Wood mouse  (Apodemus sylvaticus)

The wood mouse is classified as Least Concern (LC) on the IUCN Red List (1).

The wood mouse (Apodemus sylvaticus) is the most common native rodent in Britain (2). It has brown fur with a reddish tinge (3) and a white or greyish belly (2). The alternative common name of this species is the long-tailed field mouse, as the tail is often roughly the same size as the combined head and body length (3). This species can be distinguished from the similar yellow-necked mouse as it lacks a yellow collar that forms a bib on the chest (2).

Widespread and common throughout Britain and continental Europe, reaching as far north as southern Scandinavia (4). The wood mouse is not present on many of the smaller British islands, but where it does occur on islands it is often the result of introductions (4).

You can view distribution information for this species at the National Biodiversity Network Gateway.

A highly adaptable species, the wood mouse exploits a wide range of habitats, providing that they are not overly wet (4).

Wood mice are generally nocturnal, but males, or females suckling young may be active for short times during the day (4). They feed on seeds, invertebrates, fruits, nuts, seedlings, moss and fungi (4), and food is often stored within tunnel systems (3). All mice engage in 'refection' in order to fully digest food; they eat soft faeces that have already passed through their digestive system once, allowing carbohydrates to be fully digested the second time around (3).

Breeding occurs from March/ April until October, and peaks in July and August (4). In summer, females defend breeding ranges against other females (4). Dominant males may be aggressive, and have been reported to chase and even kill juveniles (3). Before mating, males are known to produce a string of ultrasounds, which may serve to pacify the female (3). Gestation takes 25 or 26 days (3), and the litter, which consists of two to nine young (4), is born at night within the nest (3). Nests are made in underground tunnels, inside hollow logs, bird or dormice nesting boxes or in dense vegetation (3). Between four and seven litters are produced each year (4), and females are able to conceive whilst still suckling the previous litter (3). The young are fully weaned after about 18 days, and usually start to breed the year after their birth, but if they were born early in the year they may breed during the year of birth (4).

Wood mice do not hibernate, but during winter males and females may group together when sleeping for extra warmth (3). The maximum life-span is 18 to 20 months. This species has many predators, including foxes, weasels, cats, owls and kestrels (4); the wood mouse has evolved a number of strategies to avoid these predators, it can make impressive leaps to safety, and can shed the skin of the tail if it is gripped anywhere other than its base, allowing the mouse to escape. The skin does not grow back; instead the area of the tail dies and falls off (3).

Although this species is not threatened at present, loss of woodlands, hedgerows and changes in agriculture may all negatively affect wood mice. Chemicals used in agriculture may also pose a threat, either directly, or via contamination of food sources (4).

No conservation measures or legal protection is in place for the wood mouse, which is an important source of food for many carnivores and owls (2).

There may be further information about this species available via the National Biodiversity Network Gateway.

View information on this species at the UNEP World Conservation Monitoring Centre.

For more on the wood mouse:

• The Mammal Society wood mouse fact sheet:
  http://www.mammal.org.uk/index.php?option=com_content&id=219