 If the owner wishes to sell the island then the Department has a pre-emptive right.After two months the Conservatoire National du Littoral has the next pre-emptive right and then after another 2 months the town of Blaye has a final pre-emptive right to acquire the island.The Île Verte, Île du Nord and Île Cazeau comprise about 800 ha and because of their natural state provide a fine stopping off place for migrating birds.