In temperate climates, such as we have in Europe, and in the northern parts of North America, winter can be a difficult time for animals. The weather is cold, there is often snow on the ground, and food is in short supply. Some animals hibernate through the winter, while others struggle on through the harsh weather. Smaller mammals, such as rodents, often store dry food in caches that they can return to when there is nothing fresh available. Squirrels, for example, hide nuts to bide them through hard times. But some rodents go to greater lengths.
Out of the over six hundred members of the mouse family, the steppe mouse (Mus spicilegus) is one of the three closest species to the familiar house mouse (Mus musculus). It is found from the easternmost border of Austria, through Hungary, Romania, and Serbia, and out into the steppe lands of Ukraine and western Russia. They are found primarily in and around agricultural land and orchards, and rather less in the wild grasslands where they presumably originated. Indeed, while the species seems to have diverged from the house mouse around three million years ago, long before modern humans were around, today it seems to rely upon us to create the unnatural habitats in which it thrives best. In this respect, it resembles the house mouse, which only rarely lives outdoors.