 The park is of international importance for eight of its plant species and 69 of its vertebrate fauna.It has some 95 breeding species of birds, is also very important for over 300 species of a wide range of transient and overwintering species, and serves as an essential stopover point for large numbers of migratory birds and waterfowl.The Ebro delta has the world's largest colony of Audouin's gulls.