this way, a zone immediately south of the Sahara could be delimited as possible wintering quarters for the Sedge Warbler. Taking into account earlier records of sedge warbler, the area in question was narrowed down to a region in the immediate vicinity of Senegal . Finally, the birds were located in an area of one hundred square kilometers in the vicinity of the Djoudj National Park in northern Senegal.
Reproduction
The male of the reed warbler is not involved in the rearing of the young, this is done exclusively by the females. Males of the reed warbler compete with all other males for every female in the immediate vicinity of the territory. As a result, about sixty percent of all sedge warbler broods are descended from more than one male. Clutches of six eggs were even found, in which the young were descended from five different males.
Stock situation
The status of the species is very serious. The amelioration of the 20th century had a particularly devastating effect, which led to a massive decline in the population and a loss of large parts of the distribution area through the destruction of habitats.
The latest population estimates assume a total number of singing males in Europe of 10,000 to 15,000 specimens. The species is classified with V ( Vulnerable ) on the IUCN Red List .
In Germany the species is threatened with extinction (Red List Cat. 1). It belongs to Annex I of the EU Bird Protection Directive (RL 79/409 / EEC).
literature
- Hans-Günther Bauer, Einhard Bezzel , Wolfgang Fiedler (eds.): The compendium of birds in Central Europe: Everything about biology, endangerment and protection. Volume 2: Passeriformes - passerine birds. Aula-Verlag Wiebelsheim, Wiesbaden 2005, ISBN 3-89104-648-0 .
- Dominic Couzens : Rare Birds - Survivors, Evolution Losers and the Lost. Haupt Verlag, Bern 2011, ISBN 978-3-258-07629-4 .
- Benedikt Gießing: Many fathers for one brood - advantageous or inevitable for the female ?: on the mating system and population genetics of the Sedge Warbler. (Acrocephalus paludicola). Diss. Univ. Cologne 2002.
- A. Helmecke, D. Sellin, S. Fischer, J. Sadlik, J. Bellebaum: The current situation of the sedge warbler Acrocephalus paludicola in Germany. In: Ber. Bird protection. 40, 2003, pp. 81-90.
- Franziska Tanneberger, Jochen Bellebaum, Martin Flade: Hope for the "sparrow of the fens". In: Nature magazine. , 21, 2, 2007, pp. 42-43. (popular science article).
- Heinz Wawrzyniak, Gertfred Sohns: The sedge warbler "Acrocephalus paludicola". Westarp-Wiss.-Verl.-Ges., Hohenwarsleben 2004, ISBN 3-89432-840-1 . (The Neue Brehm Library, Vol. 504).
Web links
- Acrocephalus paludicola in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 31 of 2009.
- Videos, photos and sound recordings of Acrocephalus paludicola in the Internet Bird Collection
- "Operation Sedge Warbler - the great story of saving a small bird" radio broadcast as part of "SWR2 Knowledge"
- Age and gender characteristics (PDF; 1.3 MB) by Javier Blasco-Zumeta and Gerd-Michael Heinze (English)
- Sedge Warbler feathers
Single receipts
- ↑ Not a single reed warbler anymore . In: MOZ.de . ( moz.de [accessed on September 8, 2018]).
- ↑ a b Couzens, p. 84.
- ↑ Aquatic Warbler - Website for the discovery of the wintering area ( Memento of December 5, 2008 in the Internet Archive )
- ↑ Couzens, p. 85.
- ↑ Couzens, p. 83.
- ↑ Christoph Grüneberg, Hans-Günther Bauer, Heiko Haupt, Ommo Hüppop, Torsten Ryslavy, Peter Südbeck: Red List of Germany's Breeding Birds , 5 version . In: German Council for Bird Protection (Hrsg.): Reports on bird protection . tape 52 , November 30, 2015.