Bank vole
| Bank vole | ||||||||||||
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Bank vole ( Myodes glareolus ) |
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| Myodes glareolus | ||||||||||||
| ( Schreber , 1780) | ||||||||||||
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The Rötelmaus ( Myodes glareolus , Syn. : Clethrionomys glareolus ) or Waldwühlmaus is a kind within the genus of Rötelmäuse ( Myodes ) corresponding to the subfamily of voles is assigned. It has formed several subspecies , three of which are represented in Central Europe . The name Rötelmaus goes back to the red-brown back coat color, while the name Waldwühlmaus on the preference of this kind for shady habitats in forests back or close to them. This species is one of the most common mammals in Europe , so it is considered safe.
features
The relatively small type of mouse with a head-torso length of seven to more than 13 centimeters has a tail length of 3 to 6.5 cm and weighs between 12 and 35 grams. The species shows size and weight differences of up to 300 percent between populations in different regions.
The back fur is red-brown to fox-red, sometimes also yellowish. The flanks are brownish to gray-brown and mostly cream-colored. The peritoneum is whitish to gray. The undercoat is gray. The paws are light-colored. The black hair at the end of the tail is slightly longer than the rest of the hair on the tail and clearly differentiated from it in color. The ears are large to medium-sized at nine to 16 millimeters.
The bank vole has a typical rodent bite, which consists of two enlarged incisors and six molars each (back teeth) in the upper and lower jaw . With increasing age, all molars develop roots and show a degree of growth in contrast to the constantly growing teeth of other vole species.
Graphically, the bank vole tooth formula can be expressed as follows:
The left and right halves of the dentition are identical, so that usually only one side is shown.
distribution and habitat
The bank vole is found in large parts of Europe and northern Asia. According to some sources, it is the most common mammal in Central Europe. Their habitat is formed by beech and mixed forests , near-forest hedges and bushes, and wetlands. It is also often found near rivers . Gardens near the forest are also accepted as habitats . There the bank vole also builds its nests in barns , storage sheds, garden sheds or other wooden structures that are rarely used . Indications of an existing nest include foliage , dry moss cushions and twigs that were entered and deposited by the bank voles.
In the south of Europe the bank vole is closely tied to the distribution limit of the common beech . Accordingly, it is only common in the north of the Iberian Peninsula and northern Greece . In Scandinavia and England , the distribution area extends to the 68th parallel to the north, further than that of the deciduous forests . In northern Scandinavia the bank vole gives way to coniferous forests due to the lack of deciduous forests and shares its northern border with the spruce . The Altai forms the eastern limit of distribution . In the Alps , the bank vole can also be found above the tree line , up to an altitude of 2,400 m. However, it is more common below the tree line in the mixed mountain forests.
Nests and Buildings
Bank voles usually build their nests and burrows underground, with the tunnels only a few centimeters below the surface. These structures include an extensive network of paths under the leaves or snow cover. The construction includes blind aisles and extensions in which food supplies can be stored and the nest can be created. If the nest is in one of the extensions of the building, it is on average 45 centimeters below the surface. However, nests are also created on the surface, in the vegetation , in rotting tree stumps or underneath dead wood trunks . The nests are made of different materials and upholstered in different ways. Nests were found that consisted entirely of moss or were additionally padded with frayed wood. There are also nests made of dry leaves, mostly with moss as a supplement. But animal hair or bast fibers are also used.
In addition to rearing young, the nests also serve as a place to stay for individual animals, as a feeding place or storage space. At low temperatures, the animals' energy requirements when they stay in a nest are considerably lower. The mutual warming of several animals in a nest has little influence on the energy consumption of the individual animals. This has been proven by studies on individual animals and those wintering in groups.
activity
The activity of bank voles is distributed over several phases throughout the day, with the number, duration and time of day of these phases depending on the season. On average, the total daily activity time is one and a half to six hours, which are divided into three to nine activity phases. The highest number of activity phases and the maximum of the total duration of daily activity are in summer and winter, the respective minima in spring and autumn. Activity peaks occur especially at dusk , in the morning and in the evening.
