Wood shrew
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Wood shrew ( Sorex araneus ) |
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| Linnaeus , 1758 |
The wood shrew ( Sorex araneus ) is a mammal from the shrew family . It populates large parts of Europe and northern Asia .
Mark
The head-trunk length is 65 to 85 mm, the tail length 35 to 47 mm and the weight 6.5 to 14.3 g. The top is black-brown, the flanks are light brown, and the bottom is gray. In young animals the upper side is lighter and the transition to the light flank color is flowing.
The closely related, spread widely in western Central Europe, crowned shrew is on average slightly smaller. In her, the dark brown color on the back is usually narrower and contrasts more clearly with the light brown color on the flanks. In both species, however, the body size and the coloration of the specimens vary significantly and so there are ultimately no reliable external distinguishing features. They can only be recognized with certainty through genetic testing and minor differences in the skeletonized skull. In Central Europe, this also applies to the very closely related Wallis wood shrew found in southern Switzerland . The pygmy shrew is smaller, the upper side is not clearly two-tone, but rather gray-brown, the tail proportionally longer and quite noticeably thickened. Your eyes are proportionally even smaller. Alpine shrews , water shrews and swamp shrews have black to blackish-gray fur, the latter two species are also significantly larger and stronger. The only distantly related native white-toothed shrews , i.e. the field , house and garden shrews , differ from the wood shrew, among other things, in the ears that are not covered by hair, the white instead of dark brown tooth tips and the occasional long, protruding hair on the tail.
distribution
The distribution area of the wood shrew includes Central, Eastern and Northern Europe as well as parts of Asia and extends east to Lake Baikal and the Himalayas . In France and the Iberian Peninsula there are only isolated occurrences in the Massif Central and the Pyrenees ; there the species is otherwise replaced by the black-backed shrew. The wood shrew is also absent in Ireland and largely in the Mediterranean region, where, as in south-eastern Europe, its occurrence is limited to mountainous regions.
habitat
The wood shrew reaches the highest densities in moist forests and wet meadows, but also colonizes almost all other land habitats up to crevices and sand dunes.
Way of life
The animals are diurnal and nocturnal. The diet consists mainly of earthworms , insects and their larvae and snails , and small vertebrates are rarely eaten. Reproduction takes place from April to October, most litters are born in spring and early summer. A female has two to four litters a year, each containing 1 to 11, usually 4 to 7 young. The newly born, very immature young mice weigh only 0.4 grams. The eyes open at 20 to 22 days of age, after 30 days the young animals are independent. In the wild, the animals reach a maximum age of 16 months.
Towards winter, from around August, wood shrews reduce size and weight. The organs, the brain and the skull capsule then also lose size. This shrinkage is reversed in spring and in summer the animals have regained their original size and mass.
Research by the Polish zoologist August Dehnel since its publication in 1949 has made it known as the Dehnel rule that the body of these insectivores shrinks seasonally, towards winter, by up to 20% in length and grows back to its original size after winter . Contrary to the Bergmann rule , the animals get through a time with less food.
In October 2017, the German biologist Moritz Hertel and his team presented studies based on a new method. Individuals were marked subcutaneously with 7 × 1.5 mm transponders (Uno Pico) and anesthetized, measured using a 26 keV X-ray scan and weighed to the nearest 0.01 g. These measurements were repeated several times on these individuals during the period from July to September of the next year, i.e. over a period of about 14 months. On average, it was found that the skull bone shrinks by 15.3% from the maximum in summer to winter and then grows again by 9.3% until spring. The body mass decreases from autumn to winter by 17.6%, and then increases dramatically by 83.4% until spring. A comparison between animals living in the wild and in the laboratory reveals that the shrinkage is not triggered by starvation, but rather by a genetically inherited program.
Existence and endangerment
The wood shrew is the most common shrew in Central Europe and safe in Germany; the world population is also safe according to the IUCN .
literature
- Stéphane Aulagnier, Patrick Haffner, Tony Mitchell-Jones, Francois Moutou, Jan Zima: The mammals of Europe, North Africa and the Middle East. Haupt Verlag, Bern, Stuttgart, Vienna, 2009, ISBN 978-3-258-07506-8 .
- Eckhard Grimmberger: The mammals of Germany. Quelle & Meyer Verlag, Wiebelsheim, ISBN 978-3-494-01539-2
- Anthony J. Mitchell-Jones, Giovanni Amori, Wieslaw Bogdanowicz, Boris Krystufek, PJH Reijnders, Friederike Spitzenberger, Michael Stubbe, Johan BM Thissen, Vladimiŕ Vohralik, Jan Zima: The Atlas of European Mammals. Poyser, London, 1999, ISBN 0-85661-130-1 , pp. 42-43.
- Erwin Stresemann (founder), Konrad Senglaub (ed.): Excursion fauna of Germany. Volume 3: Vertebrates. 12th, heavily edited edition. G. Fischer, Jena et al. 1995, ISBN 3-334-60951-0 , pp. 369-370.
Individual evidence
- ^ Javier Lázaro 'Correspondence information about the author Javier Lázaro. - Javier Lázaro, Dina KN Dechmann, Scott LaPoint, Martin Wikelski, Moritz Hertel: Profound reversible seasonal changes of individual skull size in a mammal. Current Biology, October 23, 2017; doi: 10.1016 / j.cub.2017.08.055 (English)
- ↑ Strange skull shrinkage orf.at, October 23, 2017, accessed October 29, 2017.
- ↑ Javier Lázaro, Dina KN Dechmann, Scott LaPoint, Martin Wikelski, Moritz Hertel: Profound reversible seasonal changes of individual skull size in a mammal. Current Biology, October 23, 2017; doi: 10.1016 / j.cub.2017.08.055 (English)
Web links
- Sorex araneus in the endangered Red List species the IUCN 2008. Posted by: Amori, G. (Small Nonvolant Mammal Red List Authority) & Temple, H. (Global Mammal Assessment Team), 2008. Retrieved on October 13 of 2008.