Unique among natural heritage sites world-wide is the Sagarmatha National Park, which includes Mt. Everest (8,848 m) and other high peaks such as Lhotse Shar, Cho Oyu, Ama Dablam, Pumori, Kangtega, Gyachung Kang, Thamserku and Kwangde. Located North-east of Kathmandu, Sagarmatha National Park is 1,148 sq km. in area and consists of the upper catchment areas of the Dudh Koshi, Bhote Koshi and the Imja Khola rivers. Much of the park lies above 3,000m. Sagarmatha is rugged, with deep gorges, glaciers and unnegotiable ice and rock faces. Locally known as the 'Khumbu', it is the home of the famous Sherpa people. The Sherpas make a living by farming barley and potatoes and graze their yaks in high altitude pastures. Young Sherpas have also made their name in mountaineering and the trekking industry has of late become the community's economic mainstay. In 1979 the park was declared a World Heritage Site. Trees such as rhododendron, birch, blue pine, juniper and silver fir are found up to an altitude of 4,000 meters above which they give way to scrub and alpine plants. In late spring and summer, the hillsides around the villages of Namche Bazaar, Khumjung, Thyangboche and Thame are a riot of colours with several species of rhododendon in bloom. Wildlife most likely to be seen in Sagarmatha are the Himalaya tahr, ghoral, musk deer, pikka (mouse hare) weasel and occasionally jackal. Other rarely seen animals are Himalayan black bear, wolf, lynx and snow leopard. Birds commonly seen are Impeyan pheasant, blood pheasant, snow cock, snow pigeon, red billed and yellow billed chough, Himalayan griffin vulture and lammergeier.