Eurasian harvest mouse

The Eurasian harvest mouse is a tiny mouse that lives both in woodland and on farmland. It is found in central Europe and the Mediterranean countries, and as far east as Japan. The Eurasian harvest mouse first appeared in Sweden in 1985.

The world’s smallest rodent

The Eurasian harvest mouse is one of the world’s smallest rodents, weighing just 7 grams. The fur of the adult is uniformly brick red, brownish-orange or reddish-brown on the upper side, and white on the underside. The boundary between the upper and under sides is sharply demarcated. Its tail is much longer than its body, and the mouse can use it as a fifth leg when climbing, like a small monkey.

This may be needed when climbing up crop stalks to pick grains of corn.

Eats seeds and insects

The Eurasian harvest mouse mostly eat seeds and other plant matter. During the winter, it also hunts for insects. It builds a nest half a metre above the ground – a round ball, like a small bird’s nest – in grass or bushes.

Reproduces quickly

Just like other rodents, the Eurasian harvest mouse reproduces quickly. The female can have seven litters in a year, with up to seven pups in each litter.

Spreading in Sweden

Eurasian harvest mice have started to spread in Sweden in recent years, forming populations from Skåne in the south up as far as the Torne Valley in the far north. Some have migrated into Norrbotten from Finland, where there are permanent populations. The Eurasian harvest mice found in southern Sweden probably came from Denmark with the help of humans, as shown by DNA tests carried out on Finnish and Swedish mice.

If you spot a dead mouse, take a close look to see if it could be a Eurasian harvest mouse. This will help us to learn how the species is spreading in Sweden. To humans, the Eurasian harvest mouse may look like a nasty little rodent, especially as it can climb and can even build small ‘bird nests’ in the grass. These nests are also something that can tell us if the Eurasian harvest mouse is present in an area.