The living habits of lemmings and the mystery of the "Great Death Migration"

Lemmings are mammals that live in the Arctic all year round. They have an oval body shape, short limbs, and are smaller than ordinary mice. They can grow up to 15 cm. They have thick and short tails, small ears, and timid eyes. But when forced, When cornered, it will get angry and fight back. The Eskimos call it the animal from the sky, and the Scandinavians call it the "sky rat." This is because in a certain year, their number will increase greatly, just like the heavenly soldiers and...