Whether the animals are diurnal or nocturnal depends on many influences. In areas where the strictly nocturnal yellow-necked mouse ( Apodemus flavicollis ) occurs in high density, bank voles evade their competitive pressure, for example , by being predominantly diurnal, while in the same area they are predominantly nocturnal and twilight- active when the yellow-necked mouse is low.
In summer the animals are mostly nocturnal and thus avoid the high hunting pressure of their diurnal predators. In winter, the activity phases are relatively evenly distributed over the entire day. In autumn and spring, the distribution of activity between day and night is irregular and characterized by the transition of the different behavior patterns into summer and winter.
nutrition
The bank vole's diet in spring consists of grasses , herbs and seedlings . In summer and autumn , the spectrum of possible food sources expands to include buds , seeds , fruits , mosses and mushrooms . In winter, tree bark also serves as a food source in large quantities . The bank vole eats insects , spiders and worms , and occasionally bird eggs, all year round . For the winter she stores acorns , beechnuts and other seeds.
Natural enemies
The bank vole is an important source of food for many predators . These are, for example, the red fox , the lynx , the European wildcat or martens such as the ermine , the weasel and the polecat . The hawk owl , which is native to the boreal coniferous forests , lives almost exclusively on bank voles during the breeding and rearing period. Other owls , such as the barn owl , the tawny owl , the long-eared owl or the eagle owl , as well as other birds of prey such as falcons , hawks or sparrowhawks , belong to the bank vole hunters. They also do not disdain the black and white stork or the gray heron . In addition to birds and mammals , snakes such as adders or grass snakes also prey on bank voles.
Reproduction
Bank voles are very social animals, they usually live in groups. The mating is polygamous and promiscuous . Dominant females defend their territories, in which they live with their offspring, against other females and lower-ranking males. The female territories partially overlap with those of other females. Dominant males defend larger territories that overlap with those of several females. When mating, the females prefer these dominant, local males over lower-ranking, non-local males. As a rule, reproduction takes place in the summer months. While the reproductive period is limited to the months of May to July in years with a scarce food supply, it can extend to March to November when there is good food supply, for example after beech or oak fattening . In mountain forests, bank voles reproduce all year round with a very good food supply. The tendency to multiply in winter is more pronounced among populations in the mountains than among those living in the lowlands. In addition to the food supply, the amount of space and the length of daylight are decisive factors for the sexual activity of bank voles. During field studies in Poland , for example, it was found that female bank voles only become pregnant if their own territory has a certain minimum size. Shortly before giving birth, the females become more aggressive, the territory sizes shrink, and the territorial distance increases. The overlapping territories decrease considerably in this phase. Sexual development of male bank voles is delayed when adult, dominant males live in close proximity.
The gestation period is seventeen days with optimal food supply, but can be extended to up to 24 days in nursing ( lactating ) females. The mean gestation period was determined to be three weeks.
Female bank voles shed in the wild two to a maximum of three times in their life. In laboratory tests, an average number of 3.1 litters per female was determined. After a gestation period of 18 to 23 days, three to seven young are born. The average is 3.5 boys per litter .
The young are born blind and naked , only a few whiskers are on the lips. The first hair on the back appears after three days. However, it takes up to 25 days for the young gray fur to fully develop, which is then changed for the first time after 34 to 38 days. The auditory canals open on the eleventh day after birth, one day later the young animals open their eyes. But they are weaned only after 20 to 25 days.
The sexual maturity usually starts after nine weeks. However, the young female animals can become sexually mature after four weeks, whereas the males after eight weeks at the earliest. When the young animals participate in reproduction so early and strongly, the population increases rapidly in nutrient-rich summers. Females born early in the year who already participate in reproduction in their year of birth usually do not survive the following winter, which was proven by the removal of animals with uterine scars in control catches in winter. The females born in late summer and autumn do not participate in reproduction until the following year and have a higher life expectancy in years with a low population density.
