Tundras are biomes located around the North Pole, and are usually covered in snow, but when the summer comes, the snow thaws and some plants grow.
The soil in most tundras is frozen permanently because of the freezing temperature that can reach -50 °C, which is just enough for an arctic fox to survive without freezing to death.
Some animals such as arctic foxes, polar bears, sled dogs, gyrfalcons, etc. live in this frigid environment. Many of the birds that live in these icy climates leave before winter strikes so that they will not freeze to death. Some mammals like the polar bear and the arctic fox live all year round in the tundra.