The area includes the most ornithologically interesting parts of the Calestienne and Famenne, along the River Meuse. A large variety of habitats are present including calcareous dry grasslands and woodlands.
Species listed on Annex I of the EC Birds Directive occurring on passage or in winter include Milvus migrans, Circus cyaneus, Falco peregrinus, F. columbarius, Pandion haliaetus and Pluvialis apricaria.
National Low International High1,419 ha of IBA covered by Nature Reserve (Nature Reserves of lesse et Lomme, 1,419 ha). 22,426 ha of IBA covered by Special Protection Area (Lesse et Lomme, 22,426 ha).