Vol en formation de grues cendrées (Grus grus) (Cher (18), France). Tags: vol; formation en V; grue cendrée; Grus grus; Gruidae; voler; migration; migrer; ciel gris; oiseau; échassier; automne; groupe; espèce migratrice; contre-jour; comportement; flight in V; formation; ashy; crane; to fly; flying; to migrate; gray sky; bird; wader; autumn; group; migrating species; France; flock; common; troop; migratory; migrant; back-light; wildlife; behaviour; behavior; nature;