The Lac du Der-Chantecoq was inaugurated in 1974 as a water reservoir destined to regulate the level of the Marne river, which supplies the Seine, in the event of floods. It also feeds the watercourses during low water periods. Over time, the lake located on a wide migratory corridor has become a haven and a stopover for thousands of birds. Among them, the common crane (Grus grus) comes to rest on its way towards warmer countries. With global warming, some also choose to winter in the lake. Quiet zones have been created on its waters to welcome the birds.