The field vole or short-tailed vole is a grey-brown vole, around four inches in length, with a short tail. It is one of the most common mammals in Europe, with a range extending from the Atlantic coast to Lake Baikal; these voles are found in such as woodland, marsh or on river banks. Although they make shallow burrows, they build nests above ground, they are an important food source for owls and some other predators and their population size tends to peak and trough cyclically. Field voles breed prolifically in summer, but all year round under snow. Females produce up to seven litters a year, each averaging from four to six young which are weaned after about fourteen days; the field vole is both widespread and common and is listed as being of "Least Concern" by the IUCN. The field vole is a small, dark brown rodent with a short tail, distinguishable from the related common vole by its darker and shaggier hair and by its more densely haired ears; the head and body length varies between the tail between 1 and 1.75 inches.
The weight is 0.7 to 1.8 ounces. The voice is a faint, low squeak and it emits a range of chattering sounds; the field vole has a palearctic distribution. Its range extends throughout Western Europe and eastwards to Lake Baikal in Siberia and north west China and northward to Norway and Finland, it thins out southwards towards the Mediterranean Sea. It is found in a range of habitats including meadows, field borders, woodland verges, upland heaths, marshes and river banks and tends to prefer wet areas, it is found at altitudes of up to about 1,700 metres. The field vole is more active by day than the common vole, it excavates shallow burrows close to the surface of the ground, under leaf litter and under snow in winter. It makes surface runs through tall vegetation, routes along which it can scurry back to safety if danger threatens. Off these are dedicated defecation sites and it leaves little piles of chopped up grass stalks nearby; the field vole is a herbivore and feeds on grasses, root tubers and other vegetation and gnaws bark during the winter.
It eats invertebrates such as insect larvae. Among the plants it favours are the grasses Agrostis spp. and Festuca rubra, the yarrow, clover and buttercups. The voles choose species with high digestibility where possible and avoid some common plants amongst which they live such as the tufted hairgrass and rosebay willowherb; the animals have low energy reserves and these are only able to sustain them for five to fourteen hours. Because of the low availability of food in the winter, drier habitats are unable to sustain populations of much over two hundred animals per hectare; the number of voles expands with the arrival of spring and the better availability of food supplies. Field voles are an important part of the diet of barn owls and they are preyed on by kestrels, other owls, stoats and snakes. Though numerous, they have little impact on man except in plague years when the may cause significant damage to crops. Field voles are induced ovulators; the field vole breeds throughout the year but the breeding season peaks in summer.
The nest is made on or just under the surface of the ground in a clump of grass or sedge. The gestation period is about three weeks and up to a dozen young; these grow suckle for twelve days and leave the nest at twenty one days, reaching sexual maturity soon afterwards. Like the common vole, the field vole is subject to population explosions. Females become pregnant again soon after parturition; the pregnancy rate is nearly 100% in late spring but falls during midsummer only to rise again later. Mortality in the nest is about 20% but may rise to 50% in the middle of summer when the digestibility of the food supplies fall. Life expectancy is about two years but is lower for spring-born individuals than for ones born in the year. Male field voles maintain a territory but females just have a home range which may overlap with that of a neighbour. After leaving the nest, young female voles remain in or near their mother's home range but young males are forced to disperse by the aggressiveness of the adult males.
Female field voles sometimes spontaneously move in the time gap between weaning one litter and producing the next, a phenomenon typical of this species. One of the causes of the large population swings that occur in the field vole is the scramble competition which comes into play when the most desirable food plants are less available in mid summer. At this time litter sizes may fall, growth rates slow down, there may be increased mortality of young in the nest, adults may lose weight and some may die. Similar competition can occur in winter when the availability of greenstuff fails and starvation ensues; the field vole is common over most of its wide range, although thinning out towards the peripheries and may be locally scarce where conditions are less suitable. The population seems stable over the long term though there are marked fluctuations from year to year; the IUCN in its Red List of Threatened Species has therefore listed it as being of "Least Concern"
Eutheria is one of two mammalian clades with extant members that diverged in the Early Cretaceous or the Late Jurassic. Except for the Virginia opossum, from North America, a metatherian, all post-Miocene mammals indigenous to Europe, Africa and North America north of Mexico are eutherians. Extant eutherians, their last common ancestor, all extinct descendants of that ancestor are members of Placentalia. Eutherians are distinguished from noneutherians by various phenotypic traits of the feet, ankles and teeth. All extant eutherians lack epipubic bones; this allows for expansion of the abdomen during pregnancy. The oldest-known eutherian species is Juramaia sinensis, dated at 161 million years ago from the Jurassic in China. Eutheria was named in 1872 by Theodore Gill. Distinguishing features are: an enlarged malleolus at the bottom of the tibia, the larger of the two shin bones the joint between the first metatarsal bone and the entocuneiform bone in the foot is offset farther back than the joint between the second metatarsal and middle cuneiform bones—in metatherians these joints are level with each other various features of jaws and teeth Eutheria contains several extinct genera as well as larger groups, many with complicated taxonomic histories still not understood.
