No less than 32 streams and 15 rivers form the Orne. It spreads its 105 miles (170 km) in length over the Calvados and Orne departments and crosses nearly 60 municipalities. It flows into the Channel after many meanders and having dug its bed at the edge of the schist cliffs of the Norman Switzerland. Its wide estuary constitutes a protected habitat of reed beds and dunes home to significant biodiversity. Sedentary, migratory, aquatic, or marine birds such as the Eurasian Curlew, the Oystercatcher, and the Great Cormorant thrive among the sea buckthorns, the Muscari, or the Salicornia.