Common Cranes (Grus grus) usually gather in mid-October or early November to begin their migration to warmer skies. They leave northern Europe for a long journey of 1,550 miles (2,500 km) down south. The cranes always follow the same route. In France, it is a corridor almost 124 miles (200 km) wide. Although able to cross the country in one go, they often stop to rest. Common Cranes sometimes fly at night to benefit from cooler, denser air that better regulates their body temperature during exercise.