In mid-autumn, when temperatures drop in Scandinavia, the Common Cranes (Grus grus) start their migration towards the Iberian Peninsula and the Maghreb. They invariably follow the same route. In France, the crane flocks follow a 124 miles (200 km) wide air corridor from Lorraine to Aquitaine, via Champagne and the Gascony moors. Most of them continue to Extremadura in southern Spain. To save their strength, they prefer to glide using the thermodynamics of the air masses. Flapping flight is reserved for night, in bad weather, and over the sea.