Polar oyster vole
| Polar oyster vole | ||||||||||||
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Polar oyster vole ( Myodes rutilus ) |
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| Scientific name | ||||||||||||
| Myodes rutilus | ||||||||||||
| ( Pallas , 1779) |
The polar bank vole ( Myodes rutilus ) is a species of vole that belongs to the genus of bank voles ( Myodes ).
features
With a head-trunk length of eight to eleven centimeters, the polar bank vole is similar in size to the bank vole ( Myodes glareolus ). With two to four centimeters, the length of their densely hairy tail is usually less than 40 percent of the body length and thus shorter than that of the bank vole. A conspicuous brush consisting of protruding tail hairs protrudes five to eight millimeters over the end of the tail . The fur on the back of the polar bank vole is significantly redder than that of the bank vole. The flanks are colored yellowish gray. The ears are large to medium-sized with eleven to 16 millimeters. Adult polar bank voles weigh ten to 30 grams .
Reproduction
The breeding of the polar bank voles takes place from the beginning of May to the end of September. If the population density is too high, however, the breeding period ends in the middle of summer . The females from the first two litters usually already participate in reproduction. Because of the exertions involved, these animals do not survive the fall . Neither are the females from the previous year who die after up to three litters. The females from the later litters overwinter and only breed in the following year. The first litter is usually smaller than the following. As a rule, five to seven young are born.
distribution
The distribution area of the polar chicklet extends in the northern Holarctic from northern Fennoscandia ( Norway , Sweden and Finland ) through Siberia and Alaska to Canada . In the Eurasian part of the distribution area, the southern distribution limit shifts from west to east and further south . While the northern limit of distribution remains almost at the same latitude . In eastern Asia , the distribution area on Sakhalin and Hokkaidō has the greatest latitude with a north-south extension from 43rd to 73rd parallel.
In some areas, the polar bank vole occurs together with the bank vole ( Myodes glareolus ). While the bank vole dominates in the south of the common distribution areas, the relationship shifts towards the north in favor of the polar bank vole. In the common areas of distribution with the gray bank vole ( Myodes rufocanus ), the polar bank vole is so strongly dominated by the gray bank vole that the polar bank vole stops reproducing when the density of the gray bank vole is high. It is only when the density of the gray voles decreases in late summer that reproduction of the polar bank vole starts again.
As a habitat , the polar chalk vole prefers meso- and eutrophic grass and herb-rich forests . To the north of the spruce border, the polar ootel evades to lichen-rich pine forests . In the coniferous forests it prefers locations rich in moss . It is seldom found in swamps , fields or in fields . The polar chalk vole hardly digs tunnels, but prefers naturally occurring hiding spots.
nutrition
Compared to the other bank vole species, the polar bank vole eats significantly more seeds and fewer bark and green parts of the plant. Of the berries and the seeds they contain, the polar ootel only eats the pulp and the inside of the seeds. She disdains the fruit and seed pods . In winter, the arctic volute climbs trees and bushes and eats buds and lichens there. As a winter supply, the polar ootel collects seeds, for example from Melampyrum species ( quail wheat ).
Natural enemies
Like many other small mammals , the polar bank vole is a popular prey animal for many predators . Therefore, it is nocturnal during the day-night cycle. During the continuous light in arctic summer, see polar day , waking phases occur all day.
literature
- Jochen Niethammer, Franz Krapp (Hrsg.): Handbook of mammals in Europe. Volume 2, Part 1: Rodentia 2 (Cricetidae, Arvicolidae, Zapodidae, Spalacidae, Hystricidae, Capromyidae). = Rodent II. Academic Publishing Society, Wiesbaden 1982, ISBN 3-400-00459-6 (very detailed textbook).
Web links
- Myodes rutilus inthe IUCN 2013 Red List of Threatened Species . Posted by: Linzey, AV, Henttonen, H., Sheftel, B. & Batsaikhan, N., 2008. Retrieved December 29, 2013.