In years with a high population density, the area sizes are significantly smaller, the stress in the animals and the aggressiveness among each other are considerably greater. In such years and when food is scarce, infanticide - killing young animals - occurs by females on the young of females in neighboring territories. Infanticides by males have also been observed. The young animals that are killed are usually eaten.
The bank vole has an average life expectancy of 1.5 years, but it can reach an age of around 4 years when kept.
Tribal history
Evidence for the distribution of the genus Myodes in Europe is already available from the late Pliocene . Evidence from the Pleistocene is available for the bank vole in its recent form . After the end of the Würm Ice Age , the species spread widely. Due to the bank voles' preference for forested habitats, finds of remains are considered an indicator of forest cover and a temperate climate for paleontology .
Bank vole as a pest
Since the bank vole also feeds on tree bark in winter and debarks beeches, maples and larches up to several meters high, it is considered a forest pest . By eating seedlings, it also damages seedlings and can significantly impair the regeneration of the forest. The harmfulness of bank vole is relatively low in a healthy ecosystem , because significant damage is only recorded when it occurs in large numbers. Due to the large number of natural enemies, however, the bank vole regulates itself relatively quickly ( predator-prey relationship ).
Bank vole as a disease vector
For the fox tapeworm , the bank vole an intermediate host . By the infestation with the larvae of tapeworms the bank vole is weakened and so an easier prey for the definitive host, the fox. But dogs and cats also eat the infected animals and then excrete infectious eggs, which humans can ingest by handling the pets or their excretions. It is a false intermediate host in the development cycle of the fox tapeworm , since the infection is not passed on to the ultimate host, but a development of fins takes place in the organs of an infected person, primarily in the liver , lungs and brain , which causes the clinical picture of alveolar echinococcosis . A cure is only possible with an early diagnosis; alveolar echinococcosis is the most common worm disease in humans that causes death.
In addition to the fox tapeworm, which the bank vole indirectly transmits to humans via fox, cat or dog, the bank vole also transmits many pathogenic germs. One of the most noteworthy is the serotype Puumala - PUU for short - of the hantavirus , which causes a hemorrhagic fever . The bank vole is considered the main carrier of PUU in endemic areas . Various scientific studies have shown that the occurrence of PUU infections in humans is closely related to the size of the bank vole populations. The Swabian Alb , Lower Franconia , Lower Bavaria and the Eifel are particularly endemic areas in Germany . In Austria , most PUU cases in 2004 were reported from Carinthia and Styria . However , cases of the disease are also known from other European countries, such as Sweden , Finland , Belgium , France , Italy , the Czech Republic , Slovenia , Croatia , Greece and Russia .
The infection is triggered by direct or indirect contact with infected animals and their excretions - urine , feces or saliva . The viruses are also still infectious if the mice's excrement or urine has dried out and the viruses are absorbed via the respiratory tract, for example when dusting in basements , sheds, stables or storage facilities that are polluted with rodent excreta . The ingestion of food or water contaminated with rodent excrement can also trigger the disease.
Individual evidence
- ↑ Paul-Walter Löhr, Franz Müller, Joachim Jenrich: Small mammals: body and skull features, ecology . Ed .: Association for Natural History in Osthessen eV, Fulda. 1st edition. Michael Imhof Verlag, Petersberg 2010, ISBN 978-3-86568-147-8 , p. 85-90 .
- ↑ Hantavirus infection on medizin.de (accessed April 10, 2011)
- ↑ Increase in hantavirus infections in Germany, Belgium and France - Hanta virus: is the result of the increase in the bank vole population? , Article from July 22, 2005 on medical-enzyklopaedie.de (accessed April 10, 2011)
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 .
Web links
- Photos of forest damage caused by bank voles
- Animal Diversity Web
- Myodes glareolus inthe IUCN 2013 Red List of Threatened Species . Posted by: Amori, G., Hutterer, R., Kryštufek, B., Yigit, N., Mitsain, G., Palomo, LJ, Henttonen, H., Vohralík, V., Zagorodnyuk, I., Juškaitis, R ., Meinig, H. & Bertolino, S., 2008. Retrieved December 29, 2013.
