Field signs
Field voles tend to be more reluctant to enter Longworth traps than other small mammal species. They dig burrows that are roughly the diameter of a table tennis ball, often with ‘lawns’ that are created by grazing around the burrow entrance. Latrines of bright green, cigar-shaped droppings and feeding stations of grass, rush or sedge chopped into small piles are often found along runs made through grass.
Nests can sometimes be found at the base of grass tussocks and under reptile refugia on survey or monitoring sites.
Habits
The field vole is found mainly in grassland, arable fields, roadside verges and gardens with plenty of grassy cover. It can also be found in young forestry plantations and at low densities in marginal habitats such as hedgerow, dunes and moorland.
Field voles are most active at dawn and dusk although they become more nocturnal in summer and more diurnal in winter, spending most of their time in burrows amongst the grass or along runs under grass tussocks. They are herbivorous feeding mostly on grasses, seeds and occasionally mosses, with teeth that are open-rooted, growing continuously throughout the animal’s life.
Reproduction and life cycle
The field vole breeds mainly from April to September, producing two to seven litters of one to eight young per year. Females born before June may reproduce in the same year and can mate as soon as they are weaned at 14 to 21 days. Very few individuals survive two winters.
In the UK, many populations exhibit fluctuations which cycle with either a three to four year pattern or seasonally with irregular year on year changes. Usually the population either declines in spring then increases in late summer to autumn, or peaks in early summer and declines in late summer. Predator numbers can follow these cycles.
Distribution, status and conservation
The field vole is thought to be Britain’s most numerous mammal. Widespread throughout the UK and in Kent, but absent in Ireland, it has an IUCN conservation status of Least Concern. It can cause damage to young plantations, grassland and cereal crops, reaching densities of more than 400 per hectare in grassy clear-felled areas.
The field vole is an important prey item for birds of prey making up 40% of the barn owl’s diet and being found in 67% of hen harrier pellets. Other predators include heron, kestrel, buzzard, fox, stoat, weasel, American mink and badger. It is sometimes brought in by domestic cats.
Threats include overgrazing, habitat loss, scrub growth and poisoning with rodenticides. It can do well in conservation field margins and meadows.
