The boreal lynx (Lynx lynx carpathicus) is the only large feline present in the wild in mainland France where it is considered endangered. Since its reintroduction in the 1980s, the population monitoring has been carried out nationwide by the Wolf-Lynx network coordinated by the French Biodiversity Office, which regularly detects signs of presence outside the historic areas of the Jura, Vosges and Alpine massifs. The method of detecting the presence of the lynx analyzes the recurrence of its appearances by successive and overlapping biennial periods of one year based on the biological cycle of the species. Its cartographic restitution is in the form of 6.2 square miles (10 km2) meshes, the standard unit used at the European level.