In Canada, it’s winter. Red-sided garter snakes are hibernating. This means they are sleeping. They sleep in groups. They stay underground to stay warm. In spring, it gets warmer. Then the snakes wake up. They leave their dens. They slither out of the ground.
What guides them? Their sense of smell. They pick up smells from the ground and air. Each snake remembers the smell of its summer home. When the seasons change again, they return to their winter dens.
When red-sided garter snakes migrate, they move by the hundreds.