Field vole (picture credit: David Chapman)
Fact file
Latin name
Microtus agrestis
Threat status
Least concern (Global)
Least concern (Europe)
Least concern (UK)
Etymology
Field voles are also known as short-tailed field mice, which helps explain the origin of the word vole. Vole is a shortening of “volemouse”, which originally came from the Norwegian “vollmus”, meaning “field” (voll) “mouse” (mus).
Identifying features
Small vole with smaller, less prominent ears and shorter tail than a bank vole. Colour varies from grey to yellow-brown, but the underside is always paler. Tail is less than 40% of the body length (bank vole tails longer).
Habitat
Grassland, often longer and ungrazed. Can be found in young woodlands with could grass ground cover, as well as hedgerows and moors occasionally.
Numbers
The current population estimate for the UK is 59.9 million (95% confidence interval: 37 million - 80.3 million) from the Mammal Society Review of the Population and Conservation Status of British Mammals. Some UK populations have cyclical increases (see more below).
Distribution
Across north Europe and into Russia. North into Scandinavia and south into parts of Spain, Portugal, and Croatia.
Diet
Herbivorous, mainly feeding on grass stems and leaves, preferring species with high nutrition. Mosses may also make-up a proportion of the diet.
Size
Adult field voles weigh about 20 to 40g. Adult body length is 9cm to 12.5cm with tails 3cm to 4cm.
Life span
Only around 1 year.
Breeding
The breeding season in field voles is from March to October, though it can be earlier in some years. Young that are born early in the season are able to breed in the same year. Field voles have 1-8 young per litter and several litters per year. Young become independent after 14-21 days.
Survey techniques
Field Voles are usually surveyed using live trapping, as they can be difficult to identify unless you have it in hand. They can also be identified from field signs, including small tunnels cut through long grass, with small piles of nibbled grass stalks along them.
Legislation in the UK
Field voles are not protected in UK law, and a licence is not required to live trap them (though we highly recommend anyone looking to live trap gains some experience first!).
Population Explosions
Some populations of field voles go through cycles of population increases every 3-4 years. In peak years, numbers can explode to the point where they can damage crops, pastures and even orchards. It is not clear why these cycles occur, though predator pressure, disease and food availability have all been implicated. In the UK, there does not seem to be any biogeographical link, such that adjacent populations may be in different phases of the cycle, or not cyclical at all. This variation is useful for predators, as across the landscape there are always likely to be numerous field voles to eat!
Predators
Field voles are important for most UK predator species, especially kestrels and weasels which are specialist vole hunters. Red foxes and domestic cats are more generalists hunters, but they both take a significant number of voles as part of their diet. Field voles themselves may not be that charismatic (though we think they are!), but they are very important in the diet of many other species.