The common vole (''Microtus arvalis'') is a

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

Distribution and habitat

The common vole is hardly restricted in means of distribution and habitat and inhabits large areas of

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...

but, apart from the

Orkney vole The Orkney vole (''Microtus arvalis orcadensis'') is a population of the common vole (''Microtus arvalis'') found in the Orkney Islands, off the northern coast of Scotland, as well as in the Channel Island of Guernsey. Orkney voles are about 10% ...

, not the

British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isl ...

. As ''Microtus arvalis'' followed human civilization, primary and secondary habitats can be distinguished. The primary habitats are everything but dense forests, such as

meadow A meadow ( ) is an open habitat, or field, vegetated by grasses, herbs, and other non- woody plants. Trees or shrubs may sparsely populate meadows, as long as these areas maintain an open character. Meadows may be naturally occurring or arti ...

s, heath lands, and fallow land. The secondary habitats are mainly agricultural fields, where shallow sloped areas are preferred. The natural food of the common vole is

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...

, but it also feeds on many agricultural crops (within secondary habitats) and here its reproduction is faster than in primary habitats.

Reproduction, demography, and predation

After

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ...

of 16 to 24 days, females give birth to 3 to 8 juveniles, weighing between 1.0 and 3.1 g. Weaning is around the 20th day. Female juveniles can be impregnated from the 13th day after birth. Hence, first birth can be given from the 33rd day. During annual reproduction, which starts in March and ends in October, females usually have three reproductive cycles. The average life span is 4.5 months, which means that most animals die after the last reproduction in October, while the latest offspring in the year survives the winter and starts reproduction the following spring. Weights can reach 51 g in males and 42 g in non-pregnant females. Sex ratio at birth is equal, but becomes female-biased as the animals mature or with increasing population density when the ratio can level off to 3:1 or even 4:1 in favour of females. These ratios depict an intense competition for female mates, which leads to higher mortality and dispersal rates among the males. Population density varies seasonally and exhibits a considerable long-term fluctuation that shows typically three-year or five-year cycles. Densities can range from 100 individuals per ha (very low level) over 500 individuals per ha (medium level) up to 2000 individuals per ha in some years. As reaction females' reproduction can decrease or even stop. Not only influenced by population level, reproduction rate can change with the amount and quality of food and light. Self-regulation (e.g. decrease of reproduction rate) has been addressed to be a response to increased population densities. However, ''M. arvalis'' is one of the main food sources of a considerable number of predators in

Central Europe Central Europe is an area of Europe between Western Europe and Eastern Europe, based on a common historical, social and cultural identity. The Thirty Years' War (1618–1648) between Catholicism and Protestantism significantly shaped the a ...

. Buzzard,

kestrel The term kestrel (from french: crécerelle, derivative from , i.e. ratchet) is the common name given to several species of predatory birds from the falcon genus ''Falco''. Kestrels are most easily distinguished by their typical hunting behaviou ...

, long-eared owl,

tawny owl The tawny owl (''Strix aluco''), also called the brown owl, is commonly found in woodlands across Europe to western Siberia, and has seven recognized subspecies. It is a stocky, medium-sized owl, whose underparts are pale with dark streaks, a ...

, and

barn owl The barn owl (''Tyto alba'') is the most widely distributed species of owl in the world and one of the most widespread of all species of birds, being found almost everywhere except for the polar and desert regions, Asia north of the Himala ...

are some of the birds that feed on the common vole and so delimit population sizes. Ground-predators are mainly

weasel Weasels are mammals of the genus ''Mustela'' of the family Mustelidae. The genus ''Mustela'' includes the least weasels, polecats, stoats, ferrets and European mink. Members of this genus are small, active predators, with long and slend ...

stoat The stoat (''Mustela erminea''), also known as the Eurasian ermine, Beringian ermine and ermine, is a mustelid native to Eurasia and the northern portions of North America. Because of its wide circumpolar distribution, it is listed as Least Conc ...

, adder,

polecat Polecat is a common name for several mustelid species in the order Carnivora and subfamilies Ictonychinae and Mustelinae. Polecats do not form a single taxonomic rank (i.e. clade). The name is applied to several species with broad similarities ...

, fox and

boar The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The species is ...

Territories and nests

''M. arvalis'' maintains aboveground runways, which expand like a

railway Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a p ...

-system through the entire home range. Voles are seldom seen outside these runways, which enable a faster and safer locomotion and easier orientation. The climbing ability of the common vole is very poor. Underground nests are dug 30 to 40 cm deep into the ground and are used for food storage, offspring raising, and as a place for rest and sleep. Nests can be shared and defended by up to five females with juveniles that are related in most cases. Females are territorial and an overlap of occupied areas does not occur. Hence, the number of colonies increases with individual number (i.e. population density). As common voles have a

polygynous Polygyny (; from Neoclassical Greek πολυγυνία (); ) is the most common and accepted form of polygamy around the world, entailing the marriage of a man with several women. Incidence Polygyny is more widespread in Africa than in any ...

mating system the males do not maintain territories and move as so-called "floaters" between several females' territories in order to mate as often as possible. They can show overlap in territories. These findings are supported by the different home range sizes of males (1200–1500 m²) and females (300–400 m²) that can decrease in both males and females as population density rises. Another response to population growth is to leave the original habitat and move towards another one. Males predominantly conduct dispersal, being most often caused by the competition for mates.

References

* Baillie, J. 1996.
Microtus obscurus

2006 IUCN Red List of Threatened Species.
Retrieved 9 July 2007. * Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 ''in'' Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore. * Niethammer, J. and Krapp, F. 1982. Handbuch der Säugetiere Mitteleuropas. – Akademische Verlagsgesellschaft Wiesbaden

External link

{{Authority control Microtus Mammals of Asia Rodents of Europe Mammals of Russia Mammals of Central Asia Mammals of Azerbaijan Mammals of Turkey Vole, Common Mammals described in 1778

Distribution and habitat

Reproduction, demography, and predation

Territories and nests

See also

References

External link