The Orne is a river with a gentle course that takes its source in Aunou-sur-Orne to throw itself 105 miles (170 km) further into the English Channel at Ouistreham. The watercourse is sometimes surrounded by deep gorges (Rochers aux Parcs, Rochers de la Houle), whose entrance has been regulated by a dam (Rabodanges) since 1960. The Orne draws a vast bend that would have earned it its name Olina (bend in Gallic). It ends in a wide estuary with a rich ornithological heritage with more than 160 species of sedentary, migratory, aquatic, or marine birds.