The park is located in Kajiado County, Kenya. The park is 39,206 hectares (392 km²; 151 square miles) in size at the core of an 8,000 km² (3,100 square mlesi) ecosystem that spreads across the Kenya-Tanzania border. The local people are mainly Maasai, but people from other parts of the country have settled there attracted by the successful tourist-driven economy and intensive agriculture along the system of swamps that makes this low-rainfall area, average 350 mm (14 in), one of the best wildlife-viewing experiences in the world with over 400 species of birds including water birds like pelicans, kingfishers, crakes, hamerkop and 47 raptor species. The park protects two of the five main swamps, and includes a dried-up Pleistocene lake and semiarid vegetation.