Wildlife watch: Field mouse
Mice might not be the most popular of garden wildlife - but field mice play an important role in our gardens. Kate Bradbury explains ways to help them and how to prevent them coming inside your house
Also known as the wood mouse, the field mouse is a small, sandy brown mammal with big ears, big eyes and a long tail. Britain’s most widespread rodent, it’s common in woodland and grassland and also frequents gardens, even in very urban areas. It eats seeds (including bird seed), plants, caterpillars, earthworms, fruit, fungi and other foods such as cat biscuits, which you might leave out for hedgehogs. It caches food to store for leaner times, although these caches are often ‘forgotten’ – you may find piles of seed husks in a corner of your shed or beneath some membrane you have laid down to suppress weeds. If the seeds are large enough – for example if you find a pile of plum stones as I often do on my allotment, you may spot teeth marks on those that have been eaten. Different rodents leave different types of teeth mark on seed husks, so with some careful investigation you should be able to identify the field mouse as your hoarder.
Field mouse burrows are typically underground. They may have several chambers and are used by several generations. Nests are made using leaves, moss and grass, with extra material added in winter. Unlike most mammals, field mice do not hibernate.
Breeding usually takes place from March to October but can continue into winter if conditions are mild and there’s a steady supply of food. Up to seven blind and hairless young are born per brood, and are cared for by their mother for up to three weeks.
How to help field mice
Helping field mice might not be the first thing you think of when caring for garden wildlife. But it’s worth remembering that these small rodents are far down in the food chain, which makes them a source of food for species further up the food chain, including foxes, weasels and owls. Indeed, field mice are an important source of food for tawny owls, who may fail to breed when numbers of small rodents is low.
What’s more, abandoned field mouse nests are used by queen bumblebees in spring. It’s thought that the smell of mouse attracts the bumblebees to the site. Bumblebees don’t gather their own nest material so will happily use the material left over by the mice, so by helping mice, you are also creating the perfect nesting habitats for bumblebees.
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To help field mice let some areas of the garden remain wild – create an open compost heap or log pile where they can nest, and let seedheads remain on plants so they have a source of food. In my garden in autumn, field mice climb sunflower stems and chew the seed head until it falls to the ground, and then they empty it of sunflower seeds, which they take back to their cache. They also enjoy windfall plums and cherries, along with plenty of other items I haven’t noticed them eating! I love supporting them in my garden and allotment.
Field mice aren’t known for living in houses like house mice. However, in inclement weather, field mice may be tempted to come into your home, for shelter. I used to sometimes find field mice in my home in winter, and one particularly stormy day a mouse relocated her nest just beneath the floorboards in my living room. She moved on when conditions outside improved.
The easiest way to stop mice coming into your home is to block entrance holes. I used wire wool and bricks to block holes both in my patio and the walls of my house, including where pipes enter the house. It’s also a good idea to relocate any bird feeders that are close to the house to the far end of the garden, as this means the mice are concentrated away from the home. Ultimately, field mice live and belong outside and shouldn’t cause you any problems.