Members of the Adapisoriculidae and Leptictida have been placed within the out-dated placental group Insectivora, while Zhelestids have been considered primitive ungulates. However, more recent studies have suggested these enigmatic taxa represent stem group eutherians, more basal to Placentalia; the weakly favoured cladogram favours Boreoeuthearia as a basal Eutherian clade as sister to the Atlantogenata
Southwestern water vole
The southwestern water vole or southern water vole is a large amphibious vole found in most of France and south-westwards through Spain and Portugal. Although considered to be a member of the same species as the Eurasian water vole and Carleton considered it distinct enough to warrant full species status, it is listed on the IUCN Red List as vulnerable. It is threatened for many of the same reasons as the northern water vole, a campaign is underway to seek protection for the species, both at a national level and at European Union level; the animal was traditionally one of the main ingredients in the Valencian dish called paella. 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
The water voles are large voles in the genus Arvicola. They are found in much of northern Asia. A water vole found in Western North America was considered a member of this genus, but has been shown to be more related to members of the genus Microtus. Head and body lengths are 12–22 cm, tail lengths are 6.5–12.5 cm, their weights are 70–250 g. The animals may exhibit indeterminate growth, they have hairy fringes on their feet that improve their swimming ability. European water vole Southwestern water vole Montane water vole Nowak, R. M. 1999. Walker's Mammals of the World, Vol. 2. Johns Hopkins University Press, London. Townsend, C. Begon, M. and Harper, J. L. 2003. Essentials of Ecology: second edition. Blackwell Publishing, Oxford
Northern mole vole
The northern mole vole is a species of rodent in the family Cricetidae. It is distributed over large parts of Eastern Asia; this vole is found in Kazakhstan, Kyrgyzstan and Ukraine, the southern parts of Russia, western Siberia, northern Afghanistan and northern China. The northern mole vole is a small mammal about 130 mm long with a short tail; the females are larger than the males. The body is wedge-shaped, the head flat, the neck short and the musculature of the forelimbs developed, it has short, brownish fur somewhat paler on the underparts. The feet are pink, it is adapted to life underground. The karyotype has 2n = 54; the Y chromosome is present, unlike in the cases of its relatives E. lutescens and E. tancrei. The northern mole vole is active all day. Activity decreases during periods of drought and in the winter, but there is no true hibernation period. A study undertaken in 2001 found the vole's adaptation to the extremes of the continental climate is based on distinct seasonal variations of thermoregulation.
The gestation period lasts three weeks, with three or four litters a year, with two to four young voles in each. These grow and are sexually mature at the age of six weeks; this vole is a colonial species, living in groups of about 10 individuals a family group of one pair of adults and young animals from one or two litters. The burrows are complex, the entrances are sealed by soil and the nesting chambers and fodder chambers are about 4 m beneath the surface; the animals feed on roots, bulbs and the juicy rhizomes of plants, in the summer and autumn they store small stocks of food. They emerge onto the surface except to distribute soil excavated from the burrow or to move to new territories, at which times they can cover distances of up to 800 m; the population size varies, being limited by infectious diseases, severe winters with deep-frozen ground, spring flooding of burrows by melt water and predatory birds and mammals
Transcaucasian mole vole
The Transcaucasian mole vole is a species of rodent in the family Cricetidae. It is found in Armenia, Georgia and Turkey; the karyotype has a low, diploid number, 2n = 17,X. Transcaucasian mole voles have no SRY Y chromosome, their sex-determination method remains unknown. Tokudaia osimensis Tokudaia tokunoshimensis
Lasiopodomys is a genus of rodent in the family Cricetidae. It contains the following species: Brandt's vole Plateau vole Mandarin vole 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