Daily Life: Harvest mice are active by day and night. Male mice roam over a territory of about 400 sq m, while females keep to a smaller area. They are very active, agile little animals, using their prehensile tail as a fifth limb to grasp grass stalks. The tail is wound around a stalk and in this way, the mouse can quickly climb the tall stems to find the seeds at the top. It breaks a seed off with its teeth, holds it with its front paws, removes the husk and gnaws into the centre.
What is eaten depends on what is available; in early spring, the mouse eats buds on bushes, new grass shoots and nectar from flowers. Seeds from crops are mainly eaten during the summer but insects such as wheatfly aphids, blackfly, grasshoppers, moths and caterpillars are also relished. Blackberries and rosehips are enjoyed in the autumn.
Harvest mice have many natural predators. They are a tasty snack for many animals including foxes, weasels, stoats, cats, owls, crows and kestrels - even toads will eat them!
Winter: When the cereal crops have been harvested in the late summer and most tall plant stems have died back, the harvest mice are left exposed and they look for shelter. In a severe winter they sometimes go into barns and outbuildings, but they usually find a nearby hedgerow. Here they build a winter nest of grass near ground level. They do not hibernate but sleep for long periods in their nest, waking up during milder spells to eat a little previously stored food or venture out on a foraging trip. They are more active during the day in winter. Many mice die of cold.