Most of the 4 million New Zealanders are of British origin. About 15% claim descent from the indigenous Maori population, which is of Polynesian origin. Nearly 75% of the people, including a large majority of Maori, live on the North Island. In addition, 231,800 Pacific Islanders live in New Zealand. During the late 1870s, natural increase permanently replaced immigration as the chief contributor to population growth and has accounted for more than 75% of population growth in the 20th century. Nearly 85% of New Zealand's population lives in urban areas (with almost one-third in Auckland alone), where the service and manufacturing industries are growing rapidly. New Zealanders colloquially refer to themselves as "Kiwis," after the country's native bird.