Few mammals are as abundant or
wide-spread as the wood mouse. Not
confined to woodlands, it is also known as the long-tailed field mouse, and they are found in fields, hedgerows and gardens, and may enter houses in the winter. They are nocturnal, shy, and fast moving but are occasionally seen if cover is moved, or when their nests are disturbed. The fur is yellowish-brown with a white-grey belly and throat. On the throat there may be a small
yellowish patch, but not a complete band. The long tail is hairless, and the pointed head has large ears and large black eyes. The body is 80 to 100 mm long and the tail is as long again. An adult wood mouse weighs between 16 and 30 g. Males and females are
similar in appearance and juveniles, weighing less than 13 g, have a greyish coat. The only similar species is the yellow-necked mouse, for which there are few records for Cornwall. This larger mouse has a complete yellow
band on the throat.
© David Chapman
© David Groves
A widespread and adaptable species, the wood mouse is found in rural and urban environments and frequently enters buildings in colder weather. They often live in
underground tunnel systems which may be occupied for many generations. In the winter wood mice may nest communally, but in the breeding season females occupy exclusive ranges. Chambers may be excavated for nesting or food storage but wood mice also use existing cavities, including bird nest boxes, to build their nests of leaves and grass in which to raise their families. Wood mice are mainly herbivorous and eat a range of seeds, nuts, grain, fruits, fungi and buds. They will also eat small invertebrates. The crop of autumn woodland seeds and nuts has a direct impact on the survival of wood mice over the winter.
Breeding from March to October and occasionally through the winter when food is
abundant, they may raise up to 4 litters of 4 to 7 young each year. They mate
promiscuously and individual litters may have up to four fathers. The litter is produced after about three weeks; three weeks later the young are weaned.
The peaks and troughs of wood mouse numbers can have a direct effect on the success
of many predators such as the tawny owl. Besides birds of prey, the wood mouse is an
important component of the diet of stoats and weasels, foxes and badgers. Many are
killed by domestic cats and some are trapped and poisoned as domestic or agricultural
pests. Contamination from exposure to slug pellets, herbicides and pesticides may
affect the survival of individuals and may serve to bioaccumulate toxins in predator
Tracks and Trails:
Wood mouse droppings are about 8 mm long, cylindrical with rounded ends and often deposited near feeding sites. The tracks may show the 4 toes of the front foot and the 5 toes of the longer back foot, which measures 20 to 30 mm. Food caches may be found in disused birds’ nests or tree hollows, often containing hazel nuts or pips with characteristic gnawing marks. The perpendicular tooth marks are similar to those left by the bank vole but the shell around the hole is heavily scratched.
In 2011, oblivious to the possible consequences, wood mice set up home in the specially constructed barn owl tower at the Lost Gardens of Heligan. Their antics on the webcam proved a popular attraction.
The wood mouse occurs throughout Cornwall and the Islesof Scilly, with the distribution of records often reflectingsurvey effort. Found from western Europe to Russia andfrom Scandinavia to the Middle East, the wood mouseoccurs across the UK and Ireland.
Did you know?:
The wood mouse’s habit of caching nuts and seeds aids the germination of tree seeds. Wood mice are excellent climbers and often compete with dormice at monitoring stations in trees. The wood mouse can shed part of its tail if caught, but it does not grow back.
The wood mouse is common and widespread and there is no specific legal protection locally or in the UK as a whole. It is considered a species of Least Concern in the IUCN Red List.
Longworth trapping and footprint tracking. Hazel nut surveys provide definitive evidence of wood mice, along with dormice and bank voles. Owl pellet analysis. Cat kill records are valuable, and wood mice are often reported from bird feeders and mouse traps.