Southern section of the sands, which reaches the Danube, is known as the Labudovo Okno. It has been declared a Ramsar wetland in 2006. The section covers an area of some and includes marshes, ponds, meanders, river islands of Žilovo, Čibuklija and Zavojska Ada, meanders of the Karaš river and the submerged mouth of the Nera into the Danube. It is one of the most important migratory birds habitat in Serbia.